Washington State University

Ask Dr. Universe

Chimps Just Don’t Want to Be Human!

January 6th, 2012

Dear Dr. Universe,
Is it possible to cross a chimpanzee with a human?
Dave W.

Chimpanzee mom and baby. Wikipedia

Chimpanzee mom and baby. Wikipedia

Excuse me? I suppose I’ve got the question straight, but I’m having a hard time trying to imagine my chimpanzee buddies having any desire to join the human family. No offense, but from what I’m told chimps are pretty content with how they look.

We could think about this question several different ways. The one I just referred to we could call “aesthetic.” Another is what we call “ethical.” Ethics has to do with whether something is right. And both aesthetics and ethics have something to do with the queasy feeling in your stomach about the question.

Then there’s your question: can it can be done?

So I went to ask Professor Michael Skinner. He said, “NO.”

Professor Skinner is the director of the Center for Reproductive Biology at WSU. He studies how animals reproduce, so he’s got a pretty good handle on your question. I also got the feeling he felt pretty strongly about this. So I’ll repeat his answer: “NO.”

Well, that kind of takes care of the other angles, doesn’t it?

But why not? After all, you’ve probably read that, when it comes to their genes, chimpanzees and humans are 98 or 99 percent alike.

Although humans and chimpanzees share a common ancestor, their evolution split apart millions of years ago. So the “99 percent similar” genetic makeup of humans and chimps doesn’t mean all that much.

Professor Skinner told me that the 99 percent refers only to a fairly basic comparison of proteins and not the actual “DNA sequence,” which is what really makes us what we are. In fact, scientists are busy right now trying to unravel the human DNA sequence as part of the Human Genome project.

Professor Skinner also told me that the sperm and egg from a chimp and human just wouldn’t recognize each other. Since reproduction is all about the sperm and egg getting together, this is a pretty major problem.

Within the past few years, scientists have been able to inject, with a very tiny needle, uncooperative human sperm directly into a human egg. This is called “in vitro fertilization.” But even if you tried to do this between humans and chimps, their bundles of genes, called chromosomes, wouldn’t match up.

One definition of “species,” such as humans, is that it cannot breed with another “species,” such as chimpanzees. Now, this definition doesn’t always hold up. For example, horses and donkeys can breed to make mules. But horses and donkeys are much, much closer in their ancestry than are humans and chimps. And even so, mules cannot reproduce, which means not everything between the donkey and horse matched up correctly. As Professor Skinner says, “If species COULD cross breed easily, we’d have many fewer species.”

Genetic engineers can put genes from one species into another species, but this does not make the second species part of the first. It just means the second species has some different genes.

Maybe your question comes from knowing about Oliver, the chimpanzee who lives at a place in Texas called Primarily Primates. Oliver walks upright and likes to sip beer and watch television. For these and other reasons, some people thought for a while that Oliver might be a human-chimp combination.

But recently, scientists tested Oliver’s chromosomes and found that he was indeed just a chimp. An unusual one perhaps, but a chimp. So even if chimps and humans cannot breed, Oliver has proved that chimps can develop just as bad habits as humans!

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