Deutsche Welle (English edition)

Why sex and gender aren't binary issues

Man and woman with nothing in between, gender as identical to sex ― those who deny the existence of intersex and transgende­r people like to point to biology. But science actually proves them wrong.

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Our gender is identical with our sex, written in our genes, can be clearly assigned and does not change over our lifetime. The woman on one side, the man on the other ― you're either a princess or a knight, with nothing in between. And you certainly have no say in the matter, your sex is what you're born with. Period.

People who think like this usually point to one main argument: That's the science, they say. Biology to be exact.

Yet the broad scientific consensus now looks different: Sex is a spectrum. If you want to stick with the picture, man and woman are at opposite ends, but there's a lot going on in between.

Genetics: Clearly ambiguous

XX chromosome­s = female, XY chromosome­s = male. This is how sex is formed, we learn in school. In people with XX chromosome­s, a vagina, uterus and ovaries normally form in the womb. In XY, penis and testicles are formed.

Clearly, the sex chromosome­s are important, but it's not quite so simple.

For example, there are people whose physical traits are female,

but they carry the "male" sex chromosome­s XY in their cells, and vice versa.

A gene located on the short arm of the Y chromosome, called SRY, determines (along with other players) whether or not testes will form in an embryo. If, for example, this gene is not read due to a mutation, or remains silent, so to speak, no testes will develop despite XY chromosome­s.

On the other hand, testes can grow in people with XX chromosome­s if the gene jumps over to the X chromosome (presumably during cell division) and is read.

So how sensible is it to determine sex after birth, as is mostly done at the moment, solely on the basis of externally visible sexual characteri­stics?

Nothing is set in stone

Naturally occurring variations in sex chromosome­s are many and varied. This can also have an effect on the visible sexual characteri­stics, the genitals. Here, too, there are several gradations between the fully formed penis and the externally visible part of the clitoris.

Individual­s who cannot clearly be assigned one of the binary sexes refer to themselves as intersex or inter*. The United Nations estimates that 1.7% of the world population belongs to this group. The number is comparable to that of red-haired people in the world.

Since 2018, newborns like this can be registered as "diverse" in Germany. Other countries, such as Australia, Bangladesh and India, also recognize a third sex.

Sex can also change over a lifetime ― or more precisely the gonadal sex identity can. Chinese researcher­s found this out in a study on mice.

The genes responsibl­e for this change are DMRT1 and FOXL2, which normally balance the developmen­t of ovaries and testes in a kind of yin-andyang relationsh­ip. When there was a change in these genes, the gonadal sex phenotype could change even in adult animals.

The changing symphony of hormones

Testostero­ne: The male hormone! Estrogens and progestero­ne: The female hormones! That's what they teach you in school, but again, it's not that simple.

Men and women as well as gender-diverse individual­s all have these sex hormones in their bodies. Average progestero­ne and estradiol (the most potent natural estrogen) levels barely differ between the sexes.

If one is looking for binarity in hormone levels, one should rather distinguis­h between "pregnant" and "not pregnant," according to a review study on recognized sex characteri­stics by American psychologi­sts. This is because only pregnant women are far out of the ordinary in terms of estradiol and progestero­ne compared to all other people.

In children there is no significan­t difference in sex hormones. It is not until puberty that testostero­ne levels in particular go up, so that males on average have more testostero­ne than females.

But according to recent findings, this difference was also overestima­ted for a long time due to a failure of research, since testostero­ne was stereotypi­cally studied only in men and estrogens only in women.

Today, targeted research is being conducted on the hor

monal overlap between the sexes. It has also been discovered that hormone levels depend to a remarkable extent on external factors and are not, as previously assumed, purely geneticall­y predetermi­ned.

Expectant fathers, for example, have less testostero­ne over the period of their partner's pregnancy. The supposedly female hormones estradiol and progestero­ne, on the other hand, are produced more when individual­s compete for dominance ― a behavior that is stereotypi­cally considered masculine.

What gender is your brain?

There are some difference­s between the brains of men and women. Men's brains are larger on average. Individual brain regions also differ in average size, density of connection­s and type and number of receptors.

However, again, researcher­s cannot pinpoint the male or female brain. Each brain is quite unique and rather resembles a mosaic with different "male" and "female" parts.

At least, that's how researcher­s from Tel-Aviv Univer

sity described it in a study. A quarter to half of the 1,400 brains studied showed this sex patchwork. So things remain complicate­d in the head, too.

This also applies to the brains of trans people, who are being studied in a more targeted way. In terms of what individual brain regions look like, trans people are sometimes closer to their perceived gender and sometimes closer to their assigned gender.

It's safe to say that there's no pure binarity of sex characteri­stics. Any supposedly "biological" arguments in this direction are not in line with the current state of science.

Sex and gender are issues as complex and versatile as the humans (and mice and other animals) who carry them.

This article was adapted from German.

 ??  ?? Men have a penis, women have a vagina — it's not actually as simple as sex ed wants you to believe
Men have a penis, women have a vagina — it's not actually as simple as sex ed wants you to believe
 ??  ?? There's more than just male and female
There's more than just male and female

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