[The scientists] must have been ignoring the data.
Or perhaps those biologists really [believed what the data told them], but claimed otherwise for some purpose. Maybe they were all exaggerating -- human evolution hadn't really stopped, but had slowed down substantially. Some of them may have been lumping together what they didn't really know about the last 10,000 years with their thoughts about the last 100 years, when mortality rates in Western nations really have decreased. But it's clear that most of them weren't considering the actual data of the last 50,000 years of human evolution.
Hawks really has no clear explanation for this massive denial of reality but that is because he is a scientist who accepts a somewhat idealistic view of his profession. He writes:
I think that biologists are mostly convinced not by theory -- however simple -- but by concrete examples.But as Thomas Kuhn showed in his famous Structure of Scientific Revolutions, theories and interpretive paradigms do shape scientists' perceptions of concrete evidence and its meaning and scientists are not unaffected by broader cultural and political conditions.
In the wake of Germany's defeat in WWII cultural and ideological imperatives throughout the West tended to privilege explanations of human development and differences grounded in sociology, psychology, and cultural anthropology. Evolutionary explanations of human differences were too closely associated with Nazi race theory to be acceptable. To advance them was unthinkable and, for those who might privately recognize the implications of data, dangerous. Data pointing toward recent human evolution were therefore unrecognized, ignored, or suppressed.
That such explanations are beginning, for the first time in half a century, to be taken seriously by scientists is a significant cultural indicator. We are, I think, in the midst of a classic "paradigm shift" such as Kuhn described in his work. And, I also believe, this shift in perception is not unrelated to the collapse of the Soviet empire and the consequent discrediting of Marxist theory.
Whether or not the new emerging paradigm will represent an improvement on the one that has dominated Western thought for half a century I cannot say, but the fact that such a shift is taking place should give pause to those who somewhat naively assert the objective authority of "science". There is no such thing as disinterested authority. Science is ultimately a human endeavor and as such, despite institutional and procedural correctives, is subject to human error.