Human evolution: special cancer gene (Introduction)

by David Turell , Tuesday, May 03, 2022, 23:21 (934 days ago) @ David Turell

Our genes control cancer less than our primate ancestors:

https://www.newscientist.com/article/2318407-a-single-genetic-mutation-made-humans-more...

"Cancer is relatively rare in other primates. For example, autopsies of 971 non-human primates that died at Philadelphia Zoo in Pennsylvania between 1901 and 1932 found that only eight had tumours.

"Read more: https://www.newscientist.com/article/2318407-a-single-genetic-mutation-made-humans-more...

"To learn why we are more susceptible to cancer, Christine Iacobuzio-Donahue at Memorial Sloan Kettering Cancer Center in New York and her colleagues compared hundreds of genes between humans and 12 non-human primate species.

"They discovered that we have evolved a slightly different version of a gene called BRCA2 since we split from chimpanzees.

"BRCA2 is known as a tumour suppressor gene because it is involved in DNA repair. However, the researchers found that a single DNA letter change in the human BRCA2 gene has made it 20 per cent worse at repairing DNA compared with other primate versions of the gene, which could explain our higher cancer rates.

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"At this stage, we don’t know why BRCA2 has evolved to become less active in humans than in other primates, says Iacobuzio-Donahue. One possibility is that reduced BRCA2 activity has been selected for in humans to enhance fertility, since research shows that women with BRCA2 variants linked to cancer seem to become pregnant more easily, she says.

"If so, this fertility boost may have come at the cost of higher cancer rates, she adds."

Comment: the advantage must be fertility. We generally make one baby at a time, and going back to primitive times, mothers nursed for over two years which generally blocked ovulation. This means we needed to have a high fertility rate to overcome these factors slowing reproductive rates. As a result, our cancer rate is 20%, while primates are at one percent. Back to theodicy concerns, did God disregard the trade-off consequences? I assume god thought the reproductive rates most important.