Evolutionary trees have been around since Charles Darwin, who used the idea of a “tree of life” to map out the relationships between humans and primates. Other researchers continued his work, developing what are known as phylogenetic trees.

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But a recent look at the actual genetic relationships between organisms in those trees reveals that the anatomy-based classification system might miss the mark. Trees were historically mapped using morphology — the similarities and differences in organisms’ anatomy. Below the surface, however, creatures can be more genetically similar to organisms that aren’t on their traditional tree.

Although biologists have created “molecular trees” that map out genetic similarities between species, they often completely contradict the morphological classifications that group organisms by how they look. When the researchers compared both kinds of trees and mapped them based on where animals live, they found that those with molecular similarities were more likely to live near one another than those that simply looked similar.

“For example, tiny elephant shrews, aardvarks, elephants, golden moles and swimming manatees have all come from the same big branch of mammal evolution — despite the fact that they look completely different from one another (and live in very different ways),” Matthew Wills, a paleobiologist at the University of Bath and a co-author of the study, says in a news release.

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Those animals share more than molecular similarities — they all come from Africa. The researchers say that geographic distribution is a way to validate, and possibly shake up, evolutionary trees.

The research also showed that convergent evolution — when unrelated species develop characteristics independently — is much more common than previously thought. As scientific methods continue to evolve, the study implies, so should the ways we look at past attempts to make sense of animal relationships.