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.

Click here for the complete article.

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April 17, 2009

The Emergence of Consciousness in Phylogeny

comparative studies,evolution — alice @ 12:00 am

Michel Cabanac, Arnaud J. Cabanac, Andre Parent
Article in Behavioural Brain Research

Abstract
The brains of animals show chemical, anatomical, and functional differences, such as dopamine production and structure of sleep, between Amniota and older groups. In addition, play behavior, capacity to acquire taste aversion, sensory pleasure in decision making, and expression of emotional tachycardia and fever started also to be displayed by Amniota, suggesting that the brain may have began to work differently in early Amniota than in Lissamphibia and earlier vertebrates. Thus we propose that emotion, and more broadly speaking consciousness, emerged in the evolutionary line among the early Amniota. We also propose that consciousness is characterized by a common mental pathway that uses pleasure, or its counterpart displeasure, as a means to optimize behavior.

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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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February 25, 2008

Emotion — new issue

evolution,journal — thomasr @ 7:15 am

A new issue of Emotions is out, with articles on the inter- and intrapersonal functions of smiling, emotion and time perception, and the automaticity of emotion recognition.

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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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November 13, 2007

Rare great ape fossil challenges theory of primate evolution

evolution,human nature — thomasr @ 4:21 am

From physorg.com: Archaeologists have discovered the ancient jawbone of what appears to be a new species of ape that was very close to the last common ancestor of gorillas, chimpanzees and humans, a study released Monday said. The 10-million year-old fossil, complete with 11 teeth, was recovered from volcanic mud deposits in Kenya’s Nakali region on the eastern edge of the Rift Valley in 2005 by a team of Japanese and Kenyan researchers. The researchers say the fossil fills what was until recently something of a void in the fossil record, and challenges one of the working assumptions of primate evolution.

Genetic studies suggest that humans and great apes split from a common ancestor about eight million years ago, but paleontologists have struggled to find fossils for the ancestors of modern African great apes for the past 13 million years. However scientists found plenty of fossil evidence for great apes in Europe and Asia during that period and they also noted some similarities between some of those apes and contemporary African apes.

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September 15, 2007

Brain stem may be key to consciousness:

From MindHacks
An article in this week’s Science News discusses whether the brain stem may play a more central role in consciousness than it’s usually given credit for.

It focuses on children with hydranencephaly, a where the cortex fails to develop in children and instead, the space is filled with cerebral spinal fluid.

Typically, affected children survive only a few months after birth, but those that do survive seem to remarkably more conscious than you would guess based on theories that suggest the cortex is where all the action happens to support consciousness.

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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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May 22, 2007

Resting states in unconscious monkeys

Nature has an interesting report from Marc Raichle‘s laboratory that studies the resting states in monkeys. This study not only demonstrates that resting states occur in non-human primates, but that it is possible to find such activity during unconscious states.

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May 21, 2007

Smarter, sentient whales

animal minds,evolution,theory of mind — thomasr @ 4:13 am

whale.jpgRecent studies have shown that the brains of sperm whales is second in size only to human (relative to body size). It is about 60% larger in absolute mass than that of an elephant. How this brain evolution has occurred is the topic of a most interesting article in PLoS Biology, authored by Lori Marino et al. In this article the authors also forcefully argue that the increased brain size is paralleled by a comparable increase in cognitive complexity. As the authors write:

We believe that the time is ripe to present an integrated view of cetacean brains, behavior, and evolution based on the wealth of accumulated and recent data on these topics. Our conclusions support the more generally accepted view that the large brain of cetaceans evolved to support complex cognitive abilities.

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December 17, 2006

What was the hobbit?

evolution — thomasr @ 9:59 am

28654_homo_floresiensis.jpgPloS Biology has a very nice feature article on the “hobbit”, aka Homo floresiensis.

From the article:

Who—or what—is Homo floresiensis? The tiny hominid bones, which a joint Australian-Indonesian team unearthed in 2003 on the Indonesian island of Flores, have quickly become as celebrated (and derided) as any find in the tempestuous history of human paleontology. The mystery that shrouds these ancient skeletons, nicknamed hobbits after the diminutive characters in J. R. R. Tolkien’s novels, seems to deepen with every study published. Two main camps have emerged, each certain they can settle the question. But many other paleoanthropologists confess they still have no idea.

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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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September 21, 2006

Hominid evolution and development

evolution,human nature — thomasr @ 2:50 am

Childhood is perhaps the defining feature of humanity. But how did it evolve? And when? Apart from Neanderthals, growth patterns of prehistoric humans are rarely studied because of the dearth of fossils that combine evidence from the head as well as the body.

This is why the 3.3-million-year-old juvenile partial skeleton of Australopithecus afarensis — the earliest known juvenile hominid skeleton of any kind — is so important.

This Nature Web Focus looks at what we know about the evolution of human development, and features exclusive video interviews with the scientists behind this discovery alongside current research, features and analysis, and an archive of related palaeontological finds.

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September 16, 2006

Aggression gene and impulse control

evolution — virgil @ 12:18 pm

A version of a gene previously linked to impulsive violence appears to weaken brain circuits that regulate impulses, emotional memory and thinking in humans, researchers at the National Institutes of Health’s (NIH) National Institute of Mental Health (NIMH) have found. Brain scans revealed that people with this version — especially males — tended to have relatively smaller emotion-related brain structures, a hyperactive alarm center and under-active impulse control circuitry. The study identifies neural mechanisms by which this gene likely contributes to risk for violent and impulsive behavior through effects on the developing brain.

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The Role Of Evolutionary Genomics In The Development Of Autism

evolution — virgil @ 12:16 am

In an article to be published in a forthcoming issue of Journal of Evolutionary Biology, Dr Christopher Badcock and Professor Bernard Crespi explore the ‘imprinted brain hypothesis’ to explain the cause and effect of autism and autistic syndromes such as Asperger’s syndrome, highlighted by the book ‘The Curious Incident of the Dog in the Night-Time,’ which involves selective disruption of social behaviour that makes individuals more self-focussed whilst enhancing skills related to mechanistic cognition.

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