Tails are useful in many ways, but — unlike these vervet monkeys pictured in Lake Mburo National Park in Uganda — humans' closest primate relatives lost the appendages about 25 million years ago. (Photo credit: imageBROKER/Shutterstock via CNN Newsource) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Humans have many wonderful qualities, but we lack something that’s a common feature among most animals with backbones: a tail. Exactly why that is has been something of a mystery. Tails are useful for balance, propulsion, communication and defense against biting insects. However, humans and our closest primate relatives — the great apes — said farewell to tails about 25...