7.2: Learning from Primates

Homologies and Analogies

While primates are fascinating animals in their own right, we study non-human primates in anthropology with the ultimate goal of understanding more about our own biology and evolutionary history. There are two main ways non-human primates can help illuminate human evolution. The first is through homology, that is, traits that are shared between species because they inherited them from a common ancestor. Humans and chimpanzees, for example, share a good deal of physical and behavioral traits. Because both species have them, those traits were almost certainly present in the common ancestor we shared roughly 6 to 8 million years ago.

The second way is through analogy, also called convergent evolution. This is when two species independently evolve similar traits because they face similar environmental pressures, not because they share a recent common ancestor. Baboons and humans are a good example. Both have relatively long legs, but not because they inherited that trait from the same ancestor. Rather, both species moved into open savanna environments where covering large distances efficiently was a survival advantage, and longer legs solve that problem. The same selective pressure, acting on two different lineages, produced the same solution. When we understand why baboons evolved a particular trait, it can give us strong clues about why our own ancestors did too.

Together, homology and analogy make non-human primates valuable for understanding the forces that shaped human evolution, which is exactly why they are a part of biological anthropological study.

Conclusion

The Order Primates is a diverse and fascinating group of animals united in sharing a suite of characteristics—visual specialization, grasping hands and feet, large brains, and extended life histories—that differentiates us from other groups of mammals. In this chapter, we laid the foundation for exploring the great diversity of species that make up the Primate Family Tree and where humans fit into this larger primate picture.

You can see a summary of the primate suite of traits in the box below: