What Chimps Can—and Can’t—Teach Us About Ourselves

When people ask why I study chimpanzees, the answer they often want to hear is "to better understand humans." We seem to have a deep-seated fascination with the idea that apes reveal our own true natures—our primitive selves.

In some ways, this is true. Chimps are our closest living relatives, and it’s correct that we have learned certain lessons about ourselves from studying them. But chimps can’t show us everything about ourselves. If we think of them as a reflection, we’re liable to overlook what’s unique and fascinating about chimps—as well as what’s unique and fascinating about ourselves.

The Close Relationship Between Chimps and Humans

There are some points in favor of thinking chimpanzee behavior is relevant to our own. First, their ancestors were related to ours and our genetics are indeed very similar. Besides us, the apes (gorillas, orangutans, and chimps) are the only ones left from our whole Hominidae lineage. So, in a way, they’re all we’ve got.

And they do seem similar, too, in terms of their bodies and their behavior. For example, they mostly give birth to single offspring, and then mom takes care of that child for a long time, including breastfeeding for several years from only two nipples. That similarity can be seductive.

Elephants do those things too, though. And they also have relatives that seem, to many of us, indistinguishable. Two main types of elephants (African, and Asian) diverged from each other evolutionarily about 7 million years ago. They are very different species, and no known cross-breed youngster has ever survived. Still, many people think of elephants as basically all the same.

We diverged from our own common ancestor with chimps only 6 million years ago—so time-wise, it’s sensible that we see ourselves in them, across so narrow a gap. The genetic divide is slim indeed: Chimps are more closely related to us, and us to them, than either of us is to gorillas (since chimps have more chromosomes than we do, no cross-breed is possible).

Where Chimps and Humans Differ

Yet there are at least four reasons to be cautious about interpreting ourselves through a chimp lens.

First, chimps aren’t the “former us,” as if evolution froze for them 6 million years ago while it forged ahead for every other species on the planet. Quite a lot has happened in those intervening years, and chimps are exactly as far away in time from the shared ancestor as we are.

That said, the (quite narrow) environments they continue to live in may more closely resemble the common ancestor’s than the (much, much broader) environments humans live in today. And since environment shapes the body and behavior, it may be reasonable to think they more closely resemble the common ancestor—in body and behavior—than we do. But we can’t yet say for sure.

Second, there are large differences among the modern apes. There are even differences among the chimpanzee species themselves in terms of social behavior (like partner-bonding vs. promiscuity) and social organization (matriarchy vs. patriarchy, for example). Those differences are reflected in their body shapes, which differ widely despite the fact that most wild apes live in similar natural environments. Male gorillas weigh about 400 pounds, for example, and female orangutans weigh about 80.

Third, it is difficult to describe “universal chimp behavior.” Different communities of chimps behave differently, for a variety of reasons—one of which is what their environment looks like. Do they use sticks as tools? Depends on whether they live near termites. Do they hold hands above their heads while they groom each other? Depends on what their mom did.

Without a homogenous “chimp” way of behaving, it is hard to compare “chimps” to humans. Does the existence, somewhere, of a single instance of something mean that chimps do that? What percent of them need to do it before we can say it characterizes how chimps are? The same difficulty arises in finding universal human behavior. My mother does not have her ears pierced. If you find a teenage boy in Vietnam who has his ears pierced, what does that tell you about my mom?

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Fourth, and maybe most thorny of all: Sometimes the same behavior means different things. This is true between humans; imagine how much more difficult to interpret these behaviors in another species.

Sometimes when humans press their palms together it means they’re enjoying a performance (applause); sometimes it means they’re about to start a game (patty cake); sometimes it means they’re killing a mosquito; and sometimes it means they are communicating with a higher power (praying). It would be hard for my cat to tell the difference.

And just because we’re fairly confident that some behaviors are used for similar reasons between species (hugging, for example, or sneezing), that certainly doesn’t mean they all are. I’m growing some small potatoes on my kitchen counter, and every few days I turn the pot so that the leaves are facing me again, instead of out the window. Do those leaves repeatedly turn toward the sun because they want to—because they like it? I think most people would say no; if a chimp did it, I’d guess most would say yes. (Both of those answers might be correct; it depends on how we define “want” and “like” and “correct.”)

To offer another example: Chimpanzees show their front teeth when they are very afraid; humans do it when they are very friendly. Misinterpreting it either way has big consequences for understanding relationships.

Takeaway

Interpreting this field of research can be a challenge. Our origins are fascinating to us, and we try our best to understand them. We use a lot of tools to help us: religion, philosophy, genetics, archeology, psychology, physics, astronomy, biology, literature. Yet chimpanzees are astoundingly interesting in their own right. That they might offer us insights about ourselves is an added utility—but certainly not their only one.