We humans share a lot of DNA with chimps and other primates, so there’s no real doubt we reside fairly close to these other creatures on the evolutionary tree. But yet, there are some major gaps in the standard story of how primates transitioned into humans. I’ve recently become aware of a novel, eerily compelling, hypothesis that – if accepted – would appear to fill these gaps quite nicely.
To put it simply, the hypothesis is that: Somewhere back in early proto-human history, there was a primate-pig hybrid. Most probably a hybrid of a pig with a chimp, or some sort of proto-chimp.
The idea was publicized via a Physorg post a month and a half ago — but somehow I missed that post when it came out, and just noticed it recently due to a tip from a colleague.
The theory seems outrageous at first, but once you read through the detailed argumentation, it starts to seem reasonably convincing – and then disturbingly, fascinatingly believable. Although of course, lacking slam-dunk evidence, it remains an intriguing speculation…
The creator of the hypothesis, the geneticist Eugene McCarthy, has written a wonderfully clear exposition of the available evidence. In fact his essay is so accessibly written that I’m not going to bother giving you a point-by-point recapitulation of his data and argumentation– my main goal in this brief article is just to direct you to McCarthy’s essay, and say YOU MUST READ THIS.
McCarthy is an expert on hybrids, and marshals extensive evidence that distant species can, indeed, mate with each other and produce viable offspring. It doesn’t happen all that often; but evolution is built on things that don’t happen often – yet provide interesting advantages when they do happen, which are then propagated through the generations.
The multiple resemblances between humans and pigs have been repeatedly noted by various artistic minds, most dramatically by George Orwell in Animal Farm. South Park fans will be reminded of Eric Cartman’s classic song and dance routine. Medical researchers are well aware of the peculiar compatibility between pig and human, which is why some current xenotransplantation research centers on transplanting pig organs into humans.
McCarthy gives an extensive list of human characteristics that differ from ANY primate, yet closely resemble pigs. One interesting point is the way human backbones combine primate characteristics with pig characteristics. In his analysis, what enabled early humans to start walking upright and come out of the trees down to the ground, was the combination of more pig-like backbones and more pig-like big butt muscles.
Obviously — our cartilaginous noses, omnivorous eating habits, pudgy hairless skin and dozens of other piggy traits notwithstanding — we’re on the whole more primate-like than pig-like. But McCarthy’s hypothesis is not that we’re half-primate / half-pig; it’s rather that, at some point way back when, a pig mated with a primate, producing a hybrid that then mated with a primate again. After a few more generations of back-crossing with primates, one had a strange sort of primate, blessed with various pig characteristics.
If we have partly piggish origins, why isn’t this obvious from our DNA? Because genetics is complicated. In general, when a hybrid of species A and species B back-crosses with species A, and this back-crossing is continued over many generations, it can be fairly hard to pick out the traces of species B in the DNA of the resultant descendants — even when clear traits resulting from B exist in the descendants’ phenotypes.
It does seem to me that it might be possible to use machine learning technology to search for primordial pig traces in the human genome. Suppose one started with a database of genetic information from multiple examples of organisms known to arise via hybridization followed by repeated generations of back-crossing. Potentially, one could then train machine learning algorithms to recognize the hidden signatures of ancestral hybridization. These signatures could then be searched for in the human genome. It’s an interesting research direction — though it wouldn’t be easy; for sure one would need extensive proteomic data as well as genomic data. Hybridization with backcrossing is a case where one may see approximate preservation of tertiary protein structure even as gene sequences change over time. Still — perhaps AI technology, which will one day likely dethrone us as the smartest on the planet, will also allow us to better probe the nature of the beasts from which we originated.
From a broader evolutionary-theory perspective, a confirmation of hybrid human origin would constitute yet another piece of evidence that creative leaps often emerge from synergetic or symbiotic combination of disparate, independent entities. The current cell emerged via symbiogenesis from early, simpler cells and mitochondria, which used to be separate entities. DNA and RNA may have existed separately at once point, then fused together into a common machinery. Creativity in the human mind is often explained via concept blending. It could be that many of the punctuated equilibria observed in the evolution of species, were actually triggered by cross-species hybridization.
But I imagine most readers will be less drawn to the evolutionary-systems-theory implications, than the qualitative human aspect of the hypothesis.
I find that, since reading McCarthy’s essay, I look at people a bit differently. Put simply: Everyone looks a good bit more piggy than they used to. It’s a disturbing, yet somehow oddly satisfying feeling . Looking at the world through the eyes of the primate-pig origin theory, I feel almost as if the piggish nature of human beings was really obvious to me all along, at the gut level, but just not something I explicitly acknowledged … due to the lack of scientific back-up, which Dr. McCarthy has now graciously provided.
Try it for yourself. Read McCarthy’s list of human-pig parallels — then do some people-watching, perhaps in a crowded buffet or bar, or the nosebleed seats in the stadium at a sporting event. Peruse various photos online, of your fellow homo sapiens, particularly when engaged in acts of consumption or states of strong emotion. Yes, there’s a lot of monkey there – no one rational could doubt that — but don’t you see a fair bit of pig as well?
Nietzsche observed that “man is a rope between animal and superman.” As a good transhumanist, I tend to agree. But as a friend quipped when I pointed McCarthy’s theory out to them, perhaps a revision is in order….
“Man is a rope between chimp-pig and superman” ?