Why cant other mammals walk on their back legs?

Question

i know many primates can but they also use their knuckles for support?

i was also wondering if anyone has eve trained a cat, dog, etc. to walk on its back legs for a long period of time?

Answer 1

Walking bipedally is generally very impractical. It would a total overhaul of the skeletons of most mammals, as their feet, legs, joints, and backs are not set up for so much weight support and balance. Humans can use their arms so well because they evolved for swinging through the trees, but most mammals don't have the arm range that would make freeing up the front limbs useful.

Knee and back problems are far more common in humans than other mammals, and balance is far more difficult (how many dogs have you seen trip and fall compared to humans?).

Basically, the payoffs aren't worth the drawbacks for most animals.

Answer 2

That's just not the way God made them.. but, can't monkeys and gorillas walk upright for a little ways? I dunno. But I wouldn't feel too sorry for them, most of the mammals on all fours can outrun us.  

Answer 3

I saw on tv that a dog lost it's front legs and only walks upright with it's back legs.

Answer 4

I have seen a story about a dog that lost its front legs and was able to learn to walk on its hind legs, and I've seen videos of dogs doing it as a trick.

I think other mammals do not walk like we do because we walk in a way that does not make good use of energy and is bad for our spines.  We developed this walk, I think, to make use of our opposable thumbs, etc, but our walk versus a four-legged creature wastes a lot of energy and sacrifices a lot of balance.

Answer 5

I agree with most of the answers you have already, but you need to look at the whole anatomy.  I have also seen videos of the dog with out front legs.  Amazing.  I have also seen a man with no arms play a guitar with his feet and toes.

Have you seen humans without a big toe try to walk?  Our opposable thumbs and large toes do set us apart. Very hard to balance without the large toe.  Yes, other primates do walk upright, but none have the hip structure to walk and run as we do.  A chimp running will revert to a 4 leg pace by using his arms.

How about cats versus other vertebrates?  Ever notice they have  hip sockets, but no shoulder joints?  Their arms and shoulder blades are held in place my muscle and tendons basically.

Have fun

Answer 6

Their spines aren't designed for it. Bipedal animals (such as you and I) have spines that were designed for upright locomotion. While a few animals such as bears and certain primates can walk upright for short periods they always revert to quadrapedal stances. It has to do with the center of gravity and the relative lengths (and strengths) of legs. A horse is immensely strong and can run like the wind but to stand upright would involve hoisting a lot of weight above its center of gravity and its legs simply aren't designed for it.