Many people believe that the brains of men and women are so different that they can have sex from Venus or Mars.
A new study has confirmed this theory after revealing that 1,000 genes are more active in males than females.
This study looked at how female and male mouse brains are different by probing the areas of human behavior that can be programmed to ‘rating’,’mating’,’mating’ and other behavioural patterns.
The behaviours — for example, male mice’s quick determination of a stranger’s sex, females’ receptivity to mating, and maternal protectiveness — help the animals reproduce and their offspring survive.
The Stanford Medicine researchers believe that these brain differences could also reflect the gender differences in men and women.
The new research examined how the male and female brains of mice differed by probing specific areas which are responsible for programming ‘rating. dating. mating. and hating behaviours. Stanford Medicine researchers believe these differences may also be reflected in women’s brains.
Researchers studied male and female mice at different stages of the estrous cycle. To examine the differences in gene expression between genders, scientists probed four areas of the brain.
Scientists discovered that the brains of both sexes contained more than 1000 genes by analysing the tissue.
These genes were used as entry points to identify specific brain groups that can orchestrate certain sex-typical behaviors. Nirao Shaikh, study author and professor of psychiatry, neurobiology and behavioral sciences, said, “Using these gene entries, we’ve identified particular brain cells which orchestrate this sexy behaviours.”
Over millions of years, animals have inherited social behaviors that are sex-typical from their brains.
Men mice are quick to recognize when someone is sexing outside their territory.
They immediately strike if the male intruder is a female. They will initiate courtship if it is a woman.
Female mice are more aggressive than their male counterparts, and will attack any threat to their babies.
Their instinctive nature to look after their kids and catch any lost children is far greater than that of males.
It all depends on their stage.
Shah stated that these primal behaviors are crucial to survival and reproduction and are largely instinctive.
It’s likely too late to teach how to fight or mate once you’re in a situation.
“The evidence shows that brains are not purely blank pieces waiting to be moulded by environment influences.
Researchers discovered that some genes are risk factors for certain brain disorders. These are found in sex more than others.
Researchers identified 29 genes that are high-risk for autistic spectrum disorder (also known as autism spectrum disorders in men and women) as more active than others.
The researchers also discovered genes that are linked to multiple sclerosis and Alzheimer’s disease, which both tend to affect women more than men. They were activated more in female mice.
These brain structures were shared between mammals and humans.
The researchers believe that males need some genes to be working harder, and females need other genes to be working harder — and that a mutation in a gene that needs high activation may do more damage than a mutation in a gene that’s just sitting around.
In addition to identifying more than 600 genetic differences between the different estrous cycles, this study revealed that females have many variations in their gene activation levels. This is the menstrual cycle in women. Female mice, however, don’t have it.
Shah who spent his entire career studying the role of sex hormones in regulating sex-typical behaviors, said, “To discover, within these small brain structures, many hundred genes whose activation levels depend only upon the female’s stage”
These brain structures were shared between mammals and humans, according to the research.
Shah claimed that “Mice aren’t human beings.” “But, it is reasonable to assume that similar brain cell types may be found to play roles within our sex-typical and social behaviors.”
Shah added that migraines, epileptic seizures, and other psychiatric conditions can be varied during menstrual cycles.
“Our results of differences in gene activation across cycles suggest that there is a biological reason for the variation.”
Previous attempts to find gene-activation differences between male and female rodent brain cells have come up with only about 100 of them — seemingly too few, the researchers believe, to generate the numerous profound differences in known instinctual behaviour.
Shah stated that Shah was able to find about 10 times as many genes, in addition to the 600 female genes whose activity levels vary according the stage of the reproductive cycle.
“All in all, this amounts to 6 percent of mice’s genes being controlled by the stage or sex of their cycle.”
Shah described the method used by his team as finding needles among a haystack.
He said that the mission-critical cells for these sexual-type rating, dating and mating behaviour displays, account for less than 0.0000 per cent of the total brain cells.
To determine what makes these cells tick, you had to separate them from the surrounding cells. Then examine their genetic content one at a time.
The researchers vastly improved their chances by zeroing in on scarce but crucial cells that are responsive to oestrogen — that is, cells that have receptors for this major female sex hormone.
Oestrogen also exists in males but in lower amounts.
Women’s oestrogen levels and those of another hormone, progesterone, wax and wane on a roughly monthly basis, like phases of the moon — as do corresponding female-sex-typical behaviours in many mammals.
Estrus and maximum sexual receptivity in mice are marked by high levels of both hormones. The polar opposite (or diestrus) stage in mice is marked by low levels.
Shah was able to purify tissue from each of the four key brain structures in a way that enriched the resulting brain-cell population for oestrogen-responsive cells — the ‘needles,’ in his analogy.
Researchers compared the activity of males, females with estrus, and females with diestrus to find 1,415 genes.
These cells are not all oestrogen-responsive.
The scientists found that only one of the 36 species in mice was necessary for male mice to quickly recognize an unknown mouse’s sex and behave accordingly.
One brain structure had 27 different types of Oestrogen-responsive cells, which could be identified by various patterns or gene activation.
Knocking out the performance of just one of those cell types — but not of the other 26 — transformed females who would ordinarily be sexually interested into ones who rejected sexual advances.
Shah explained that “This is likely just the tip” of the iceberg. These and other brain structures may contain more features that can be used to differentiate sex, but it’s worth learning how to find them.
Cell published the study.