2.0.6 How People Began: Primatology - Overview

Version 1.3 March 2013                                               (Previous Version)

There is almost a consensus among scientists as to how humans evolved. 

Between 4 and 7 million years ago in Africa, chimpanzees, bonobos and humans (hominids) split from our common ancestor, tree dwelling fruit eaters who supplemented their diet with meat.

·       When the climate warmed the forest turned into grasslands, meaning survival rates were increased by the ability to stand on the back legs to see predators and game over the tall grass.

·       Predators such as big cats can't run long distances – they overheat and frequently tire before the game.  Hominids who could lose heat, by having more sweat glands and less body hair (and darker skin to avoid sunburn), could run longer distances to tire out game, and survived better.

·       Humans survived by cooperating and using tools in hunting and gathering plant food.

·       Humans also survived because their brains were not just bigger but more complex, with more layers of neurons that enable greater degrees of abstraction and sophistication.

·       Like bonobos, early humans mated face to face, so, compared to apes, males with bigger penises were more likely to have children.  As humans lost body hair, suckling infants survived better if they could clutch, compared to apes, more fatty breast tissue around mother’s nipples.

·       Human survival depended on our intelligence, cooperation, tool use, running, language and culture – not on gender differences.  Despite our different genitalia, men and women, compared to most other species, are more similar in body size.  Though men are mostly (but not always) bigger and stronger than women, and women mostly (but not always) have greater verbal skills than men, both sexes have essentially the same physical dexterity, stamina and mental ability.

·       Some early humans spread out of Africa into Eurasia.  Some speculate that humans evolved further in Eurasia and these species also spread back to Africa.  Our species, homo sapiens sapiens, probably evolved in Africa, spread into Eurasia, and overcame the earlier species. 

·       As humans moved away from the equator into colder climates where the sunlight was less intense, those with lighter skin produced more vitamin D, those with narrower eyes and shorter noses got less frostbite, and were more likely to survive, producing the superficial racial difference we see now, especially in our skin colour and faces.

We work through the next level of detail on each of the above issues (more).  After considering this evidence, we’ve looked for a way to state our conclusions briefly, and we come to the following summary.

Is this the best way to state our conclusions in this area?  Click on feedback, or add a comment below, if you can improve the substance or the phrasing.

  more                                                              Statement 12

This story reinforces our choice to value diversity by emphasizing that:

·       Supposed racial differences aren’t based on significant genetic differences: the variation between random individuals of the same “raceâ€� is greater than the difference between people of different races.

·       Both sexes were essential to food production and our survival: both sexes are equal.

This story shows there is no need for supernatural explanations of how we came to be as we are.