November 9, 2009

Wired for Hunger: The Brain and Obesity

From the Dana Foundation:For most of human history, food was not readily available; storing energy helped ensure survival. Humans thus evolved to eat whenever food is at hand-a tendency that in the modern world may contribute to widespread obesity. Researchers are starting to determine the brain circuitry responsible for this default “eat” message. Marcelo Dietrich and Tamas Horvath tell the story of false starts and measured successes in obesity research. They propose that developing successful obesity therapy may require combining drug therapy with psychological or psychiatric approaches, as well as exercise. In the sidebar, they examine the opposite of obesity: anorexia nervosa.

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March 27, 2008

The first hominin of Europe

hominin.jpgIn this week’s Nature, an article reports on the discovery of a human lower jaw associated with stone tools and animal bones from the Sima del Elefante in northern Spain. The finds have been dated to between 1.1 and 1.2 million years using a variety of dating techniques, making the site the oldest and most accurately dated record of human occupation in Europe.

From the article:

Here we report the discovery of a human mandible associated with an assemblage of Mode 1 lithic tools and faunal remains bearing traces of hominin processing, in stratigraphic level TE9 at the site of the Sima del Elefante, Atapuerca, Spain. Level TE9 has been dated to the Early Pleistocene (approximately 1.2–1.1 Myr), based on a combination of palaeomagnetism, cosmogenic nuclides and biostratigraphy. The Sima del Elefante site thus emerges as the oldest, most accurately dated record of human occupation in Europe, to our knowledge.

The study of the human mandible suggests that the first settlement of Western Europe could be related to an early demographic expansion out of Africa. The new evidence, with previous findings in other Atapuerca sites (level TD6 from Gran Dolina), also suggests that a speciation event occurred in this extreme area of the Eurasian continent during the Early Pleistocene, initiating the hominin lineage represented by the TE9 and TD6 hominins.

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December 10, 2007

Are Humans Evolving Faster?

From physorg.com –  Researchers discovered genetic evidence that human evolution is speeding up – and has not halted or proceeded at a constant rate, as had been thought – indicating that humans on different continents are becoming increasingly different.

We used a new genomic technology to show that humans are evolving rapidly, and that the pace of change has accelerated a lot in the last 40,000 years, especially since the end of the Ice Age roughly 10,000 years ago,” says research team leader Henry Harpending, a distinguished professor of anthropology at the University of Utah.

Harpending says there are provocative implications from the study, published online Monday, Dec. 10 in the journal Proceedings of the
National Academy of Sciences:

“We aren’t the same as people even 1,000 or 2,000 years ago,” he says, which may explain, for example, part of the difference between Viking invaders and their peaceful Swedish descendants. “The dogma has been these are cultural fluctuations, but almost any temperament trait you look at is under strong genetic influence.”

“Human races are evolving away from each other,” Harpending says. “Genes are evolving fast in Europe, Asia and Africa, but almost all of these are unique to their continent of origin. We are getting less alike, not merging into a single, mixed humanity.” He says that is happening because humans dispersed from Africa to other regions 40,000 years ago, “and there has not been much flow of genes between the regions since then.”

“Our study denies the widely held assumption or belief that modern humans [those who widely adopted advanced tools and art] appeared 40,000 years ago, have not changed since and that we are all pretty much the same. We show that humans are changing relatively rapidly on a scale of centuries to millennia, and that these changes are different in different continental groups.”

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Subliminal smells bias perception about a person’s likeability

From physorg.com — Anyone who has bonded with a puppy madly sniffing with affection gets an idea of how scents, most not apparent to humans, are critical to a dog’s appreciation of her two-legged friends. Now new research from Northwestern University suggests that humans also pick up infinitesimal scents that affect whether or not we like somebody. “We evaluate people every day and make judgments about who we like or don’t like,” said Wen Li, a post-doctoral fellow in the Cognitive Neurology and Alzheimer’s Disease Center at Northwestern’s Feinberg School of Medicine and lead author of the study. “We may think our judgments are based only on various conscious bits of information, but our senses also may provide subliminal perceptual information that affects our behavior.”

“Subliminal Smells Can Guide Social Preferences” was published in the December issue of Psychological Science. Besides Li, the
study’s co-investigators include Isabel Moallem, Loyola University; Ken Paller, professor of psychology in the Weinberg College of Arts and Sciences at Northwestern; and Jay Gottfried, assistant professor of neurology at Feinberg and senior author of the paper.

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November 26, 2007

Social neuroeconomics: the neural circuitry of social preferences

Combining the methods of neuroscience and economics generates powerful tools for studying the brain processes behind human social interaction. We argue that hedonic interpretations of theories of social preferences provide a useful framework that generates interesting predictions and helps interpret brain activations involved in altruistic, fair and trusting behaviors. These behaviors are consistently associated with activation in reward-related brain areas, such as the striatum, and with prefrontal activity implicated in cognitive control, the processing of emotions, and integration of benefits and costs, consistent with resolution of a conflict between self-interest and other-regarding motives.

Fehr & Camerer in Trends in Cognitive Science 2007 Oct ; 11(10): 419-27

Hubmed

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September 9, 2007

Science: special issue on social cognition

socialcognition.jpegScience is running a special edition on social cognition this week. It contains papers on the evolution of social cognition

Living in Societies – Caroline Ash, Gilbert Chin, Elizabeth Pennisi, and Andrew Sugden

All Together Now–Pull! – Greg Miller

Evolution in the Social Brain – R. I. M. Dunbar and Susanne Shultz

Social Components of Fitness in Primate Groups – Joan B. Silk

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September 6, 2007

Higher social skills are uniquely human

chimp1.jpgA new study published today in Science reports that humans have distinctive social skills. Esther Herrmann, lead author of the study, answers Scitizen’s questions.

Apes bite and try to break a tube to retrieve the food inside while children follow the experimenter’s example to get inside the tube to retrieve the prize, showing that even before preschool, toddlers are more sophisticated in their social learning skills than their closest primate relatives, according to a report published in the 7 September issue of the journal Science.

This innate proficiency allows them to excel in both physical and social skills as they begin school and progress through life.

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November 16, 2006

Neanderthal genotyping spurs novel scientific field

neanderthal1.jpgThe reality of a complete Neanderthal genome draws near, as two papers report the sequencing of large amounts of Neanderthal DNA. The results help answer some central questions on human evolution. This novel trend in gene research opens up a new research field that by some is called “ancient genomics”. The question is, when will we see a gene sequencing of Homo Erectus or Homo Habilis.

Nature.com (requires subscription) Full Text | PDF | Editor’s summary

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October 15, 2006

Dressing up with hormones

womandressed.jpgWomen tend to be influenced by their ovulation status when they pick their clothes. “Near ovulation, women dress to impress, and the closer women come to ovulation, the more attention they appear to pay to their appearance,” said Martie Haselton, the study’s lead author and a UCLA associate professor of communication studies and psychology. “They tend to put on skirts instead of pants, show more skin and generally dress more fashionably.”
You can get the PDF version of the article here.

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April 5, 2005

The Role of Dreams in the Evolution of the Human Mind

evolutionary psychology — thomasr @ 6:15 am

In a new article in Human Nature Review, Franklin et al. argue that “Rather than a simple threat rehearsal mechanism, it is argued that

dreams reflect a more general virtual rehearsal mechanism that is likely to play an important role in the development of human cognitive capacities.”

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March 27, 2005

Evolutionary developmental psychopathology

evolutionary psychology — thomasr @ 12:19 am

Clinical taxonomy will tend to reflect a nonepistemic agenda that is itself mutable according to the strictures established by prevailing norms and resources. This conclusion implies that the search for a single scheme of psychiatric classification capable of serving the needs of both researchers and clinicians may well be futile.

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