Thread by @sharonmoalem

The evolutionary arms race will never really end between microbes and humans. They (microbes) have as much to lose as we do if it does.

Microbes are responsible for some of the most profound differences between humans which we can still observe even today. This has been true since the first human.

Some humans are born able to naturally resist HIV. This is thanks to them inheriting a small but significant genetic change - CCR5 delta 32.

Most humans do not have CCR5 delta 32.

HIV takes advantage of this fact.

Having inherited resistance to HIV (CCR5 delta 32) does come at steep cost it seems. A much shorter life expectancy due to an increased risk from dying from other infections like influenza.

So which is the ‘better’ genetic inheritance?

Resistance to HIV (CCR5 delta 32), but having a shorter life expectancy due to susceptibility to other microbes.

Or

Being susceptible to HIV and having a longer life expectancy, unless you happen to become infected with HIV.

When it comes to assessing the merits of all of the trade-offs in biology the answer in a word is always going to be the same = depends.