Some of the genes that cause Alzheimer's or multiple sclerosis may have protected our ancestors from sheep or cattle diseases

[nearwildheaven]

This is per a story in Nature, which is about as reliable as it gets. People who are studying the genomes of Northern European ancestors have discovered this link.

It’s long been known that the sickle cell trait protects people from malaria. Who would think that genes that cause such devastation can possibly have benefited mankind, in a roundabout way?

https://www.msn.com/en-us/health/other/ancient-dna-reveals-reason-for-high-multiple-sclerosis-and-alzheimer-s-rates-in-europe/ar-AA1mL5OJ?ocid=winp2fptaskbarhover&cvid=7ac8c5654f6a4b3889426d891fb45c15&ei=17