Scientists are not completely sure when hair evolved, but they have a few ideas. One theory is that hair may have evolved from scales. Scales offer protection from the environment and help animals to regulate their body temperature. Hair may have evolved as an extension of these scales, providing even more protection and insulation.Another theory suggests that hair may have evolved from spines. Spines are sharp, pointy structures that some animals use for defense. Hair may have evolved as a softer, less dangerous version of these spines.Whatever the case may be, it is clear that hair is a very old feature of the animal kingdom. Fossil evidence suggests that hair was present on some of the earliest land-dwelling animals, which lived over 300 million years ago. So, hair has been around for a very long time!