• Dr Eugene McCarthy points to features that distinguish us from primates
  • He says that the only animals which also have these features are pigs
  • Controversial hypothesis has been met by significant opposition
PUBLISHED: 09:45 GMT, 30 November 2013 | UPDATED: 10:49 GMT, 30 November 2013

The human species began as the hybrid offspring of a male pig and a female chimpanzee, a leading geneticist has suggested.
The startling claim has been made by Eugene McCarthy, of the University of Georgia, who is also one of the worlds leading authorities on hybridisation in animals.
He points out that while humans have many features in common with chimps, we also have a large number of distinguishing characteristics not found in any other primates.
Domestic Pig
Louis, the chimpanzee who starred as 007 in TV adverts for PG Tips tea
The origin of the species? A remarkable new theory advanced by a leading geneticist suggests that human beings may have originally emerged as the hybrid offspring of a male pig and a female chimpanzee
Dr McCarthy says these divergent characteristics are most likely the result of a hybrid origin at some point far back in human evolutionary history.
What's more, he suggests, there is one animal that has all of the traits which distinguish humans from our primate cousins in the animal kingdom.
'What is this other animal that has all these traits?' he asks rhetorically. 'The answer is Sus scrofa, the ordinary pig.'
Dr McCarthy elaborates his astonishing hypothesis in an article onMacroevolution.net, a website he curates. He is at pains to point out that that it is merely a hypothesis, but he presents compelling evidence to support it.
 

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Scientists currently suppose that chimpanzees are humans' closest living evolutionary relatives, a theory amply backed by genetic evidence.
However, as Dr McCarthy points out, despite this genetic similarity, there are a massive number of divergent anatomical characteristics distinguishing the two species.
These distinguishing characteristics, including hairless skin, a thick layer of subcutaneous fat, light-coloured eyes, protruding noses and heavy eyelashes, to name but a few, are unmistakeably porcine, he suggests.
There are also a number of less obvious but equally inexplicable similarities between humans and pigs in the structure of the skin and organs.
Indeed, pig skin tissues and heart valves can be used in medicine because of their similarity and compatibility with the human body.
Similarities: Dr Eugene McCarthy suggests that humans' hairless skin and subcutaneous fat could be explained by porcine ancestry
Similarities: Dr Eugene McCarthy suggests that humans' hairless skin and subcutaneous fat could be explained by porcine ancestry
Dr McCarthy says that the original pig-chimp hook up was probably followed by several generations of 'backcrossing', where the offspring of that pairing lived among chimps and mated with them - becoming more like chimps and less like pigs with every new generation.
This also helps to explain the problem of relative infertility in hybrids. Dr McCarthy points out that the belief that all hybrids are sterile is in fact false, and in many cases hybrid animals are able to breed with mates of the same species of either parent.
After several generations the hybrid strain would have become fertile enough to breed amongst themselves, Dr McCarthy says.
Unsurprisingly, Dr McCarthy's hypothesis has come in for substantial criticism from orthodox evolutionary biologists and their Creationist opponents alike. 
One important criticism, which dubs his theory the 'Monkey-F******-A-Pig hypothesis', is that there is little chance that pigs and chimps could be interfertile. The two orders of creatures, according to evolutionary theory, diverged roughly 80million years ago, a ScienceBlogs post points out.
'[J]ust the gradual accumulation of molecular differences in sperm and egg recognition proteins would mean that pig sperm wouldn’t recognize a chimpanzee egg as a reasonable target for fusion,' PZ Myers writes.
Furthermore, the blogger explains, while chimps have 48 chromosomes, pigs have just 38.
He adds: 'Hybridizing a pig and a chimp is like taking half the dancers from a performance of Swan Lake and the other half from a performance of Giselle and throwing them together on stage to assemble something. It’s going to be a catastrophe.'
Finally, he suggests rather impudently that Dr McCarthy do the experimental work himself and try mating with a pig to see how far he gets.
But Dr McCarthy believes that, in the case of humans and other creatures, his hybrid modification to evolutionary theory can account for a range of phenomena that Darwinian evolution alone has difficulty explaining.
Despite the opinions of some peer reviewers that Dr McCarthy's work presents a potentially paradigm-shifting new take on conventional views of the origins of new life forms, he has had difficulty finding a publisher, so he has chosen to publish a book-length manuscript outlining his ideas on his website.
In its conclusion he writes: 'I must admit that I initially felt a certain amount of repugnance at the idea of being a hybrid. The image of a pig mating with an ape is not a pretty one, nor is that of a horde of monstrous half-humans breeding in a hybrid swarm.
'But the way we came to be is not so important as the fact that we now exist. As every Machiavellian knows, good things can emerge from ugly processes, and I think the human race is a very good thing. Moreover, there is something to be said for the idea of having the pig as a relative.
'My opinion of this animal has much improved during the course of my research. Where once I thought of filth and greed, I now think of intelligence, affection, loyalty, and adaptability, with an added touch of joyous sensuality — qualities without which humans would not be human.'