This past week I’ve been getting all sorts of questions from people about the strange study just reported in the British tabloid The Daily Mail. Some scientist in Georgia claims that humans are formed by hybridizing apes and pigs. At first, I thought it was a hoax or some outrageous parody or Poe, or possibly an example of the media distorting the original results beyond all recognition, because it’s so crazy that it’s hard to imagine any legitimate scientist making that claim. But a little digging shows it’s not a hoax or parody: there is a crackpot scientist out there who had made the claim, and naturally the media loved it and published it without any fact-checking (as usual).
First, the assertion: a Georgia geneticist, Dr. Eugene McCarthy (a sad coincidence that he has the same name as the groundbreaking anti-Vietnam War presidential candidate in 1968) claims that humans have evolved by hybridization between a boar and a female chimpanzee. Anyone trained in genetics or evolution will immediately do a double-take reading this, because it so far off the edge of crazy that it cries out to be examined further. So you click on the link, and what do you find? Is there a ton of genetic data, peer-reviewed and published in a respectable journal, that would allow us to take the claim seriously? No, not even close. Not only is it a wild claim made on a personal website without any peer review (the classic sign of crackpot science), but the evidence is not genetic at all, even though the author claims to be a legitimate geneticist! Once you go to the original link, you find that it’s a list of superficial fleshy similarities between the soft tissues of pigs and humans: naked skin, thick skin, sweating, protruding cartilaginous nose, eyebrows, heavy eyelashes, short thick upper lip, earlobes, and a long list of minor similarities in the skeleton and rest of the anatomy. Anyone who is a vertebrate anatomist familiar with phylogenetics will immediately notice that these are highly correlated characters that all occur together when a a lineage becomes less hairy, or else they are symplesiomorphic features shared by most placental mammals. What the list doesn’t point out is all the huge and fundamental differences in the skeleton he doesn’t mention, especially the unique “cloven-hoofed” even-toed hands and feet of pigs with the “double-pulley” astragalus bone, which unites them with all other artiodactyls (the “even-toed” hoofed mammals), a feature seen in no primate or any other organism on earth; and the huge differences in the skull, braincase and ear region that allow any competent anatomist to immediately distinguish a pig from any primate. Once again, it’s a classic case of someone not trained in a given field (anatomy and phylogenetics) dabbling in someone else’s orchard, cherry-picking data he doesn’t understand, and ignoring everything that flatly contradicts his ideas. Surprisingly, the one thing I would expect him to list—the low-cusped bunodont dentition of pigs and primates—isn’t mentioned (again, it’s convergent evolution since pigs and many primates have an omnivorous diet, as do bears and peccaries, who also convergently evolve bunodonty). As P.Z. Myers pointed out (he calls it the “MFAP hypothesis”, “monkey fucked a pig”), it’s very similar to the long-discredited “aquatic ape” theory of Elaine Morgan—cherry-pick a handful of superficial anatomical characters associated with loss of body hair in apes and tell a just-so story, ignoring all the rest of the evidence.
So what about the genetic evidence? This is the biggest surprise of all: this geneticist doesn’t mention it once! For good reason: there is no genetic evidence in favor of the idea, and mountains of genetic evidence against it. As anyone who remembers the early days of molecular phylogeny knows, one of the oldest techniques for telling how closely related two animals are is to attempt to hybridize their DNA. Human and chimp DNA hybridizes easily in a test tube, since it’s roughly 98% the same. Other primates don’t hybridize as well, since they share fewer common alleles with us. Long ago, the early DNA hybridization studies showed that pigs and primates have very few alleles in common, about the same as primates share with any other distantly related order of placental mammals. As both P.Z. Myers and “Artiofab” pointed out in recent blogs, however, there are huge problems hybridizing pigs and chimps. Pigs have 38 chromosomes, chimps have 48. You simply can’t have a fertile hybrid with this many mismatched chromosomes. Even human/chimp hybrids are impossible for the same reason, because we have different numbers of chromosomes. And huge sections of chimp and pig DNA are radically different, so even if he did manage to separate the strands in a lab and hybridize them, they would not continue to develop. Then there’s the problem with the sperm of pigs even recognizing the ovum of a chimp, since the eggs have their own protein coats that are specific to their species, and prevent insemination from alien sperm. In addition, there’s the problem with immunological rejection: any tissue that is foreign to us is attacked by antibodies before it can get very far. This is why transplants of organs between species is very difficult. (Immune rejection is the reason for the failure of creationist Leonard Bailey’s unethical experiment in replacing the defective heart of “Baby Fae” with a baboon heart, rather than a heart from a more closely related organism like a chimp). The pig’s sperm would be wiped out by a big immune reaction, just like any other invading virus or bacterium or foreign body. Not to mention this big problem: how in the world does he imagine that a female chimp mated with a boar? This guy definitely has an overactive imagination!
These genetic and anatomical differences are so difficult to overcome precisely because both lineages have been separated since the early radiation of the placental mammals, probably in the latest Cretaceous 70-80 m.y. ago, when dinosaurs still roamed the planet. The two groups diverged long ago and have been evolving separately since then, so there’s no way lineages from these two very different parts of the placental family tree can ever hybridize. Again, the long list of mistakes he makes in citing shared plesiomorphic characters shows that this guy is not up to date on phylogenetic thinking. (Even more bizarre: he thinks platypuses are crosses between birds and mammals, even though those two lineages have diverged 300 m.y. ago).
There’s no point in beating this ridiculous scientific argument to death any further. But this raises the next question: who is this Eugene McCarthy, and how did he go off the deep end of crackpot science? According to his website, he appears to have earned a legitimate Ph.D. in genetics from the University of Georgia in 2003, but contrary to claims made in the media, he is not affiliated with University of Georgia any more. I’m sure they don’t want his name associated with their distinguished program now. (Sadly, most of the media coverage falsely hypes his reputation, including some headlines which call him “the world’s leading geneticist”). Instead, he is an independent working out of his house, making claims on the internet and hasn’t published a peer-reviewed item in almost a decade (and that was about legitimate areas where hybridization does occur in animals). As his website points out, his current work has not met with a good reception in the scientific community, a fact which he claims (as do all crackpots) is due to a great conspiracy of scientists to suppress his radical, groundbreaking flashes of genius, a trope so overused it has its own name: the Galileo fallacy. (First sign of a crackpot: self-publication of grandiose claims. Second sign: no peer review because they are all conspiring against him). As he says on his website, www.macroevolution.net:
During my years at the genetics department, I became increasingly dissatisfied with the standard explanation of evolution. The more I read about fossils, the more convinced I became that Darwin’s account of the evolutionary process was fundamentally flawed. Moreover, in my study of hybrids I became aware that an alternative way of thinking about evolution, what I now call “stabilization theory,” could do a better job of explaining the available data.
Uh-oh, another one of those people who don’t understand basic evolutionary science trying to come up with solutions to problems that don’t exist. For one thing, he’s clearly not read anything recent about fossils. As I pointed out in my 2007 book on the topic, we have an excellent fossil record of both pigs and primates (including humans), and no such crazy hybridization scheme is supported by the fossil record: we have plenty of transitional fossils which show progressively more human-like fossils, going back to over 7 m.y. ago—and not once is a pig required to explain any of it. Instead, he seems to have drunk the Kool-Aid of creationism, which makes a big deal about “macroevolution” as being impossible, even though that’s been shown to be false many times.
But is this guy a creationist? Nope, he’s just another crackpot trying to do his own version of evolution without benefit of learning from the rest of science, or listening to more rational scientists (who should have trained him better years ago). In fact, he’s not liked on any of the creationist websites either (this kind of claim is even more repugnant to them than the idea that we are descended from common ancestors with apes and other primates). Unfortunately, creationists treat him as a legitimate scientist, and lump his crazy ideas in with real science to smear legitimate ideas in evolutionary biology. Then there are the crazies out there like conspiracy nut Alex Jones, who took the story as an excuse for a huge anti-science rant, giving his audience even more reasons to distrust science (despite the facts that science rejects clowns like McCarthy). Even stranger, he seems to have offended a lot of Muslims, since the pig is a vile animal in their culture, and most are antievolutionary anyway. (Not to mention the passages from the Quran that claim Jews are descended from pigs). So he has no natural audience that I can think of, and I would be worried about retaliation from the Muslim community, especially if they issue a fatwa on him.
Even more surprising, this idiotic story appeared for the first time back last July, and made no splash in the media at all. So why is it being reported again last week? It is well known that “The Daily Fail” is a cheesy tabloid full of garbage, hostile to science, and often running a lot of pseudoscientific nonsense including stuff from creationists and cryptozoologists and climate deniers. Who knows why it was reprinted six months after it was first reported, but now lots of other media (both print and online) from around the world are picking up this nonsense, and giving it unwarranted exposure. Even Jimmy Kimmel used it as the basis for an outrageous but hilarious sketch on his show. As usual the media play to the sensationalist and the bizarre, without doing even minimal fact-checking, because “if it bleeds, it leads”. As I’ve pointed out in previous posts about the ridiculous story of “Kraken” arranging bones into art, or the stupid “documentaries” about mermaids and living versions of the extinct great white shark Carcharocles megalodon on cable TV, the media is full of these “shocking” stories that will grab an audience no matter how scientifically worthless they are. This is par for the course in the modern media, and it seems we are all helpless to stop it.
But what about the side effects on the public’s perception of science? As “Artiofab” points out:
Publicizing ridiculous independent, unpublished scientific hypotheses at the same level as academically-scrutinized published scientific papers confuses the lay audience into thinking that all scientific research is similarly incompetent. In the Information Age, wherein everyone has the same ability to throw something online, not discriminating between “this is something some loonie put online” and “this is a well-researched study reviewed by independent authorities” leads to all kinds of pseudoscientific nonsense, some of which just plain kills people.