What gives women the edge? It’s the X-factor!

Females live longer, have better immune systems, are less prone to Covid and have a higher pain threshold. So...

OSCIENCE THE BETTER HALF by Sharon Moalem (Allen Lane €28)

N THE radio the other day, a female virologist was explaining that, across the globe, two-thirds of all deaths from Covid-19 are men. ‘And we don’t have the faintest idea why,’ she went on.

And here, in hard covers, comes an instant reply to this conundrum, and a few others.

Sharon Moalem is, wonderfully, a man, an American scientist, physician and author, who probably gets teased a lot. I wonder if he has met the equally male American playwright Tracy Letts? I imagine they would have a lot to talk about.

His book, though, is brilliant, original and groundbreaking, highly readable and genuinely useful. His thesis is simple: that because of their chromosomes, women are genetically superior to men. They live longer, have stronger immune systems, are better at fighting cancer, have more stamina than men. They are even more likely to see the world in a million more colours, for goodness sake.

Every human has two sex chromosomes, one inherited from your mother and one from your father. Women have two X chromosomes, while men have one X and one Y.

What I never realised is the disparity in size and usefulness between these two. The X chromosome contains around 1,000 genes, while the Y chromosome has only about 70, most of which are involved in making sperm. So we can pretty much discount the Y completely and concentrate on the far more powerful and useful X chromosome.

SO WOMEN have two of them and it was thought until recently that one of them, the weaker X chromosome, essentially went to sleep while the stronger X chromosome got on with its work. But that’s not true. Women’s second X, it turns out, operates as a back-up system, so that if anything goes wrong in the body, all the second X chromosomes can band together and sort it out. Men do not have this option.

With immense patience, and a certain amount of useful repetition for the hard-of-thinking, Moalem explains what this means in practice. Having two X chromosomes gives women a degree of genetic flexibility that men lack.

It’s why women still live, on average, between three and five years longer than men. It’s why 95 per cent of people who reach the age of 110 are female. It’s why fewer premature female babies die than premature boys. It’s why twothirds of the deaths from Covid-19 around the world are male.

I have often thought that women can withstand more pain than men, but I had put this down to the fact that they give birth to babies, and men happily don’t. Also, all the women I have ever known have liked much hotter baths than men do. Why would that be?

Moalem doesn’t mention the bath thing for some strange reason, but the evidence he does come up with is both convincing and curiously reassuring.

For instance, I have often wondered why there are still 105 boys born for every 100 girls almost everywhere in the world. Is that because boys are the stronger sex? No, it’s because girls are harder for the mother’s body to ‘build’, and that’s because equipping each girl with two X chromosomes, one of which has to be ‘silenced’ to act as a back-up, is one of the most sophisticated tasks it has to do.

THIS difficulty in ‘building’ a girl is why most of the babies who die very early in pregnancy are female, hence the disparity in numbers.

Here are stories of women surviving on desert islands when all the men die out, of women overcoming viruses and bacteria while men succumb, to the extent that reading this book as a biological male feels a little like thumbing through a medical encyclopaedia and deciding that you’ve got every illness in there and are going to die.

As recently as 2017, two-thirds of all the people around the world who died from tuberculosis were male. In a huge study of children, researchers discovered that ‘boys had twice the prevalence of any developmental disability and excess prevalence for ADHD, autism, learning disabilities, stuttering or stammering, and other developmental delays’.

It all comes down to the inherent fragility of the male’s single X chromosome.

Women’s stronger immune system can have its disadvantages, though. One is that its strength makes it more likely to turn on the body and start treating that as a disease to be vanquished.

Accordingly many more women than men suffer from autoimmune diseases such as lupus and multiple sclerosis. Moalem calls this ‘the cost and result of women’s genetic superiority’.

This is one of those books you want to read out to people, with something on every page to make you say ‘good grief!’

Like all science writers these days, Moalem sugars the pill with some excellent stories, of Franz Kafka’s tuberculosis, of how vaccination actually works and who really discovered it. Unlike most science writers, he can actually write, which is a considerable relief.

You will end the book with your mind expanded, and the world feeling slightly more manageable, which is a great feeling to have, especially now.