Some cheery notes

I thought it would be nice to start out Monday morning with a cheery topic.

The Black Death wiped out 30% to 50% of the population in Europe, the Middle East, and northern Africa. This was in the 14th Century, but those old medievals left us modern types with a sad biological legacy: in those times, men and women developed genes that seem to have helped them survive the Black Death, and those genes, still swimming in our bloodstreams today, make us more susceptible to some diseases today.

“Our genome [note: genomes are the complete set of genetic material we carry around] today is a reflection of our whole evolutionary history" as we adapt to different germs, said Luis Barreiro, a senior author of the research.  Take the genes that bring the bubonic plague: they have a huge impact on our immune systems.

After taking DNA from the skeletons of over 200 Black Death victims, Barreiro and his colleagues picked out four genes that, for some, protected them against the bacteria that brings bubonic plague, and for some, provided protection against it. The Black Death was spread by bites from infected fleas.

Black death victims in mass grave

“A hyperactive immune system may have been great in the past but in the environment today it might not be as helpful,” said Hendrik Poinar, an anthropology professor at McMaster and another senior author.

Of course, this brings up the question of whether the COVID-19 pandemic will have a large impact on human evolution down the line. Barreiro says no, on the grounds that the death rate is so much lower, and most COVID victims have already had children.

But he adds, that doesn't mean that other pandemics aren't lying in our future, and the more deadly ones will continue to shape human genetics.

So, you see, this is all far off in the future, so don't worry about it!