Several studies published recently on the brain got us thinking…
Human brains vs. Neanderthal brains
German and French researchers compared CT scans of human and Neanderthals at various growth stages and published their results in Current Biology. The brains in each species started out the same size and shape, but as each grew, their shapes changed. Both begin elongated, but human brains become more round and globular. Despite having similarly large brains, according to Science Now:
The differences suggest that Neandertals did not see the world the same way we do and may not have been as adept at language or forming complex social networks.
Human brains vs Chimpanzee brains
Excitingly, the same researchers had another similar study published last Friday. Using the same scanning techniques, they compared chimp and human brains at different ages. Unlike the Neanderthals, even at birth, the brain shape is different and in fact, according to the paper, “there is no overlap between the two species throughout ontogeny.” In addition, “the shape changes associated with this early “globularization phase” are unique to humans.”
Another study published last week in PLoS Genetics explains a by-product of this brain uniqueness—a weaker immune system. It all has to do with a type of white blood cells called natural killer cells, or NK cells. NK cells are crucial in fighting disease in both chimpanzees and humans, but they do a better job in chimps— chimps are not susceptible to diseases like HIV and malaria.
Human NK cells seem to have evolved differently. NPR had a great story on the research this week.
The kind of NK cells that are good for getting lots of blood to the developing fetus are not as good for dealing with infection, and vice versa.
And whereas the chimpanzees develop the cells good for infections,
The human system, on the other hand, seems to be optimized for getting lots of blood to the developing fetus so our big brains can grow the way they're supposed to.
More Human Brain
Finally, how about two items that are good for the brain? A study published in PLoS One yesterday shows that the video game Tetris may reduce Post-Traumatic Stress flashbacks. And Jonah Lehrer, one of our favorite neuroscience writers, has a great blog post in Wired today about the pleasure we get from preparing our own meals.
Image from Science- Credit: (baby skulls, L) P. Gunz et al., Current Biology, 20 (9 November 2010); (Adult skulls) Philipp Gunz/MPI EVA Leipzig