How being a MOTHER makes you SMARTER
Hormone swings DON’T make you moody. A new book by a top neuroscientist debunks enduring myths about the female mind
DESPITE 40-odd years as the owner and operator of a female body and brain — more than half of those spent working as a neuroscientist (having completed my masters and PhD, I am now director of The Neuroscience Academy) — I realised I’d given close to zero consideration to how my female brain influenced my everyday life.
When asked, people are quick to rattle off a list of attributes they believe are due to innate biological differences in the brains of men and women. We love the idea that women have ‘female brains’, men possess ‘male brains’ and that, in turn, our brains govern ‘feminine’ or ‘masculine’ behaviours, aptitudes, preferences and personalities.
You’ll be familiar with some of these ideas. Because of their ‘female brains’, women are emotional; can’t read maps, but can multi-task; prefer people to things; and don’t ask for promotions. And because of their ‘male brains’,
men can’t read emotions and so on. Closely related to the notion that the brains of men and women are different is the idea that any differences are permanently hardwired by genes or hormone exposure in the womb.
The assumption is that nature matters, nurture doesn’t.
The misconception that gender differences are innate, and therefore fixed, flies in the face of the wellestablished fact that our brains are plastic — ie, that they continue to change throughout our whole lives.
In fact, there is no such thing as a ‘male brain’ or a ‘female brain’ — male and female brains are much more similar than they are different.
Instead, each of our brains is a unique mosaic of different features, some male-like, some female-like, with plenty of features best described as androgynous.
Think of it like this: our brains are assembled of many hundreds of little parts that are coloured pink if they are female-like and blue if they are male-like. Viewed from a distance, some women have brain mosaics that are strongly pink-tinged, others in men appear to be the bluest of blues, but most of us have brain mosaics coloured various shades of indigo, purple and mauve.
Indeed, a team led by the Tel Aviv University neurobiologist Daphna Joel has found compelling evidence that adult brains show extensive overlaps in so-called ‘male’ and ‘female’ features.
The researchers scanned the brains of more than 1,400 adults and found some features were more common in females or males. But up to half of the 1,400 brains contained features common to both, she reported in the Proceedings of the National Academy of Sciences in 2015.
Prenatal hormones may give foetal brains a small push in one direction or the other — for example, the effects of testosterone exposure early in pregnancy can masculinise some regions of the brain.
And boys and girls do differ a tiny bit during infancy. The average newborn girl is ever so slightly smaller, less fussy, easier to soothe and more socially aware than the average boy. Her language, memory and motor skills also track slightly ahead during the first year.
However, that early hormonal ‘push’ can be either enhanced — or entirely eliminated — by how girls and boys are raised.
My thinking is this: even as little as 60 years ago, it was rare for women to work as politicians, lawyers or doctors. There were very few female scientists. Since then, this situation has changed dramatically — but prenatal hormone levels haven’t.
Despite increasing social equality, however, entrenched beliefs still exist about ‘male’ and ‘female’ brains. These beliefs can often create selffulfilling prophecies.
WHY DO MEN THINK THEY’RE BRIGHTER?
AROUND the world, many men still believe they are smarter than women. This destructive gender stereotype emerges in childhood. A study published in Science in 2017 found that six-year-old girls have already absorbed gendered beliefs about intelligence, despite there being zero difference in academic ability.
Girls believe ‘brilliance, giftedness and genius’ are male qualities, said the study, led by psychologists at the University of Illinois.
Little girls were less interested in games they perceived as meant for ‘really, really smart kids’.
They went from being enthusiastic about playing ‘smart-kid’ games at age four and five to saying: ‘This isn’t for me’ at six. But boys the same age didn’t hold the same beliefs.
It gets worse: the six-year-old girls happily grouped boys into the ‘children who are really, really smart’ category, but not their own gender.
BRAIN IS REFINED BY MOTHERHOOD
IN 2016, the neuroscientist Elseline Hoekzema, of Leiden University in the Netherlands, MRI-scanned the brains of 25 first-time mothers before and after pregnancy and compared their brains with 20 women who’d never been pregnant.
Her report gave us our first detailed insight into how pregnancy changes the structure of women’s brains.
Pregnancy was associated with pronounced, long-lasting shrinkage of grey matter in regions related to social cognition and empathy. The hippocampus, associated with memory, also lost volume.
Rather than degeneration, however, this loss of volume reflects a streamlining of the brain’s circuits, making them more efficient. It’s likely that a process of refinement and specialisation of social areas of the brain takes place during pregnancy.
Dr Hoekzema ran tests to see whether changes were related to real-life skills. The first was a survey of maternal attachment, which included statements such as: ‘I would describe my feelings for the baby as dislike’ or ‘intense affection’, or: ‘When I have to leave the baby, I usually feel rather sad.’ The greater the bond between a mother and her baby, the greater the changes in their grey matter.
An MRI scan monitored the mother’s brain responses to photos of either their own or strangers’ babies.
When women looked at photos of their own offspring, regions that showed the strongest activation corresponded to the regions that thinned during pregnancy.
Looking at someone else’s baby had no effect on neural activity. This supported the idea that brain changes had occurred in areas linked to social cognition and empathy.
Dr Hoekzema and her colleagues believe the changes are caused by ‘the unequalled surges of sex steroid hormones (such as oestrogen, progesterone, prolactin, oxytocin and cortisol) that a woman is exposed to during her pregnancy’.
However, MRI scanners are not powerful enough to reveal such occurrences in useful detail.
Instead, we need to turn our attention to the brains of rodents.
Motherhood makes female rodents smarter. Compared to their child-free sisters, mothers are superior at learning, remembering, foraging and predatory tasks. They’re braver, less anxious and less stressed.
The mothers’ newly-acquired intelligence persists for life. Older
female rats who’ve had multiple pregnancies have better memories and show fewer signs of brain ageing than virgin sisters.
In human mothers, brain changes are similarly long-lasting. Two years after Dr Hoekzema’s initial scans, 11 of the women were scanned again. In all of them, most of the alterations had endured.
THE TRUTH ABOUT PERIODS AND MOOD
THE belief that our monthly cycle affects our cognitive skills is widespread. Google it. You’ll find headlines such as: ‘Periods cripple women’s careers’.
The scientific community has investigated these claims by looking closely at how sex hormones directly alter our capacity to think, reason and remember.
One predominant hypothesis is that we’re at our cognitive best at ‘masculine’ tasks when we’re ‘least hormonal’ and best at ‘feminine’ tasks when ‘most hormonal’. One of the most ‘masculine’ mental tasks is considered to be something called mental rotation — the ability to rotate 3D objects in your imagination. One notion is that women excel at 3D rotation only when all hormone levels are low, such as during their period.
However, two Swedish scientists at Uppsala University — psychologist Dr Malin Gingnell and Inger Sundström Poromaa — have analysed the evidence.
They reported in the journal Frontiers In Neuroscience in 2014 that the majority of studies fail to show any changes in mental rotation ability due to the ‘time of the month’.
The scientists also looked at two classic tests of mental prowess: verbal fluency and verbal memory.
Verbal fluency tests ask you to name, for example, as many words beginning with ‘G’ as you can within one minute. Verbal memory tasks involve remembering lists of words naming random objects.
The average woman performs better than the average man, so, according to the menstrual theory, women should perform better at verbal fluency and memory when oestrogen levels are high. But the review found little evidence in support of this — there were no clear changes in memory ability across the menstrual cycle.
This is good news! Our cognitive capabilities and intelligence are not held captive by hormones. We have clear evidence that women can learn, remember and reason throughout our fertile years and beyond. Who knew?
There is more good news when it comes to premenstrual syndrome (PMS). More than 150 symptoms can be used to diagnose this — they include mood swings, foggy thinking, anger, fatigue, sore breasts, headaches and bloating.
PMS is widely blamed on low levels of oestrogen, combined with a sudden drop in progesterone. However, it is extraordinarily difficult to find a consensus on how many women actually suffer it. I expected to find stacks of research and clear-cut statistics.
This is not the case. One major analysis found just under half of women globally suffer PMS. But the prevalence varies across countries — a 2014 study, published in the Journal of Clinical Diagnosis and Research, found that in Iran, 95% of women claim to suffer from PMS, whereas in France it’s only 12%.
Sarah Romans, a professor of psychological medicine at the University of Otago in New Zealand, is not convinced the menstrual cycle is the root of all mood variability — or that women are the ‘emotional victims’ of their reproductive biology.
In 2012, her report in the journal Gender Medicine analysed 47 studies on the link between time of the month and mood. Taken together, the studies failed to find any clear evidence of mood changes driven by the phase of the menstrual cycle.
She says: ‘We should consider more broadly what’s going on in our lives and take a look at the quality of our relationships and our physical health before blaming reproductive function.’