Yale researchers solve mystery of disappearing bird digit
Monday, September 5, 2011 - 16:30
in Biology & Nature
A genomic analysis shows that precursor cells pb that form index finger in five-fingered vertebrates can form the "thumb " (in orange) or first digit in three-digit bird wing Evolution adds and subtracts, and nowhere is this math more evident than in vertebrates, which are programmed to have five digits on each limb. But many species do not. Snakes, of course, have no digits, and birds have three.