241 posts · 335,279 views
Evolutionary Biology, Life Science, Science Education, Human Evolution, and Stuff.
Lead What causes some individuals to be more violent than others? Obviously, being male is a risk factor for violence and more broadly for criminal behavior. The behavior of one's parents or other adult caretakers, as one is growing up, has been implicated in some studies as well. Poverty is an indirect factor as it can be associated with more direct risk factors.
A new study in PLoS looks specifically at one of several possible environmental factors linked to arrest patterns in general and arrest for violent crimes in particular: Exposure to lead. Read the rest of th... Read more »
John Wright, Kim N Dietrich, M Douglas Ris, Richard W Hornung, Stephanie D Wessel, Bruce P Lanphear, Mona Ho, Mary N Rae, & John Balmes. (2008) Association of Prenatal and Childhood Blood Lead Concentrations with Criminal Arrests in Early Adulthood. PLoS Medicine, 5(5). DOI: 10.1371/journal.pmed.0050101
A very large Azhdarchid shown with a human for scale. Azhdarchids were pterosaurs (flying reptile-like creatures) of the Cretaceous. These included some gigantic critters with up to a 10 meter wing span, but also some little ones (2.5 meters or so). Most reconstructions of these flying animals have them skim-feeding across the surface of bodies of water, grabbing near-surface animals with their beaks.
A new paper in PLoS criticizes this view suggesting that there is very little evidence in support of it, and offers an interesting alternative interpretation of Azhdarchid morpho... Read more »
Mark Witton, & Darren Naish. (2008) A Reappraisal of Azhdarchid Pterosaur Functional Morphology and aleoecology. PLoS ONE, 3(5).
Could even this bird be reanimated, gene by gene? When you are extinct you're extinct. Everything about you is dead and gone. There are no more of you, every individual in your species is kaput, non existent, used up, as the Pima Indians would say, you are hokum (like a car with a flat tire). In fact, you are hohokum (like a car with no tires). Your existence is erased. You are as blotto as a budgie in Burbank.
Indeed, every bit of your being, every gene in your genome, every base pair in your DNA, is no longer extant.
Or is it? Read the rest o... Read more »
Andrew Pask, Richard R Behringer, Marilyn B Renfree, & Erik I Svensson. (2008) Resurrection of DNA Function In Vivo from an Extinct Genome. PLoS ONE, 3(5). DOI: 10.1371/journal.pone.0002240
Impacts from warming are evident in satellite images showing that lakes in Siberia disappearing as the permafrost thaws and lake water drains deeper into the ground. Credit: NASA Earth Observatory A new study led by NASA links anthropogenic climate change to a wide range of effects. The study involved scientists from about a dozen institutions and agencies, and looked at biological impacts arising from global temperature increase since the 1970s. The article is published in Nature. According to lead author Cynthia Rosenweig, "This is the first study to link global temperature data se... Read more »
Cynthia Rosenzweig, David Karoly, Marta Vicarelli, Peter Neofotis, Qigang Wu, Gino Casassa, Annette Menzel, Terry Root, Nicole Estrella, Bernard Seguin.... (2008) Attributing physical and biological impacts to anthropogenic climate change. Nature, 453(7193), 353-357. DOI: 10.1038/nature06937
A recent study of dog genetics, published in PLoS, seeks to improve the quality of genetic research by better understanding the underlying patterns of genetic variation at the level of specific dog breeds. Read the rest of this post... | Read the comments on this post...... Read more »
Pascale Quignon, Laetitia Herbin, Edouard Cadieu, Ewen Kirkness, Benoit Hédan, Dana Mosher, Francis Galibert, Catherine André, Elaine Ostrander, Christophe Hitte.... (2007) Canine Population Structure: Assessment and Impact of Intra-Breed Stratification on SNP-Based Association Studies. PLoS ONE, 2(12). DOI: 10.1371/journal.pone.0001324
Food webs --- the network of trophic (eating) interaction among the many species sharing a habitat or biome -- is a much studied aspect of ecology. Food web and other similar phenomena such as dispersal syndromes are epiphenomena of evolution, resulting from the negotiation of competitive and cooperative interactions among many individuals. Indeed, the food web is the gross-level movement of energy within the ebb and flow of entropy and life-based energy capture. This flow of energy is fundamental to all life systems.
The delicacy or vulnerability of a particular habitat ... the ... Read more »
Jennifer Dune, Richard D Williams, Neo D. Martinez, Douglas h Erwin, & . (2008) Compilation and Network Analyses of Cambrian Food Webs. PLoS Biology, 6(4), 1-16. http://biology.plosjournals.org/perlserv/?request
Some of my colleagues are downplaying the recent paper in science showing a: that mastodons are elephants and b: that birds and dinosaurs ... in particular Tyrannosaurus rex and turkeys ... are related. (See here and here, for instance)
Yes, it is true that these phylogenetic findings are wholly uninteresting, being exactly what we expected. But that is WHY these particular phylogenies were carried out.
You see, the research is being done with organic material that is very very old, and is amazingly, remarkably, unexpectedly and astoundingly preserved. The point of using... Read more »
C Organ, M H Schweitzer, W Zheng, L M Freimark, L C Cantley, & J M Asara. (2008) Molecular Phylogenetics of Mastodon and Tyrannosaurus rex. Science, 320(5875), 499-499. DOI: 10.1126/science.1154284
Inequality in mortality is the most poignant reminder of persistent, often multi-generational differences in socioeconomic status (SES). Poor people are more likely to get sick and die than rich people. As a society develops over time, one would hope that this disparity would be reduced, but in fact, it often increases. Recent research published in PLoS Medicine heralds this bad news.
This study is fairly unique in that it examines life expectancy across counties, which are the smallest demographic unit for which the appropriate kind of data are collected. The study examines dea... Read more »
Majid Ezzati, Ari Friedman, Sandeep Kulkarni, Christopher Murray, & Thomas Novotny. (2008) The Reversal of Fortunes: Trends in County Mortality and Cross-County Mortality Disparities in the United States . PLoS Medicine, 5(4). DOI: 10.1371/journal.pmed.0050066
One of the most important evolutionary transitions in human prehistory was the rise of modern humans (Homo sapiens) from earlier hominids. A newly reported fossil from Tanzania provides an important new data point necessary to understand this transition.
Read the rest of this post... | Read the comments on this post...... Read more »
M DOMINGUEZRODRIGO, A MABULLA, L LUQUE, J THOMPSON, J RINK, P BUSHOZI, F DIEZMARTIN, & L ALCALA. (2008) A new archaic Homo sapiens fossil from Lake Eyasi, Tanzania. Journal of Human Evolution. DOI: 10.1016/j.jhevol.2008.02.002
Life is complex. The way a living system works can be described in a series of increasingly refined models, each fleshing out details of the previous model. Typically, description at one level raises questions about what is happening at the finer level. These questions induce hypotheses which drive experimental work which produces ever more detailed knowledge.
A paper about memory, just published in Cell, is an example of one incremental step in this process. In short, this research works out some of the fine detail at the molecular level for the process of forming visual mem... Read more »
S GRIFFITHS, H SCOTT, C GLOVER, A BIENEMANN, M GHORBEL, J UNEY, M BROWN, E WARBURTON, & Z BASHIR. (2008) Expression of Long-Term Depression Underlies Visual Recognition Memory. Neuron, 58(2), 186-194. DOI: 10.1016/j.neuron.2008.02.022
That elephants have an aquatic ancestry has been suspected for some time now. Moreover, the idea of elephant aquatic origins and elephant origins in general is part of a growing realization that many of the world's aquatic mammals originated in a couple of regions of Africa that were for a very long time enormous inland seas (but that is another story I won't cover here).
The earlier evidence came from observation of the ontogeny of the kidneys in elephants, during which the kidneys take on the characteristics that are found in aquatic mammals generally. That resea... Read more »
A Liu, E R Seiffert, & E L Simons. (2008) Stable isotope evidence for an amphibious phase in early proboscidean evolution. Proceedings of the National Academy of Sciences, 105(15), 5786-5791. DOI: 10.1073/pnas.0800884105
Recently published research shows that individual humans will be nicer (more altruistic) when there is the possibility that the recipient of an act can respond verbally. The paper, "Anticipated verbal feedback induces altruistic behavior" is published in Evolution and Human Behavior for March. Read the rest of this post... | Read the comments on this post...... Read more »
Developmental dyslexia is a disorder affecting as many as 17% of school children. This neurological disorder involves an impairment in reading skills, and has been found to be "associated with weak reading-related activity in left temporoparietal and occipitotemporal regions" in English speakers. However, different abnormalities in the brain are associated with dyslexic readers in the non-alphabetic Chinese language, according to research just published in the Proceedings of the National Academy of Sciences.
This is not terribly surprising. Earlier research had shown that indiv... Read more »
W Siok, Z Niu, Z Jin, C A Perfetti, & L H Tan. (2008) From the Cover: A structural-functional basis for dyslexia in the cortex of Chinese readers. Proceedings of the National Academy of Sciences, 105(14), 5561-5566. DOI: 10.1073/pnas.0801750105
Ever since 3,599 years ago humans have been asking the question "Why did our furry elephant go extinct?"
What caused the woolly mammoth's extinction? Climate warming in the Holocene might have driven the extinction of this cold-adapted species, yet the species had survived previous warming periods, suggesting that the more-plausible cause was human expansion.
The woolly mammoth went extinct less than four thousand years ago. The bones of miniaturized woolly mammoths have been found in Siberia dating to about 3,600 years ago. Indeed, woolly mammoths, the furry elephant of... Read more »
David Nogués-Bravo, Jesús Rodríguez, Joaquín Hortal, Persaram Batra, Miguel Araújo, & Anthony Barnosky. (2008) Climate Change, Humans, and the Extinction of the Woolly Mammoth. PLoS Biology, 6(4). DOI: 10.1371/journal.pbio.0060079
It is a little ironic that all nature enthusiasts know that it is "bad" to feed the animals ... they become dependent on the food, and in some cases will become a nuisance or dangerous, prying open cars or breaking into homes to get more food. Then the animal has to be put down or moved to a new habitat. But that sort of bad outcome is more common with, say, bears than it is with, say, chickadees. The irony here is that bird lovers, who are always nature enthusiasts, do not seem to balk at setting up bird feeders. In fact, approximately on half a million metric tons of seed is put out f... Read more »
Gillian Robb, Robbie A McDonald, Dan E Chamberlain, & Stuart Bearhop. (2007) Food for thought: supplementary feeding as a driver of ecological change in avian populations. Frontiers in Ecology and the Environment, preprint(2008), 1. DOI: 10.1890/060152
Gillian Robb, Robbie A McDonald, Dan E Chamberlain, S James Reynolds, Timothy JE Harrison, & Stuart Bearhop. (2008) Winter feeding of birds increases productivity in the subsequent breeding season. Biology Letters, 4(2), 220-223. DOI: 10.1098/rsbl.2007.0622
According to a study just out in PLoS, you can learn to be nice. This study, using functional MRI brain imaging, assessed brain activity while meditation experts produced a meditative state called a "loving-kindness-compassion state" (and here I was thinking that the "loving-kindness-compassion state" was Vermont... ). Read the rest of this post... | Read the comments on this post...... Read more »
Antoine Lutz, Julie Brefczynski-Lewis, Tom Johnstone, Richard Davidson, & Bernhard Baune. (2008) Regulation of the Neural Circuitry of Emotion by Compassion Meditation: Effects of Meditative Expertise. PLoS ONE, 3(3). DOI: 10.1371/journal.pone.0001897
The ape human split is a bit of a moving target. In the 1970s and early 1980s, there were geneticists who placed it at very recent (close to 4 million years ago) and palaeoanthropologists, using fossils, who placed it at much earlier. During the 1980s, the ape-human split moved back in time because of the importance of sivapithecus, then later in time when Sivapithecus slipped and fell out of the hominid/hominin (human ancestor) family tree. Meanwhile the geneticists were moving towards a more and more recent split. At one point not too long ago, all the evidence converged with the spli... Read more »
B Richmond, & W L Jungers. (2008) Orrorin tugenensis Femoral Morphology and the Evolution of Hominin Bipedalism. Science, 319(5870), 1662-1665. DOI: 10.1126/science.1154197
A "radiation" (sometimes called an "adaptive radiation") is when a single ancestral species gives rise to a number of novel species, often in a fairly short (geological) period of time. Following this radiation event, it seems often to be the case that subsequent speciation is less common. In fact, many living clades that have only a small number of extant species have such radiations in their history. It is quite possible that the radiation event occurred for reasons local in time and space, such as a recent extinction leaving various niches open, or the presence of a particular adaptat... Read more »
Significant cultural and physical differences ... the stuff of race and ethnicity ... are prominent when people move across continents or between them. Eventually, the ponderous events of history, which involve occasional foldings in the continuum of human variation, causing apparent patchiness, are offset by the frequent events of human activities, resulting in genetic and cultural admixtures. What colonialism, invasion, and migration do is undone.
A new study out in PLoS Genetics examines this phenomenon for Latin America, with a study of genetic admixture. Read the rest ... Read more »
Sijia Wang, Nicolas Ray, Winston Rojas, Maria Parra, Gabriel Bedoya, Carla Gallo, Giovanni Poletti, Guido Mazzotti, Kim Hill, Ana Hurtado.... (2008) Geographic Patterns of Genome Admixture in Latin American Mestizos. PLoS Genetics, 4(3). DOI: 10.1371/journal.pgen.1000037
A common presumption is that behavior is part of phenotype, and since phenotype arises from genotype (plus/minus Reaction Norm), that there can be a study of "behavioral genetics." This is certainly an overstatement (or oversimplification) for organisms with extensive and/or complex neural systems, such as humans and mice. Neural systems probably evolved (not initially, but eventually) to disassociate behavior with the kind of pre-determined micro-management of behavior that a simple gene-behavior link requires. However, in organisms with neural systems the size of the period at the end ... Read more »
Dietrich Gotzek, D Shoemaker, Kenneth Ross, & Stuart West. (2007) Molecular Variation at a Candidate Gene Implicated in the Regulation of Fire Ant Social Behavior. PLoS ONE, 2(11). DOI: 10.1371/journal.pone.0001088
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