This just rolled through my Google Reader and I want to share it with the World as it explains exactly one of my own favourite theories!
Why you aren't covered in hair
"The fact that, like all other primates, our ancestors also grasped their mothers' fur is suggested by the grasping reflexes that are still present in human infants. If one places a finger in the hand of a newborn it will respond by firmly grasping the finger. Or if a newborn's feet are touched it will respond by curling the toes in what looks like a grasping motion. But why should a human infant have such reflexes? A likely answer is that they are the vestiges of an ancient reflex to grasp the mother's fur.
Luckily, however, the infant's lack of ability to hold onto the mother could be compensated for by the mother's ability to hold onto the infant. For one of the remarkable advantages of bipedalism is that it frees the arms to carry things.
However, the mother's ability to hold the infant was only part of what was needed. The other part was the mother's strong desire to hold the infant. This is because continually clutching an infant is hard work. One can imagine that many of our early ancestors found the task so daunting that they frequently put the infant down while they did other things, only to have it snatched by a predator or swarmed over and destroyed by insects. Clearly, anything that aided in strengthening the maternal desire to hold the infant would have been selected for. But what sort of factors could have strengthened such a desire?"I have long-believed that we were over-looking a very serious conflict between the baby's need to be held and the mother's need to be free of the baby to work - as the gatherer part of the Hunter/Gatherer pair it was essential that mothers could have free hands. But putting the child in a bed on the ground is a high-risk behaviour, especially if the mother is out of arms reach. And so the baby sling was invented.
So you put all of the pieces of the puzzle together and it all makes sense:
- Human has evolved to bi-pedal life.
- Human has evolved to hair-free state.
- Baby can no longer cling to mother.
- Mother needs to move about for food and shelter.
- Baby is at mortal risk if left lying on the ground.
- Baby needs to be within instant access of breast for frequent feeding.
- Human designs baby wearing solution that allows mothers to have free hands and continue to carry baby.
- Baby continues to have instinctive fear of being alone in a prone position. This distresses mother.
So our poor "stone age babies in a space age world" (Dr James McKenna) want to spent all the 24 hours in an upright position nestled directly between the mother's breasts, never laid on their backs, never away from body contact. But our space age mothers in a stone age body need to put the baby aside for the bulk of their day so they can do other things and despair the baby who cries in distress whenever laid in his bed, whether awake or in a light sleep and spends most of her time fruitlessly trying to do so.
It is so simple.