Why do we walk upright?

Walking upright was probably caused by a change in environment leading to a change in behaviour that was followed by a change in bodyplan.

 

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Nicely nonspecific.

 

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It's very simple my friend. At some point in history an alien species came to Earth, seeing that we were still walking on 4 limbs instead of 2 they chose to blend their genes with our own. In this way humans began to walk on 2 limbs not all of them, and thus was born modern man. The question comes into play, just what the purpose of this was? And how much of the DNA is still intact? What has changed, etc.

 

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I can see several advantages: So you can carry a child, so you can throw a weapon, so you can run faster...

Without the need to smell for prey, we could more easily scout out animal tracks at that height...or watch for predators...

 

Increased use of hands ---> Walking upright

or

Walking upright ---> Increased use of hands


?

 

For a science forum, you guys are all woefully clueless about evolution!! It's ok, I like teaching you to use your noggin!

We (humans) aren't the only great apes that walk upright- within, the past 2 million years, there have been a dozen others.

Humans just happened to outcompete them all to extinction.

Now why didn't other families of apes learn to walk upright?
Look here.

As you can see, only the genus homo resulted in upright walkers, with relativesw. This is a product of environment. Hominidae are the great apes, yet only those who live in Africa, Homininae, became terrestial. Compared to the tropical rainforests of Southeast Asia, Africa doesn't have much to support large arboreal apes. In fact, it can't. That's why there aren't any there.

The current line of thinking is that several million years ago, global climate change turned the jungles of Africa into savannah. This pushed the apes out of the forest and into the savannah- including our Homo ancestorts. They were already running around on their knuckles. The step to upright stance, which was driven by tool use, was a direct product of living an exposed life on the savannah. Groups of ancestral Homos could mob would-be predators, stoning them.

This behavior reinforced itself- groups that could use tools better, survived longer. Better tool use was associated with a more upright stance. Over time, Homos became adapted to life on the plains, while the ones in the forest stayed in the forest. Then Homo sapiens began to outcompete the other upright apes, and drove them all to extinction.

Gorillas and chimps were largely left alone, as they lived in the forest and did not compete with the plain dwelling Homo sapiens.

 

That's what I said.

 

You left out the environmental part, and the reason why we're the last walking apes.

If Africa was covered in jungle, we'd still be in the trees.

 

Unless humans caused the deforestation through fire.

 

Uh, Africa defoliated before humans existed.

 

You've got to be kidding

 

Prove it. We did it in Australia.

Not at all. Being able to run down prey is an important skill. Humans have the advantage here, we have endurance.

 

That Africa began losing trees before the first hominids walked upright?

Uh, alright.
Pliocene. We see the modern savannah animals in the fossil record, which would imply that the climate had changed from one that favored forest creatures, to one that favored hoofed ones. It began 5 million years ago. Recogniziable Homonids- 2.5 MYA.

This leads me to conclude that the climate change occured before humans were around to do it.

Besides the problems with time, I find it nigh impossible that pre-humans with only stony tools and the rudiments of society would be able to obliterate hundreds of thousands of sqaure miles of lowland tropical rainforest. Furthermore, why would they do it?
Slash and burn is a purely agricultural thing. Agriculture occured several orders of magnitude sooner than the paleolithic.

Did what in Australia?

 

U gotta specify that man. There's kids out there gonna be wondering if Car Lewis or Asafa Powell could run down a cheetah

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Or it might have been as simple as, being able to walk is more sexually attractive than not being able to walk.

 

That works fine for men's dangly bits, not so well showing off the vulva.

 

Then WHY is it sexually attractive? Because it's different? I hate when people use that as an end answer.

 

More to the point, can we run down a deer? The answer is yes.

 

The kids would say "owned". Do you want me in paper or plastic?

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