The MFAP Hypothesis of Human Origins rides again!


A couple of years ago, I wrote a rebuttal to a crackpot claim for the origin of humans, which I called the MFAP Hypothesis. "MFAP" is short for "monkey fucked a pig", which actually pretty much summarizes the whole idea. Eugene McCarthy (no, not that Eugene McCarthy) assembled a list of superficial similarities between humans and pigs -- hairlessness, protruding noses, "snuggling", that sort of thing -- and concluded that a miscellany of appearances overwhelmed the actual genetic relationships and the absence of a feasible genetic mechanism to permit human-porcine hybridization to lead to the inevitable conclusion that, in the distant past, our primate ancestors bred with pigs.

It's got to be a joke, but McCarthy is very, very serious, and claims that, because he has a Ph.D. in genetics, it must be a reasonable hypothesis.

It's obviously bogus. I tried to explain that. Donald Prothero tried to explain it. Michael Egnor thought it was as plausible as the idea that humans are evolved apes, so he does have that one rather elliptical bit of support from a fellow crackpot.

But now, after years of mumbling, McCarthy has assembled a rebuttal of sorts. His first efforts are mainly attempts to discredit my competence.

First, please note that PZ Myers is neither trained as a geneticist, nor is he an expert on hybridization. I myself have a masters and Ph.D. in genetics from one of the leading genetics departments in the country (the University of Georgia's) and I've spent a lifetime investigating hybridization. According to Wikipedia, PZ Myers has a B.S. in biology and a Ph.D. in biology. The same article says that he studies zebra fish in connection with his research in the field of developmental evolutionary biology.

Uh, zebrafish? Vertebrate model system known for its utility as a tool for studying vertebrate genetics? I've also worked with Drosophila, and have been teaching genetics since the 1990s.

So, OK, let's just say I know zilch about genetics. Doesn't matter; my original criticisms still stand, and most importantly, his claim that two species separated by 80 million years of evolution can interbreed ought to be testable. If not by directly breeding humans and pigs, by tests with pigs and rhesus monkeys, or pigs and cats, or cats and dogs, or mice and honey badgers, or whatever off-the-wall combination you can think of. There are genetic barriers to hybridization, and this self-proclaimed expert in hybridization just waves them away.

Do the experiments. Show me that we're all wrong about the ability of distant species to interbreed.

He then starts going through the strange list of attributes that he claims supports his hybridization theory: cancer incidence, for instance.

In short, then, I claimed that cancer is rare in non-human primates and experts in the field do in fact say that cancer is rare in non-human primates. Why, then, does PZ Myers complain? Isn't it he who's being false?

I didn't say it was false: I even include the low incidence of melanoma in a list of differences between us and apes. I said it was non-unique and irrelevant. Cancer rates are lower in non-human primates than in us because cancer is a disease of aging. It's also to a degree a consequence of exposure to human-created carcinogenic agents. And that cancer is rare in other primates is not evidence that we are descended from pigs, which also have lower rates of cancer.

Likewise, in connection with female orgasm, I quote Desmond Morris, a well-known zoologist and ethologist, as follows "female orgasm in our species is unique amongst primates…If there is anything that could be called an orgasm [in nonhuman primates], it is a trivial response when compared with that of the female of our own species." So again, I've attributed the claim to a competent expert. So why does Myers say that I've listed these two traits "falsely"? Indeed, it seems that his own claim about my falseness is false.

Again, I said it was irrelevant. I'm not particularly impressed with Morris, whose reputation rests on being a prolific pop-biologist, and I don't know why McCarthy should be, either -- he got his degree with research on sticklebacks, a mere fish with no possible connection to genetics.

Orgasms are not unique to humans. Even if they were, it's a non sequitur -- that observation wouldn't be evidence for pig hybridization.

And I'm not sure why Myers should consider it "bizarre and irrelevant" that pigs snuggle and chimpanzees do not. To me, it's just another trait that an expert, in this case Jane Goodall, cites as distinguishing humans from chimpanzees. An it's also one that links us to pigs.

Chimpanzees are social animals that certainly do "snuggle" with one another. A litter of puppies also cuddle up together…does that imply that we are descended from puppies?

He does go on and on with this nonsense, and then gives me an ironic challenge:

What I would say to PZ Myers is: "Stop all the speculating and propounding and explain why the traits that distinguish us from chimpanzees consistently link us with pigs. Offer a different hypothesis accounting for our affinity to pigs. Put up or shut up!"

O Geneticist and Expert in Hybridization: you're the one speculating and making the outrageous claim. I think the onus is on you to do the experiment, not me.

I'm not going to Offer a different hypothesis accounting for our affinity to pigs, because I see no particular affinity between humans and pigs other than the ones due to our common status as mammals. I'm not seeing it on a molecular level in any cladograms comparing pig and human genes, either. My hypothesis is that there is no particular affinity, that the two species have been diverging since the time of their last common ancestor in the Mesozoic, and that Eugene McCarthy is a very silly man.


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"You're the one...making the...claim. I think the onus is on you to do the experiment, not me." Right on! That is what all these pseudoscientists do; try to shove the burden of coming up with evidence to show their claims are wrong onto those who are pointing that out. It is the person or people making the claim who have the burden of coming up with evidence to show they are right.

By Larry Esser (not verified) on 06 Dec 2015 #permalink

I think McCarthy needs to run that experiment himself, though I have no idea how he'll get the sow to sign the consent form...

A little off topic, but in botany we deal with such bizarre chimeras as a matter of course - intergeneric hybridization is relatively common, and even interfamilial hybridization sometimes occurs. Hybridization between species with differently numbered karyotypes produced most familiar gramiform crops. This is actually a pet peeve of mine - when "zoocentric" biologists dismiss eccentric hypothesis out of hand. Obviously mfap lacks credibility, but not due to in-principle considerations as implied by most commentary on the issue - it is probaly more plausible than most would care to admit (which is of course different than saying it is correct).

By blacklodgebob (not verified) on 09 Dec 2015 #permalink


While I agree that plants do display more tolerance for karyotype variability and hybridization in general, this tolerance does not extend well to animalia in most cases. Particularly where fertility is concerned. Although certain types of fish seem to have greater tolerances and amphibian hybrid complexes are well documented. This extends to a degree in sea urchins as well. But, overall hybridization is not as well tolerated as it is in plants. I hope Dr.McCarthy takes on the challenge posed here and decides to accept the burden of proof.....and all the consequences that entails.

Let us assume that monkeys and pig copulation is highly unlikely to produce viable progeny. In Diseases for Space, Carl Sagan possibly suggested viruses can infect genes with genetic material from other species in a way a little more likely of success. Does this seem like a possibility?

So why hasn't this theorist found someone who will take DNA from pig, chimp, and human, and compare them? Isn't that easy nowadays?

By Hank Roberts (not verified) on 19 Dec 2015 #permalink