Find the odd one out

A population splits into two or more groups and these groups occupy the different ecological zones. This is known as

There are two opposing views about origin of modern man. According to one view Homo erectus in Asia were the ancestors of modern man. A study of variation of $DNA $ however suggested African origin of modern man. What kind of observation on $DNA$ variation could suggest this

$A$ : Sometimes, some babies have a small tail.
$R$ : This is just a type of mutant variety