"Natural selection has also shaped some human genes that appear to control particular kinds of thought . Take language. Our capacity to learn a language shows some signs of being a hard-wired instinct . That suggested that genes shaped language, and yet at the time scientists didn’t know of a single language-linked gene. Now they have one. It was discovered in a family in London who suffered a hereditary difficulty with both speech and grammar. In 2002 British scientists announced that the family members who had language problems all carried a mutant form of a gene they called FOXP2. Brain scans later revealed that people who carry mutant forms of FOXP2 have less activity in a language-related region of their brain called Broca’s area.
Scientists then compared human FOXP2 to the version carried by other mammals. Obviously, FOXP2 does not produce a capacity for language in other species. But in a 2005 experiment with mice, scientists showed that it influences animal communication. Mouse pups with only one working copy made far fewer cries to their mother. Those without any working copies made no cries at all .
A comparison of silent and non-silent substitutions revealed that FOXP2 has undergone intense natural selection in humans. Scientists were even able to estimate when that natural selection took place: less than two hundred thousand years ago. That just so happens to be around the time our species first emerged. These results hint that full blown language was a late-arriving skill and has only evolved relatively recently in the hominid lineage."
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