Revealed: Surprising difference between male and female brain

Male brains are 10 per cent bigger, but this does not change the function. Photo / Getty Images

Has the old adage men are from Mars and women are from Venus finally been debunked?

There is no discernible difference between male and female brains, according to Dr Lise Eliot.

The Chicago Medical School neuroscientist claims it is nurture rather than nature that is to blame for differences in male and female behaviour, reports the Daily Mail.

"People say men are from Mars and women are from Venus, but the brain is a unisex organ," Dr Eliot said on-stage at the Aspen Ideas Festival this week.

"We have the exact same structures.

"There is absolutely no difference between male and female brains."

Dr Eliot's comment dispute previous studies which have claimed to reveal demonstrable differences in the structure of the organ.

Dr Eliot said anyone searching for tangible differences between the make-up of the brain in men and women will be sorely disappointed, according to the Atlantic.

Neuroscientists have yet to find a single circuit which is wired differently in either male or female brains, stated Dr Eliot, who penned the book Pink Brain, Blue Brain.

Any differences between the sexes can be explained by our environment rather than our DNA.

For example, Dr Eliot said that anyone – regardless of gender – can be competitive or aggressive, however, men and women have different methods of expressing those traits based on social norms.

"We keep looking for a biological difference, finding it, it inevitably gets discredited, and yet we still seem so eager to find another one," she told the audience.

Even the oft-cited statistic that male brains are around 10 per cent larger than female brains does not disprove the theory, Dr Eliot said, since all men's organs are proportionally bigger on average.

There is also no difference in function between the two, she claims.

Debunking previous studies and long-held views that female brains are in some way different to their male counterparts is crucial to disrupt the current power structures, Dr Eliot said.

If scientists and academics started every investigation and study on the assumption that men and women are equally capable, the results they draw would be radically different.

For example, a number of academics, including then-Harvard University president Lawrence Summers, have pointed to a 1970 study which showed men outperform women 13 to one in the math portion of the SAT assessment to explain why more women aren't at the top of STEM fields.

"People said brilliance in math is a male phenomenon," Dr Eliot told the audience.

It turned out the disparity in the results was due to the fact that young women were being discouraged from studying STEM (Science, Technology, Engineering, and Mathematics) subjects.

As soon as more programs were established to encourage women into these fields, the disparity in the ratio plummeted to three to one, Dr Eliot said, and is now almost completely closed.

"We live in a gender-binary world," she explained.

"The default assumption is that these differences are hard-wired ... But male and female brains are not much [more] different from each other than male or female hearts or kidneys."

The claims from the Chicago Medical School academic dispute a range of studies into the differences between the male and female brain.

Researchers from the University of Pennsylvania scanned the brains of 1,000 men, women, boys and girls to determine whether there was a difference in the wiring between the genders.

The experts concluded that the male brain is wired from front to back whereas the female brain is crisscrossed from left to right.

Published in the journal Proceedings of the National Academy of Sciences, the University of Pennsylvania researchers said the differences in wiring would explain why men tend to be better at performing one task, such as cycling, while woman are more equipped for multi-tasking.

However, Dr Eliot believes the wide-ranging conclusions extrapolated from the researchers' observations into neutral circuitry were overstretched.

The Pink Brain, Blue Brain author points to the fact that the average age of the participant in the University of Pennsylvania study was "15 years of age", meaning most of the subjects were "mid-way through brain development".

In older participants, the striking differences in neural wiring were much less noticeable.

Writing in a blog post for the Huffington Post, Dr Eliot said: "Dr. Verma and colleagues actually found less sex difference in the oldest group (17-22 years old), probably because boys are catching up to girls in brain development at this time.

"Which gets to a likely basis for their striking, widely-publicised picture: Girls mature about 1-2 years ahead of boys – in their brains as much as their height and reproductive organs – so virtually any snapshot at mid-puberty is likely to find a sex difference."

Dr Eliot also highlights that the sample size of 1,000 participants used in the study is another clue that any differences in the male and female brain are pretty minor.

"Any time you need 1000 people to reach statistical significance, this should tip you off that the differences are modest, and measurable only at the population level — as opposed to a slam-dunk difference you can expect between every boy and girl," Dr Eliot wrote.

Last year, researchers from the University of Zurich found female brain rewards friendly and helpful behaviour, while male brains tend to encourage narcissistic acts.

For the study, Dr Alexander Soutschek and his team looked at the areas of the brain that are active when charitable decisions are made in two groups - one of 27 men and one of 26 women.

This area, known as the striatum, is found in the middle of the brain, and is responsible for the assessment of reward, becoming active when a decision is made.

Subjects made decisions between a "selfish reward option" in which only the subject obtained 10 Swiss francs ($14.72) and a '"prosocial reward option" in which both the subject and another person receive 7.50 Swiss francs ($11.04).

The study showed that the striatum was more strongly activated in female brains during prosocial decisions than during selfish decisions.

By contrast, selfish decisions led to a stronger activation of the reward system in male brains.

How has the shape of our brains evolved over time

Researchers at Germany's Max Planck Institute for Evolutionary Anthropology discovered that key evolutionary changes in our brain shape occurred roughly 100,000 to 35,000 years ago.

The Homo sapiens' brain took on a globe-like shape that's "rounder and less overhanging".

By contrast, our Neanderthal ancestors' brains had a more elongated shape.

The evolution of our brain shape coincided with major developments in behaviour, as Homo sapiens began to:

• Build tools
• Develop a working and long-term memory
• Possess self-awareness
• Use language
• Plan activities
• Understand numbers
• Pay attention to their surroundings
• Develop emotions

The brain began to look more like a globe as a result of bulging in the parietal area and the cerebellum.