lunes, 19 de enero de 2015

Different Tastes: How Our Human Ancestors' Diets Evolved

... Scientists recently sequenced the genomes of a Neanderthal woman from a cave in Siberia and a Denisovan girl from the same cave. This revealed that both Neanderthals and Denisovans once interbred with the ancestors of modern humans.

To learn more about the lives of Neanderthals and Denisovans, researchers investigated genes that prior studies linked to the activity of eating in modern humans. Changes in diet such as cooking food and domesticating plants and animals are thought to have played major roles in the evolution of hominins — the group consisting of humans and their relatives after they split from the chimpanzee lineage — such as increases in brain size.

A key area of interest for the scientists were genes for taste receptors, which are molecules on taste buds that help people taste flavors. They found that the genes for two bitter taste receptors, TAS2R62 and TAS2R64, mutated in hominins after the ancestors of chimpanzees and hominins diverged, making the hominin versions inoperative. They found that this mutation occurred before the split between the ancestors of modern humans — Neanderthals and Denisovans. It remains uncertain what specific bitter molecules these receptors target, but they may be substances that are common in the diets of most or all great apes, but that are rare or absent from hominin diets.

"Since we know these mutations are specific to the human lineage, perhaps we can learn something about human evolution by figuring out what substances the functional versions of these receptors are responsible for tasting," said lead study author George Perry, an anthropological geneticist at Pennsylvania State University in University Park. [...]