Aggressive women more likely to have sons, study

Women who are aggressive are more likely to give birth to boys rather than girls, a new study has claimed.

According to the Daily Telegraph, researchers in New Zealand say females with high testosterone levels tend to have sons rather than daughters.

Now, before everyone gets carried away here, it’s worth pointing out that these findings stem from experiments done on cows.

But is it a load of old bull, you may ask?

Well, for starters, this is not a new theory, and would certainly explain ‘The Wartime Effect’ – in which a disproportionate number of boys are born at the end of periods of hardship, such as wars.

But is this just a coincidence? Or even a statistical anomaly? The team led by Dr Valerie Grant, at the University of Auckland, certainly doesn’t think so.

They have established what they believe to be a clear link between high levels of testosterone - which is associated with dominant female behaviour - in cow wombs and the likelihood of giving birth to a bull calf.

They did this by extracting follicles from cow ovaries and testing them to see how high the testosterone levels were before the eggs were fertilised.

And, surprise, surprise, the eggs which had been exposed to higher levels of testosterone were more likely to develop into male embryos.

The team wrote:

“Results showed that follicular testosterone levels were significantly higher for subsequently male embryos.”

It suggests sperms carrying ‘Y’ chromosomes – present in male animals – are more likely to fertilise an egg if it has been exposed to testosterone.

Now, it’s certainly a good story. And for every woman I think backs this theory up, I can think of a multitude of examples which disapprove it.

But does the same research apply to human embryos? Or even embryos even closer to our genetic make-up, like chimps?

Besides, it only establishes a link between testosterone and the likelihood of giving birth to male offspring.

Women’s testosterone levels fluctuate all the time, regardless of whether they are naturally aggressive people. Stress, for example, can increase levels.

So is it a load of old bull? Probably. But then, I am no scientist from New Zealand.