What are some theories as to why hominids became bipedal?

Question

What are some theories as to why hominids became bipedal?

Answer 1

The monkey-like creatures needed to assume an upright posture to wade through water, so eventually their descendants evolved to already be in that position.

Answer 2

they were created that way

Answer 3

This has to be added to the theories, lol, brain damage:

http://www.msnbc.msn.com/id/5479501/

Could it be: ape falls out of tree, gets brain damage walks upright because of PTSD nevers go up trees again, finds a nearby cave for protection, can't eat the same so finds nuts and, in need, uses rock to crack open nut, rock breaks, she is attacked uses the sharp rock as knife.  Teaches her young all these new ways. One generation, total change.

Answer 4

Bipedalism was better for climbing trees and then later for running away.

It is all about what works in the survival game.

Even more telling than the upright pelvis and hip joint is the position of the shoulder blades.

With the scapula on the back the arms are useful for pulling yourself up into trees, but it makes your front legs almost useless for high speed running.

If we accept the evidence that hominids were apes that adapted to more open forests anything that gave an advantage in running away from predators would increase you likely hood of survival immensely over your slower brothers, and the evidence points toward early hominids living in tribes just like all other apes do.

Even if the advantage was just in being able to cover the 30 or 40 feet to the nearest tree first ot would make a dramatic difference in who lived and who got eaten.

You can also see something in modern chimps.

Chimps hunt monkeys and eat them. They hunt monkeys by separating. As one part of the tribe chases the monkeys in the trees the other members of the tribe run ahead of them on the ground, and can run enough faster that they can climb up into the trees and set up an ambush.

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Answer 5

The aquatic/wading ape theory, where an erect posture was assumed in order to wade through deep water.

The 'tree to tree' vanishing savannah theory, where we started to walk upright to cover longer distances between stands of trees.

Energy conservation, as bipedal motion uses less energy.

Tool use, a more upright position was needed as we started to use our hands to carry things, and they couldn't be used as feet.

Personally I prefer the 'aquatic ape' theory.

Answer 6

Hominids are not full bipedal by nature. They only walk on two legs when necessary to reach something or threaten others with size. Much the same as a bear, would you consider it bipedal? Everything in nature evolves to serve a purpose, so apes walk on rear legs when necessary.

Answer 7

There are many theories...

Less time spent in trees!

Trees did not provide enough food sources!

The high grasses of the savannah, encouraged hominds to stand upright to detect incoming predators (Stretching, like meercats)!

The ability to carry food, tools and babies, more efficiently!

Introduction to a part-time aquatic lifelifestyle (Standing in shallow tide pools) Monkeys can't swim!

In order to run, while hunting!

Answer 8

The compulsion to shoot each other.

Answer 9

All depends on who screwed who. Maybe the quadrupedal women had an affinity for bipedal men? or vice versa.

Answer 10

I notice there are an awful lot of stock answers straight out of text books here. Dont you people ever get out in the field and find some answers for yourselves.To answer the question. Hominids have always had two legs only, this is what makes us bi-pedal.