Scientists writing in the journal Cell said the mutation in a gene known as EDAR endowed humans with extra sweat glands, a mutation that proved successful and spread across the region.
People who inherited the variant may have reproduced more successfully because having more sweat glands helped their bodies cool off in hot, humid weather, the researchers said.
The researchers said the mutation may have been successful from an evolutionary standpoint because it made people with it more attractive to the opposite sex by allowing them to grow thicker hair or fuller breasts, the Los Angeles Times reported Friday.
Similar mutations in genes controlling bone density, skin color and immune system function were almost certainly vital factors in helping humans adapt to environments as they spread across the globe, the researchers said.
"You can let the genome tell you what's been important in human evolution," senior study author Pardis Sabeti, a Harvard computational geneticist, said.
Powerful computers allowed the researchers to track down significant genetic changes apparently linked to evolutionary change.