Scientists in Darwin’s time and through most of the 20th century could only work out the branches of the evolutionary tree of life by looking at the structure and appearance of animals and plants. Life forms were grouped according to similarities thought to have evolved together.
If you look different to your close relatives, you may have felt separate from your family. As a child, during particularly stormy fall outs you might have even hoped it was a sign that you were adopted.
As our new research shows, appearances can be deceptive when it comes to family. New DNA technology is shaking up the family trees of many plants and animals.
The primates, to which humans belong, were once thought to be close relatives of bats because of some similarities in our skeletons and brains. However, DNA data now places us in a group that includes rodents (rats and mice) and rabbits. Astonishingly, bats turn out to be more closely related to cows, horses, and even rhinoceroses than they are to us.
Scientists in Darwin’s time and through most of the 20th century could only work out the branches of the evolutionary tree of life by looking at the structure and appearance of animals and plants. Life forms were grouped according to similarities thought to have evolved together.
About three decades ago, scientists started using DNA data to build “molecular trees”. Many of the first trees based on DNA data were at odds with the classical ones.
Sloths and anteaters, armadillos, pangolins (scaly anteaters), and aardvarks were once thought to belong together in a group called edentates (“no teeth”), since they share aspects of their anatomy.
Molecular trees showed that these traits evolved independently in different branches of the mammal tree. It turns out that aardvarks are more closely related to elephants while pangolins are more closely related to cats and dogs.
Coming Together
There is another important line of evidence that was familiar to Darwin and his contemporaries. Darwin noted that animals and plants that appeared to share the closest common ancestry were often found close together geographically. The location of species is another strong indicator they are related: species that live near each other are more likely to share a family tree.
For the first time, our recent paper cross-referenced location, DNA data, and appearance for a range of animals and plants. We looked at evolutionary trees based on appearance or on molecules for 48 groups of animals and plants, including bats, dogs, monkeys, lizards, and pine trees.
