Wednesday, 28 April 2010

A thought about human evolution

Some time ago I watched a TV wildlife programme in which a troop of chimpanzees saw off a leopard by throwing sticks and stones. These only went vaguely in the direction of the enemy: it was essentially an aggression-display. I was later told that no chimpanzee had ever been taught how to throw missiles attempting to hit a target, which is after all a very sophisticated concept.

This set me wondering whether, when our remote ancestors descended from the trees out onto the savanna, they had already acquired this skill, or whether it came later. Consider the advantages of being able to throw things accurately. If you can throw a stone the size of a cricket ball straight enough to hit a hyena at twenty paces, you are infinitely safer than if you cannot: even a large predator such as a lion my be deterred by a few well-thrown missiles. There are also huge advantages in the gathering of food: humans cannot run fast enough to catch even a rabbit, but accurate throwing greatly increases the chances of killing small game, not to mention making it much easier to bring down fruit and nuts from high trees. Also, a bipedal posture balanced on the hind legs does not bring many advantages to humans, but it greatly facilitates the throwing of stones.

From stones we can develop into spears, and, because suitable missiles are not always available, to the creation of some kind of bag to carry a supply around. This is a highly sophisticated concept, involving foresight and planning. I do not know whether this matter has been properly investigated, but it strikes me as being very important in the history of human cultural evolution.

1 comment:

  1. Hi, Peter, my name is Michael, and I'm a first-year university student studying Anthropology. From what I've learned, human ancestors developed bipedal tendencies and moved out of trees around 4 million years ago, while they started building stone tools for hunting around 2.5 millions years ago at the beginning of the Paleolithic. Before we hunted, it's clear from fossil evidence that we only ate fruits, plants and grains.

    Our ancestors gradually became more terrestrial as it gave them the advantage of finding food lower to the ground, while birds, insects and other animals still fed on foodstuffs found in the trees. It was when they became fully bipedal that they then moved out into the savanna (because again, very few other animals would, so they have less competition for food and space), saw animals as another food resource, then began developing their technology for its use in hunting.

    The two primary reasons hypothesized for why we are bipedal are thermoregulation, and energy efficiency. About thermoregulation, when standing up, there's less horizontal surface area on your body for the sun to shine on, and there's more vertical surface area on your body for wind to blow on. And about energy efficiency, imagine a gorilla, and how much weight in its upper body actually weighs him down. Walking on two feet helps us move faster and for longer periods of time.

    Thank you for this post. I haven't studied at all during my Easter break - but this has jogged my memory of what we've just learned.