Dolphins Were Once Hairy Creatures
This is a dolphin with no fur on its body. Hair first appeared on mammals around 300 million years ago. However, 30 million years ago, a change made the descendants of dolphins retreat to water and lose the need for hair. Whales and porpoises share the same branch in the dolphin’s evolutionary tree, explaining their lack of hair. At the same time, the descendants of these mammals who stayed on land retained their hair and eventually evolved into hippos, cows, giraffes, and more.
These underwater mammals are known as cetaceans, and they’ve developed an extra layer of fat for the lack of fur. It is a natural evolution that helps control and regulate their body heat while not hindering their ability to navigate through water. Despite this, you can still see the telltale sign of hairs on the chins of newborn dolphins.