Expert: John Shea - 6/9/2009

Question
Dear Expert,
  I want to state something before I begin with the question: I am not racist towards any ethnic group, and believe that no ethnic group is in any way better than another.  We are different simply because we have been shaped by different environmental forces.  Having said that I have a question that I did not feel comfortable asking my professor in my Evolutionary Biology class because of its sensitive nature.  I have no political agenda and believe that all sincere academic questions are valid, regardless of the related historical/political factors.  I would like to know, and I may be incorrect even in my generalizations, why is it that many ethnic African individuals share a closer facial likeness with our evolutionary predecessors, than say a northern European.  I fully realize that this question is very sensitive and I mean no insult to any person or group; I am just very curious.  By facial features I mean the proportions of the jaw & zygomatic bones, and the shape of the nose, nostrils and lips.  What would be the evolutionary advantage of having these features or of changing them as Europeans and Asians have.  The only thing I could think of is a larger nose might be beneficial in moisturizing and cooling inhaled air in hot arid environments.  In no way do I mean implying anything of a derogatory nature, these are just my observations.  Please answer this question if only to correct my observations. I have not been able to find any information on the subject because of its semi-taboo nature.  Thank you very much for your time. Shanti.

Answer
Dear Vajko
I suppose the answer I give has to depend on my understanding of the question.
First, if by "ancestors" you mean the oldest known Homo sapiens (like the Omo Kibish and Herto fossils from Ethiopia) I'd guess the similarity has to do with a combination of factors -similar environmentally-induced pressures for temperature, humidity, etc. If humans evolved there in East Africa, you'd expect more similarities between them and their local descendants than between those ancestors and living humans who had been living in very different kinds of habitats for a long time.
You also have to understand that we don't know a lot more about the appearance of these early humans than what we can infer from their bones.  Skeletally, no living human is morphologically any closer to pre-Homo sapiens fossils than any other one.
The high cheekbones and prognathism to which you refer are widely-variable in expression among East Africans, but it probably reflects patterns of genetic drift, sexual selection and media bias.  (High cheekbones are considered attractive by many westerners, so advertisers and television programs tend to select models/actors with such features.)  Racist caricatures tended to exaggerate African prognathism, so some people focus in on this when what they see among living Africans seems to "confirm the stereotype".  East African alveolar skeletal prognathism is relatively modest, and again, possibly reflects the retention of an ancestral condition.  (Hard to know, we have few fossils of early Homo sapiens or their immediate precursors in East Africa.)
The big nose = moisturizer and radiator hypothesis is a generally-accepted explanation for the large noses one sees among northern Europeans and Asians and other populations who have lived for prolonged periods in cold and/or dry climates.
These subjects aren't (or shouldn't be) taboos.  The fact that humans differ from one another geographically is a fact.  Most of these differences probably reflect patterns of sexual selection among small, Ice Age populations combined with modest degrees of environmentally-induced selective pressure.  The notion that these morphological differences mean much in terms of the intellectual, moral, or spiritual variability among humans has been refuted by more than two hundred years of scientific studies.
Cheers,
John Shea