Question about evolution of man?

Question

okay, I was thinking that other day about evolution of man. if it is more advantageous to walk on all four limbs for 4-legged mammals, like to keep more balance and not trip over stuff, why are humans walking upright today? Why didn't evolution just keep us walking on all fours?

More: why did the human lose the tail that most ape-like so-called ancestors have? isn't it more advantageous for natural selection adaptation to keep this usefull limb, which could have been used for lots of benefitial stuff nowadays?

Answer 1

The tail thing has been explained by an above answerer.

Oyvey, I'm afraid you are wrong, as running on four legs is faster and also means an animal can run for longer (research the pronghorn).

I have no idea if I'm right here, but I think the reason we became bipeds is because we gradually started using tools. However, to manipulate tools, our 'feet' needed to be nimble. So we got hands, which weren't damaged as much during running or climbing. Also, if hominids ran on two legs, then they could use the spare hands for carrying tools, which they did of course (spears), for hunting.

Other primates are beginning to use tools now. There is a photo of an Orangutan using a primitive spear to collect leaves.

http://www.getfrog.com/blog/wp-content/t...

I wouldn't bother looking for info about this photo though, as most of them say that the Orangutan is fishing, completely ignoring the fact that they are strict herbivores.

Unless they are starting to eat meat too...

Answer 2

sorry but i do not believe in evolution. there are many theories about how man came to b. scientist always say somethin about how  the world came to b n then all of a sudden they chang their story... like when i was in elementary school there was 9 planets now they claim that theres only 8. evolution i believe was something created based on an idea... if our DNA is only 2% different than a monkey.. shouldnt they drastically changed throughout the time we evolved? besides if man was created through evolution how come we are the only kind of human being and why are we the only ones that have the ability to manipulate the world as we been doin throughout the years? there are many other animals w. great capabilities so why didnt they evolve to our extent?

Answer 3

> "Why didn't evolution just keep us walking on all fours?"

There are several theories about this - but perhaps the most prevalent one is because our ancestors moved out from forested areas onto the savannah. There it is an advantage to be able to stand upright, and to be able to therefore see farther (just like the meercats standing sentry).

Our ancestors had already started to evolve more sophisticated manipulative hands (like chimps and other apes), and this more upright position freed-up our hands for even MORE manipulation and tool manufacture/use. This is a significantly advantageous feature, so it was strongly selected for and we became more and more bipedal and more and more dextrous.

> "More: why did the human lose the tail that most ape-like so-called ancestors have? isn't it more advantageous for natural selection adaptation to keep this usefull limb, which could have been used for lots of benefitial stuff nowadays?"

Our nearest relatives - the other Great Apes (chimpanzees, gorillas, orangoutans) all also lack tails. So the loss of the tail happened long before humans diverged from the other apes.

Most of the great apes are only partly arboreal - they all spend significant amounts of time on the ground. And tails are mostly useful foir balance and grip while climbing - not really an advantage on the ground. Therefore our tails were less useful, and got lost.

Answer 4

Walking on two legs is evolutionary advantageous because , accounting for the shape of the rest of our bodies, one can run faster on two legs.  If I am wrong and running on all fours is faster, than I'd guess that running on twos is still fast enough for humans to avoid being killed in the wild.  

A tail would be worthless.  It requires space and energy, not to mention the risk of an extra extremity that could lose heat on cold days or be a detriment if injured.  A tail might have been cool, but apparently we can survive just fine without them.

Answer 5

First of all, we still have a tail but it is much smaller than the tails of other primates. It is only 3 to 5 vertebrate long and it is called coccyx.  

Second, our tail became shorter as our ancestral specie stop using it (the same thing has happened with our appendix, small toes and wisdom teeth).

Third, bipedalism (walking on 2 feet) has its own advantages. From Wikipedia:

"Limited and exclusive bipedalism can offer a species several advantages. Bipedalism raises the head; this allows a greater field of vision with improved detection of distant dangers or resources, access to deeper water for wading animals and allows the animals to reach higher food sources with their mouths. While upright, non-locomotory limbs become free for other uses, including manipulation (in primates and rodents), flight (in birds), digging (in giant pangolin), combat (in bears and the large monitor lizard) or camouflage (in certain species of octopus). Running speeds can be increased when an animal lacks a flexible backbone, though the maximum bipedal speed appears less fast than the maximum speed of quadrapedal movement with a flexible backbone - the ostrich reaches speeds of 65 km/h and the red kangaroo 70 km/h, while the cheetah can exceed 100 km/h."