Human Evolution

[Mjt]

Love this Puppy!
I wanna go to Peru

[AUSloth]

What? A South American story with no Martians Mayans?

[Darwinsbulldog]

Originally Posted by AUSloth

What? A South American story with no Martians Mayans?

Sorrie, I was busy and forgotified.

Fishie wrote:-

Love this Puppy!
I wanna go to Peru

Ulike dead people?

[the_gelf]

Is there a bit missing where they ignore that it's just a mass grave

[Mjt]

Originally Posted by Darwinsbulldog

Sorrie, I was busy and forgotified.

Fishie wrote:-

Ulike dead people?

Very much Puppy, but only the really really old dry ones, not the new wet squishy ones

[Darwinsbulldog]

I think I may make some savings in underarm deoderant!

ScienceDaily (May 30, 2012) — New findings from the Monell Center reveal that humans can identify the age of other humans based on differences in body odor. Much of this ability is based on the capacity to identify odors of elderly individuals, and contrary to popular supposition, the so-called 'old-person smell' is rated as less intense and less unpleasant than body odors of middle-aged and young individuals.
"Similar to other animals, humans can extract signals from body odors that allow us to identify biological age, avoid sick individuals, pick a suitable partner, and distinguish kin from non-kin," said senior author Johan Lundström, a sensory neuroscientist at Monell.
Like non-human animals, human body odors contain a rich array of chemical components that can transmit various types of social information. The perceptual characteristics of these odors are reported to change across the lifespan, as are concentrations of the underlying chemicals.
Scientists theorize that age-related odors may help animals select suitable mates: older males might be desirable because they contribute genes that enable offspring to live longer, while older females might be avoided because their reproductive systems are more fragile.
In humans, a unique 'old person smell' is recognized across cultures. This phenomenon is so acknowledged in Japan that there is a special word to describe this odor, kareishū.
Because studies with non-human animals at Monell and other institutions have demonstrated the ability to identify age via body odor, Lundström's team examined whether humans are able to do the same.
In the study, published in the journal PLoS ONE, body odors were collected from three age groups, with 12-16 individuals in each group: Young (20-30 years old), Middle-age (45-55), and Old-age (75-95). Each donor slept for five nights in unscented t-shirts containing underarm pads, which were then cut into quadrants and placed in glass jars.
Odors were assessed by 41 young (20-30 years old) evaluators, who were given two body odor glass jars in nine combinations and asked to identify which came from the older donors. Evaluators also rated the intensity and pleasantness of each odor. Finally evaluators were asked to estimate the donor's age for each odor sample.
Evaluators were able to discriminate the three donor age categories based on odor cues. Statistical analyses revealed that odors from the old-age group were driving the ability to differentiate age. Interestingly, evaluators rated body odors from the old-age group as less intense and less unpleasant than odors from the other two age groups.
"Elderly people have a discernible underarm odor that younger people consider to be fairly neutral and not very unpleasant," said Lundström. "This was surprising given the popular conception of old age odor as disagreeable. However, it is possible that other sources of body odors, such as skin or breath, may have different qualities."
Future studies will both attempt to identify the underlying biomarkers that evaluators use to identify age-related odors and also determine how the brain is able to identify and evaluate this information.

http://www.sciencedaily.com/releases...0530172426.htm

Source [FREE paper]:-

Mitro, S., A. R. Gordon, et al. (2012). "The Smell of Age: Perception and Discrimination of Body Odors of Different Ages." PLoS ONE 7(5): e38110.

Our natural body odor goes through several stages of age-dependent changes in chemical composition as we grow older. Similar changes have been reported for several animal species and are thought to facilitate age discrimination of an individual based on body odors, alone. We sought to determine whether humans are able to discriminate between body odor of humans of different ages. Body odors were sampled from three distinct age groups: Young (20–30 years old), Middle-age (45–55), and Old-age (75–95) individuals. Perceptual ratings and age discrimination performance were assessed in 41 young participants. There were significant differences in ratings of both intensity and pleasantness, where body odors from the Old-age group were rated as less intense and less unpleasant than body odors originating from Young and Middle-age donors. Participants were able to discriminate between age categories, with body odor from Old-age donors mediating the effect also after removing variance explained by intensity differences. Similarly, participants were able to correctly assign age labels to body odors originating from Old-age donors but not to body odors originating from other age groups. This experiment suggests that, akin to other animals, humans are able to discriminate age based on body odor alone and that this effect is mediated mainly by body odors emitted by individuals of old age.

http://www.plosone.org/article/info%...l.pone.0038110

[Darwinsbulldog]

Gavrilets, S. (2012). "Human origins and the transition from promiscuity to pair-bonding." Proceedings of the National Academy of Sciences.

A crucial step in recent theories of human origins is the emergence of strong pair-bonding between males and females accompanied by a dramatic reduction in the male-to-male conflict over mating and an increased investment in offspring. How such a transition from promiscuity to pair-bonding could be achieved is puzzling. Many species would, indeed, be much better off evolutionarily if the effort spent on male competition over mating was redirected to increasing female fertility or survivorship of offspring. Males, however, are locked in a “social dilemma,” where shifting one’s effort from “appropriation” to “production” would give an advantage to free-riding competitors and therefore, should not happen. Here, I first consider simple models for four prominent scenarios of the human transition to pair-bonding: communal care, mate guarding, food for mating, and mate provisioning. I show that the transition is not feasible under biologically relevant conditions in any of these models. Then, I show that the transition can happen if one accounts for male heterogeneity, assortative pair formation, and evolution of female choice and faithfulness. This process is started when low-ranked males begin using an alternative strategy of female provisioning. At the end, except for the top-ranked individuals, males invest exclusively in provisioning females who have evolved very high fidelity to their mates. My results point to the crucial importance of female choice and emphasize the need for incorporating between-individual variation in theoretical and empirical studies of social dilemmas and behaviors.

http://www.pnas.org/content/early/20...17109.abstract

A shame that the full paper is not available for free- Sergey Gavrilets may not always be right, but his arguments are always innovative and interesting. Not that I think he is wrong here. So we will have to be content with the write-up from SD:-

Female Choice Key to Evolutionary Shift to Modern Family

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It is a question that has puzzled evolutionary biologists for years: Why did we stop being promiscuous and decide to settle down to start families? (Credit: © XtravaganT / Fotolia)

ScienceDaily (May 30, 2012) — It is a question that has puzzled evolutionary biologists for years: Why did we stop being promiscuous and decide to settle down to start families?
Sergey Gavrilets, professor of ecology and evolutionary biology at the University of Tennessee, Knoxville, may have found the answer, and it lies in the power of female choice. The study reveals how females chose their mates played a critical role in human evolution by leading to monogamous relationships, which laid the foundation for the institution of the modern family.
Using mathematical modeling, the associate director for scientific activities at the National Institute for Mathematical and Biological Synthesis (NIMBioS) at UT has discovered that the transformation may have occurred when early-hominid females started choosing males who were good providers.
Gavrilets' findings are published in the Proceedings of the National Academy of Sciences.
The "sexual revolution" entailed males first competing with other males for dominance, as a way to get matings. However, low-ranked males—and eventually all males except those with the highest societal stature—began supplying females with provisions in what is called "food-for-mating" to get a leg up on the competition. Females showed preference for the "provisioning" males, leading males' energy to be spent on providing for females and females becoming increasingly faithful. This spurred self-domestication and the modern family as we know it today.
"This change has confounded scientists for a long time because many species would be much better off evolutionarily if the effort spent on males competing for mates was redirected towards increasing female fertility or survivorship of their offspring," said Gavrilets.
The study demonstrates mathematically that the most commonly proposed theories for the transition to human pair bonding—or coupling—are not biologically feasible.
However, the study advances a new model showing that the transition to pair-bonding can occur when female choice and faithfulness, among other factors, are included. The result is an increased emphasis on males provisioning females over male competition for mating.
"The study reveals that female choice played a crucial role in human evolution," said Gavrilets.
According to Gavrilets, the transition to coupling has opened the path to intensified male parental investment, which was a breakthrough adaptation with multiple anatomical, behavioral and physiological consequences for early hominids and for all of their descendants. It shifted the dynamic away from males competing with each other for sex to males competing with each other to see who is a better provider to get better mates.
"Pair bonding laid the foundation for a later emergence of the institution of the modern family," said Gavrilets.

http://www.sciencedaily.com/releases...0530172011.htm

[Darwinsbulldog]

Tiny Genetic Variations Led to Big Changes in the Evolving Human Brain

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Illustration of neurons. Changes to just three genetic letters among billions contributed to the evolution and development of the mammalian motor sensory circuits and laid the groundwork for the defining characteristics of the human brain. (Credit: © nobeastsofierce / Fotolia)

ScienceDaily (May 30, 2012) — Changes to just three genetic letters among billions contributed to the evolution and development of the mammalian motor sensory circuits and laid the groundwork for the defining characteristics of the human brain, Yale University researchers report.
In a study published in the May 31 issue of the journal Nature, Yale researchers found that a small, simple change in the mammalian genome was critical to the evolution of the corticospinal neural circuits. This circuitry directly connects the cerebral cortex, the conscious part of the human brain, with the brainstem and the spinal cord to make possible the fine, skilled movements necessary for functions such as tool use and speech. The evolutionary mechanisms that drive the formation of the corticospinal circuit, which is a mammalian-specific advance, had remained largely mysterious.
"What we found is a small genetic element that is part of the gene regulatory network directing neurons in the cerebral cortex to form the motor sensory circuits," said Nenad Sestan, professor of neurobiology, researcher for the Kavli Institute for Neuroscience, and senior author of the paper.
Most mammalian genomes contain approximately 22,000 protein-encoding genes. The critical drivers of evolution and development, however, are thought to reside in the non-coding portions of the genome that regulate when and where genes are active. These so-called cis-regulatory elements control the activation of genes that carry out the formation of basic body plans in all organisms.
Sungbo Shim, the first author, and other members of Sestan's lab identified one such regulatory DNA region they named E4, which specifically drives the development of the corticospinal system by controlling the dynamic activity of a gene called Fezf2 -- which, in turn, directs the formation of the corticospinal circuits. E4 is conserved in all mammals but divergent in other craniates, suggesting that it is important to both the emergence and survival of mammalian species. The species differences within E4 are tiny, but crucially drive the regulation of E4 activity by a group of regulatory proteins, or transcription factors, that include SOX4, SOX11, and SOX5. In cooperation, they control the dynamic activation and repression of E4 to shape the development of the corticospinal circuits in the developing embryo.
Other Yale-affiliated authors of the paper are Kenneth Y. Kwan and Mingfeng Li.
Primary funding for the research came from the National Institutes of Health and March of Dimes.

http://www.sciencedaily.com/releases...0530152201.htm

Shim, S., K. Y. Kwan, et al. (2012). "Cis-regulatory control of corticospinal system development and evolution." Nature advance online publication.

The co-emergence of a six-layered cerebral neocortex and its corticospinal output system is one of the evolutionary hallmarks of mammals. However, the genetic programs that underlie their development and evolution remain poorly understood. Here we identify a conserved non-exonic element (E4) that acts as a cortex-specific enhancer for the nearby gene Fezf2 (also known as Fezl and Zfp312), which is required for the specification of corticospinal neuron identity and connectivity. We find that SOX4 and SOX11 functionally compete with the repressor SOX5 in the transactivation of E4. Cortex-specific double deletion of Sox4 and Sox11 leads to the loss of Fezf2 expression, failed specification of corticospinal neurons and, independent of Fezf2, a reeler-like inversion of layers. We show evidence supporting the emergence of functional SOX-binding sites in E4 during tetrapod evolution, and their subsequent stabilization in mammals and possibly amniotes. These findings reveal that SOX transcription factors converge onto a cis-acting element of Fezf2 and form critical components of a regulatory network controlling the identity and connectivity of corticospinal neurons.

ABS ONLY:-

http://www.nature.com/nature/journal...ry-information

[Darwinsbulldog]

In your face, Michel Foucault!

http://en.wikipedia.org/wiki/Michel_...ine_and_Punish


Johnstone, R. A. and A. Manica (2011). "Evolution of personality differences in leadership." Proceedings of the National Academy of Sciences 108(20): 8373-8378.

When members of a group differ in their preferred course of action, coordination poses a challenge. Leadership offers one way to resolve this difficulty, but the evolution of leaders and followers is itself poorly understood. Existing discussions have frequently attributed leadership to differences in information or need among individuals. Here, however, we show that in an n-player, repeated coordination game, selection leads to evolutionary branching and diversification in intrinsic leadership among the members of a population even in the absence of any variation in state. When individuals interact in pairs, repeated branching is possible; when individuals interact in larger groups, the typical outcome is a single branching event leading to a dimorphism featuring extreme intrinsic leaders and followers. These personality types emerge and are maintained by frequency-dependent selection, because leaders gain by imposing their preferences on followers, but fail to coordinate effectively when interacting with other leaders. The fraction of intrinsic leaders in the population increases with the degree of conflict among group members, with both types common only at intermediate levels of conflict; when conflict is weak, most individuals are intrinsic followers, and groups achieve high levels of coordination by randomly converging on one individual's preferred option, whereas when conflict is strong, most individuals are intrinsic leaders, and coordination breaks down because members of a group are rarely willing to follow another.

http://www.pnas.org/content/108/20/8373.abstract
http://www.pnas.org/content/108/20/8373.full.pdf

[Darwinsbulldog]

McNally, L., S. P. Brown, et al. (2012). "Cooperation and the evolution of intelligence." Proceedings of the Royal Society B: Biological Sciences.

The high levels of intelligence seen in humans, other primates, certain cetaceans and birds remain a major puzzle for evolutionary biologists, anthropologists and psychologists. It has long been held that social interactions provide the selection pressures necessary for the evolution of advanced cognitive abilities (the ‘social intelligence hypothesis’), and in recent years decision-making in the context of cooperative social interactions has been conjectured to be of particular importance. Here we use an artificial neural network model to show that selection for efficient decision-making in cooperative dilemmas can give rise to selection pressures for greater cognitive abilities, and that intelligent strategies can themselves select for greater intelligence, leading to a Machiavellian arms race. Our results provide mechanistic support for the social intelligence hypothesis, highlight the potential importance of cooperative behaviour in the evolution of intelligence and may help us to explain the distribution of cooperation with intelligence across taxa.

http://rspb.royalsocietypublishing.o....0206.abstract
http://rspb.royalsocietypublishing.o....0206.full.pdf