Eugene M. McCarthy (no known relation) is a pseudo-evolutionary crackpot biologist famous for his completely ridiculous crackpot idea that “humans evolved after a female chimpanzee mated with a pig” (known as the MFAP hypothesis). Now, McCarthy does have relevant credentials, which he knows to exploit in debates – indeed, McCarthy has made serious academic contributions on hybridization (though other academic commentators have noted even here his tendency to endorse any speculative and unsupported claim that looks like it’ll fit his hypothesis) – and his idiocy has therefore predictably attracted occasional attention from various less-than-serious news media outlets over the last decade. Scientific journals and establishments have been less impressed with his work, which is partially why the media likes to portray him as a victim. You’ll find a short and to-the-point critique of his ideas here.
McCarthy’s “Stabilization theory” is laid out in the manuscript The Hybrid Hypothesis: A new theory of human origins submitted to the OUP but not accepted after peer-review (it is currently published on his website). In the manuscript, McCarthy rejects the Modern Synthesis, and specifically that natural selection is a primary driver of evolution, as well as the fact that microevolution is responsible for macroevolution. Instead, he plumps for a kind of saltationism that occasionally veers close to creationist baraminology (indeed, McCarthy’s creationist leanings are notable: “To me, organisms have a far greater value when they are seen as ancient and unchanging, existing today much a they did when they came into being long ago, in the remoteness of time. They become something more than mere pawns, forever changing at the behest of a tyrannical environment.” Also “Hitler was Darwin’s biggest fan,” which is as false as McCarthy’s claims about biology, but a telling reminder of his care for facts and accuracy.) In particular, McCarthy argues that hybridization between species is the primary driver of evolution. So, McCarthy claims that armadillos may have descended from ankylosaurs (because they look similar to him: “the modern giant armadillo is so similar to the ancient ankylosaurs that it is only reasonable to suppose it is descended from them”), bats are descendants of pterosaurs, whales of mosasaurs (citing – only – an 18th century anatomist), and seals from plesiosaurs. Indeed, dinosaurs weren’t giant reptiles at all, but huge mammals. Everything is, of course, completely contrary to evidence, but McCarthy has a shiny new theory-of-everything and has little time for evidence.
There’s a good criticism of his theory and how it contradicts everything we know about biology, palaentology, anatomy, genetics as well as obvious empirical evidence here. A rejoinder to McCarthy’s feeble response to the criticism is here, and a good rejoinder to McCarthy’s feeble response to to the rejoinder here. Another informative critique can be found here.
McCarthy is most infamous for his ideas about the evolution of humans, though: “We believe that humans are related to chimpanzees because humans share so many traits with chimpanzees,” he points out, so “[i]s it not rational then also, if pigs have all the traits that distinguish humans from other primates, to suppose that humans are also related to pigs?” Well, no, not really. However, after positing and promptly endorsing the extraordinary hypothesis, McCarthy admits that he has no genetic evidence, since “it can be very difficult to identify later-generation backcross hybrids derived from several repeated generations of backcrossing (and this would be especially true of any remote descendants of backcross hybrids produced in ancient times, which is what I'm proposing humans may actually be).” Since he is unable to use the genome to support his hypothesis, he instead points to morphological similarities to make his case, but disregards the fundamental morphological differences that conclusively falsify his idea, as well as the alternative explanations for the similarities that do exist. He has managed to impress both InfoWars and YourNewsWire, however. And the creationists at AiG have predictably responded by completely missing the point and applying their trademark complete lack of scientific insight or understanding.
More recently, McCarthy has expanded on his hypothesis and claimed that humans have hybridized with chickens, dogs, apes, goats, cows, and turtles. His “evidence” is based on mythological accounts (satyrs are evidence of goat-human hybrids, for instance), and imaginative interpretations of stories of women who had grossly deformed stillborn babies with peculiarly warped features.
Diagnosis: Another fine example of pure pseudoscience: Formulate a hypothesis that superficially fits certain pieces of data you’d like to fit together, ignore the vast amount of contradicting evidence, never test it, and maintain it with dogmatic rigor no matter what falsifying evidence might come your way. One might be inclined to believe that McCarthy is also completely harmless, but his work – given the media exposure – has been actively used to try to undermine the legitimacy of real science, so whatever influence he has is certainly not benign.