Why Do Humans Walk On Two Feet Instead Of All Four Like Other Mammals ?

Question

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Answer 1

I have read two different ideas about this.

1. Walking upright allows us to carry things and do other tasks with our hands while we move about.

2. When early humans emerged from forested areas onto the grasslands, standing upright allowed them to see over the grasses better in order to watch for predators or other dangers.

Answer 2

There are quite a few species that use 2 legs, all birds for instance. Via evolution (or god for the creationists), birds developed their front two limbs into wings. Helps them move a lot better than walking. Bats of all sorts are mamals who dont use their forelimbs much for walking either. Kangaroos and wallabies use their now very short and delicate forelimbs for holding and gathering food. Snakes of course gave up all 4 limbs in favour of being snakes. Likewise humans evolved (or were created) to have arms and hands and just 2 legs, so in one sense we dont walk on 4 legs because we only have 2. Some of the theories proposed are qhuite probable. In grasslands an upright posture is a definite advantage. Quite a few small annimals use it in grasslands to look above the grass to keep an eye out for danger, perhaps to see food opportunities etc. With an increasing use of that upright posture, the fore limbs are available to be used for other purposes, like gathering food, holding tools, etc.

I do not subscribe to the belief that this makes humans superior or more evolved. We just evolved differently, all species are highly evolved to suit their nich in the environment. Cockkroaches, ants, even crocodiles have demonstrated their evolved status by still being viable creatures hundreds of millions of years after their first appearance. Humans are relative new comers and after just a few million years have had such enourmous impacts on the whole planet that we run the very real risk of wiping ourselves out shortly. Come back in 100 million years and if we still exist, then you can talk about being successfull, evolved etc. Till then we are just a blip on the many paths of life. We shouldn't get too ego centric.

Answer 3

The thermoregulatory model explaining the origin of bipedalism is one of the simplest and most fanciful theories on the table, but it is a viable explanation. Dr. Peter Wheeler, a professor of evolutionary biology, proposes that bipedalism raises the amount of body surface area higher above the ground which results in a reduction in heat gain and helps heat dissipation. When a hominid is higher above the ground, the organism accesses more favorable wind speeds and temperatures. During heat seasons, greater wind flow results in a higher heat loss, which makes the organism more comfortable. Also, Wheeler explains that a vertical posture minimizes the direct exposure to the sun whereas quadrupedalism exposes more of the body to direct exposure. This might be a good theory, if any other animal experienced a similar trandformation. None has, and it's improbable we did, either.

Answer 4

The argument of holding tools as a driver for a bipedal gait is flawed. Study of apes reveals that they retain the ability to move quickly on three limbs when holding an object in the fourth. At no time to they attempt rapid movement with a bipedal gait. The driver for this evolutionary transition must be something else. At the time of the transition the climate of the Earth was very dry to the point of vast deserts. Some researchers postulate that humans who lived in proximity to the oceans enjoyed enhanced rates of survival. Apes have been observed in water environments in a prolonged vertical stance. A semi-aquatic environment would also account for the loss of body hair as it would no longer provide good insulation, the nasal bridge, the requirement of marine supplements to fulfill dietary requirements.

Answer 5

I like dr. Wheeler's theory, but the current anthropological studies suggest that our ancestors were expanding their nutritional requirements and many things seem to have happened at the same time or in rapid succession. Change in hip structure, foot structure, and brain structure as well as the ratio of the biparietal diameter of the newborn and the pelvic girdle. This increased ratio is responsible for why humans give birth to relatively underdeveloped newborns compared to the rest of the animal kingdom (kangaroos, etc. excepted).

Answer 6

Humans are bipeds, as are some apes. Most animals are quadrupeds.It's to do with the shape and design of the spine that allows humans to walk erect.Biped humanoids are a distinct development of one section of the animal kingdom.The ability to walk erect, to manually be able to make and use tools,to communicate by speech and writing,to reason with logical thinking are all things that make man different and superior to other animal species.

Answer 7

Our hands are built to be shorter than our legs, so it will be inconvenient and uncomfortable to walk on four feet. Moreover, unlike many non-primates, our skeleton allow us to balance on two feet. That's why four-legged animals have difficulty standing properly on two feet but we can because of the unique way our body is built.

Answer 8

There are some obvious advantages for a being that relies on brains more than muscle.

Higher position of the eyes makes spotting predators easier.

The important part, the brain, is more out of reach of four legged predators.

Answer 9

that's just the way it is, why do humans go into space unlike other mammals, anyway I'm not sure we are the only ones that walk on two feet, what about gorillas

Answer 10

becoz,they being superior species,hav a great deal more work to do with hands (like writing,cooking,handling appliances,computer to name a few) and use their feet only for walking.its a common principle,if u hav something precious u keep it more safely, so humans keep their hands safe and free by not using them for walking.
well accurate factor is when the monkeys were developing into human beings they started using their hand more and more for other tasks then walking;eventually this lead to new posture in which their backs straightened up,this in turn rendered hands useless for walking and so the man learnt to balance himself on only 2 legs and use his hands for other works.got it?