An article in the Sunday magazine of the normally liberal New York Times is about animal personalities;
Alison Bell has done related experiments with sticklebacks. It has long been clear to researchers that fish that have lived for many generations in the proximity of dangerous predators are less bold and less aggressive than animals that have lived relatively risk-free. What Bell discovered is that those cautious tendencies outlast the presence of risk, even by a generation. When she moved sticklebacks who had always lived in a high-risk environment into a low-risk environment, she found that not only did they retain their cautious tendencies, but so did their offspring.
So we learn that fish are extraverts or introverts just like humans. And that it’s a genetic trait that shows up in just a few generations of living in a different environment.
If personality is a genetic trait in fish, why not in humans? Wouldn’t humans living in different environments eventually develop personality traits which provide a better survival advantage in their environments? Isn’t it logical to conclude that, after tens of thousands of years, humans living in Africa would develop genetically different personalities than humans living in Europe or in Asia?