414: Love Darts in the Backyard

Love Darts in the Backyard:

Koene and Schulenberg found that love darts are indeed part of a grand sexual arms race. Love darts have evolved many times, initially as simple cones but then turning into elaborate harpoons in some lineages. In the same species in which these ornate weapons have evolved, snails have also evolved more powerful tactics for delivering their sperm, including increasingly complex glands where the darts and hormones are produced. These aggressive tactics have evolved, it seems, in response to the evolution of female choice. Species with elaborate love darts also have spermatophore-receving organs that have long, maze-like tunnels through which the sperm have to travel. By forcing sperm to travel further, the snails can cut down the increased survival of the sperm thanks to the dart-delivered hormones.

Evolutionary hypotheses tested, common descent, and neat biology. Nice pictures, too.

413: Introduced Predators Transform Subarctic Islands from Grassland to Tundra -- Croll et al. 307 (5717): 1959 -- Science

Introduced Predators Transform Subarctic Islands from Grassland to Tundra -- Croll et al. 307 (5717): 1959 -- Science:

Top predators often have powerful direct effects on prey populations, but whether these direct effects propagate to the base of terrestrial food webs is debated. There are few examples of trophic cascades strong enough to alter the abundance and composition of entire plant communities.

This is neat stuff, especially in light of item 411. These fragile ecosystems came together through a complex interaction of species, each adapting to the community and adapting the community along the way. Changing the community has huge consequences.

412: ECOLOGY/EVOLUTION: The Difference a Week Makes -- Sugden 307 (5717): 1843b -- Science

ECOLOGY/EVOLUTION: The Difference a Week Makes -- Sugden 307 (5717): 1843b -- Science:

Not all monarch populations migrate, and parasite prevalence is known to be lower in the migratory monarch populations. Butterflies from migratory populations inoculated with a protozoan parasite showed reductions in flight performance and endurance in experimental cages, probably because the parasite influenced metabolic processes associated with flight (there were no changes in wing morphology associated with the presence of the parasite). The authors estimate that the impairment would lengthen the migratory journey from 9 to 10 weeks. Under these conditions, parasitized butterflies would likely suffer a reduced chance of reaching their destination, thus accounting for the differences in parasite burden between migrant and nonmigrant monarchs.

An evolutionary hypothesis on the evolution of migration in monarchs.

411: Save a Lizard, Save a Plant -- Coombs 2005 (328): 3 -- sciencenow

Save a Lizard, Save a Plant -- Coombs 2005 (328): 3 -- sciencenow

A lizard eats a rare plant's fruit. The lizard goes extinct, and nothing can make the seeds germinate. Co-evolution.

410: Flexible fossil shows tyrannosaur's softer side - Preserved soft tissue could reveal inner workings of dinosaur bones.

news @ nature.com - Flexible fossil shows tyrannosaur's softer side - Preserved soft tissue could reveal inner workings of dinosaur bones.:

A thigh bone from a 70-million-year-old Tyrannosaurus rex has given fossil experts an unexpected treasure: well-preserved soft tissue. The stretchy material, which may contain the remnants of blood vessels and cells, could shed light on how dinosaurs' bodies worked.

This could help us understand dinosaurs and the evolution of life, especially birds.

409: Mice with wonky sperm offer clues to infertility in men | Science Blog

Mice with wonky sperm offer clues to infertility in men | Science Blog:

For 40 percent of the estimated six million American couples battling infertility, the problem lies with the man. But help may be on the way.

New research in mice by scientists at Rockefeller University and the Population Council sheds light on the causes behind male infertility. The findings, reported in the March issue of Developmental Cell, also include potential targets for developing a reversible male contraceptive.

Common descent, etc.

408: RNA-Dependent Cysteine Biosynthesis in Archaea -- Sauerwald et al. 307 (5717): 1969 -- Science

RNA-Dependent Cysteine Biosynthesis in Archaea -- Sauerwald et al. 307 (5717): 1969 -- Science

The evolution of a pathway for producing a form of RNA essential to protein synthesis. Most organisms have one pathway, but certain methanogenic Archaean bacteria lack that pathway. Common descent made people interested in the different pathways, and this research examines the evolution of a novel mechanism.

407: Glycan Foraging in Vivo by an Intestine-Adapted Bacterial Symbiont -- Sonnenburg et al. 307 (5717): 1955 -- Science

Glycan Foraging in Vivo by an Intestine-Adapted Bacterial Symbiont -- Sonnenburg et al. 307 (5717): 1955 -- Science:

Germ-free mice were maintained on polysaccharide-rich or simple-sugar diets and colonized for 10 days with an organism also found in human guts, Bacteroides thetaiotaomicron, followed by whole-genome transcriptional profiling of bacteria and mass spectrometry of cecal glycans. We found that these bacteria assembled on food particles and mucus, selectively induced outer-membrane polysaccharide-binding proteins and glycoside hydrolases, prioritized the consumption of liberated hexose sugars, and revealed a capacity to turn to host mucus glycans when polysaccharides were absent from the diet. This flexible foraging behavior should contribute to ecosystem stability and functional diversity.

How bacteria evolve in different guts, how guts adapt to bacteria. Evolution at work.

406: Genome-wide non-mendelian inheritance of extra-genomic information in Arabidopsis

Genome-wide non-mendelian inheritance of extra-genomic information in Arabidopsis

Here we show that Arabidopsis plants homozygous for recessive mutant alleles of the organ fusion gene HOTHEAD (HTH) can inherit allele-specific DNA sequence information that was not present in the chromosomal genome of their parents but was present in previous generations. This previously undescribed process is shown to occur at all DNA sequence polymorphisms examined and therefore seems to be a general mechanism for extra-genomic inheritance of DNA sequence information. We postulate that these genetic restoration events are the result of a template-directed process that makes use of an ancestral RNA-sequence cache.

This conclusion is not uniform, De Rerum Natura thinks there may be other, natural selection based, explanations. If the authors are right, it's a complex, extra-genetic inheritance mechanism, if DRN is right, it clarifies the power of selection. In either event, evolutionary theory advances.

405: Acne as contraception

My Blemished Past (washingtonpost.com):

It is too late for me -- my psyche is already pitted -- but let me congratulate the scientific team at Birmingham University in England, whose researches have led them to the thesis that acne may be a kind of evolutionary contraceptive. In mimicking the symptoms of illness, the scientists speculate, pimples might form a sexual no-go zone that prevents humans from reproducing before they are physically and psychologically ready for it.

Zits as a Darwinian cold shower: It is a theory that many teenagers will find immediately convincing.

I don't know the origin of this, but it's an interesting evolutionary hypothesis, if nothing else.

404: Yeast findings link processes in human heart disease, cancer

Yeast findings link processes in heart disease, cancer | Science Blog:

By studying a little-known yeast too primitive to get diseases, Johns Hopkins researchers have uncovered a surprising link between two processes at play in heart disease and cancer in people. In experiments with yeast known as S. pombe, the researchers discovered that a gene that helps the organism make cholesterol also helps it survive when oxygen is scarce. The finding, described in the March 25 issue of Cell, offers a new strategy for killing infectious yeast, but it also suggests that cells' efforts to make cholesterol and detect oxygen levels might be connected in people, too.

How's that for common descent? We find a link between two processes in yeast, and think that they might be linked in humans. That's common descent, and nothing but.

403: Palaeoanthropology: Looking for the ancestors

Palaeoanthropology: Looking for the ancestors:

Here, in a cave where generations of people have sought refuge, the team is trying to put controversy aside to concentrate on the next chapter of its research. The goal is to identify a transitional species — the hominins who later evolved into the hobbit's clan.

Evolutionary hypothesis being tested.

402: Casual Sex or Wedding Bells? -- Bohannon 2005 (323): 5 -- sciencenow

Casual Sex or Wedding Bells? -- Bohannon 2005 (323): 5 -- sciencenow:

Decades of research indicate that people tend to trust those with faces similar to their own and are even more likely to marry them. Evolutionary theory provides an explanation for the first tendency: we are wired to recognize and help our kin because they are likely to share our genes. But evolution should also protect us against the dangers of inbreeding by preventing us from hopping in the sack with close relatives.

To find out how these conflicting motivations play out, Lisa DeBruine, a psychologist at St. Andrews and Aberdeen Universities, Scotland, presented 144 college students with 36 pairs of computer-generated faces. The faces in each pair were of the same race and the opposite sex as the viewer, but one was manipulated to have facial features more similar to those of the viewer.

As in earlier studies, the students found faces more trust-worthy if they were like their own. When it came to the prospect of a one-night stand, students found facial similarity a turn-off, DeBruine reports online today in the Proceedings of the Royal Society B: Biological Sciences. She concludes that people are less sexually attracted to individuals who look like kin in order to avoid inbreeding.

Evolutionary hypothesis tested.

401: Widespread Parallel Evolution in Sticklebacks by Repeated Fixation of Ectodysplasin Alleles -- Colosimo et al. 307 (5717): 1928 -- Science

Widespread Parallel Evolution in Sticklebacks by Repeated Fixation of Ectodysplasin Alleles -- Colosimo et al. 307 (5717): 1928 -- Science:

Genetic evidence shows that sticklebacks repeatedly lost their armor as they entered freshwater. Evolutionary hypothesis tested.

This is very cool work and a neat system. We knew that the species had repeatedly invaded freshwater habitats, and we know that they repeatedly evolved similar body forms. What they did here was show what genetic changes were associated with some of that parallel evolution. These are natural evolutionary experiment. Evolution is repeatable.

398-400: The Dynamic Gut -- Pennisi 307 (5717): 1896 -- Science

The Dynamic Gut -- Pennisi 307 (5717): 1896 -- Science. Snakes, birds, frogs and mammals all have to deal with bouts of starvation followed by rapid feeding. Scientists are studying how their intestines have evolved to handle those changes efficiently.

397: What's Eating You? -- Pennisi 307 (5717): 1897 -- Science

What's Eating You? -- Pennisi 307 (5717): 1897 -- Science. Tadpoles have to trade-off between tail size (speed) and gut size (food absorbtion) based on levels of predation. Chemicals produced by predators induce tail growth, higher food competition induces gut growth. This is an evolved response which allows adaptation to changing environments.

396: Independent recruitment of a conserved developmental mechanism during leaf evolution

Independent recruitment of a conserved developmental mechanism during leaf evolution. Though leaves evolved twice, the developmental regulation is shared by both clades. An evolutionary hypothesis tested, and new hypotheses proposed.

395: Evidence that sensory traps can evolve into honest signals

Evidence that sensory traps can evolve into honest signals. Evolution of sexual signalling. An evolutionary hypothesis tested.

394: Affinities of "hyopsodontids" to elephant shrews and a Holarctic origin of Afrotheria

Affinities of "hyopsodontids" to elephant shrews and a Holarctic origin of Afrotheria. The Afrotheria are a clade of mammals which molecular phylogenies indicate are basal to the placental mammals. A fossil from North America indicates that the clade is not monophyletic. New evolutionary hypotheses will have to be formed and tested as new data come in. Very interesting.

393: Two episodes of microbial change coupled with Permo/Triassic faunal mass extinction

Two episodes of microbial change coupled with Permo/Triassic faunal mass extinction. Chemical markers indicate two periods of bacteria faunal change through a mass extinction. Understanding the history of life, and the evolutionary processes behind it.

392: Encoding social signals in the mouse main olfactory bulb

Encoding social signals in the mouse main olfactory bulb. How do mice use smell as to grease the social wheels? Specific cells respond to specific compounds, distinguishing signals from males. Females respond to artificial doses of that compound, indicating a role in sexual isolation, and the speciation of mice.

390: Full-genome RNAi profiling of early embryogenesis in Caenorhabditis elegans

Full-genome RNAi profiling of early embryogenesis in Caenorhabditis elegans. Nature reports a full list of the genes active in the first 2 rounds of cell divisions in the nematode C. elegans. We care because of common descent.

391: Biodiversity: Gut feeling for yeasts

Biodiversity: Gut feeling for yeasts. A survey of beetle guts reveals 200 new species of yeast. Understanding the evolution of the beetles helps explain the diversity of yeasts.

389: No Organ Left Behind: Tales of Gut Development and Evolution -- Stainier 307 (5717): 1902 -- Science

No Organ Left Behind: Tales of Gut Development and Evolution -- Stainier 307 (5717): 1902 -- Science. The evolution of the gut's development tells us about the origins of diseases, and it tells us how humans fit into the grand tree of life with fish, flies and worms.

388: Host-Bacterial Mutualism in the Human Intestine -- Bäckhed et al. 307 (5717): 1915 -- Science

Host-Bacterial Mutualism in the Human Intestine -- Bäckhed et al. 307 (5717): 1915 -- Science:

New studies are revealing how the gut microbiota has coevolved with us and how it manipulates and complements our biology in ways that are mutually beneficial. We are also starting to understand how certain keystone members of the microbiota operate to maintain the stability and functional adaptability of this microbial organ.

A review of the state of knowledge on the evolution of the human gut ecosystem. Lots of diseases to cure there, and evolution is at the core of it all.

387: Elephants do impressions - Mimicry of trucks and zoo-mates shows range of vocal repertoire

news @ nature.com - Elephants do impressions - Mimicry of trucks and zoo-mates shows range of vocal repertoire.:

Researchers have recorded two African elephants (Loxodonta africana) that are adept mimics. One does a decent impression of an Asian elephant, and another is, remarkably, a dead ringer for a passing truck. The skilful impressions are far from the traditional grunts of an average African elephant. …

Tyack suspects that elephants' versatile vocal skills may help them recognize each other and therefore bond social groups together. He adds that other skilful vocalists, such as bats and dolphins, use sound for a range of social tasks including hunting and navigating

Most animals can't mimic. Mimicry is an evolutionary adaptation to sociality. Understanding the evolution of mimicry in elephant may teach us about the evolution of language in humans.

386: PALEONTOLOGY: Ready for Their Close-Up -- Sues 307 (5717): 1878 -- Science

PALEONTOLOGY: Ready for Their Close-Up -- Sues 307 (5717): 1878 -- Science. A review of a book on the evolution of mammals. Lots of transitional fossils, macroevolution, etc.

385: CELL BIOLOGY: Whither Model Organism Research? -- Fields and Johnston 307 (5717): 1885 -- Science

CELL BIOLOGY: Whither Model Organism Research? -- Fields and Johnston 307 (5717): 1885 -- Science.

A review of the status of research on model organism (like Drosophila and E. coli). What's next? Evolutionary connections, they say.

384: Stealthy Bipedal Octopuses -- Miller 2005 (324)

Stealthy Bipedal Octopuses -- Miller 2005 (324): 3 -- sciencenow:

That's why the behavior of [Octopus] aculeatus is so fascinating, says Christine Huffard, a graduate student at the University of California, Berkeley, who led the new study. The octopus can scurry along the seafloor on the tips of two arms--planting one "foot" before the other in a motion surprisingly reminiscent of human walking--while it keeps its other six arms extended in a fairly convincing algae imitation (see links below).

In the 25 March issue of Science, Huffard and colleagues also report that an Indonesian octopus, O. marginatus, performs a similar trick, walking on two arms with its other arms balled up beneath its body. The researchers interpret this behavior, perhaps somewhat imaginatively, as an impression of a rolling coconut. Both octopuses can move slightly faster in stealth mode than they can when crawling with several arms, another possible advantage, Huffard says.

Videos at Thoughts from Kansas. Camouflage is classic natural selection at work. These are co-evolved with aspects of their environment.

383: Chromosomal Evidence for Human Evolution

Cogito, Ergo Sum...Atheos: Chromosomal Evidence for Human Evolution. Chromosomal rearrangements demonstrate the shared ancestry of humans, chimpanzees and bonobos.

381-2: On the origin of life

evolgen: On the origin of life. Clay protects RNA molecules from breaking down, and also makes it easier to
reverse transcribe RNA. This bolsters the claim that clay was the substrate of early life.

Also, research on the evolutionary origins of the genetic code.

380: Smell

Love at first smell | Science Blog. The Major Histocompatibility Complex is part of the immune system, but in many species, it also serves to identify mate odors which indicate a suitable match. Since MHC is highly polymorphic, close relatives have similar MHC, while more distant relatives will be more different. MHC recognition minimizes inbreeding.

This research shows that MHC reacts with peptides in body odors from stickleback fish. The author says

Since sticklebacks use the same molecules to communicate information about their immune system as other vertebrates, this experiment can be assumed to be important for many animals, including humans.

Common descent, evolutionary hypotheses.

379: Rye not? Study may help farmers improve wheat | Science Blog

Rye not? Study may help farmers improve wheat | Science Blog:

J. Perry Gustafson, at the ARS Plant Genetics Research Unit in Columbia, Mo., and cooperators discovered the Alt3 gene in rye several years ago. Alt3 makes rye tolerant to aluminum, which is usually found just below the topsoil. But then the researchers had to physically map the rye gene, so it can be transferred into wheat by marker-assisted selection and breeding.

To do that, the group turned to rice, because it is genetically similar to rye and wheat. Among these cereals, there is a high degree of genetic similarity--what scientists call synteny. A complete DNA sequence and gene map of rice has already been established. Since many of the genes in rye and rice are in the same order, finding exactly where the aluminum-tolerance candidate gene is in the rice genome may help researchers find its location in rye.

Common descent feeds the hungry.

378: Type VII Collagen Is Required for Ras-Driven Human Epidermal Tumorigenesis -- Ortiz-Urda et al. 307 (5716): 1773 -- Science

Type VII Collagen Is Required for Ras-Driven Human Epidermal Tumorigenesis -- Ortiz-Urda et al. 307 (5716): 1773 -- Science:

Type VII collagen defects cause recessive dystrophic epidermolysis bullosa (RDEB), a blistering skin disorder often accompanied by epidermal cancers. To study the role of collagen VII in these cancers, we examined Ras-driven tumorigenesis in RDEB keratinocytes. Cells devoid of collagen VII did not form tumors in mice, whereas those retaining a specific collagen VII fragment (the amino-terminal noncollagenous domain NC1) were tumorigenic

Beating cancer thanks to common descent.

377: EVOLUTION: Fossil Horses--Evidence for Evolution -- MacFadden 307 (5716): 1728 -- Science

EVOLUTION: Fossil Horses--Evidence for Evolution -- MacFadden 307 (5716): 1728 -- Science:

Fossil horses have held the limelight as evidence for evolution for several reasons. First, the familiar modern Equus is a beloved icon that provides a model for understanding its extinct relatives. Second, horses are represented by a relatively continuous and widespread 55-My evolutionary sequence. And third, important fossils continue to be discovered and new techniques developed that advance our knowledge of the Family Equidae. The fossil horse sequence is likely to remain a popular example of a phylogenetic pattern resulting from the evolutionary process.

The article discusses some of the scientific history of the study of horse evolution, and presents a thorough review of the state of knowledge about the evolution of horses. More at Pharyngula.

What's interesting about horses is that they are a once diverse lineage now represented by a few species. That gives the impression of directionality to their evolution, a pattern not supported by the data or the theory.

In particular, while the story of horse evolution was once seen as a linear increase in size, it is now clear that there was a period of relative stasis in sizes, followed by a wide diversity of horse sizes. Extinctions eliminated much of that variation along the way, leaving the impression of direction instead of diversity.

376: The Molecular Requirements for Cytokinesis -- Glotzer 307 (5716): 1735 -- Science

The Molecular Requirements for Cytokinesis -- Glotzer 307 (5716): 1735 -- Science:

After anaphase onset, animal cells build an actomyosin contractile ring that constricts the plasma membrane to generate two daughter cells connected by a cytoplasmic bridge. The bridge is ultimately severed to complete cytokinesis. Myriad techniques have been used to identify proteins that participate in cytokinesis in vertebrates, insects, and nematodes. A conserved core of about 20 proteins are individually involved with cytokinesis in most animal cells. These components are found in the contractile ring, on the central spindle, within the RhoA pathway, and on vesicles that expand the membrane and sever the bridge. Cytokinesis involves additional proteins, but they, or their requirement in cytokinesis, are not conserved among animal cells.

Evolutionary conservation of a common core of proteins in all animals. Common descent would predict that fungi will share many of the same proteins.

375: Evolution of Oxygen Secretion in Fishes and the Emergence of a Complex Physiological System -- Berenbrink et al. 307 (5716): 1752 -- Science

Evolution of Oxygen Secretion in Fishes and the Emergence of a Complex Physiological System -- Berenbrink et al. 307 (5716): 1752 -- Science:

We have reconstructed the events that led to the evolution of a key physiological innovation underpinning the large adaptive radiation of fishes, namely their unique ability to secrete molecular oxygen (O2). We show that O2 secretion into the swimbladder evolved some 100 million years after another O2-secreting system in the eye. We unravel the likely sequence in which the functional components of both systems evolved. These components include ocular and swimbladder countercurrent exchangers, the Bohr and Root effects, the buffering power and surface histidine content of hemoglobins, and red blood cell Na+/H+ exchange activity. Our synthesis reveals the dynamics of gains and losses of these multiple traits over time, accounting for part of the huge diversity of form and function in living fishes.

Fascinating. Fish store oxygen in swim bladders to help them float and to have extra oxygen. These authors reconstruct the evolution of that ability across various biochemical and phsiological pathways.

Another one for the creationists to stew over. Information gain, new organs, the whole deal.

374: A Mitotic Septin Scaffold Required for Mammalian Chromosome Congression and Segregation -- Spiliotis et al. 307 (5716): 1781 -- Science

A Mitotic Septin Scaffold Required for Mammalian Chromosome Congression and Segregation -- Spiliotis et al. 307 (5716): 1781 -- Science:
Understanding how mammalian cells divide thanks to common descent.

373: Primate research: Die hard

Primate research: Die hard

An island population of monkeys has almost no genetic variation. Will the decimation of a hurricane cause extinction, or will inbreeding not be so detrimental there? The answers to those questions will rely on the monkey's evolution.

If the monkeys have undergone strong selection from this cause before, any harmful mutations will have been eliminated by natural selection. They might do OK.

If not, it's harder to say. Testable hypotheses from evolutionary biology.

372: Cancer biology: Sense out of missense

Cancer biology: Sense out of missense:

The gene encoding the p53 protein is mutated in more than 50% of human cancers, but quite how it is involved in tumour biology has eluded scientists for decades. Studies in Cell by Olive et al.1 and Lang et al.2, of genetically engineered p53 mutant proteins in mice, underscore the complexity of p53 cancer mechanisms, and provide a model for a human cancer-susceptibility syndrome.

It just goes back and forth. Human, mouse, human, mouse. All thanks to a common ancestor.

371: Biomechanics: Independent evolution of running in vampire bats

Biomechanics: Independent evolution of running in vampire bats:

Most tetrapods have retained terrestrial locomotion since it evolved in the Palaeozoic era1, 2, but bats have become so specialized for flight that they have almost lost the ability to manoeuvre on land at all3, 4. Vampire bats, which sneak up on their prey along the ground, are an important exception. Here we show that common vampire bats can also run by using a unique bounding gait, in which the forelimbs instead of the hindlimbs are recruited for force production as the wings are much more powerful than the legs. This ability to run seems to have evolved independently within the bat lineage. …

The absence of a running gait in all other bat species so far surveyed indicates that running may have been lost early in the evolution of bats, evolving afresh in the vampires at a later time.

Evolution of running. Science is just fascinating.

370: Systematic discovery of regulatory motifs in human promoters and 3[prime] UTRs by comparison of several mammals

Systematic discovery of regulatory motifs in human promoters and 3[prime] UTRs by comparison of several mammals:

Comprehensive identification of all functional elements encoded in the human genome is a fundamental need in biomedical research. Here, we present a comparative analysis of the human, mouse, rat and dog genomes to create a systematic catalogue of common regulatory motifs in promoters and 3' untranslated regions (3' UTRs). The promoter analysis yields 174 candidate motifs, including most previously known transcription-factor binding sites and 105 new motifs.

Important biomedical consequences of common descent? Right here. Human, mouse, rat, and dog share regulatory motifs because they share a common ancestor. Understanding them will make it easier to cure diseases and refine treatments.

369: Ancient co-speciation of simian foamy viruses and primates

Ancient co-speciation of simian foamy viruses and primates:

Here we test the co-speciation hypothesis in SFVs and their primate hosts by comparing the phylogenies of SFV polymerase and mitochondrial cytochrome oxidase subunit II from African and Asian monkeys and apes. The phylogenetic trees were remarkably congruent in both branching order and divergence times, strongly supporting co-speciation. Molecular clock calibrations revealed an extremely low rate of SFV evolution, 1.7 times 10-8 substitutions per site per year, making it the slowest-evolving RNA virus documented so far. These results indicate that SFVs might have co-speciated with Old World primates for at least 30 million years, making them the oldest known vertebrate RNA viruses.

This is a testable evolutionary hypothesis of the speciation in two different groups. Nothing else currently explains the congruence of the phylogenies of host and parasite.

368: Genetic relatedness predicts South African migrant workers' remittances to their families

Genetic relatedness predicts South African migrant workers' remittances to their families:

Data on remittances sent by South African migrant workers to their rural households of origin allow an explicit test, to our knowledge the first of its kind for humans. Using estimates of the fitness benefits and costs associated with the remittance, the genetic relatedness of the migrant to the beneficiaries of the transfer, and their age- and sex-specific reproductive values, we estimate the level of remittance that maximizes the migrant worker's inclusive fitness. This is a much better predictor of observed remittances than is average relatedness, even when we take account (by means of a multiple regression) of covarying influences on the level of remittance. But the effect is modest: less than a third of the observed level of remittances can be explained by our kin-altruism model.

We've discussed inclusive fitness and kin selection before. This is a test of kin selection in humans, and shows that evolutionary hypotheses can generate accurate predictions about humans, too.

367: Genetic effects on sperm design in the zebra finch

Genetic effects on sperm design in the zebra finch:

Sperm design and function are important determinants of male reproductive success and are expected to be under strong selection. The way that spermatozoa phenotypes evolve is poorly understood, because there have been few studies of the quantitative genetics of sperm. Here we show, in the zebra finch Taeniopygia guttata, an extraordinary degree of inter-male variation in sperm design that is independent of sperm swimming velocity. A quantitative genetics study using data from over 900 zebra finches in a complex breeding experiment showed that sperm head, mid-piece and flagellum length are heritable, that negative genetic correlations exist between sperm traits, and that significant indirect (maternal) genetic effects exist. Selection on the zebra finch sperm phenotype may be low because sperm competition is infrequent in this species, and this, in combination with negative genetic correlations and maternal genetic effects, may account for the variation in sperm phenotype between males. These results have important implications for the evolution of sperm in other taxa.

Common descent, evolutionary hypothesis testing, new predictions generated. Very neat.

366: Optimal eye movement strategies in visual search

Optimal eye movement strategies in visual search:

We find that humans achieve nearly optimal search performance, even though humans integrate information poorly across fixations. Analysis of the ideal searcher reveals that there is little benefit from perfect integration across fixations—much more important is efficient processing of information on each fixation. Apparently, evolution has exploited this fact to achieve efficient eye movement strategies with minimal neural resources devoted to memory.

Theoretical evolutionary models of efficient eye movement generate testable predictions.

365: Molecular determinants and guided evolution of species-specific RNA editing

Molecular determinants and guided evolution of species-specific RNA editing:

Here I report striking variation between species in the recoding of synaptotagmin I (sytI). Fruitflies, mosquitoes and butterflies possess shared and species-specific sytI editing sites, all within a single exon. Honeybees, beetles and roaches do not edit sytI. … Taken together, these data support a phylogeny of sytI gene editing spanning more than 250 million years of hexapod evolution. The results also provide models for the genesis of RNA editing sites through the stepwise addition of structural domains, or by short walks through sequence space from ancestral structures.

Common descent, and evolution generates new testable hypotheses. Very cool.

363: CELL BIOLOGY: Division of Labor -- Hurtley 307 (5716): 1693d -- Science

CELL BIOLOGY: Division of Labor -- Hurtley 307 (5716): 1693d -- Science:

Eukaryotic cells contain a dynamic array of cytoskeletal elements--microtubules--that organize key events in the cell's life cycle, including cell division. The regulation of microtubule polymerization and depolymerization, processes that both occur at the so-called plus ends of microtubules, must therefore be carefully controlled. Mennella et al.looked at the role of two kinesins (KLPs) and how they cooperate to control appropriate microtubule dynamics

All eukaryotes have a common ancestor (eukaryotes have cells with nuclei and organelles). They also share this mode of controlling microtubules.

364: The first cleavage of the mouse zygote predicts the blastocyst axis

The first cleavage of the mouse zygote predicts the blastocyst axis:

One of the unanswered questions in mammalian development is how the embryonic–abembryonic axis of the blastocyst is first established. It is possible that the first cleavage division contributes to this process, because in most mouse embryos the progeny of one two-cell blastomere primarily populate the embryonic part of the blastocyst and the progeny of its sister populate the abembryonic part.

By looking at a mouse, we generate a testable hypothesis about all mammals, and maybe all deuterostomes: They should all work the same way. This research matters because of common descent.

362: HIV

Evolution at Work (and creationism nowhere in sight): Corante > The Loom >:

So here we have evolutionary trees and natural selection at the very core of a vitally important area of medical research. Yet we are told again and again by op-ed columnists and certain members of boards of education that evolution is nothing but an evil religion and that creationism of one flavor or another is the future of science. You'd expect then that Intelligent Design or some other form of creationism would help reveal something new about this HIV. But it has not. That should count for something.

In a case we've covered before, the first full phylogenetic analysis of the virulent HIV strain from New York reveals a roadmap to future research. Evolutionary hypotheses provide testable hypotheses.

361: Evolutionarily conserved pathways in yeast and mammals

Thanks to the dubious biologist we learn that Mammals feed off yeast pathway:

The biochemical pathway that senses amino acid deficiencies in yeast is also at work in mammals, researchers report in this week's Science. While this signaling initiates amino acid synthesis in yeast, it alters eating behavior in rats, according to senior author Dorothy Gietzen of the University of California, Davis.

Common descent. Too cool.

360: New Fairy Shrimp Species

New Fairy Shrimp Species Found in Idaho (washingtonpost.com):

Dana Quinney and a colleague, Jay Weaver, first noticed the carnivorous shrimp in 1996. It took them nearly 9 years to compare the animal to the existing species and realize they had something entirely different.

"If you're just a little biologist like me, you're kind of a generalist," she said. "Many species of fairy shrimp look very much alike and it not only takes an expert but it takes an expert and a good microscope to tell them apart. This one is really, really, really different from all the other species in the world."

The new species has several spines on its front legs, and each spine is covered with several more, even smaller spines. The belly of the shrimp is covered with patches of Velcro-like spikes, enabling it to stick to and store up to four smaller fairy shrimp of different species - its prey. The new species also have a unique long, tapered and forked tail and the males have much longer antennas than other fairy shrimp.

It's no wonder that the animals were only recently discovered, Quinney said. They prefer to live in the opaque, brown pools known as playas that only occur during good water years.

Systematic research like this reveals new parts of the world that we never knew existed. The part quoted here shows the complexity, challenges and excitement of the research.

I spent a while working on the systematics of Philippine rodents, looking through a scope at their penises. Too some people, that would be a bad summer, but it drew me deeper into biology. I was amazed to see drawers and drawers of new species, jars full of alcohol preserved specimens of new species. They were piling up, waiting for someone with the time to catalog them and describe them.

We need more biologists to do that work. The generation of biologists who have presided over museum collections is approaching retirement, and there aren't being replaced. The knowledge they have isn't being preserved.

Anyone who enjoys this stuff should grab a chunk of it and get to work. The world is a complex and beautiful place, and systematists are at the leading edge of describing the stupendous diversity of the world.

You could do worse.

359: Immune system

Potential New Approach to Fighting Cancer | Science Blog:

In mice and humans, hematopoietic stem cells (HSC) form both red blood cells and immune system cells. In mice, Yang and Baltimore succeeded in altering some HSCs so that they would generate specific kinds of T cells that aggressively attack and destroy specific cancer cells. Once the mouse immune system received this enhancement, it became able to generate its own cancer-specific T cells on a long-term basis. When helped by dendritic cells (another type of immune system cell) carrying a piece of the tumor's marker protein, the methodology achieved the complete elimination of large, established tumors. While the work is preliminary and was done with mice, says Baltimore, instructive immunotherapy could eventually be used for controlling the growth of tumors in humans.

Why do they think it will work in humans, a priori? Common descent.

350-358: Altruism

New Scientist Charity begins at Homo sapiens - Features:

These findings suggest that true altruism, far from being a maladaptation, may be the key to our species' success by providing the social glue that allowed our ancestors to form strong, resilient groups. It is still crucial for social cohesion in today's very different world. "Something like it had to evolve," Gintis says.

Evolutionary biology teaches us about how human society developed. There are still questions to answer, and debates that they discuss.

349: Human X Chromosome

Human X Chromosome Coded (washingtonpost.com):

With the X's complete code in hand, Ross and his colleagues were able to make detailed comparisons with the corresponding chromosomes of other animals, including chickens, fish and rats. The similarities and differences confirmed previous hints about how the X and Y -- and with them, sex as we know it -- arose.

It happened about 300 million years ago, long before the first mammals. A conventional chromosome in a forebear of humans -- probably a reptile of some sort -- apparently underwent a mutation that allowed it to direct the development of sperm-producing testes.

Common descent, evolutionary hypotheses tested, and new evolutionary predictions to test. Also, important data on the evolution of sex. Cool.

348: National Medals of Science

Eight Receive President's National Medal of Science | Science Blog:

Receiving the 2003 National Medals of Science were:

R. Duncan Luce, the Distinguished Research Professor of Cognitive Science at the University of California, Irvine, awarded the medal in behavioral and social sciences, has been world-renowned as a theoretical mathematician of behavior of the past 50 years. … Luce’s early work in demonstrating the laws governing behavior in humans and his development of measurement theory helped shape research in psychology, cognitive neuroscience, and sociology for more than three decades. It formed part of the theoretical base on which computer modeling of behavior was developed.

Three medals were bestowed on researchers in the biological sciences.

J. Michael Bishop, Chancellor and University Professor at the University of California, San Francisco, has been a leading contributor to cancer research for the past 30 years. He shared the Nobel Prize in 1989 with Harold E. Varmus for demonstrating that normal cells contain genes capable of becoming cancer-causing genes, a revolutionary finding that inaugurated a new era of research on the genetic origins of cancer. Bishop’s subsequent analysis of genetic changes in human cancers also influenced scientists worldwide. …

Also in the biological sciences, Solomon H. Snyder, the Distinguished Service Professor of Neuroscience, Pharmacology and Psychiatry at Johns Hopkins University School of Medicine, was acknowledged for discoveries that form the basis of most modern neurobiology. He transformed scientists’ understanding of neurotransmitters and their receptors in the nervous system. He pioneered the labeling of receptors and extended the technique by which numerous other neurotransmitter receptors in the brain are identified. His techniques became universally applied to the rational design of new drugs for psychiatric disorders and other conditions. …

Meanwhile, Charles Yanofsky, the Morris Herzstein Professor of Biology at Stanford University was honored for discovering an essential element in the genetic code – the linear relationship between the structures of genes and their protein products – the one gene-one protein relationship. This was an important foundation to his subsequent experiments on the regulation of gene expression. His work has revealed how controlled alterations in RNA structure allow RNA to serve as a regulatory molecule in both bacterial and animal cells. …

In engineering, John M. Prausnitz, a professor of chemical engineering at the University of California, Berkeley, received the medal for a career reputation as one of the main architects of chemical manufacturing processes in the United States. …

Carl R. de Boor, Professor Emeritus, University of Wisconsin, Madison, received the Medal of Science in mathematics. …

In the physical sciences, G. Brent Dalrymple, Dean and Professor Emeritus, at Oregon State University, was honored for his work that improved the measurement of geologic time to new levels of precision, accuracy and application in the research of Earth’s past climates, as well as biological histories and major tectonic processes. He spent most of his career applying careful measurements to acquire the ages of rocks and minerals to verify and determine the timing and sequence of significant events in the history of the Earth and solar system. His methods were applied to dating the Lunar rocks that were returned from the Apollo 17 landing, for example.

Dalrymple was a leader in the plate-tectonic revolution, building and operating the Menlo Park Laboratory for precise dating of Earth’s magnetic-field reversals. …

Riccardo Giacconi, Research Professor at The Johns Hopkins University’s Department of Physics & Astronomy … won the 2002 Nobel Prize in physics for laying the foundations of cosmic X-ray astronomy.

So, of the 8, I count 5 whose research is grounded in evolution or generates specific evolutionary hypotheses. Models of behavior which rely on game theory are fundamentally evolutionary. We've discussed evolution in cancer within the human body. Understanding neurotransmitters in mice tells us about human brains because of common descent. Understanding the genetic code is applicable to all of life for the same reason. Did you see that about bacterial and animal cells? Common descent, too.

The kicker is the guy dating ancient rocks and fossils.

That's pretty impressive for a theory that's supposed to be in crisis.

347: Alcohol

Boozer genes identified | Science Blog:

How much alcohol we drink could be influenced by our genes, scientists reveal in a new study. Researchers from the Department of Experimental Psychology at the University of Bristol, in collaboration with colleagues from the University of Oxford, found that the amount of beer, wine and other alcoholic drinks that people regularly consume, and possibly an individual’s susceptibility to addiction, may be related to differences in genetic make-up.

In honor of St. Patrick's Day, The History Channel was talking about alcohol all evening. Turns out there was a long period of European history when alcohol, served straight or in water, was a major part of people's diets, since it killed bacteria. This project doesn't test it, but it suggests evolutionary hypotheses.

346: Evolution of hemichordates

Pharyngula::Torquarator bullocki:

Years ago, there was a hypothesis to link the two. Their common ancestor was a wormlike crawler with tentacles called the Lophenteropneusta, and there were suspected representatives of this 'missing link' photographed on the deep sea floor. The worms crawl on the surface of the mud, slurping it in one end and excreting it out the other, leaving behind looping trails of tubelike fecal material. These abyssal worms were thought to have tentacles, but the results of a new paper in Nature show that this is not the case, which means that these worms are 'just' enteropneusts, and the morphology of the common ancestor of the two hemichordate classes is once again wide open. That's not so terrible, though; what's interesting are these fascinating new enteropneust species that Holland et al. have found.

Testing and revising evolutionary hypotheses of the evolution of hemichordates.

345: Who's at risk during stopovers - the heavy or light bird?

The Biology Refugia: Who's at risk during stopovers - the heavy or light bird?:

It seems that the risk of being heavy due to fuel loads with respect to reduced escape performance is overestimated. The higher exposure of light birds due to more intense foraging and displacement to suboptimal habitats is probably of higher biological significance by offering conspicuous prey for predators.

The lower risk of heavy birds when prey of different body condition is available for predators has implications for modelling optimal migration behaviour, and predation risk is perhaps not an important factor for migrants when deciding on site use.

Evolved strategies, testable evolutionary hypotheses.

344: State-dependent impulsive models of integrated pest management (IPM) strategies and their dynamic consequences

State-dependent impulsive models of integrated pest management (IPM) strategies and their dynamic consequences. One goal of IPM is to minimize natural selection, and therefore pesticide resistance. Evolutionary biology makes food cheaper.

343: Why rats can't vomit

An interesting discussion of Why rats can't vomit. The final examination of the evolution of vomiting is of particular interest.

342: Evolution of Races

The New York Times > Opinion > Op-Ed Contributor: A Family Tree in Every Gene:

Last fall, the prestigious journal Nature Genetics devoted a large supplement to the question of whether human races exist and, if so, what they mean. The journal did this in part because various American health agencies are making race an important part of their policies to best protect the public - often over the protests of scientists. In the supplement, some two dozen geneticists offered their views. Beneath the jargon, cautious phrases and academic courtesies, one thing was clear: the consensus about social constructs was unraveling. Some even argued that, looked at the right way, genetic data show that races clearly do exist.

Descent with modification. Evolutionary hypotheses tested.

341: Adaptive Coding of Reward Value by Dopamine Neurons -- Tobler et al. 307 (5715): 1642

Adaptive Coding of Reward Value by Dopamine Neurons -- Tobler et al. 307 (5715): 1642 -- Science:

It is important for animals to estimate the value of rewards as accurately as possible. Because the number of potential reward values is very large, it is necessary that the brain's limited resources be allocated so as to discriminate better among more likely reward outcomes at the expense of less likely outcomes. We found that midbrain dopamine neurons rapidly adapted to the information provided by reward-predicting stimuli. Responses shifted relative to the expected reward value, and the gain adjusted to the variance of reward value. In this way, dopamine neurons maintained their reward sensitivity over a large range of reward values.

Evolutionary hypothesis tested.

340: Insect Sex-Pheromone Signals Mediated by Specific Combinations of Olfactory Receptors -- Nakagawa et al. 307 (5715): 1638

Insect Sex-Pheromone Signals Mediated by Specific Combinations of Olfactory Receptors -- Nakagawa et al. 307 (5715): 1638 -- Science:

We describe two male-specific olfactory receptors (ORs) in the silk moth, Bombyx mori, that are mutually exclusively expressed in a pair of adjacent pheromone-sensitive neurons of male antennae: One is specifically tuned to bombykol, the sex pheromone, and the other to bombykal, its oxidized form. Both pheromone ORs are coexpressed with an OR from the highly conserved insect OR subfamily. This coexpression promotes the functional expression of pheromone receptors and confers ligand-stimulated nonselective cation channel activity. The same effects were also observed for general ORs. Both odorant and pheromone signaling pathways are mediated by means of a common mechanism in insects.

The evolution of a sex-pheromone system common to many insects. Common descent and the raw material for speciation through sexual isolation.

339: A Transmembrane Intracellular Estrogen Receptor Mediates Rapid Cell Signaling -- Revankar et al. 307 (5715): 1625

A Transmembrane Intracellular Estrogen Receptor Mediates Rapid Cell Signaling -- Revankar et al. 307 (5715): 1625 -- Science:

Estrogen (17ß-estradiol, E2) represents one of a family of steroid hormones that act through soluble intracellular receptors. Once activated, these receptors translocate to the nucleus, where they function as ligand-dependent transcription factors (1, 2). This mode of action of two such estrogen-binding receptors, ER{alpha} and ERß, is reasonably well understood (3, 4). However, the existence of functional ERs associated with the plasma membrane has been debated (5). It has been suggested that such membrane receptors mediate the rapid nongenomic signaling events widely observed following stimulation of cells and tissues with estrogen, including the generation of the second messengers Ca2+ and nitric oxide as well as the activation of receptor tyrosine kinase and protein-lipid kinase pathways (1, 6–9). The cellular consequences can include adhesion, migration, survival, proliferation, and cancer. Novel receptors and novel forms of ER have been postulated to mediate many of these signal transduction events (8).

Estrogen is more than just a sex hormone. It has evolved to serve many purposes, and occurs widely in animals.

338: High-Throughput Mapping of a Dynamic Signaling Network in Mammalian Cells -- Barrios-Rodiles et al. 307 (5715): 1621

High-Throughput Mapping of a Dynamic Signaling Network in Mammalian Cells -- Barrios-Rodiles et al. 307 (5715): 1621 -- Science. Cell signalling in yeast, flies, roundworms, and humans. Common descent.

337: Worldwide Phylogeography of Wild Boar Reveals Multiple Centers of Pig Domestication -- Larson et al. 307 (5715): 1618

Worldwide Phylogeography of Wild Boar Reveals Multiple Centers of Pig Domestication -- Larson et al. 307 (5715): 1618 -- Science:

Mitochondrial DNA (mtDNA) sequences from 686 wild and domestic pig specimens place the origin of wild boar in island Southeast Asia (ISEA), where they dispersed across Eurasia. Previous morphological and genetic evidence suggested pig domestication took place in a limited number of locations (principally the Near East and Far East). In contrast, new genetic data reveal multiple centers of domestication across Eurasia and that European, rather than Near Eastern, wild boar are the principal source of modern European domestic pigs.

The evolution of domestic and wild pigs. It may also clarify how different human populations have evolved to handle different diets.

336: Isolation of an Algal Morphogenesis Inducer from a Marine Bacterium -- Matsuo et al. 307 (5715): 1598

Isolation of an Algal Morphogenesis Inducer from a Marine Bacterium -- Matsuo et al. 307 (5715): 1598 -- Science:

Ulva and Enteromorpha are cosmopolitan and familiar marine algal genera. It is well known that these green macroalgae lose their natural morphology during short-term cultivation under aseptic conditions and during long-term cultivation in nutrient-added seawater and adopt an unusual form instead. These phenomena led to the belief that undefined morphogenetic factors that were indispensable to the foliaceous morphology of macroalgae exist throughout the oceans. We characterize a causative factor, named thallusin, isolated from an epiphytic marine bacterium. Thallusin induces normal germination and morphogenesis of green macroalgae.

Co-evolution between algae and bacteria. This may help explain the origin of multicellularity in plants.

330-335: Ancient Mars: Wet in Many Places -- Paige 307 (5715): 1575

Ancient Mars: Wet in Many Places -- Paige 307 (5715): 1575 -- Science:

New results from the Mars Express Orbiter mission reveal multiple deposits of minerals formed in the presence of liquid water. They reinforce the conclusion that ancient Mars was warmer and wetter than it is today, and increase the number of promising localities to search for evidence of past life.

How do we know what to look for on Mars? Evolutionary biology on earth.

329: CELL BIOLOGY: Does Notch Take the Sweet Road to Success? -- Lowe 307 (5715): 1570

CELL BIOLOGY: Does Notch Take the Sweet Road to Success? -- Lowe 307 (5715): 1570 -- Science:

Given that Notch is crucial for animal development, it is not surprising that elaborate mechanisms have evolved to control expression of the Notch gene. … Okajima et al. unveil a new mechanism for controlling Notch expression, which depends on regulating the amount of Notch at the cell surface.

An evolutionarily conserved signalling pathway in animals. Common descent, stabilizing selection.

328: BZR1 Is a Transcriptional Repressor with Dual Roles in Brassinosteroid Homeostasis and Growth Responses -- He et al. 307 (5715): 1634

BZR1 Is a Transcriptional Repressor with Dual Roles in Brassinosteroid Homeostasis and Growth Responses -- He et al. 307 (5715): 1634 -- Science. Understanding how plant hormones work on one species explains the development of many plants, even though the details of the plants' responses vary by species.

327: ALZHEIMER'S DISEASE: Play and Exercise Protect Mouse Brain From Amyloid Buildup -- Marx 307 (5715): 1547

ALZHEIMER'S DISEASE: Play and Exercise Protect Mouse Brain From Amyloid Buildup -- Marx 307 (5715): 1547 -- Science:

As the population ages, finding ways to stave off the debilitating brain degeneration of Alzheimer's disease becomes ever more critical. New results with a mouse model of the condition now provide further support for the idea that "use it or lose it" applies as much to the mind as to the body.

Mice? Human? A cure for Alzheimer's? Common descent at work.

326: STKE: Checkpoint Control at the Golgi -- Chong 307 (5715): 1537b

STKE: Checkpoint Control at the Golgi -- Chong 307 (5715): 1537b -- Science. Like many projects in cellular biology, this summary makes no reference to the species studied, because common descent of all life suggests that it's going to work the same way in most eukaryotes.

325: ECOLOGY/EVOLUTION: Sons and Daughters -- Sugden 307 (5715): 1535a

ECOLOGY/EVOLUTION: Sons and Daughters -- Sugden 307 (5715): 1535a -- Science. Biases in the male/female ratio in springbok vary according to local conditions. This is predicted by evolutionary theory, and understanding the evolutionary mechanism behind it is an ongoing research project.

324: The Long March of Human Genes -- Pasotti 2005 (309): 4

The Long March of Human Genes -- Pasotti 2005 (309): 4 -- sciencenow:

In the new study, geneticist François Balloux and colleagues at the University of Cambridge show that geographic distance from Ethiopia (the place where the oldest human remains have been found) correlates with the genetic diversity of 51 present human populations distributed worldwide. The research gives support to the theory that, as humans left Africa, some versions of their genes became progressively lost over the migration routes. Thus, populations farther from Ethiopia are characterized by lower genetic variability.

The evolution of humans over the last 100,000 years.

323: The causes of HIV resistance in Europe

news @ nature.com - Did Black Death boost HIV immunity in Europe? - Experts argue over whether smallpox or plague should take the credit.:

Devastating epidemics that swept Europe during the Middle Ages seem to have had an unexpected benefit - leaving 10% of today's Europeans resistant to HIV infection.

But epidemics of which disease? Researchers claimed this week that plague helped boost our immunity to HIV, but rival teams are arguing that the credit should go to smallpox.

A mutation found in 10% of Europeans is responsible for the HIV resistance. The scientists are arguing over whether smallpox or plague exerted the selective pressure (evolution!) that made this mutation common.

If it was plague, that suggests that it wasn't caused by the bacterium usually blamed for the plague, but a different virus. Evolution offers new insights into our own past.

322: Palaeobiology: Dating earliest life

Palaeobiology: Dating earliest life:

To my regret, the ancient Greenland rocks have not yet produced any compelling evidence for the existence of life by 3.8 billion years ago. The reader is reminded that another debate on early life is currently in progress on 3.5-billion-year-old rocks in Western Australia, where chains of cell-like structures, long identified as genuine fossils, have recently been downgraded by some workers to the status of artefacts produced by entirely non-biological processes. To have a chance of success, it seems that the search for remnants of earliest life must be carried out on sedimentary rocks that are as old, unmetamorphosed, unmetasomatized and undeformed as possible. That remains easier said than done. For the time being, the many claims for life in the first 2.0–2.5 billion years of Earth's history are once again being vigorously debated: true consensus for life's existence seems to be reached only with the bacterial fossils of the 1.9-billion-year-old Gunflint Formation of Ontario.

Rocks thought to contain the earliest evidence of life may not. Other possible early evidence of life is still being examined. This is how science works. We gather evidence, generate hypotheses, test them, generate new hypotheses, and move forward. Evolutionary biology inspired this research, and all evidence indicates that life existed at least 2 billion years ago. Did it exist 4 billion years ago? Maybe, but we'll only find out with more research.

320: Flu New

Silflay Hraka: Flu New:

The H5N1 bird flu virus might be acquiring a greater ability to spread from human to human, recent cases in Vietnam suggest. But as two elderly relatives of patients killed by the bird flu test positive for the virus and yet have no symptoms, there are also indications that it may not be as lethal as currently thought.

The 2004 outbreak of H5N1 in Vietnam stopped in spring after the country killed millions of infected and exposed poultry. But outbreaks resumed in December, probably because the virus persisted in ducks showing no symptoms, say flu experts. Since December, 22 people have tested positive for H5N1 in Vietnam, of whom 14 have died, including one woman from Cambodia.

As Bigwig explains, as did Rachel some time back, viruses become less virulent because of evolution. The more deadly a virus, the less likely it is that the host will live long enough to pass it on. A non-virulent virus in a closed population will be more evolutionarily fit than a virulent virus. The opposite is true of viruses in transient populations. Then it's better for the virus to reproduce fast, kill its host, and spread to new hosts who will carry the virus to new populations.

Evolutionary hypothesis tested.

321: Crystal structure of a membrane-bound metalloenzyme that catalyses the biological oxidation of methane

Crystal structure of a membrane-bound metalloenzyme that catalyses the biological oxidation of methane. A crystal structure in one species is probably similar in other species. Common descent, research motivated by evolutionary biology.

319: Structural basis of HutP-mediated anti-termination and roles of the Mg2+ ion and L-histidine ligand

Structural basis of HutP-mediated anti-termination and roles of the Mg2+ ion and L-histidine ligand. We expect this structure to be the same across numerous species because of … common descent.

318: Cycles in fossil diversity

Don't read the excerpt if you don't want to.

Cycles in fossil diversity:

The 62-Myr cycle is strong. It might be a largely biological process or a variation in the integrity of the fossil record; however, in either case it is also worth considering geophysical processes that could be driving it. We consider seven possibilities. First, periodic passage of the solar system through molecular clouds, Galactic arms or some other structure could periodically perturb the Oort cloud and cause variations in the rate of comet impacts on the Earth24. It has been argued14 that a 140-Myr period between spiral arm crossings is consistent with existing astrophysical constraints, and that such passages can affect climate by varying the cosmic ray flux. Second, laboratory simulations of mantle plumes, under idealized conditions, show relaxation oscillator modes in which plumes reach the surface at regular intervals for six to nine cycles25. Similar behaviour in the Earth could cause periodic volcanism. Third, the Sun currently oscillates up and down across the Galactic plane every 52–74 Myr (ref. 26), but plausible responses24 would seem to occur every mid-plane crossing (namely 26–37 Myr). Moreover, the period is not constant, but decreases to half when we encounter higher-density Galactic arms. Fourth, solar cycles could affect climate, but solar theory27 predicts that long-period oscillations do not occur. Fifth, Earth orbital oscillations could affect climate. Using an orbital integration package28 and nine point-mass planets, we found no significant cycles with periods of 62 Myr or 140 Myr. Changes in obliquity were not included in our calculations. Sixth, one or more companion stars to the Sun could trigger periodic comet showers. However, a 62-Myr orbit is unstable to perturbations from passing stars. The interaction of two or more short-period companions could generate a longer periodicity (for example, through beats), but our simulations suggest that mutual perturbations would probably destroy any regularity. Last, 'Planet X' is a proposed large planet that perturbs the Kuiper belt and could yield periodic comet showers on the right time scales29. No evidence for it exists.

Although no explanation exists, the 62-Myr cycle is not a subtle signal. It is evident even in the raw data (Fig. 1a), dominant in the short-lived genera (Fig. 2) and strongly confirmed by statistical analysis. We do not know whether this cycle is a variation in true diversity or only in observed diversity, but either case requires explanation and implies that an unknown periodic process has been having a significant impact on Earth's environment throughout the Phanerozoic. Most models seem to make testable predictions, so we are hopeful that the cause of this behaviour will not remain a mystery for long.

The authors demonstrate a clear 62 million year cycle in fossil diversity. They don't understand it, but macroevolutionary theory, combined with astronomy and geology, generate a number of testable hypotheses. That's science. It's good science. It doesn't answer every question, but it moves our knowledge forward.

317: Anthropologists walk tall after unearthing hominid

Anthropologists walk tall after unearthing hominid:

The remains of a hominid that date back nearly 4 million years have been uncovered by a field team in Ethiopia.

The discovery, announced in Addis Ababa on 4 March, looks set to provide crucial new evidence on early man's ability to walk upright.

That is, the evolution of bipedalism.

316: Spatial bistability of Dpp-receptor interactions during Drosophila dorsal-ventral patterning

Spatial bistability of Dpp-receptor interactions during Drosophila dorsal-ventral patterning. The mechanism controlling the expression of certain genes which control dorsal-ventral patterning involves complicated (and pretty) feedback loops.

Scientists are interested in fly development because it informs us on all of insect development (insects are the most diverse Class of animals) and common descent of all life suggests that similar processes may operate in human development.

315: The immunoglobulin superfamily protein Izumo is required for sperm to fuse with eggs

The immunoglobulin superfamily protein Izumo is required for sperm to fuse with eggs. Mouse sperm, human genes, hamster eggs. Wrap it up in common descent, and you've got a protein that controls passage of the sperm through the egg membrane.

314: Integral role of IRF-5 in the gene induction programme activated by Toll-like receptors

Integral role of IRF-5 in the gene induction programme activated by Toll-like receptors. A study of the regulation of mouse genes which clarifies the human immune system. Common descent.

313: Roots Engage in Underground Chemical Warfare

Roots Engage in Underground Chemical Warfare | Science Blog:

In these experiments, however, root exudates did not kill all of the tested strains of bacteria. One particular strain of Pseudomonas syringae, a bacterium that causes disease in both tomatoes and Arabidopsis, has a seemingly fail-safe mechanism to overcome the plant's defenses. The bacterium not only survives exposure to the antimicrobial substances, it also blocks the plant's ability to produce them.

So plants evolve root antibiotics, then bacteria evolve a response. That's evolution.

312: The secret 'walnut defense'

The secret 'walnut defense' | Science Blog:

These laboratory experiments, led by ARS research chemist Russell J. Molyneux of the agency's Western Regional Research Center at Albany, showed that a popularly grown walnut known as Tulare was remarkably resistant to Aspergillus. Molyneux did the work with chemist Noreen E. Mahoney at the Albany laboratory and with University of California, Davis, collaborator Jim McKenna. Davis researchers Charles A. Leslie and Gale H. McGranahan also participated.

Tulare's secret defense? It's gallic acid, found only in the nutmeat's thin skin, or pellicle, according to Molyneux. Tulare walnuts contained one-and-one-half to two times more gallic acid than, for instance, Chico walnuts, the most Aspergillus-susceptible of the walnuts that the researchers tested.

Evolved defenses against a toxic fungus.

311: No Stone Age Unturned -- Coombs 2005 (308): 4 -- sciencenow

No Stone Age Unturned -- Coombs 2005 (308): 4 -- sciencenow:

Stoneking and his team compared Mlabri DNA with that from neighboring tribes. Astonishingly, all of the Mlabri mitochondrial DNA turned out to be identical--a total lack of variation that hasn't been found in any other human population. As hunter-gatherer societies are thought to have less genetic diversity, the lack of variation suggests that the Mlabri descended from a hunter-gatherer culture. However, unlike other hunter–gatherer groups, the Mlabri share genetic information with neighboring agricultural hill tribes as well as other agricultural groups in Southeast Asia.

…

The results, published this month in the journal Public Library of Science, Biology, demonstrate that "hunter-gatherers have changed and evolved, particularly in response to interactions with agricultural groups," says Stoneking.

Humans evolved as they transition from foraging, to agriculture, and back to hunter/gatherer. Evolutionary hypotheses tested.

310: Three major beetle groups come up one testicle short

Three major beetle groups come up one testicle short | Science Blog:

A surprisingly large number of beetles are missing one of their testes, the male gonads of insects. As far as the researchers who discovered this can tell, the insects are not in any way bothered or impaired by this absence.

That group of beetles shares a suite of characters, their missing testicle is their inheritance from a common ancestor.

309: Atherosclerosis Gene Found -- Avasthi 2005 (308): 2 -- sciencenow

Atherosclerosis Gene Found -- Avasthi 2005 (308): 2 -- sciencenow:

For the first time, scientists have identified a gene turned on by fatty food. Researchers say the gene, found in both mice and humans, conclusively links high-fat diets to heart disease.

Hmmm. Common descent? Yep.

308: Oldest fossil human protein ever sequenced

stranger fruit » Oldest fossil human protein ever sequenced:

An international team led by researchers at the Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology in Liepzig, Germany and Washington University in St. Louis, has extracted and sequenced protein from a Neanderthal from Shanidar Cave, Iraq dating to approximately 75,000 years old.

Understanding ancient fossils helps us understand human evolution.

307: Tailing the Cause of a Rare Heart Disease | Science Blog

Tailing the Cause of a Rare Heart Disease | Science Blog:

To confirm that the mutant EYA4 does indeed cause cardiomyopathy, the researchers turned to the zebrafish, whose genetic machinery for cardiovascular development closely resembles that of mammals.

Common descent curing disease.

306: Evolution of Cartilage

Pharyngula::Invertebrate cartilages:

The data on invertebrate cartilaginous endoskeletons presented here offer unique insights into the evolution of vertebrate skeletal tissues. The ability to form cellular connective tissues structurally similar to cartilage without type II collagen is a feature that appeared before the evolution of vertebrates, supporting the notion that cartilage is not simply an embryonic adaptation (as per Romer), but was present in vertebrates before calcification evolved.

Something like cartilage is ubiquitous in the Metazoa.

Tangled Bank

At Living the Scientific Life. It's enormous, but packed with scientific goodness. Enjoy.

305: Omega-3 fatty acids

news @ nature.com - Secret of fish oil's healthy effects revealed - Synthetic version could one day treat range of inflammatory diseases.:

Their work in human cells and in mice showed that omega-3 fatty acids in the fish oil are converted into lipids that seem to suppress inflammation. Aspirin speeds up that conversion.

The researchers have now pinned down the effect even further by focusing on one of the lipids, called resolvin E1. First they found that healthy human volunteers fed both aspirin and fish oil had resolvin E1 in their bloodstream. Then they created a synthetic form of the lipid and tested its properties.

The lipid inhibited the migration of particular human immune cells and dramatically reduced inflammation on the skin of rabbits. Serhan and his team believe that resolvin E1 works in the body to tone down inflammation, and report their results in The Journal of Experimental Medicine1.

Mice, rabbits and humans all respond similarly to a combination of aspirin and omega-3 fatty acids. Common descent, baby.

302-304: Darwin in the Crib

Carl Zimmer describes evolutionary insights into crying and colic. Crying is a signal babies send to get attention. Babies in agricultural societies cry less after weaning, because people stop responding after the babies are weaned. In hunter/gatherer societies, the babies cry more after weaning. The lesson:

If colic follows this pattern, it is not a cause for collective Western guilt that we don't live as foragers. Instead, it's a call to understand the evolutionary roots of the behavior of our children--both for their well-being and our own sanity.

301: Flies key to genetic research

Flies key to genetic research - The Honolulu Advertiser - Hawaii's Newspaper:

Hawaiian picture wings, sometimes called pomace flies, vinegar flies or drosophila, are believed to have evolved from a single-introduced fly. Some folks just call them fruit flies, but they are different from the introduced fruit flies that attack the state's oranges, papayas and other crops.

They have evolved to feed on specific plants in the Hawaiian environment, and have developed unique wing patterns and behaviors. They have also been used extensively in genetic research.

“Hawai'i's picture wings are marvels of nature. Few species have contributed so much to human understanding of genetics. Research on their immune systems may one day lead to a cure for AIDS, cancer, or the West Nile virus,” said Kieran Suckling, policy director of the Center for Biological Diversity.

The Fish and Wildlife Service has proposed that 12 species be listed as endangered, but the applications disappeared along the way.

Evolution, cures for diseases, common descent: the whole gamut.

Reflections on 300 examples

Chris Mooney asks "should scientists refer to the well-adapted features of a given organism as having been 'designed,' even though we all know these are the result of natural selection?" and cites
this article in The Scientist :: Journals and intelligent design:

Biologists often get angry about the publication of studies defending "intelligent design," the notion that biochemical systems could not have been produced by evolution because they are "irreducibly complex," and as such, must have been "designed" by an unknown entity. But a careful reading of some recent studies suggests that researchers haven't been shying away from using the word "design" in a way that can only be described as teleological.

Scientists shouldn't be afraid of writing to their audience, and metaphors are useful when the audience understands it. When scientists refer (in research discussed here) to insects being "designed to function at high levels of oxygen consumption," other scientists understand that to mean "evolved through a process of natural selection on existing variation." In the strictest sense, adaptation could be considered a metaphor, implying teleology and putting the cart before the horse, but that's life. It's convenient to talk about an adaption for a purpose, even if we don't mean it.

There are several goals the Evolution Project has served. By skimming the surface of evolutionary research, it offers some small pool of examples for people, like the Kansas Board of Education, to look at and see what research is going on using and improving evolutionary biology. Steps toward disease cures, better insecticides, and the search for other life in the universe are a few of the themes that come out of that.

Another objective is debunking creationist claims. If someone says, "Have evolutionary biologists ever demonstrated speciation?" you can search through the archives and find examples. Or you can find an example of information gain through evolution (or here). Not that these aren't also available through TalkOrigins, et al., but "let a thousand flowers bloom."

A third objective is to present a sense of the volume and nature of scientific research to the public. Most creationists and most scientifically literate members of the public have never looked inside Nature or Science, let alone the Journal of Mammalogy. The writing isn't for them, so that makes sense.

If scientists have lost the public, it's because we don't explain what we're doing well enough. No one takes the research from a weeks worth of journals and does a quick overview of research in a field, as represented by this week's Paleobiology. You'd never write a whole article in Science Times on "Pulsed origination and extinction in the marine realm," but paleontology isn't all about dinosaurs. Research like Michael Foote's, or the discussion of how to deal with poorly curated museum material, or an analysis of early Jurassic phytoplankton, are all better examples of modern paleontology.

A survey of Zootaxa shows that new species aren't that rare, it's just the charismatic megafauna. Scientists know that, but all that the public ever hears about is a new bird or mammal. In January and February, Zootaxa published 65 papers, describing new species and revising our evolutionary understanding of at least 65 groups. There's a bird paper or two, and some fossil bats, but most of that new diversity is in flies, beetles, moths, and roundworms. That's also not surprising to biologists, but I bet even physicists and quantum chemists would be taken aback by that.

Biology is in a fascinating place. One one hand, we have a grand, unified theory, something physics still lacks. On the other hand, the raw material of biology is stil being documented. We don't even know whether there are 5 million species in the world or 100 million. It's probably around 12 million, but we've only described 1.2 million. Particle physicists don't have a grand, unified theory, but they pretty much know what kinds of particles there are.

So at one end, biology is capable of very theoretical work, mathematical in its abstraction. On the other end, it's about running around fields with a net. The challenge to biologists, and scientists in general, is to present that diversity of styles to the public. How do you put an experiment on the number of eggs a bird lays into a context that the public will care about? At it's simplest level, this is an elegant and non-obvious hypothesis based on evolutionary biology, and it checks out. Does the public care about Darling's hypothesis, per se? Probably not. Do they care that evolutionary biology makes testable predictions? Yes. Farmers and pet bird owners might care about testable predictions evolution makes about bird reproduction. The public will be interested in the general reproductive aspects of this.

Every scientific paper should be summarized, by the author or a colleague, in a blog post. Many paper's abstracts had one sentence that was interesting to the public, or maybe parts of two sentences. The blog summary would use that sentence, explain why a scientist would care, and what it means to the public.

The public neither understands nor cares to understand the scientific context of a paper. So use metaphors that work for the community. But also present a clear, public statement of what this research means in simple terms. I've done that for 300 papers, and I'll keep going. Anyone who wants to help, send those summaries to me.

If you don't feel ready for that, remember, every book you buy through our Amazon links helps fund this project. Every ad you click at the top or side of the page gives whole pennies to the cause. If you see a paper you'd like summarized, send us a link.

Thanks for your support, and here's to the next 300.

"Superman" by R.E.M. from the album Lifes Rich Pageant (1986, 2:54).

300: "Methanothermal" systems on Titan?

Titan's Atmosphere Comes from Ammonia, Huygens Data Say | Science Blog:

Cassini radar spotted a crater the size of Iowa when it flew within 1,577 kilometers (980 miles) of Titan on Tuesday, Feb. 15. "It's exciting to see a remnant of an impact basin," said Lunine, who discussed more new radar results that NASA released at an AAAS news briefing today. "Big impact craters on Earth are nice places for getting hydrothermal systems. Maybe Titan has a kind of analogous 'methanothermal' system," he said.

Hydrothermal systems play an important role in theories of the origin of life. Could those "methanothermal" systems play the same role on Titan? We don't know yet.

299: Deep sea life

news @ nature.com - Deep-sea mission finds life in the Lost City - Chalky spires in the Atlantic depths play host to primitive archaea.:

The inside walls of these porous spires house a colony of archaea that have adapted to a diet of hydrogen and methane, which also rise from the vent beneath. "This is one of the significant findings of this study," says Stefan Sievert, a microbiologist at Woods Hole Oceanographic Institution in Massachusetts. "The whole system seems geared toward methane production or methane consumption," he says, which is "the kind of system that might have been present on the early Earth".

Archaea are the likely ancestors of multicellular life, and these live in conditions like those of early life. These scientists went to great lengths (and great depth) to understand evolution better.

298: Insecticides

Stealth Worms May Improve Insect Pest Control | Science Blog:

Known as entomopathogenic nematodes (EPN), the juvenile stage of these tiny worms travels with bacteria in its intestine that specifically kill certain insect species. Nematodes in the family Steinernematidae are associated with Xenorhabdus bacteria; those in the family Heterorhabditidae harbor Photorhabdus bacteria. Both types of EPN operate in similar ways.

Scientists work hard to make families monophyletic (all the descendants from a common ancestor). The similarities between the two families indicates common ancestry. Understanding how different members of the families evolved to kill specific insects will help scientists tailor insecticides to pest species without killing predatory insects and pollinators.

297: Neuroscientists Pinpoint New Function for Mirror Neurons

Neuroscientists Pinpoint New Function for Mirror Neurons | Science Blog:

[T]he UCLA team found that pre‑motor mirror neuron areas of the brain -- areas active during the execution and the observation of an action -- ascribe intentions to actions when presented within a context. Previously, these neurons were thought to be involved only in action recognition.

Understanding this may help treat numerous diseases. It makes sense that the brain structures that recognize actions expanded its function to ascribe intentions to actions. Evolution works by building on existing structures.

296: Primitive brain is 'smarter' than we think

Primitive brain is 'smarter' than we think | Science Blog:

Primitive structures deep within the brain may have a far greater role in our high-level everyday thinking processes than previously believed, report researchers at the MIT Picower Center for Learning and Memory in the Feb. 24 issue of Nature. The results of this study led by Earl K. Miller, associate director of the Picower Center at MIT, have implications about how we learn. The new knowledge also may lead to better understanding and treatment for autism and schizophrenia, which could result from an imbalance between primitive and more advanced brain systems.

Learning how monkeys learn teaches us how humans learn, which may help cure these diseases. Why do we care about monkey brains? Because we share a recent ancestor with them. Common descent!

295: The Hobbit's Brain

The Hobbit's Brain:

Falk and her colleagues made a careful study of the size and shape of the Hobbit brain [based on CT scans], and then they created three-dimensional models of the brains of other hominids. They compared it to the brains of average female humans, a female pygmy, and a microcephalic girl. (They chose females because the Hobbit skull is believed to belong to a female.) The scientists also looked at endocasts of fossil hominids.

Zimmer describes four evolutionary hypotheses about the evolution of Homo floresiensis. (Not Homo floresensis.) Each has slightly different implications for human evolution, especially our understanding of the development of large brains in the genus Homo.

294: Elephant breakdown

Elephant breakdown:

Neuroscience has demonstrated that all mammals share a ubiquitous developmental attachment mechanism and a common stress-regulating neurophysiology. Now, a wealth of human–animal studies and the experiences of human victims of violence are available to help elephants and other species survive.

Understanding human psychology helps treat elephants. Common descent!

293: Human immunodeficiency virus: Refolding the envelope

Human immunodeficiency virus: Refolding the envelope:

HIV has evolved to avoid neutralization by human antibodies. New atomic-level details reveal that such evasion involves substantial refolding of its exterior glycoprotein.

How HIV evolves new, information rich, structures to evade the immune system.

292: Chew on This -- Hill 2005 (223): 3 -- sciencenow

Chew on This -- Hill 2005 (223): 3 -- sciencenow. Investigating the evolutionary significance of loud chewing in termites.

291: Closing the Gender Gap -- Beckman 2005 (228): 2 -- sciencenow

Closing the Gender Gap -- Beckman 2005 (228): 2 -- sciencenow. Experiments on the way rhesus monkeys' respond to spatial problems show gender differences which diminish with age. When trained, the young monkeys were equal. This has implications for teaching human children, and for Harvard's president.

290: Pax3 functions at a nodal point in melanocyte stem cell differentiation

Pax3 functions at a nodal point in melanocyte stem cell differentiation. Comparing mouse and human stem cell differentiation mechanisms. Common descent.

289: Induction of photosensitivity by heterologous expression of melanopsin

Induction of photosensitivity by heterologous expression of melanopsin:

We conclude that mammalian melanopsin is a functional sensory photopigment, that it is the photopigment of ganglion-cell photoreceptors, and that these photoreceptors may use an invertebrate-like phototransduction cascade.

The photopigment controlling circadian rhythms are similar to the pigments used by invertebrates. Common descent.

288: Nature - Evolutionary conservation of cell death mechanisms

DRP-1-mediated mitochondrial fragmentation during EGL-1-induced cell death in C. elegans:

Genetic analyses in Caenorhabditis elegans have been instrumental in the elucidation of the central cell-death machinery, which is conserved from C. elegans to mammals. One possible difference that has emerged is the role of mitochondria. By releasing cytochrome c, mitochondria are involved in the activation of caspases in mammals. However, there has previously been no evidence that mitochondria are involved in caspase activation in C. elegans. Here we show that mitochondria fragment in cells that normally undergo programmed cell death during C. elegans development.

My emphasis. Cells die the same way from mammals to pseudocoelomate roundworms. Evolutionary hypothesis tested and confirmed. Human development (and potential cancer cures) is better understood thanks to evolution.

Brownback and Corzine call for stronger action on Sudan

This is at Thoughts from Kanas.

287: Postprandial cardiac hypertrophy in pythons

Physiology: Postprandial cardiac hypertrophy in pythons:

Oxygen consumption by carnivorous reptiles increases enormously after they have eaten a large meal in order to meet metabolic demands, and this places an extra load on the cardiovascular system. Here we show that there is an extraordinarily rapid 40% increase in ventricular muscle mass in Burmese pythons (Python molurus) a mere 48 hours after feeding, which results from increased gene expression of muscle-contractile proteins. As this fully reversible hypertrophy occurs naturally, it could provide a useful model for investigating the mechanisms that lead to cardiac growth in other animals.

Understanding rapid heart grown in pythons could help heal heart defects in humans. Evolution and common descent at work.

286: Kin selection and cooperative courtship in wild turkeys

Kin selection and cooperative courtship in wild turkeys:

Here I show, using genetic measures of relatedness and reproductive success, that kin selection can explain the evolution of cooperative courtship in wild turkeys. Subordinate (helper) males do not themselves reproduce, but their indirect fitness as calculated by Hamilton's rule more than offsets the cost of helping. This result confirms a textbook example of kin selection that until now has been controversial and also extends recent findings of male relatedness on avian leks by quantifying the kin-selected benefits gained by non-reproducing males.

One of the great advances in evolutionary biology was the formalization of kin selection over the non-rigorous "group selection" that prevailed through the 60's. This research validates the evolutionary prediction that males will forgo reproduction to help a relative if the benefits to the family line outweigh the costs to the helper.

This is a sophisticated and non-obvious evolutionary hypothesis which is consistently borne out in the wild.