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Geneticist Dr. Eugene McCarthy claims that humans have descended from hybrids of pigs and chimpanzees:

A 2013 Phys.Org article explained:

he has amassed an impressive body of evidence suggesting that human origins can be best explained by hybridization between pigs and chimpanzees. Extraordinary theories require extraordinary evidence and McCarthy does not disappoint. Rather than relying on genetic sequence comparisons, he instead offers extensive anatomical comparisons, each of which may be individually assailable, but startling when taken together.

McCarthy documents his hypothesis at Macroevolution.net

Is this hypothesis correct?

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Didami
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    "Rather than relying on genetic sequence comparisons, he instead offers extensive anatomical comparisons" - Yikes, that doesn't sound good. Check out [Parallel Evolution](https://en.wikipedia.org/wiki/Parallel_evolution). Anatomical similarity seems less likely to be proof of a more recent common ancestor than genetics. – called2voyage Jun 13 '16 at 14:59
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    Check out refutation here-http://observationdeck.kinja.com/no-humans-are-not-chimp-pig-hybrids-1474029809 and here-https://www.theguardian.com/science/occams-corner/2013/dec/04/theory-chimps-pigs-hybridisation – pericles316 Jun 13 '16 at 15:17
  • @pericles316: Want to make an answer based on those? – Oddthinking Jun 13 '16 at 16:29
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    After the edits, this question is not so bad anymore, and it is indeed entertaining! – T. Sar Jun 13 '16 at 17:23
  • @Oddthinking-Will try! – pericles316 Jun 15 '16 at 05:17
  • Some, but not all? :) – paul garrett May 21 '22 at 21:29
  • Reminds me of the "polar bear is a weasel" meme based on looking at their body shape. – Schwern Jul 17 '22 at 18:13
  • Is it possible that he made a publicity stunt betting that evidence based on genetic analysis could be vague? After all a common ancestor (way before monkeys branched out) is very probable. – FluidCode Jul 21 '22 at 14:58

2 Answers2

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The hypothesis that humans descended from chimp-pig hybrids can be denied on the following points.

  1. Hybrids between different orders of mammals are very rare due to the genetic differences and differences in chromosome number.

    Despite McCarthy's suggestions to the contrary, reports of hybrids between different orders of mammal, though, are, literally, incredible. His suggestion that the platypus is the result of hybridization between mammals and birds – an even bigger ask – seems to rest on a misunderstanding of the inheritance of chromosomes. Although some of the genetics of platypuses seems birdlike, this is much more consistent with its primitive state, and a mark of a shared inheritance between birds and reptiles (preserved in primitive mammals) than direct evidence for miscegenation.
    Source: "No, Humans Are Not Chimp-Pig Hybrids", Observation Deck

  2. No genomic evidence is currently present for the chimp-pig hybrid hypothesis. There is also no evidence of the occurrence of similar genetic material from both parents in the hypothesized chimp-pig hybrid which will confirm or predict the success of a hybridization event.

    He offers no such evidence, possibly because every published genomic study of pigs, human, and non-human apes suggests that the former are only distantly related to the latter two. Pigs and apes are both placental mammals, but not very related to one another. So their last common ancestor may have been sometime in the late Cretaceous, 70ish million years ago. The claim that the gametes of a pig and a chimp would be compatible in any sort of way requires evidence that other such large crosses are possible.
    Source: "No, Humans Are Not Chimp-Pig Hybrids", Observation Deck.

  3. A major genetic difference between humans/higher apes and pigs is that they do not share a working version of gal-transferase.

    That gene is called galactose-alpha-1,3,galactotransferase — gal-transferase for short . All mammals except humans and higher apes have a working version of gal-transferase, which coats cells with an antigen (a molecule that our immune system reacts to). This means if pig tissue is transplanted into humans our immune system will mount a drastic rejection response as our bodies detect the antigen and attack it. Pigs weren't part of that lineage. This is a fact, established by comparative research on genomes. Humans are closely related to chimpanzees (and gorillas), with whom we share this missing gene. We simply aren't particularly close, genetically, to pigs. And that means we aren't the offspring of cross-species sexual relations.
    Source: "Pigs and Chimpanzees Living in Sin?", Psychology Today

TL;DR: Referring to Dr Du and Prof Feng, physiological similarities between pigs and humans was maintained at a genetic level of 84% homology between the two species. However, detailed analysis showed that there were several important differences.

The analysis of the pig genome, published in Nature last year and available free does reveal shared similarities with humans – and why not? It shares similarities with many other mammals, too. But there seems no especially close relationship between the pig genome and the human genome, which is what one would expect had some hybridization occurred in the past few million years.
Source: "Evolutionary theory that a chimp mated with a pig is pure sausagemeat", The Guardian

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There is evidence of the opposite.

Here are some comprehensive references that based on genetic evidence show how actual human evolution probably happened. Some basics: Pääbo, 2003. Stringer, 2012 comments on what makes modern humans human - of course without mentioning members of the Suidae family. Finally, the introduction of Harris and Nielsen, 2016 gives a good overview over recent - at least Eurasian - population history).

Sklivvz
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    We require references even for negative searches, please visit our meta if you need to know how to reference them. – Sklivvz Jun 13 '16 at 22:42
  • I still think that the statement about phylogeny is so clearly accepted consensus that it does not need a reference (just as the earth not being flat) but I added some references for early morphological-molecular combination approaches for the sake of the argument. They show that molecular and anatomical data tend to converge and if not that differences occur on rather low taxonomical levels. Especially the paper about arthropod phyolgeny shows that the molcularly established clades are still linked to mophological data. I also added some references for ACTUAL modern human evolution. – AlexDeLarge Jun 13 '16 at 23:52
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    @Sklivvz -- How in the world are you going to find references that dispute nonsense? This is not a scientific hypothesis; if it was it would have been presented at a scientific conference or published in a scientific journal, and then the stuff would have hit the fan. Instead, this Monkey Effed A Pig (MFAP) hypothesis is yet another piece of random nonsense posted on the internet. – David Hammen Jun 14 '16 at 00:24
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    @DavidHammen The fact you called it the MFAP Hypothesis shows you found the Pharyngula rebuttal, which is a reference that disputes this nonsense. – Oddthinking Jun 14 '16 at 02:00
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    @AlexDeLarge we expect answers to be on point, referenced and respectful. I've removed the stuff that didn't actually answer the question in an acceptable way. You might want to add citations from that literature. – Sklivvz Jun 14 '16 at 08:11
  • I strongly disagree that the parts you removed are inacceptable answers. I might have been polemic (which should be alright given the hypothesis at debate). But it is valid to refer to basic principles of current day science - the argument that good research is published in peer-reviewed scientific journals and that this would be sufficient to reject to deal with this hypothesis is perfectly fine for debate. I further argued that genetic and morphological evidence rarely disagree strongly - also an argument against the hypothesis. All my points related to the actual question and had support. – AlexDeLarge Jun 14 '16 at 16:04