Because, New Scientist reports, it may have given us ours:
When genetically engineered into mice, the human DNA seems to activate genes in the budding wrist and thumb. Chimp and monkey versions, on the other hand, seem only capable of switching on genes in the developing shoulder.
While such evidence doesn’t prove that HACNS1 – as the stretch of DNA is named – caused our species’ opposable thumbs to blossom, it offers a tantalizing and testable glimpse at the evolution of Homo sapiens, says James Noonan, a genomicist at Yale University in New Haven, who led the study along with colleague Edward Rubin of Lawrence Berkeley National Laboratory in California.