What is the most plausiable explanations for the evolution of bipedalism?

Question

What is the most plausiable explanations for the evolution of bipedalism?

Answer 1

As forests receded, the ability to brachiate (move through trees) became less important. Standing upright had one distinct advantage in the more open environment; the ability to see over savanna grasses and thus detect approaching predators. Whether as a side advantage or initial, bipedalism also freed up the front limbs allowing for greater dexterity of the 'hands'. This may also have stimulated evolution of the cerebrum, which ultimately led to development of language.

Answer 2

-It frees a set of hands up that normally wouldn't be free.

-It makes us taller and more able to reach things (like food).

Answer 3

Like most things that involve evolution, it is probably a combination of all the positive attributes.  It frees the hands, makes wading in water more efficient, gives a better view, helps cool during the hottest part of the day, makes you appear bigger, allows you to reach higher in trees and probably a few others.

Answer 4

There are several explanations and one may be no more plausible than another. Many of the explanations by anthropologists seem t confuse effect and cause. Such as, " the free up of hands for tool use ", hypothesis.

Answer 5

This is, I believe unknowable without a precise history of our evolution. Mary's explanation is the common one. There was a french anthropologist who suggested it was because humans were littoral from early in their development (lived by and next to the shore), so they would wade out into the shallows to catch fish... and this brought them upright. When I first heard this I was dubious, but I later learned that humans have something in common only with whales and dolphins, and that is a layer of subcutaneous fat... which would point to the possibility that this explanation is somewhat credible.

Answer 6

ha...

I had an answer but Ichabod's is so much better.

edit

Answer 7

well the automobile hadn't been invented yet, so people were forced to walk...  :)

Answer 8

"The origin of bipedalism, a defining feature of hominids, has been attributed to several competing hypothesis. The postural feeding hypothesis (Hunt 1996) is an ecological model. The behavioral model (Lovejoy 1981) attributes bipedality to the social, sexual and reproductive conduct of early hominids. The thermoregulatory model (Wheeler 1991) views the increased heat loss, increased cooling, reduced heat gain and reduced water requirements conferred by a bipedal stance in a hot, tropical climate as the selective pressure leading to bipedalism. "

In order:

Postural feeding: It's noted that chimps are often vertical when feeding. The theory says that when human fore bearers moved out on to the savanna, it was easier to walk on two legs.

Behavioral model: This is where s*x comes in. Those that could carry food to a female were more likely to produce offspring.

Thermoregulatory model: Standing upright reduces the amount of sun hitting the body. Also being upright exposes more of the body to cooling winds. Those that stood up did better.

Yet another theory says "bipedalism was more efficient than quadrupedalism for long-distance terrestrial locomotion, and was favored when resources became scarcer and more widely separated during the drying of African forests."

http://www.sciencedirect.com/science?_ob...

Still another suggests living near water lead to more fat in the diet (bigger brains) and wading to gather food lead to walking on two legs.(See below)

Given the various theories I prefer the Savanna as the prime cause of bipedalism There was less shade, resources were further away and you needed to carry food back.