Author: Micah Gerstner
Artist: Luli Fukukawa
Editor: Savina Hui
Sex is Simple – Right?
Historically, there have been two distinct categories of sex, male and female. This
distinction can be found in ancient religious and historical texts, and has endured to
even today, with the definition taught to each person in school. A male is someone who
has a penis and testes, with XY chromosomes. Usually they have other traits too, like
an adam’s apple and a deep voice. Males also tend to be taller on average and have more
body hair than females. On the other hand, females have a vagina, ovaries, breasts, and
XX chromosomes. Their hormonal profiles are largely determined by FSH and estradiol,
which change based on their age: a menopausal woman has a different hormonal profile
than girls before and after puberty. Within sexes, there is a lot of variation in physical
characteristics, yet we still feel confident in describing people as male or female.
Sex hasn’t always been so simple. People with indeterminate genitalia and sex
expression similarly date back to ancient texts. The Sumerian text of Enki and Ninmah
shows Ninmah creating one who is “without penis or vagina.” Early rabbinic literature,
namely the Mishnah in a section called the Bikkurim, describes laws around androgynos
and tumtum, persons of indeterminate sex and concealed genitalia respectively. Even
the Hellenes had Hermaphroditus, a son of the gods with male and female features
after the gods caused him and a nymph to merge into one being. Throughout history,
humans have been looking for explanations as to how people can appear to be of multiple
sexes or of none, and how these people should be treated.
How does sex develop?
Sexual differentiation begins within the first few months of foetal development.
Before any sex organs are developed, the gonad is bipotential – with the right stimulus,
it can develop into either ovaries or testes. In most cases, if the genes in the sex-
determining region of the Y chromosome (SRY) are present and activate during the 6 th
week of development, a cascade of chemical reactions will stimulate the gonad to
develop into testes and suppress the development of the female reproductive system.
If the SRY is absent, either through mutation or the presence of two X chromosomes,
the female reproductive system will develop instead.
For most people, this process goes undisturbed and they have a normal sex expression.
Figures are inconclusive about how many infants are born with atypical sex expression,
though a recent review suggests 0.02-0.05%. However, sex development doesn’t stop at
birth. Sex continues to develop during puberty, with the expression of secondary sex
characteristics and eventually culminating in sexual maturity. This phase usually
involves hormonal expression. Atypical sex expression may present as delayed or
incomplete puberty, or even traits from the opposite sex, such as breast development
in boys or virilisation in girls. These individuals may appear to have typical genitalia and have been assigned a specific sex, but instead have a disorder of sex development that
wasn’t identified at birth.
One of the earliest reviews on sexual non-dimorphism suggested that the incidence
rate of live births is around 1.7%; however a letter to the editor suggested that it
might instead be 0.37% because of issues surrounding the figures used. In each of the
studies regarding the prevalence of these conditions, the researchers acknowledge
that there is a lack of data on intersex individuals and that each figure may include
different conditions for their estimation.
Differences in Sex Development (DSD)
DSDs are a broad group of conditions, which are poorly defined in medical literature
due to a lack of standardisation. However, DSDs are grouped based on the
characteristics they tend to share: is it caused by chromosomal variation? Is it due to
sex hormone insensitivity? Witchel suggests that DSDs can be classified into
categories such as XX DSD, XY DSD, Sex Chromosome DSD, Gonadal Development
DSD, Persistent Mullerian DSD, and malformation DSD. These conditions occur due to
random chance mutations, recessive genes, or errors during meiosis or mitosis.
Perhaps the most well known of these conditions come from chromosomal variation.
Klinefelter syndrome is a condition in which more than one X chromosome is present in
a phenotypic male, such as XXY. They may have a smaller phallus and testes at birth, or
it may present as smaller during puberty. It is also common for these people to develop
gynecomastia, enlargement of male breasts, during puberty. A similar condition exists
in phenotypic females known as Turner syndrome. These individuals lack an X
chromosome and are usually described as simply X or XO. They tend to have an
increased risk of cardiovascular and neurocognitive disorders, as well as having “streak
gonads,” or connective tissue in place of ovaries which typically renders them infertile.
Life Beyond XX and XY
People with intersex conditions have always been and will continue to be a part of our
societies for years to come. As medicine continues to develop, researchers will be
better equipped to understand these conditions and what they mean for us as humans.
The existence of these individuals suggests that a binary category of sex isn’t accurate
to the entire human experience. Certainly, these classifications have been helpful both
socially and medically, but perhaps it’s time to reexamine the importance humanity
places on sex.
After all, how do intersex people fit into a society with binary male and female
dimorphism as the norm? What about the law regarding sex? Should intersex
individuals be forced into a category that doesn’t reflect their biological reality, or be
excluded from single-sex spaces? Should they have their genitalia corrected via surgery to fit into this binary society? These are questions that we will have to
contend with for the upcoming decades as we continue to learn more about these
conditions, both from research about them and listening to the people who have them.
kinesismagazine.com 