[Question_Assumptions]

The reason why they don't study it is that too many biologists of the 19th century, filled with Darwinist zeal, tried to use phenology to arrange human races into an evolutionary model of more and less advanced humans on an evolutionary scale, going so far as to look at Tasmanians as a "missing link". The same thing happened with the study of general intelligence or IQ. Basically, both areas of study were used toward (generally unwarranted) racist and have thus cast a racist shadow over the whole enterprise. People feel that even talking about such issues seriously is to step upon a slippery slope that ends no place good.

[USConstitutionBuff]

Zeal they had, but it was racist zeal not Darwinist. Evolution through natural selection would make one assume that each human population was suited to the climate its recent ancestors had come from. Darwin, who was quite progressive for a man of his day (he related the bravery of a woman who killed herself rather than submit to slavery and questioned that if her skin where white wouldn't her sacrifice be compared to a Roman matron rather than brute animal obstinacy in the Voyage of the Beagle), Darwin was convinced by the shoddy "science" of racist skull shapers that some human populations would eventually prove unfit or evolve. Modern science shows that there is very little actual genetic difference and that we are all more recently one people than anyone had imagined.