The Hybrid Theory

A Rebuttal of Prothero’s Criticisms


The well of true wit is truth itself.
—George Meredith

Since so much misinformation has been put out about my alternative theory of human origins, I’ve decided to start writing a series of responses, lest anyone mistake my silence for an inability to address the various objections that have been raised. I thought the most straightforward way of doing this would would be simply to copy each article criticizing the theory, paste it into a page on this website, and then insert my responses. The first of these articles, entitled HOGWASH!, which I address on this page, is by American paleontologist and geologist Donald R. Prothero. It was first published on Skepticblog on Dec. 12, 2013, and can be read here. Please note that Dr. Prothero is neither trained as a geneticist, nor is he an expert on hybridization. The following is a copy of his article, which castigates not only my theory, but me personally, as well. The text is a verbatim copy-and-paste of his original except in that my comments are inserted at the relevant points within his text. So then, Dr. Prothero, let's begin!


by DONALD PROTHERO, Dec 04 2013

It occurs to me that a better title for Dr. Prothero’s article would be WISH-WASH! (which my dictionary defines as “insipid talk or writing: claptrap, twaddle, thin drink”). This I say because the entire piece, from beginning to end, strikes me as mere pontificating, a product of little labor, small thought and no research. Worse, it’s just what Thomas Henry Huxley (quoted in Wollaston, 1921, p. 119) famously said that Bishop Wilberforce did, that is, making use of impressive powers of communication “to try and burke, by a display of authority, a free discussion on what was, or was not, a matter of truth.” And, of course, Huxley also commented that “he would sooner claim kindred with an ape” than with such a man. I agree with that sentiment, except that I suppose I’d have to substitute “pig” for “ape,” and “Dr. Prothero” for “Bishop Wilberforce.”

One might wonder why I’ve waited so long to respond to this amalgamation of claptrap, but it’s so riddled with mistakes that I’ve dreaded having to write anything long enough to address so many errors. But here goes!

Our ancestor? Not likely…

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.

"Some scientist" (That’s me! Gene McCarthy! :D)

rise of man

The theory in a nutshell:

Specifically, I suggest that the facts we have from observation best fit the supposition that a chimpanzee- or bonobo-like animal anciently crossed with a pig to produce an offspring that then mated back ("backcrossed") to a chimpanzee. The theory then posits that further backcrossing to chimpanzee occurred in subsequent generations, so that the amount of pig in the descendant hybrids was greatly diluted so that they became much more like chimpanzees than pigs. However, as might be expected, certain traces of pig would remain. Humans, it proposes, emerged from the resulting highly variable hybrid population.

But, Dr. Prothero, I do not claim "that humans are formed by hybridizing apes and pigs.” Here, you misrepresent me. I merely offer a theory that explains our origins in that way. Actually, the explanation is a bit more complicated than what you describe (see sidebar at right).

Dr. Prothero, forgive me for saying so, but there’s a big difference between claims and a theories. The former are the domain of religion, the latter, of science.

At first, I thought it was a hoax or some outrageous parody or Poe,

Here, you’re absolutely correct. It’s not a hoax or parody. It’s carefully documented and serious from beginning to end (although I do realize that it will always seem like a parody to someone who hasn't absorbed the arguments and the evidence presented). I’m sorry you find it outrageous. Personally, I see it merely as entertaining a hypothesis.

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.

Actually, the Daily Mail never contacted me for comment, so there are some distortions and misrepresentations in their account of the theory. But the same is true of you, Dr. Prothero. You never contacted me and you have attributed certain things to me that I’ve never said. And as for the craziness you perceive, Mark Twain once commented, and I think very accurately, that “In all matters of opinion, our adversaries are insane.”

But a little digging shows it's not a hoax or parody: there is a crackpot scientist out there who had made the claim,

“Crackpot scientist”
(That’s me again! :D)

Dr. Prothero, as I’ve said, there is a large difference between claiming a fact and proposing a theory. With regard to our ancestry, I do only the latter. What I do claim is that there is a great deal of data that appears to be consistent with that theory (and inconsistent with the theory that we are descended from the apes alone). And though I do realize there are many conservative scientists who don't want to hear anything that might rock the boat, I will also say that if we are to make any progress in science, we need a few fresh ideas now and then. Just because the theory is radically inconsistent with the theory that you embrace doesn't make me a crackpot. If that were true, then anyone who proposed an idea that disagreed with your views, or with what you pronounce to be the view of all “sane” scientists, would be a crackpot. That would give you a little too much power. The theory might (or might not) be wrong. But whichever is the case, it doesn't say anything about whether I’m cracked. The only thing that would do that would be if I made a definite claim and offered no evidence and arguments to support it. As it is, I do the opposite. I offer only a theory and I present a lengthy and detailed argument supported by a mountain of evidence.

and naturally the media loved it and published it without any fact-checking (as usual).

I have two issues with this comment. First, I find it misinformed to say “as usual.” My wife is a long-time professional journalist, and I have seen the great lengths that she and her colleagues go to in order to check facts. In comparison, I would say most scientists that I know are slackers. Certainly, you haven't done much in the way of fact checking for your article, Dr. Prothero. And I challenge you to find even a single false statement that I have made, anywhere on this website. By “false,” I do not mean inconsistent with your beliefs. Rather, I mean factually and demonstrably false or, to put it another way, inconsistent with observation. Second, as to the media loving it, my experience has been that most journalists I’ve talked to have, if anything, erred on the side of caution.

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.

(There’s that “claims” again!) :D

I do have to agree, Dr. Prothero, with your implied assessment of Senator Eugene McCarthy. I’ve always been an admirer myself. Too bad that you seem to have a contrary opinion of me.

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.

I am trained in genetics and evolution. I hold a Masters and Ph.D. in genetics, which I obtained at the University of Georgia Department of Genetics studying under some of the leading figures in genetics and evolutionary biology, several of whom are members of the National Academy of Sciences. So far as I know, however, you are not trained in genetics. How is it, then, that you feel qualified to make such pronouncements?

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!

Again, I am “a legitimate geneticist.” You, Dr. Prothero, to my knowledge, are not. And since you are not a geneticist (again, correct me if I’m wrong), I’ll try to explain the genetics of backcrossing in a way that even you, without any background in genetics or any special knowledge of hybridization, will understand.

Why genetic analysis of this question is difficult:

Now in the specific case of a hypothetical pig producing hypothetical offspring with a hypothetical ape, it would be very easy to determine via genetic analysis whether that offspring was a pig-ape hybrid. After all, half its chromosomes would be derived from an ape and half from a pig. Moreover, those chromosomes would be intact.

However, if that hybrid backcrossed with an ape and produced an offspring, already in that second generation things would be a little more complicated. First because, the proportion of genetic material derived from pig would be reduced to about 25 instead of 50 percent of the genome (this is a mean expectation, the actual fraction would vary from one backcross individual to another).

Moreover, in any given individual produced by this first-generation backcross (i.e., in any given B1 hybrid), one would expect even those DNA sequences derived from pig to be converted to a certain extent toward the chimpanzee version of the sequence. This is because, during prophase I of meiosis in the B1 hybrids, single-stranded pig-derived DNA would form heteroduplexes with single-stranded ape-derived DNA and pass through Holliday junctions (the effects of this process are explained at length elsewhere on this website). But suffice it to say that passing through these junctions would tend to convert any pig-derived DNA sequences toward the chimpanzee version of that sequence (on average 50 percent of the mismatched pig nucleotides would be converted to match the chimpanzee nucleotide).

And then, with each further generation of backcrossing, the proportion of pig-derived DNA would be reduced by 50 percent, and the level of similarity of that DNA to pig would also be reduced by 50 percent. So very rapidly — even if the parents in the original cross (chimp and pig) differed by, say, 20 percent at the nucleotide level — in about three generations of backcrossing to chimpanzee, you would end up with an animal that was 98 percent similar to chimpanzee in terms of its nucleotide sequences. So ordinary approaches to the analysis of genetic data would tell you nothing.

But even leaving these theoretical expectations aside, we know that identifying the original parentage of later-generation hybrids is a difficult genetic task, even when you’re not talking about hybrids produced by modern-day breeders and not about a hybridization even that occurred millions of years ago.

And yet, for reasons I’ve explained at length elsewhere, you might have very large phenotypic differences due to differences in gene dosage (and such differences do often arise in later-generation hybrids), even if sequence differences were minimal. For example, the various differences between someone with Down’s syndrome and an ordinary human being, result not from sequence differences, but from differences in gene dosage. In terms of sequences, Down’s and non-Down’s individuals are identical.

But first let me say in general that different problems can require different approaches to their solution. One example I’ve often cited is the prosecution of criminal cases. For some crimes, fingerprints can be found on the crime scene and can be introduced in evidence. However, there are many cases where no such evidence is available and it’s necessary for the prosecutor to obtain a guilty verdict by other means. For example, a man wearing gloves might hold up a bank. There would be no fingerprints on the scene but witnesses and video recordings of the robbery might well suffice for a conviction. In the same way, in certain cases, genetic analysis is an easy and useful approach. But it isn't always—just as fingerprint evidence isn't useful in those criminal cases where the perpetrator wears gloves. Now then, please read my explanation of the genetics (in the sidebar at right).

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.

Several problems here. First, if by “superficial” you mean “external,” then you’re simply wrong. I list many internal traits, about as many as external. But if you mean “non-essential” or “unimportant” — which I suspect is the case — then that’s just your opinion. In other words, you have not explained why such traits should be dismissed. So for “superficial similarities,” we can read “similarities summarily dismissed by Dr. Prothero.”

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.

Dr. Prothero, are you saying that you are a vertebrate anatomist? I thought you were a paleontologist. But leaving that aside, such arguments don't cut the mustard. Let’s take your second explanation first. For people who believe that the history of evolution can be accurately represented as a tree (a phylogeny), a symplesiomorphic feature is an ancestral feature that is shared by two or more extant taxa. So it seems you’re saying that these features I list, which are found in humans but not in chimpanzees (and not in other non-human primates, for that matter), are shared by most placental mammals. The point is that these human traits are not present in (not shared with) other primates. So this supposed explanation doesn't really explain anything at all, does it? That is, it doesn't explain why these human traits are all found in pigs but not in non-human primates. But the theory that we’re pig-chimp hybrids does.

As to your first explanation, if these are highly correlated traits that supposedly occur along with hair loss, why don't we see them consistently in other types of naked mammals, such as whales, seals or naked mole-rats? Again, it’s not a good explanation of the fact that we consistently see in pigs so many traits that distinguish us from other primates.

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.

Dr. Prothero, I myself can immediately distinguish a pig from any primate. But it’s not rocket science. The point, which you seem to be missing, is that in identifying a putative hybrid of unknown parentage, the usual method is not to compare the putative parents (in this case that would be comparing a pig and a primate, as you are doing), but rather to compare the traits of the putative hybrid to those of the putative parents in order to see whether the traits of the hybrid can all be assigned to one or the other of the two parents. If such is the case, biologists regularly assume — at least in the case of less controversial crosses — that the organism is a hybrid derived from crossing of those two parents. But they reach this conclusion because it mingles their traits, and not because the putative parents are distinguishable. Your argument is like saying:

Cloven hooves: And as for your much-vaunted trait (cloven hooves), which is supposed to set artiodactyls apart from all other mammals: Are you aware that pigs are variable in this respect? There are various breeds of hog, so-called mulefoot pigs, that have a solid hoof like horses do, which, remember, are non-artiodactyls. This trait often arises as a spontaneous mutation in pigs. In fact, it’s a single-gene mutation, which in my opinion suggests it’s not the profound distinction you suggest (learn more about mulefoot pigs).
  1. A donkey and a horse are very different animals that expert horse breeders can easily distinguish;
  2. A mule has long ears and says hee-haw;
  3. No horse has long-ears or says hee-haw;
  4. Ergo, mules are a kind of donkey.

Do you see that there’s a problem with this line of reasoning?

Once again, it’s a classic case of someone not trained in a given field (anatomy and phylogenetics) dabbling in someone else’s orchard,

Dr. Prothero, I spent long, and not particularly pleasant, years formally studying phylogenetics in graduate school. Moreover, in studying for the last thirty years anatomical traits relating to the possibility that humans might be hybrids, I have developed a fairly extensive knowledge of comparative anatomy. But even after all my studies, I’d never venture to describe it as my orchard.

cherry-picking data he doesn’t understand,

My method in collecting those traits was to scour the literature for years for any traits that experts — often your comparative anatomists (so it's their orchard and their cherries!) — said distinguished humans from chimpanzees and other primates. It’s an exhaustive list (or at least, I've done my very best to make it exhaustive). I cite my sources. I haven’t left anything out, at least not intentionally.

and ignoring everything that flatly contradicts his ideas.

Wrong again. I’ve actually devoted two long chapters to the only two traits, bipedality and our large brain size, that didn’t seem to jive with the hypothesis that we are pig-chimp hybrids, that is, those two traits are found in humans and not in other primates, but also not in pigs. According to the hypothesis, human traits not found in chimps, should be found in pigs. As I say, however, I account for these discrepancies in those two chapters (here and here).

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).

Here, Dr. Prothero, you betray the fact that you haven’t actually taken the time to read what I have to say, or at least it seems you haven’t read it carefully. The pig-chimp theory has always included a discussion of this topic with respect to humans, apes, and pigs (see this page). I quote from it at length in the section inserted immediately below (my rebuttal of your arguments continues immediately thereafter).

Excerpt from a discussion of pig molars found elsewhere on this site:

In human beings, “the molar cusps are blunt [“bunodont”] rather than sharp [“crenate”] as in apes” (Romer 1966). [I’ll assume, Dr. Prothero, that you as a paleontologist know who Romer is!] Pig molars are also bunodont, and so similar to those of human beings that fossil pig teeth have actually been mistaken for those of prehistoric human beings.

One such molar, found in Nebraska in 1917, prompted scholars to name a new genus, Hesperopithecus or “Ape-Man of the West” (see Figures 8.7 and 8.8). This tooth, which was thought to date to the Pliocene (which ended about 1.6 million years ago), became a center of controversy, both in the popular press and in academe. By 1924, prominent English anatomist Sir Grafton Elliot Smith (1924, pp. 6-7) had joined the bandwagon of scientists trumpeting what had by then been dubbed Nebraska Man: “The discovery of this tooth may seem rather a frail and hazardous basis upon which to build such tremendous and unexpected conclusions; and many, if not most, scientists have grave doubts as to the justification of such an interpretation. But the specimen was discovered by a geologist of wide experience, and its horizon has been satisfactorily established. Moreover, the determination of its affinities and its identification as one of the higher primates closely akin to the Ape-Man of Java, Pithecanthropus, has been made by the most competent authorities on the specific characters of fossilized mammalian teeth, Professor Osborn and Drs. Matthew and Gregory, who not only have had a wider experience of such material than any other paleontologists, but also are men of exact knowledge and sound judgement.”

After the furor had continued unresolved for three years, Osborn (1925), then director of the American Museum of Natural History, was prompted to exclaim, “In the whole history of anthropology no tooth has ever been subjected to such severe cross-examination as this now world famous tooth of Hesperopithecus. Every suggestion made by scientific skeptics was weighed and found wanting.” In the same year (1925), this tooth was actually introduced in court as evidence for the defense at the Scopes “monkey trial.” Imagine the blush that came to erudite cheeks when further excavation revealed that all the great ballyhoo had been inspired by the humble molar of a pig! “An ancient and honourable pig no doubt,” quipped The Times when the news came out, “a pig with a distinguished Greek name, but indubitably porcine”

The Times, London: “Hesperopithecus Dethroned,” Feb. 25th, 1928.

As P.Z. Myers pointed out (he calls it the “MFAP hypothesis”, “monkey f[*****] 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.

As I’ve already mentioned, I’ve done my best to make the list exhaustive, so it’s not cherry picking.

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.

Who's picking cherries now? I discuss, at length, the genetics bearing on this subject here and here, so I won’t repeat myself here, except to say that your comments are misleading and seem to reflect that you haven’t even bothered to read, let alone absorb, that discussion. Perhaps you’re not even aware that it exists?

As both P.Z. Myers and “Artiofab” pointed out in recent blogs, however, there are huge problems hybridizing pigs and chimps.

I’ve responded to P.Z. Myers here. As for the anonymous “Artiofab,” who knows who he (or she) might be? Even Dr. Prothero, who cites this digital will-o’-the-wisp, realizes the need for quotation marks. (This is exactly the sort of wish-wash I mentioned at the outset of this critique.) But I'll say no more. This spooklight “Artiofab” merely parrots Myers and is therefore best ignored.

Pigs have 38 chromosomes, chimps have 48. You simply can’t have a fertile hybrid with this many mismatched chromosomes.

Counterexamples to the claim that hybrids from parents with differing chromosome numbers are always sterile:

Counterexample #1: Donkey (2n = 62) x Mountain Zebra (2n = 32). The difference in chromosome counts here is not 10, but 30. And yet this cross produces partially fertile hybrids (documentation).

Counterexample #2: White-collared Lemur (2n = 48) × Brown Lemur (2n = 60). This cross, too, produces partially fertile hybrids, despite the diploid chromosome counts differing by 12 (documentation).

Counterexample #3: Goat (2n = 60) × Sheep (2n = 54). It's well documented that goats and sheep can cross and that the female hybrids occasionally produce offspring (documentation).

Counterexample #4: Sitatunga (2n = 30) × Bongo (2n = 33♂/34♀). A backcross to Sitatunga has been reported (documentation). These animals differ markedly in appearance.

I’m sorry, but here, you’ve certainly wandered out of your orchard, Dr. Prothero. As the twentieth century’s foremost expert on mammalian hybrids, Annie P. Gray noted in the preface to her reference work Mammalian Hybrids (1972, p. viii), which compiled information about all such hybrids then known, “no close correlation was found between the chromosome count or the duration of gestation and the ability of species to hybridize.” And in looking at thousands of avian and mammalian crosses, I have reached much the same conclusion myself, except that rather than saying there is no close correlation, I might say there is certainly no strict rule. The thing that people unfamiliar with the phenomenon of hybridization often think is that sterility and fertility are absolutes. What in fact occurs in most hybrids is that there is a reduction in the quality and quantity of gametes produced, that is, they usually make fewer eggs and sperm than their parents do, and many of those eggs and sperm are defective. But not all. Many hybrids do produce offspring. Obviously, the easiest way to demonstrate that this old-wives’ chromosomal rule has exceptions is to provide counterexamples. So I offer a few in the sidebar at right (though this is not, by any means, an exhaustive list).

An honest, accurate assessment of the situation, then, would be to say that while hybrids do tend to be sterile when produced from crosses where the parents differ in chromosome number, nevertheless, such hybrids are known to produce occasional offspring, particularly in backcrosses. And note, that the pig-chimp theory proposes that a rare hybrid produced offspring in a backcross. So in that sense, the theory is consistent with observation.

Even human/chimp hybrids are impossible for the same reason, because we have different numbers of chromosomes.

Hybrids from parents differing radically in chromosome number:

One radical example is that between Reeves’s muntjac and the Indian muntjac. Viable hybrids are easily produced from this cross, and yet the Indian muntjac (Muntiacus muntjak) has the lowest recorded chromosome number of any mammal (males have a diploid number of 7, females have just 6 chromosomes), whereas Reeves’s muntjac (M. reevesi) has a diploid number of 46. A 40-chromosome difference! Likewise, hybridization is known between eland (2n = 31♂/32♀) and cattle (2n = 60).

This statement is out-and-out wrong. First, because a probable hybrid of a chimpanzee and a human has been formally reported; second, because we would have no way of knowing that such a cross is “impossible” even if there were no such report; third, because a huge number of successful crosses involve parents that differ in chromosome number. In the sidebar at right I note two crosses in which the parents differ radically in this respect and yet still produce hybrids.

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.

Define your terms! What does “radically different” mean? For example, one might say a turkey and a chicken are “radically different” but hybrids between the two have been produced and some individuals from that cross continue to develop to maturity (turkeys, by the way, have four more chromosomes than do chickens). And the phrase “to separate the strands in a lab and hybridize them” seems to have no meaning. Perhaps as a paleontologist you don’t realize, but in any attempt to produce a pig-ape hybrid, one would not “separate the strands” of DNA, in the lab or anywhere else. You might attempt artificial fertilization of a chimpanzee egg with pig spermatozoa (or vice versa), but you would not “hybridize strands” as part of such an attempt. So what are you talking about here?

and 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.

I’m sorry, Dr. Prothero, but this is just nonsense! If such a thing were true, then there would never be hybrids of any kind. But, of course, a vast number of crosses do produce hybrids. In my book on avian hybrids alone (Handbook of Avian Hybrids of the World, Oxford University Press, 2006), I list more than 4,000 different types of hybrids (see sidebar below for more details about this book).

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.

When you make comments like this, Dr. Prothero, I can only think that you are entirely unfamiliar with the phenomenon of hybridization. Don’t you realize that if what you are saying were true, there would be no such thing as a hybrid? Every animal hybrid cross introduces "foreign" sperm into the reproductive tract of the participating female. And yet, there are thousands upon thousands of well documented hybrids known from a wide variety of crosses. Moreover, after having looked at some ten thousand different types of animal crosses, I can say that immunological reactions to "foreign" sperm such as you describe have been reported only very rarely, in just a handful of cases.

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!

Is it “this guy’s” overactive imagination? Or your underactive one? Do I really have to describe exactly what would occur? Other people don’t seem to have any trouble imagining it. In fact, one Swedish artist did an entire art exhibit in Gothenburg based on the mental images that came to him in connection with the initial pig-chimp tryst! Every mixed mating leading to the production of a hybrid involves disparate organisms engaging in sex. Do you somehow think that the genitalia in this case would be incompatible? I don’t see why you would. And as for the ethology, I’ve discussed that issue here.

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.

Pigs and chimps (and humans) are separated by at least 70-80 m.y. of evolutionary divergence into lineages which have long gone different directions—hybridization between such long-evolving groups simply doesn’t happen

You have to realize, Dr. Prothero, that this 70-80 million year figure is merely an inference drawn from unverified axioms that you take for granted, in particular, of the axiomatic assumption that the history of evolution can be reasonably represented as a branching tree and that hybridization plays no significant role in evolution. If you’re willing to make such assumptions, then it becomes child’s play to set up trees in which organisms with lots of similarities are placed on adjacent branches, and where those that don’t are assigned to branches that are more distantly separated. So a chimpanzee and a human with DNA that differs by a couple of percent would be placed near each other. And both would be placed far from the pig, which differs from both by quite a lot, measured in terms of DNA sequences.

However, if what I’m hypothesizing is correct (and your axiom is wrong), then we are the product of backcrossing to chimpanzees, and the reason, then, that our DNA differs from theirs by only a couple of percent is due to that backcrossing, and not to our sharing a common ancestor that lived a few million years ago. So really, aren’t you putting the cart before the horse? Shouldn’t you first demonstrate that we are not pig-ape hybrids? Only if that were not true, would it make any sense to talk about such things as a common ancestor that lived 70-80 million years ago.

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.

Please don’t refer to my “mistakes” without enumerating them. Otherwise, neither I nor anyone else will know what you’re talking about. Tossing out terms like plesiomorphic and phylogenetic may impress some people, but there are others who won’t be cowed by a bit of jargon. You need to use those words to make a case. But again, you seem to be talking through your hat.

(Even more bizarre: he thinks platypuses are crosses between birds and mammals, even though those two lineages have diverged 300 m.y. ago).

Show me, Dr. Prothero, where I say that I think such a thing! You are the one expressing belief on this topic. By your comment, it’s clear that you believe that birds and mammals have remained sexually separate for 300 million years, and that you think you somehow know that no mammal has ever, at any time, mated with any bird and produced an offspring during those 300,000,000 years, whereas I merely suggest that we should investigate the possibility that such events may sometimes occur. Hardly an outrageous proposition! To that end, I have been compiling any evidence that seems relevant, and I am in the process of making that evidence available here.

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.

Reviews of Handbook of Avian Hybrids from the Oxford University Press website:

“For biologists interested in hybridization, for conservationists interested in particular species, for ornithologists interested in specific relationships, and for birdwatchers intent on evaluating plumages, this book is a goldmine.”--Integrative and Comparative Biology

“Extremely useful reference ... essential reading for biologists interested in the evolution of birds.”--Ibis

“Fine piece of work...a must for all those interested in hybridisation and speciation in birds.“=”--Contributions to Zoology

“McCarthy...has done an admirable job... Anyone interested in avian hybridism will need the handbook...provides an excellent resource for serious birders and ornithologists.” --Western Birds

“An invaluable addition to every biological reference library and to all ornithologists with the slightest potential interest in or need for avian hybrid information.”--The Emu

"The Handbook of Avian Hybrids is an impressive accomplishment, one that can be equally savored by browsing birders and appreciated by serious students of one of the biggest birding challenges out there. Highly recommended."-- Rick Wright, editor American Birding Association (

“Exhaustive... The bibliography is a mammoth 150 pages and lists over 5000 references! ... This book is an essential resource for banders, museum curators, and the serious birder. For researchers in conservation, ecology, and evolution, the book is a treasure trove of the occurrence and frequency of hybrids that could be used for preliminary comparative studies.”--Journal of Field Ornithology

“There is a high level of accuracy for individual reports in addition to the extent of the overall survey; it seems to indeed come as close to a complete compilation as is humanly possible. I have not met Dr. McCarthy, but after reviewing innumerable cases, I have a vision of a monkish figure variously cloistered in the ancient stacks of academic libraries and hunched before a computer terminal, compiling case after case with detail and accuracy that would guarantee his deliverance to a state of (academic) grace! I am sure my vision is a bit exaggerated, but it is an amazing compilation.”--William S. Moore, Professor of Biology, Wayne State University

This is all ad hominem ugliness, has no bearing on scientific discussion, and scarcely deserves a response. But I will say that I have a B.S. in mathematics (Phi Beta Kappa, magna cum laude) from the University of Georgia (1983), a M.S. in genetics (1995) and a Ph.D. in genetics (2003). I earned both of my higher degrees in the Genetics Department of the University of Georgia, of which I was a member, first as a graduate student (1989-2003), and then as a postdoc (2003-2007). During that time I studied genetics primarily from the standpoint of evolutionary biology and taught biology and genetics. I have also published various well-cited papers in the field of evolutionary genetics and bioinformatics.

As I’ve mentioned, I am also the author of Handbook of Avian Hybrids of the World (Oxford University Press, 2006), a reference book on hybridization in birds. I’ve copied some reviews from Oxford’s site and pasted them into the sidebar at right. Currently, I’m working on a second edition (and have been for several years), which greatly expands on the first edition. I also compile information on mammalian hybrids, much of which I have made available on this website.

I’m sure they don’t want his name associated with their distinguished program now.

I’m not sure who you think “they” might be, but I do assure you that when it comes to considering alternative hypotheses, not everyone at the University of Georgia is as reticent as you seem to be. After my avian hybrids book came out the President of the University of Georgia, Dr. Michael Adams, wrote me a congratulatory letter, and the university’s PR machinery touted my tome at length. And the last time I looked they still had it on display in the front lobby of the Genetics Department.

(Sadly, most of the media coverage falsely hypes his reputation, including some headlines which call him “the world’s leading geneticist”).

After all the incorrect statements you’ve made, I’d hesitate to throw stones at the media. As I’ve already mentioned, through my wife I have a fairly intimate familiarity with the practices of journalists, and most are far more conscientious (and considerate) than you seem to be. As for “the world’s leading geneticist,” that's something that ran in the headlines of some of the sloppier articles, written by people who, like you, didn’t contact me to get their facts straight. Actually, it would be closer to the mark to say that I'm a geneticist who's one of the world's leading experts on avian and mammalian hybridization.

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,

False, Dr. Prothero. I have in fact had lots of positive feedback, much of it from biologists.

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.

Wrong again. Here you’re merely putting words in my mouth.

(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,

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 “problems that don’t exist,” read “problems that Dr. Prothero hasn’t noticed.”

Get with it, Dr. Prothero! With the internet and new trends in technology, not only I, but tens of thousands of authors, many of them scientists (as you must know unless you are totally out of it) are opting to self-publish, both books and websites. There are many advantages. In particular, I find I can be much more honest than I could if I had to take into consideration being squelched by people like you. Really! Aren't you being just a tad hypocritical here? You're a blogger, so you do it yourself!

You know, I really could take an ad hominem approach just as you have. I could try to undermine your reputation, discount your accomplishments and degrees, I could call you a narrow-minded dogmatist, a bigot, a demagogue, a loudmouthed cretin, or various other things that your writings might seem to indicate. But I wouldn’t do that, because it serves no scientific point.

Are you really so uptight that you cannot countenance anyone even considering ideas contrary to your own? Does it really outrage you so much? As I’ve said, I studied evolutionary genetics for years, earning an M.S. and a Ph.D. on that topic. My career has not been the most shining, but then again, I haven’t been a lickspittle either. Perhaps you’re perfectly satisfied. Perhaps you do not perceive the problems with conventional theory that I do. But that doesn’t mean I have to shut up and leave the field to you and your intellectual allies. I have presented my arguments and evidence, and I will continue to do so, no matter what you might think of them, or of me.

And as for peer review — even if I overlook the scandals in that connection rocking scientific publishing of late — in the case of a theoretical work proposing a theory, I see no need. After all, the Origin of Species wasn’t peer reviewed. It was simply put out before the public as an explanation of how evolution occurs, and when it was, many people were interested and chose to read it. The same is true with my theoretical work. I’ve put it out, and many people have told me they think it's interesting and that they’ve enjoyed reading it, which is all I really care about. Besides, various colleagues (I’d say about ten) have in fact read various versions of my theoretical manuscript and made suggestions, many of which I have incorporated in the text.

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.

Straw man. Fossils rarely ever come up in connection with my discussion of the possibility that we might be pig-ape hybrids. So why do you even make these comments? But I suppose as a paleontologist it's hard for you to resist bringing up fossils and plugging your book. But I may say, your bringing up fossils again suggests to me that you haven’t devoted much time to reading my arguments.

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.

And you, sir, seem to have imbibed the grape juice of gradualism! You also have a rather glaring habit of substituting passive voice for citations.

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 the midst of this invective (at left) I do notice a certain admission. In saying “more rational scientists,” Dr. Prothero does concede that I am in fact a scientist! Thank you, Dr. Prothero! :D

For “crackpot,” read “independent thinker.” For “his own version of evolution,” read “a version of evolution not approved by Dr. Prothero.” For “without the benefit of learning from the rest of science” read “without Dr. Prothero being able to stop me.” For “listening to more rational scientists,” read “listening to Dr. Prothero.” For “should have trained him better,” read “should have made him express agreement with Dr. Prothero.”

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).

So you’ve looked at all of the many creationist websites out there? Aren’t you really just speaking (again) in incorrect absolutes? Actually, I know at least some creationists approve of me because they’ve contacted me to say so. What's the word for someone who makes generalizations about broad classes of people? Hmmm...What is it?

Unfortunately, creationists treat him as a legitimate scientist, and lump his crazy ideas in with real science to smear legitimate ideas in evolutionary biology.

For “legitimate scientist,” read “scientist approved by Dr. Prothero.” For “legitimate ideas,” read “ideas approved by Dr. Prothero.” For “crazy ideas,” read “ideas not approved by Dr. Prothero.”

Clown? Charming! :D

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).

For “science rejects,” read “Dr. Prothero rejects.” Many of the thousands of followers I have on Twitter are professional biologists. So they do not reject the theory out of hand. Some scientists are more open minded than others.

I’m sorry I can’t toe your line Dr. Prothero, but your opinions seem to be about as fossilized as your objects of study.

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.

Muslims now! Hmmm...What is that word? Dr. Prothero, I’ve received lots of emails, and even donations, from Muslims (and Jews), who’ve congratulated me, saying that this theory accounts for and justifies their dietary laws. Do you really have any evidence that most Muslims are anti-evolutionary? Or are you just painting with a broad brush again? Personally, I’d be more concerned about Fatwas if I were someone, like you, who seems to be describing Muslims in a general, negative light. Actually, I notice I have a lot of Muslim followers on Twitter. So you think they plan to attack me? Poppycock! I think they save their outrage for those who insult their religion.

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?

Perhaps, Dr. Prothero, because there’s something to it?

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.

Maybe you should apply for the position of Editor-in-Chief at the Daily Mail, then you could better control what others are allowed to write and read. Correct me if I’m wrong, but didn’t you just write an entire book about cryptozoology? I read that on your Wikipedia profile. But I’m sorry, your cryptozoology is no doubt rational cryptozoology, whereas any cryptozoology that contradicts your cryptozoology is crazy, trashy cryptozoology.

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.

For “unwarranted exposure” read “exposure unwarranted by Dr. Prothero.” Who does know? Could it be that people found the subject interesting and informative, even amusing? No. That can’t be it! :)

Even Jimmy Kimmel used it as the basis for an outrageous but hilarious sketch on his show.

Here I only half agree with you. It was hilarious, especially for me, given that I was the butt. But I didn't think it was outrageous. At least I myself wasn’t outraged.

As usual the media play to the sensationalist and the bizarre, without doing even minimal fact-checking, because “if it bleeds, it leads”.

Here you are, making generalizations again. As I say, through my wife I’m well acquainted with a lot of professional journalists, and I’d say their fact-checking and ethics put yours in the shade. But then again, though as a blogger you are part of this media that you seem so much to disdain, you certainly are not a professional journalist. I’ll grant you that much.

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.

So many generalizations! I’d bite my tongue if I were you. As Confucius once said, he who speaks without modesty performs with difficulty.

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.

If you have questions about any of the issues raised on this page, please feel free to contact the author.

Personally, I think the public, what you call the “lay audience” is perfectly capable of making decisions about such issues, and moreover has a right to do so. They’re allowed to reach conclusions contrary to your own, however much you and your priesthood may want to control the thoughts of those you deem an ignorant laity. When I think about people like you, I thank heaven for the internet!

And finally, I'd like to make a point about Dr. Prothero's general approach to science. In raising all the various objections he does to the proposal that a pig might successfully mate with an ape, he repeats a variety of oft-repeated but empirically unverified claims that pop up again and again when hybrids are discussed. Now, I'm sure that he himself thinks these claims are verified and true, and not mere hearsay. But I invite him to examine the primary reports about hybrids written by people who have actually studied hybridization, many of which are cited and/or quoted on this website. And if he does, he may find himself coming to doubt at least some of his beliefs regarding what's possible. Because direct observation has a wonderful way of dispelling the murk of hearsay. For my own part, my experience with hybrids has led me to regard some of my fellow scientists in a very different light. I've become a lot more like Rabelais who described (Pantagruel, Ch. 31) the students of "a little old hunchback, all misshapen and monstrous," named Hearsay, headmaster of a popular school. "Around him," writes Rabelais, "I saw innumerable men and women listening

to him attentively, and among the group I recognized several with very important looks, among them one who held a chart of the world and was explaining it to them succinctly, in little aphorisms. Thus they became clerks and scholars in no time, and spoke in choice language — having good memories — about a host of tremendous matters, which a man's whole lifetime would not be enough for him to know a hundredth part of. They spoke about the Pyramids, the Nile, Babylon, the Troglodites, the Himantopodes, the Blemmyae, the Pygmies, the Cannibals, the Hyperborean Mountains, the Aegipans, and all the devils — and all from Hearsay.

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