Human Bodies and what they were adapted for…..

In my evolutionary biology class we are discussing the evolutionary implications of human development since the stone-age. I know human evolution is a touchy topic, but even if you look at it at the not-so-controversial micro-evolutionary scale, some things might explain some human behaviors/diseases. Here are some examples:

o The pace of cultural change has been so much faster than the pace of evolution by natural selection that modern humans are largely still adapted to life in the stone age. (Evolutionary Analysis, Freeman & Herron)o For example: Humans evolved for optimal long-distance running (read Spark or this journal I have)…so it’s interesting to note why running is so good for us, because our bodies are formed ideally for it in the first place.
o Stone-age humans lived on diets rich in fish or lean game, nuts, fruits, and vegetables—so maybe that’s why our bodies are so well adapted for those types of foods and why they are particularly healthy for us (read “food cures”)


o Lactose intolerance is natural---most mammals are made to only endure milk during infancy and to slowly wean off it completely. But because our society uses dairy products everywhere, humans have gained a tolerance for it over time. Except for me, of course. I try to keep convincing Richard that he is lactose-intolerant as well because he has all of my symptoms. He only recently stopped denying it, he just loves milk too much!

o More menstrual cycling increases risk of breast cancer bc the combination of estrogen and progesterone duing the postovulatory phase of the cycle stimulates cell division in the lining of the milk ducts---and these can have more opportunities for mutations that can create cancers. (Evolutionary analysis, Freeman & Herron) Studies have shown that because we use birth control, we have a lot more menstrual cycles in our lifetime than women did in the past. They have done studies looking at tribal women, and have found that they have 1/3 of the amount of menstrual cycles than western society, because they are always either pregnant or they were nursing (and you don’t menstruate then). Their rate of breast cancer is 1/12 that of our society.