Well, this is about as bad an idea I can imagine coming from a biologist, and its justification is equally poor. The idea is to make human/chimp hybrids (“humanzees”), in the hope that their existence will convince people that Homo sapiens is not a separate, created entity, but is part of an evolutionary continuum not just with chimps, but with all species.
Our ancestors diverged from the ancestor of the two living species of chimps about 6.5 million years ago. These chimps are thus our closest living ancestors.
It’s often said that we’re nearly genetically identical to chimps, with a divergence of only about 1.25% in DNA sequence. But each protein made in the body is encoded by many DNA bases (a protein containing 100 amino acids has 300 DNA bases in its coding sequence), and so on average, as I recall, there’s at least one sequence difference or more between each human and chimp protein. And that doesn’t count DNA in regulatory regions that control gene expression. All in all, saying that we’re 99% similar to chimps doesn’t mean that we’re almost the same in terms of either our proteins or the developmental program that constructs bodies from them. But this similarity has led biologists to wonder if we could make hybrids between humans and chimps. Further, we have 23 pair of chromosomes, and the other great apes, including chimps, have 24. This would almost surely make any hybrids, even if they could develop, sterile, for the unequal chromosome numbers would impede meiosis, the formation of gametes that requires chromosomes of both parents to pair.
As I mentioned in Why Evolution is True, (footnote 51, p. 245), Ilya Ivanov, a Russian zoologist actually tried this, inseminating 3 female chimps with human sperm at a field station in French Guinea. No pregnancy or offspring resulted. (It’s likely that he used artificial insemination, though we’re not sure!) Then, later in Russia, Ivanov proposed to do the reverse experiment, inseminating human females (presumably artificially!) with chimp sperm. Fortunately, the Russians stopped the experiment, and Ivanov, for other reasons, eventually was sent off to the gulag. (There’s a long video about the work here, but I haven’t watched it.)
There are many reasons why we shouldn’t produce such hybrids. First of all, they probably wouldn’t develop anyway given the genetic divergence between the species and the fact that the one experiment trying this already failed (of course, the insemination could have been botched). But we simply can’t predict how a hybrid would develop: whether it would form an intermediate animal or some bizarre creature deeply screwed up by developmental anomalies. The different chromosome numbers would certain make the animal sterile. Given our gross ignorance of what such a creature would be like, even if it could develop, it’s best not to try.
And of course there are the ethical problems. While I think chimps should be afforded many of the rights enjoyed by humans, including the right not to be experimented on, or to not be caged up in zoos, a hybrid human-chimp would cause additional ethical dilemmas—and big ones. If it were semi-human, with a “hybrid mentality”, what rights would it have? How would it be treated? Would scientists keep it captive to do biochemical and behavioral experiments? While it’s okay to make hybrid sunflowers, this is a different kettle of primates altogether.
Yet David Barash, an emeritus professor of psychology at the University of Washington and a writer of popular books, suggests, in a new article in Nautilus (“It’s time to make human-chimp hybrids“), that we should go full speed ahead in making humanzees. His reasons, though, are not even based on scientific curiosity: they’re simply to prove a point—that humans are outlier creatures, not really part of evolution but exceptional, and perhaps created by God. Somehow humanzees will show that to be wrong. Here’s his rationale (my emphasis):
Of course, all that we know of evolution (and by now, it’s a lot) demands otherwise, since evolution’s most fundamental take-home message is continuity. And it is in fact because of continuity—especially those shared genes—that humanzees or chimphumans could likely be produced. Moreover, I propose that the fundamental take-home message of such creation would be to drive a stake into the heart of that destructive disinformation campaign of discontinuity, of human hegemony over all other living things. There is an immense pile of evidence already demonstrating continuity, including but not limited to physiology, genetics, anatomy, embryology, and paleontology, but it is almost impossible to imagine how the most die-hard advocate of humans having a discontinuously unique biological status could continue to maintain this position if confronted with a real, functioning, human-chimp combination.1
. . . it seems equally likely that faced with individuals who are clearly intermediate between human and ape, it will become painfully obvious that a rigid distinction between the two is no longer tenable. But what about those presumably unfortunate individuals thereby produced? Neither fish nor fowl, wouldn’t they find themselves intolerably unspecified and inchoate, doomed to a living hell of biological and social indeterminacy? This is possible, but it is at least arguable that the ultimate benefit of teaching human beings their true nature would be worth the sacrifice paid by a few unfortunates.
“A few unfortunates?” First of all, Barash says we already know about the continuity of all life, including our common ancestry with chimpanzees. Exhibiting a creature that’s half of each, and might be severely screwed up and deformed, isn’t going to convince people otherwise. What possible effect could exhibiting a humanzee do to those who think that humans are special, whether we be created by God or simply think we’re entitled to control the beasts and fowls of Earth (not to mention the forests)? Thinking a hybrid would change everyone’s mind is wishful thinking.
Barash recounts the story of Ivanov, whose experiments aren’t well known (that’s why I described them in WEIT). That’s interesting, of course, but then Barash goes on to push for continuing Ivanov’s work by producing humanzees. He’s not sure if it should be done by direct hybridization (artificially, of course; we can’t have humans bonking chimps), or by forming a chimera: using embryos of humans and chimps (or inserting genes from one species into the other species via CRISPR). He favors the production of chimeras, but we’re nowhere near doing that. In my view, we shouldn’t do it—not without a rationale better than Barash’s.
At the end, Barash goes into a bit of a rant how we need to produce these animals because they’ll—wait for it—refute religious claims about human excepti0nalism. But really, do we need to spend so much dosh and go to so much trouble to prove what we already know: that we are evolved creatures, splitting from our closest living relatives about 6 million years ago? Making a sad and possibly sick or deformed humanzee, merely to satisfy Barash’s need to show that Genesis is false, seems a waste of both time and money. So this advice, in Barash’s last few paragraphs, strikes me as foolish:
Looking favorably on the prospect of a humanzee or chimphuman will likely be not only controversial, but to many people, downright immoral. But I propose that generating humanzees or chimphumans would be not only ethical, but profoundly so, even if there were no prospects of enhancing human welfare. How could even the most determinedly homo-centric, animal-denigrating religious fundamentalist maintain that God created us in his image and that we and we alone harbor a spark of the divine, distinct from all other life forms, once confronted with living beings that are indisputably intermediate between human and non-human?
In any event, the nonsensical insistence that human beings are uniquely created in God’s image and endowed with a soul, whereas other living things are mere brutes has not only permitted but encouraged an attitude toward the natural world in general and other animals in particular that has been at best indifferent and more often, downright antagonistic, jingoistic, and in many cases, intolerably cruel. It is only because of this self-serving myth that some people have been able to justify keeping other animals in such hideous conditions as factory farms in which they are literally unable to turn around, not to mention prevented from experiencing anything approaching a fulfilling life. It is only because of this self-serving myth that some people accord the embryos of Homo sapiens a special place as persons-in-waiting, magically endowed with a notable humanity that entitles them to special legal and moral consideration unavailable to our nonhuman kin. It is only because of this self-serving myth that many people have been able to deny the screamingly evident evolutionary connectedness between themselves and other life forms.
When claims are made about the “right to life,” invariably the referent is human life, a rigid distinction only possible because of the presumption that human life is somehow uniquely distinct from other forms of life, even though everything we know of biology demonstrates that this is simply untrue. What better, clearer, and more unambiguous way to demonstrate this than by creating viable organisms that are neither human nor animal but certifiably intermediate?
How about just pointing to the skeleton of Australopithecus afarensis?

n.b. For what it’s worth Nautilus was originally a Templeton-funded website, but now, with the loss of some grants (presumably Templeton doesn’t want humanzees either), it’s having trouble paying off its writers.




