Am I Victorian to argue that the characteristics of Caster Semenya’s sex-determining genetics are surely not a subject for public discussion? It is private information and it should stay that way. The public has no right to such highly personal information. Genetic privacy should be protected in law.

Genes are assemblies of chemical letters called deoxyribonucleic acid or DNA that send signals to proteins to make the biological apparatuses of all living things. It has been only five years that the science community has been able to look at all of the millions of chemical letters that constitute the human genome.

Medical geneticists are able to read our genomes for disease propensity and increasingly have access to biomedical technologies that may have therapeutic applications to suit the individual’s condition. Genome genetics or genomics is therefore a frontier science and the issue of genetic privacy a relatively recent concept in the field of bio-ethics.

It is so recent in South Africa it does not feature at all in the recently gazetted Protection of Personal Information Bill (14 August 2009). I wrote to the relevant Minister Jeff Rabede to say that it would be a propitious moment to add the relevant clauses and bring thereby our legislative efforts up to date with modern times.

Still, beyond Semenya, the public has shown great interest in – and revealed a desire to know more about – how genes make the two sexes we have, men and women. I mention two as some species have one self-fertilising sex and others may have up to four. We are a two-sex species and therein lie many enigmas and mysteries.

I used to ask first-year students in demography at the University of Cape Town what the benefits of sex involving men and women were and a typical answer focused on how pleasurable it is. The answer of course is that pleasure makes the monumental energy investment in such a grotesquely akward act attractive in order to create human diversity.

Think about it if you wish in the following manner: if we were herma-phroditic like earthworms our offspring would vary little if at all in characteristics like immune responses to disease, subjecting the species to extremely high levels of mortality and almost certain extinction if they had to survive in our environment.

Diversity is therefore the key to our successful term on this planet over the last 200,000 years or so of our existence as modern homo sapiens. That includes skin pigmentation for it allowed us to survive the ravages of the sun. There many other differences in human physical charac-teristics that should be understood in this way.

Of all the many differences between you, I and everyone else it is sex that is the most fundamental in the biological design of the body. I say sex and not gender. Sex refers here to the biological apparatus of human reproduction that enables the making of varying copies of ourselves. Gender is identity that may or may not coincide with sex.

The science community is today able to describe in considerable detail what it means to say that sex is the most fundamental organizing principle in the biology of whether someone is male or female. Scholars learn the basics in high-school life sciences. Developmental Biology 101 starts with sex determination in mammals.

It goes as follows: there are about 26,000 genes that are assemblies of various lengths of DNA strings that sit on 23 pairs of chromosomes. Whereas skin colour pigmentation is regulated about 100 or so genes sitting on likely 4 chromosomes, sex determination is regulated by an entire chromosome on which sit thousands of genes.

In mammals there is a first stage called primary sex determination that is wholly chromosomal. Nurture or the environment has nothing to do with it. In almost all cases female means having the 23rd chromosomal pair as X and X and male as X and Y. Every individual must have at least one X chromosome.

Since the female is XX, each of her eggs has a single X chromosome. The male, being XY, can generate two kinds of sperm cells, half containing X and half Y. If the female egg receives another X chromosome from the male, ovaries are formed, making the offspring female. In fact, it is the SRY gene sitting on the Y chromosome that triggers testes formation.

Secondary sex-determination in mammals like us affects the body and its organs. Males have a penis, a seminal vesicle and a prostate gland. Females have a vagina, cervix, uterus, oviducts and mammary glands. In many species including ourselves there is a sex-specific bodily sta-ture, vocal cartilage and musculature determined by hormones.

I do not have the language to describe the extraordinary beauty of this biological system and to express my full appreciation of the dignity of such natural aesthetics. Charles Darwin once said how difficulty it is for us to imagine how the intricately complex human eye could in its design be a product of natural selection.

We could certainly say the same thing about our sexuality. It is amazingly simple and very functional. It works with perfect fidelity 99.99 per cent of the time, from the copying of the DNA, the assembly of genes, the formation of anatomy, the functioning of the physiology and the cellular biochemistry.

The biological system produces what is known as normal variation. Although women as a norm are typically shorter – and more curvaceous – than men, some women are taller than men. Same thing with muscles and voice tone. These variations are called quantitative because they are more or less of same thing.

Some secondary sex characteristics that are quantitative in their distribution are sensitive to the environment and nurture has an impact. Stature and nutrition is an example. Muscles and exercise is another. It is never, as some social scientists are prone to misstate, a question of nature or nurture in this instance, but of nature and nurture.

Muscle variation is of particular importance. There are clear differences between men and women. The well known study of J.A. Simoneau and C. Bouchard showed that the mean proportion of type I fibre was lower in male than in female muscles whereas the cross-sectional areas or CSAs of all fibre types was smaller in females than in male muscles. [i]

Muscular strength that vary by sex is under strong genetic control. There is not one but three kinds of strength (1) static or isometric strength (2) explosive strength or power and (3) dynamics or functional strength. There is individual variation on all three. There is also group variation.

Men on average have more explosive strength or power whereas women have more functional strength. The rare woman has the explosive strength of a man whereas the rare man the functional strength of a woman. [ii]  Variations were kept in the gene pool because they gave explosive power to male hunters in the division of labour.

There is the issue of trans-sexuality. Called congenital adrenal hyperplasia, it is surprisingly common. 1 in 1,000 people are trans-sexual. There is also the phenomenon of inter-sexuality, where individuals have ambiguous genitalia even though the chromosomal arrangments are unambiguous.

What of the so-called genetic tests? As sex is determined by the chromosome full of genes, properly speaking it is a cytogenetic test of the Y chromosome or bits of a Y chromosome that jumped onto the X. My genetics colleagues say that it is a fishing expedition, even when a full genome sequence is done.

Then, there are sex-determining genetic materials sitting other chromosomes, like the ones determining muscle fiber for example. The genes that regulate hormone production also sit on chromosomes other than X and Y. Endocrinal tests are used to test for chemical expressions but on their own they tell part of the story.

Where does that leave us? With better understanding of the grey areas between male and female? I hope so. With the new field in law and ethics to develop so that citizens are better protected against possible abuse? Even though biology has become part of popular culture we have no right to turn someone’s  biology into public property.

References

 [i] J.A. Simoneau and C. Bouchard, ‘Human variation in skeletal muscle fiber-type proportion and enzyme activities’ in American Journal of Physiology, Endocrinology & Metabolism 256 no.4 (1989) pp.E567-E572).
 [ii] G. Beunen & M. Thomis, ‘Gene driven power athletes? Genetic variation in muscular strength and power’, British Journal of Sports Medicine 40 (2006) pp.822-823.