Evolution In Action
Eating red meat introduces a potentially dangerous molecule into the body tissues … Humans cannot produce the molecule – a type of sugar – but it occurs at high levels in lamb, pork and beef … because the molecule is not naturally present in the body, it is viewed as an invader by the immune system.
An alien sugar molecule that gets into human cells from eating red meat and dairy products triggers an immune system response that could lead to the inflammation believed to be involved in heart disease, cancer and other illnesses
Not produced in humans, Neu5Gc occurs naturally in lamb, pork and beef, the so-called “red meats”. Levels are very low or undetectable in fruits, vegetables, hen’s eggs, poultry and fish.
Ajit Varki has found that this nasty complex sugar, Neu5Gc, is probably toxic, possibly carcinogenic, and most interestingly, that human sensitivity to this red meat-associated chemical happened quite recently in human evolutionary history.
Humans are genetically deficient in the common mammalian sialic acid N-glycolylneuraminic acid (Neu5Gc) because of an Alu-mediated inactivating mutation of the gene encoding the enzyme CMP-N-acetylneuraminic acid (CMP-Neu5Ac) hydroxylase (CMAH). This mutation occurred after our last common ancestor with bonobos and chimpanzees, and before the origin of present-day humans.
The human cDNA contains a 92-bp deletion resulting in a frameshift mutation. The isolated human gene also shows evidence for this deletion. Genomic PCR analysis indicates that this deletion does not occur in any of the African great apes. The gene is localized to 6p22-p23 in both humans and great apes, which does not correspond to known chromosomal rearrangements that occurred during hominoid evolution.
Interesting… It seems that modern humans are in fact less suited to eat red meat and dairy products than our ape ancestors. Evolution in action?