I am getting plenty from Cochran and Harpending's "The 10,000 Year Explosion" about the genetic changes in humans over the last ten thousand years. These two seem to know genetics and population changes well. They discuss one of the biggest events ever in human life: the foundation and spread of agriculture.
They sometimes drop a word or two during their discussion that grabs my attention but they don't seem to return to the point for elaboration and explanation. Two such points have been the development of speech and sibling rivalry in connection with lactose tolerance.
When you look up "talking" or "speaking" or "speech", you find estimates of the beginning of human language one or more millions of years ago. However, the authors I am reading mention changes and elaboration of speech and language over the last 10,000 years as a time when there was an increase in the opportunity for deception. You know, con men and such. Long ago, I read Jacques Barzun's chapter in "Science: The Glorious Entertainment" in which he emphasizes the development of vocabulary. Vocabulary may not seem very important but unless you know what I mean by "bridge", I probably can't sell you a deed for the Brooklyn bridge. Unless you know what the Eiffel Tower is, you probably won't buy my deed to it, either.
As we talk and read and look at photos more, we build up stores of concepts connected to words. You can imagine the difficulty Pasteur had in convincing people about microscopic life when they had not heard about it nor had words to describe it. I am not sure of the size of what might be called the 'common' vocabulary, concepts for which there are terms in most of the world's languages but I bet it is bigger today than it was ten thousand years ago. Sometimes, people think that intelligence and the size of one's vocabulary are related. To a large extent, I guess, the more words you know the meaning of, the more you know in general.
The other instance of an arresting comment just dropped was in the discussion of agriculture and diet. The domestication of plants was full of changes for people but at first, it meant a big change in protein. Hunting provides meat and that provides protein. Stop hunting and you are left at first with carbohydrates, ok as appetite quenchers but not as a source of protein. Scientists have noted the change in some people that allows them to continue to digest milk long past childhood, although many animals and some people can only digest the milk from their mother's body until they get a little older. At that point, it is indigestible. Unless you develop lactose tolerance. If you do, you can get protein from milk your whole life.
In discussing this change in some human populations, the authors mention that lactose tolerance may have affected sibling rivalry. I had already run into sibling rivalry in two places: Genghis Khan and baby birds. Khan had something like 13 brothers. I read that he killed them all in order to be the only heir. In the case of baby birds, I read that the egg that hatches first produces the most mature baby. When the parents feed, that more mature one tends to hog up quite a bit of the food. In some species, the more mature one pushes one or more siblings out of the nest, to their death. I don't know how many siblings are killed by other siblings but the authors wondered if an increase in the milk supply would have enabled more of them to survive.
