The Hairless Mutation Hypothesis: a Driving Force of Humanization by Enforcing Bipedalism to Hold a Baby, by Allowing Immature Baby Delivery to Enlarge the Brain after Birth, and by Making Use of Fire to Get Meat and to Cook Foods

摘要

References(81) Three characteristics, i.e., bipedalism, nakedness, and the family reproductive unit, distinguish humans from other primates. Once a hairless mutation was initially introduced, these three could be explained inseparately. All primates except humans can carry their babies without using their hands. A hairless mother would be forced to stand and walk upright to hold a baby. As her activities were markedly limited, the male partner had to collect food and carry it to her to keep their baby from starving. He must have been sexually accepted by her at any time as a reward for food. Sexual relations irrespective of estrus cycles might have strengthened the pair bond, leading to family formation. Savannahs appeared 2.5 million years ago (Ma), which forced hominins to terrestrial life, but the ground was full of danger and a larger brain became advantageous. Wildfires occurred frequently; naked hominins approached fire for warming, but soon must find burnt animals in the aftermath of wildfires. The taste of burnt meat must be a driving force for hominins to become meat-eaters. They must have learned how to control fire and how to repel hairy animals that hate fire. To compete with large carnivores with fangs and claws, they became not hunters but robbers. When robber hominins found that a carnivore had killed a prey animal, they approached the predator and repelled it away from the victim using fire, then claiming the prey intact. Major events such as the timing of global cooling, the appearance of savannahs, the appearance of early humans, decline of large predators, the manufacture of stone tools, and the start of cooking largely coincide at 2.5 Ma. Cooked meat must be tasty and easily digested, providing hominins with nutrients sufficient to enlarge the brain, while most large carnivores were forced to extinction. Thus, hairlessness created humans.