As we are in the midst of the Holiday Season it's a good time to review some of the basic biological differences between men and women, and why they matter to medicine.

So, a very short 🧵on Sex, Stress and the Holidays. The time that it takes for food to work its way through the gut is referred to as 'transit time'.

And this digestive speed differs by sex: faster in men, slower in women.

Why does sex matter? Because the absorption of many medications are influenced by transit time.

Viruses love to mutate. And some viruses mutate more than others. The biggest challenge for our immune system and any vaccination strategy that uses it, are viral mutations.

So why did the polio vaccine work while most of the #COVID19 vaccines will not?

A short thread.

1/5 The development of the polio vaccine was heralded as a major public health triumph. And it really was.

But did we just get lucky?

You see, polio has a higher mutation rate than HIV (which there's no current vaccine for). So why didn't polio escape vaccine?

2/5

Why do bartenders have the most experience dealing with the differences in how women and men metabolize a drug?

Because alcohol.

A short thread on how medicine doesn't consider drug metabolism differences between the biological sexes.

1/5 We used to think that differences in alcohol tolerance between M + F was only due to any differences in weight/fat.

But that's not the whole story.

Even when sexes are matched for weight, there is a marked discrepancy in which sex metabolizes alcohol faster, M>F.

2/5

Why are 95% of 'supercentenarians' (those who are 110 years of age and beyond) women?

Because biological sex.

And so, a short thread on sex and longevity.

1/7 From the beginning of life more girls make it their first birthday almost everywhere around the world, according to the @WHO. Girls have lower rates of prematurity and fewer complications after birth.

Females don't wait long to begin to dominate when it comes to survival.

2/7

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.

It is an unwritten law of biology that human males are much more fragile and lack the stamina and resilience in the face of biological challenges such as cancer and infections. Notwithstanding their greater muscle mass and physical strength, males are the XY heterogametic genetically weaker sex