can you answer me in english instead of chinese

Certainly, I can switch to English for our discussion.

Why humans don't have tails like a lot of other animals largely comes down to evolution. Here's an elaboration on that:

1. Skeletal Structure: Early human ancestors, such as the Australopithecines, gradually lost certain physical characteristics, including the tail, as they evolved.

2. Lifestyle Change: The transformation from arboreal to ground-dwelling likely made the tail unnecessary since it wasn’t frequently used. As early hominids adopted an upright walking and running lifestyle on the ground rather than in trees, the need for a tail bone to support body weight and movement diminished.

3. Balance Needs: While many animals use their tails for balance, humans maintained balance through different body mechanics. Our entire spine and muscular structure evolved to help us maintain balance without the need for a tail.

4. Thermoregulation: Many animals with fur use their tails for temperature regulation. Primates (including humans) adapted to regulate temperature through sweating or seeking shade, and later by building fires and shelters to deal with temperature changes.

5. Genetic Variation and Natural Selection: As the environment changed and survival conditions evolved, individuals with vestigial tail genes had less of an advantage, and perhaps even a disadvantage. Consequently, genes that could better adapt to the changing conditions were passed on, which included those suppressing the growth of tails.

6. Aesthetics and Social Evolution: Losing tails may also be related to changes in human aesthetics and social identity preference.

In essence, humans evolved without tails as the need for them waned throughout our evolutionary history; nature selected traits that didn't provide a significant advantage for survival, and the 'tailless' gene became dominant in our lineage.