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"One of the general characteristics that make primates unique are the larger brain sizes compared to body sizes in relation to other organism. His graph is limited in that it shows only the comparison of brain to body sizes of a tribe, within the family Hominidae, under a much larger taxonomic organization, the order Primates." (Primatology.net)

"Yes, we're a lot like other primates, particularly the great apes, with whom we have more than 98 percent of our genes in common. Yet elaborate displays of apparent maternal grief like Gana's may reveal less about our shared awareness of death than our shared impulse to act as though it didn't exist." - NYTimes.com

Is bigger always better? When it comes to brain size, that has long been the prevailing theory-at least among big-brained humans. But a new analysis shows that in the course of primate evolution, brains and brawn haven't always been on the rise.

It has been suggested that interconnected brain areas evolve in tandem because evolutionary pressures act on complete functional systems rather than individual brain areas. The cerebellar cortex has reciprocal connections with both the prefrontal cortex and motor cortex, forming independent loops with each. Specifically, in capuchin monkeys cerebellar cortical lobules CrusI and CrusII connect with prefrontal cortex, whereas the primary motor cortex connects with cerebellar lobules V,VI,VIIb, and VIIIa. Comparisons of extant primate species suggest that the prefrontal cortex has expanded more than cortical motor areas in human evolution. Given the enlargement of the prefrontal cortex relative to motor cortex in humans, our hypothesis would predict corresponding volumetric increases in the parts of the cerebellum connected to the prefrontal cortex, relative to cerebellar lobules connected to the motor cortex. We tested the hypothesis by comparing the volumes of cerebellar lobules in structural MRI scans in capuchins, chimpanzees and humans. The fractions of cerebellar volume occupied by CrusI and CrusII were significantly larger in humans compared to chimpanzees and capuchins. Our results therefore support the hypothesis that in the cortico-cerebellar system, functionally related structures evolve in concert with each other. The evolutionary expansion of these prefrontal-projecting cerebellar territories might contribute to the evolution of the higher cognitive functions of humans.

"Humans are sometimes said to be distinguished as "The Symbolic Species." A Research Highlights note in Nature point to the work of Addessi et al., who show that capuchin monkeys, who diverged from the human lineage ~35 million years ago, can be trained to use and assign value to tokens (symbols) for different items of food." (Deric Bownds' MindBlog)

Osvath et al. Chimpanzee (Pan troglodytes) and orangutan (Pongo abelii) forethought: self-control and pre-experience in the face of future tool use. Animal Cognition, 2008 DOI: 10.1007/s10071-008-0157-0

Do apes and monkeys have a secret language that has not yet been decrypted? And if so, will it resolve the mystery of how the human faculty for language evolved? Biologists have approached the issue in two ways, by trying to teach human language to chimpanzees and other species, and by listening to animals in the wild.

child & chimp cooperation

Chimps and apes are genetically so similar to humans - and their human-like gestures do remind us how close we are on the family tree - that scientists have long been puzzled why they don't live as long as we do. Diet-related evolutionary changes may explain it.