14 DAY TRIAL // Scientists discovered that horses are more closely related to bats than they are to cows. The only animals more closely related to horses are dogs and cats.
Scientists once thought that bats belonged to the same group of mammals as primates but now it was revealed that they are actually part of an order called Pegasoferae that includes horses, cats and dogs, cows, whales and hedgehogs. All these animals are cousins sharing a common ancestor.
But how recently have the species in the Pegasoferae order diverged from one another? Scientists wouldn't have guessed that horses and bats diverged from one another much more recently that horses and cows, but this is exactly what the DNA analysis has shown. Only dogs and cats diverged from horses more recently.
"I think this will be a surprise for many scientists", says Norihiro Okada at the Tokyo Institute of Technology, Japan. "No one expected this".
Okada and his colleagues looked at genetic mutations caused by retroposons, lengths of DNA that can copy themselves into RNA and then reverse-copy themselves back into DNA at a different location on a chromosome. Closely related species share more of these mutations than more distant relatives. The analysis by Okada's team forces a rethink of the relationships of many mammalian orders, which are currently classified by morphological and nuclear DNA sequence data.
"We need to look at fossils from a new point of view, because there must have been a common ancestor of bats, horses and dogs", Okada says.