Why is there no three-legged animals?

Some animalsthat live primarily in the wild, have a unique feature — they use their tail as additional support while on the trees. Vivid examples of such behavior can become sloths that inhabit the jungles of South America. Why evolution has endowed these animals for more more stable foot, but only the “standard” tail? Well, let’s try to sort out this issue together.

Why do animals have four legs?

As you know, most animals in nature uses a paired set of limbs designed to meet certain needs. So, meerkats upright rely on your tail and hind legs, and all known woodpeckers use the tail feathers to stronger to lean on a tree trunk.

However, the ability to stand on only two hind legs requires quite a lot of energy, as vertical standing quietly doing some muscle work. Despite the fact that the hypothetical presence of a living being, the third the hind limbs does not require any energy expenditure, the researchers believe that the pairing of feet and paws are all living things on the planet written by nature in our DNA.

Many arboreal animals use their tails as a specific tool for additional grip and support while climbing trees. The presence of two long legs prevents the kangaroo walk, as many other mammals. That is why they use their strong tail and forelimbs as “tools” that help a kangaroo push off the rear foot off the Ground while grazing.

The kangaroo tail helps the animal to push off the ground with “walking”, playing the role of additional supporting limbs

According to scientists, such a common feature of living beings on our planet was embedded in our DNA in one of the earliest and ancient moments of the evolution of life, before the first living beings populated our planet, the first appendages, which later became legs, fins, legs and flippers. Once this trait is bilateral symmetry has been imprinted in our DNA, it was impossible to change.

If you take a closer look at nature, the law of symmetry we can see in everything, not only doubles the structure of most organs of living organisms. Most likely, the presence of a pair of limbs helps animals to get the best mobility and ability to survive. In addition, such symmetry is consistent with the structure of our Central nervous system, as the spinal cord controls a couple of feet and paws passing through the center of our body. The third functional limb, in this case, sooner or later would become a useless vestige, which we graciously shielded mother nature.