If you've ever seen a dolphin swim, you may have wondered why they undulate their bodies up and down when swimming, instead of side to side as fishes do. Though they have a fishlike body, cetaceans (a ...

Tuna, salmon, mackerel. I’ve never looked at my afternoon sushi and wondered if it’s related to humans. So, I asked one of those friends named Thomas Siek. He’s a biological anthropologist at ...

Yes and no: It depends on how you classify animals. There are two main classification systems – the Linnaean system which groups organisms by characteristics and the phylogenetics system, which ...

As far back as the 19th century it was apparent to some biologists that a simple, repeated pattern underlay the differing body structures of animals. It could be seen in the segmented bodies of worms, ...

(CNN) -- 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. (CNN) — ...

In the past, many scientists believed that only mammals and birds could feel or think in complex ways. Reptiles, fish, and insects were seen as simple creatures that reacted purely on instinct. But ...