One can only speculate about why they do it: Professor challenges racial myths. The professor in question, George Armelagos, is said to be president of the American Association of Physical Anthropologists. My favorite passage in the article:
Armelagos also discussed how race has been used to directly oppress people. Many scientists thought African-Americans were better runners than whites due to an inherent quicker muscle response. However, this was only an excuse to explain why the majority of running world records were held by African-Americans. In the end, Armelagos found there was ample counter-evidence against the notion that all black people were naturally better runners.
Way to go, George!