Humans’ closest primate relatives lost their tails about 25 million years ago, but exactly how has remained a mystery. A breakthrough in genetic research may finally offer answers.

WASHINGTON — Our very ancient animal ancestors had tails. Why don’t we? Somewhere around 20 million or 25 million years ago, when apes diverged from monkeys, our branch of the tree of life ...

Small reptiles like lizards and geckos are known for their extraordinary ability to regrow their tails, a potentially lifesaving skill in the wild. But it turns out these reptiles are not the only ...

To understand how apes and humans lost their tail, Mr. Xia looked at how the tail forms in other animals. In the early stages of an embryo’s development, a set of master genes switch on ...

Many people believe that dogs wag their tails when they are happy. But, according to a new study, the behavior is actually much more nuanced than that.

For this piece on why dogs chase their tails, Sassafras Lowery, CPDT-KA, CTDI, tapped her experience as a certified professional dog trainer, and then Wailani Sung, DVM, DACVB, PhD, a veterinarian ...

The findings flip the long-held belief that dogs wag their tails when happy, and instead suggest tail wags made people happy, so we selected for the trait.