How long ago did science discover pigs' genetic similarity to humans?
June 1, 2014 1:04 PM   Subscribe

More specifically, when did scientists learn that pig skin is very similar to human skin?
posted by mtphoto to Science & Nature (4 answers total) 2 users marked this as a favorite
According to this site, the first xenotransplantation of pig skin onto a human took place in 1978.

But that's not really what you're asking.

I see where you're coming from with your question, but based on this article it looks like xenotransplantation of pig skin was discovered not because scientists learned that pig skin is similar to human skin, but because they had been trying to use other species' skin for centuries with poor success. Pig skin seems like a natural choice because it looks quite similar to human skin.

Skin grafts were carried out in the 19th century from a variety of animals, with frogs being the most popular.

With the advent of genetic engineering and cloning technologies, pigs are currently available with a number of different manipulations that protect their tissues from the human immune response, resulting in increasing pig graft survival in nonhuman primate models. Genetically modified pigs offer hope of a limitless supply of organs and cells for those in need of a transplant.

And this article says:

Transgenic pigs are promising donor organisms for xenotransplantation as they share many anatomical and physiological characteristics with humans. The most profound barrier to pig-to-primate xenotransplantation is the rejection of the grafted organ by a cascade of immune mechanisms...

I don't think this really fully answers your question, but hopefully it gives you some interesting food for thought anyway.
posted by schroedingersgirl at 1:31 PM on June 1, 2014

Thank you. Just what I was looking for. I didn't realize that the transplantation dated back to 1978.
posted by mtphoto at 2:09 PM on June 1, 2014

Paleolithic people knew a lot of anatomy. Like most hunting people they knew exactly how an animal is put together from their experience in taking them apart. If they butchered pigs they would know that a pig is quite different than say, a rabbit, having bristles instead of fur and subcutaneous fat instead of mysenteric fat.

There is some evidence that paleolithic people also sometimes butchered human beings. Those people who butchered both pigs and humans would have been able to spot the similarities right away. They would have observed that human digestive systems are most different from deer and ruminants, somewhat similar to a cat or dog or other carnivore, but closest of all to the pig. They would also have noted the relatively sparse hair and subcutaneous fat.

Of course they wouldn't have known about the genetics so perhaps this doesn't count for what you are looking for.
posted by Jane the Brown at 3:50 PM on June 1, 2014

To answer your broader question, pig insulin was used to treat people with diabetes in the early 1920s, until recombinant DNA technology came online in the late 1970s and early 1980s that had bacteria synthesize a human form of insulin. Though modern genetics as we know it wasn't around in the 20s, we learned back then that the biochemistry of pigs and humans was similar enough that some diseases could start to be treated using extracts made from organs of other animals, which are analogous to those in people.

The University of Illinois has a Comparative Genomics department that is part of the Swine Genome Sequencing Consortium, involved in helping sequence the pig genome and analyzing similarities with and differences between genomes of other organisms.

In their Publications section, they have a link to a chapter of a book called "The Genetics of the Pig", in which they discuss genomics research and evolutionary comparisons made in roughly the last 10-15 years:

"Conserved synteny between the porcine and other mammalian genomes, in particular that of humans, has already been used for almost 20 years to predict the location of genes and to identify candidate genes for important traits in the pig. The first example where this approach was used successfully was the identification of the RYR1 gene as the gene for the halothane locus on porcine chromosome 6 (MacLennan et al., 1990; Fujii et al., 1991; Otsu et al., 1991). Other well known examples where comparative mapping was successfully used to identify the candidate gene for the trait under investigation in the pig include the identification of a mutation in the PRKAG3 gene (RN locus) responsible for the excess glycogen content in pig skeletal muscle (Milan et al., 2000), and the identification of an SNP in the IGF2 gene as the causal variation underlying an imprinted quantitative trait locus (QTL) for backfat and muscle growth on porcine chromosome 2 (Van Laere et al., 2003)."

Other research is also referenced in the subsection on "Comparative Genomics":

"The development of a porcine-human comparative map accelerated with the increased efforts to map genes and ESTs (Fridolfsson et al. 1997; Wintero et al., 1998; Rink et al., 2002) on the porcine linkage maps (Ellegren et al., 1993, Johansson et al., 1995) and RH maps (Hawken et al., 1999; Robic et al., 1999; Lahbib-Mansais et al., 2000). The first comprehensive comparative maps between the porcine and human genomes were obtained by bidirectional chromosome painting by means of fluorescent in situ hybridization using individual flow-sorted chromosomes (Rettenberger et al., 1995; Goureau et al., 1996). These results revealed the presence of at least 37 conserved synteny blocks, which was somewhat lower than observed for the bovine-human comparative maps (Hayes et al., 1995; Solinas-Toldo et al., 1995). Although orthologous genes mapped in both humans and pigs, showed that several of these blocks consisted of multiple segments, the mapping resolution available at that time did not permit estimates regarding the number of conserved synteny segments between the human and porcine genomes. The first high-resolution porcine-human comparative map that was able to identify conserved synteny segments within these larger conserved synteny blocks was derived from the RH mapping of 1058 ESTs (Rink et al., 2002). Using this approach, Rink et al. (2002) were able to identify at least 60 evolutionary break-points and 90 micro-rearrangements between the genomes of humans and pigs. The availability of a high-resolution physical map based on fingerprinted BACs (Humphray et al., 2007), and in particular the availability of the end sequences (BES) of many of these BACs, allowed the development of even higher resolution human-porcine comparative maps (Meyers et al., 2005; Humphray et al., 2007)."

Other papers are available in the Publications section; there may be some there focused on medical applications, like skin grafts, etc. You could start using search terms like "conservation" when cross-referencing gene names with "epidermis" or "epidermal cells", and related sequencing work, which is where the most current analysis comes from.
posted by Blazecock Pileon at 2:27 AM on June 2, 2014

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