Tuesday 10 September 2013

Testicles and Fatherhood

This is my lab, so let's perform a thought experiment. Say I'm a sociologist (which I am) and had an interest in the social behaviour of biologists. Neuroscientists to be more precise. In such a situation, quite rightly my motives for studying them would have to be justified like any sociological enterprise should. But also, I think most people would be okay with the idea of studying a group of scientists in a social setting. Investigating, describing and analysing social relationships is the bread and butter of our work after all. However, if our sociologists were to enter the setting and tried producing a work of neuroscience, then that would not be okay. Social science is in the business of explaining social phenomena. Social theorists, statisticians, ethnographers, interviewers, modellers are counted among our number. Specialists in brain functions tend not to be. That is because sociology and neuroscience have entirely different areas of competency with their own methodological procedures, validation standards, theories, and objects of investigation. Such an experiment would find that a sociologist cannot produce technical knowledge about neuroscience that would meet the standards of neuroscience as a discipline. Therefore, pursuing the logic of the experiment, it is reasonable to expect the same is true of neuroscience. They would be to sociology what George Osborne is to economics.

So I read with interest about the adventures one American team of neuroscientists have been having with parenting, brain function and ... testicle size. Their paper, Testicular volume is inversely correlated with nurturing-related brain activity in human fathers is published by the Proceedings of the National Academy of Sciences (or, fittingly, PNAS for short) gives the game away with the title. They have found a statistical correlation between being a caring, nurturing dad and having small balls. As they put it,"our results suggest that the biology of human males reflects a trade-off between mating effort and parenting effort, as indexed by testicular size and nurturing-related brain function, respectively."

After guffawing like the child I am when it was published by the BBC this morning, I had to ask who on earth would think such a study is worthwhile. Who would stump up the cash for employing the researchers, selecting the sample, and undertaking the scans? Who got to determine the mass of participants' testicles? I have no idea. But it did sound like a piece animated by the latest manifestation of some sociobiological perspective or another. And so it is. As the paper states, it wished to test something called 'Life History Theory'. LHT is basically a way of looking at the lifecycle of any given organism or, to be more precise, what an organism invests in growing, surviving and reproducing and the trade offs it has to make. For example, Salmon invest very heavily in their reproductive strategy. Instinct eventually compels them to undertake the exhausting journey upstream to their spawning grounds to reproduce - a strategy that kills the parental organism but allows for the next generation of fish to be born. Natural selection working its way through predators and variable environmental conditions weeds out the unfit and the sick, theoretically allowing only the hardiest to spawn.

As you might expect, the trade-offs different species of plants and animals makes varies enormously. Just think about the many different ways land animals nurture their offspring. Or not. What the Emory University team are interested in is the extent to which LHT applies to humans, and what biological trade offs individuals (and in the case of research lead James Rilling, fathers in particular) make. And the title of the paper is what their statistical analysis found - nurturing dads who play an active role in raising their children appear to have lower testosterone levels and less testicle mass than those who don't. That's the trade off for human males, one could suggest.

Unfortunately, the article is buried behind a pay wall so we cannot burrow into the stats - though they have made available some supporting information alongside the abstract. But still, questions can - and should - be asked. The results only have a one-in-a-thousand chance of being the result of experimental error, so they're describing something that's true enough. But what about the numbers of men involved? 70 participants took part, but only 55 consented to having their balls weighed in. There is no control population, or wider population to compare them to. For example, in cubed millimetres testicular volumes ranged between 18,358 and 59,665. The average size was 38,064. How does this compare to men overall? I have no idea, and it would take a sample the size of your typical YouGov pool to achieve statistical significance. Getting that many men to have their testicles measured might prove something of a challenge. The second comes to the factors involved. Rilling's team also fed age, number of children, height and weight variables into their calculations and found there was no correlation between them, levels of testosterone, and testicle size. But surely other things need ruling out. LHT emphasises environmental factors. For fathers, whether they're doting or not, they tend to have different occupations, exercise to greater/lesser degrees, eat certain diets, live in particular areas, engage on varying frequency of sexual activity, and so on. It is reasonable to assume all these variables could have an effect and, therefore, it would be sensible to come up with ways of testing them. For proponents of LHT, it is curious that they did not control for the social environment of their volunteers.

I bristle at sociobiology. Or, to be more exact, how sociobiology is crudely used to justify social divisions and inequalities as immutable facts of life. A quick skim of media reports certainly does that. The complexity of the relationship between biology and society is reduced to something crude and determinist. Whichever way you look at it in a society such as ours, whether the arrow of causation is small testicles = caring dads, or caring dads = small testicles, the heavy implication is these men are emasculated. Despite LHT being a stable mate of evolutionary psychology and the simplistic nonsense that entails, to be fair to Rilling's team, they do not draw any conclusions beyond the mere observation that they have found something. Correlation isn't causation. It merely points to an association that requires further explanation on the basis of scientific investigation. Nothing more.

I'm going to return to the thought experiment sitting atop this post. Sociologists doing neuroscience and neuroscientists doing sociology is a nonsense, which is partly why they sit in separate disciplines. But this does not mean they're entirely incompatible and unable to cooperate. One is concerned with the biological processes that animate human bodies. The other with the social practices motivating them. Me, just sitting here pondering and writing for a couple of hours, have managed to come up with some ways in which the validity of this research *might* be enhanced by a dialogue with a sociological perspective. Likewise, sociology and neuroscience both would be enriched by understanding how our social practices condition and affect neurological structures, and what this means for social attachments, senses of self and identity, and so on. Unlike the traditional topics tackled by LHT, humans are simultaneously the most complex and intellectually capable species known to the science it created, but is also an animal that is more fundamentally conditioned by its relationships to its fellows than any other. To properly understand ourselves the natural and the social sciences, the biological and the sociological need to have a grown up relationship.


Anonymous said...

It might be that the reason that neuroscientists can do sociology, but the sociologists cannot do neuroscience could be the same reason why fighter pilots can ride bicycles, but cyclists can't fly fighter aircraft.

You would be surprised at the amount of work that neuroscientists have done on the effects of estrogen/androgen neuronal sculpting during brain development.

Still, stick to what you know and keep cycling.

Phil said...

Well, it didn't take much for this "cyclist" to spot major flaws with their sampling technique and use of variables. But, I'm a sociologist with statistics training so what do I know?

It really is so simple that even a dullard can follow the argument. The study of the human brain - the most complex piece of matter in the universe - is an entirely separate domain from how those brains interact to secure their means of sustenance and build societies. Go ahead, slice and dice some grey matter up on a slide, gawp at it down a microscope. You will not find there the structure of Roman legions, the key to marketing beauty products or the production process for the internal combustion engine. Still less will you find explanations for the historical variance of human societies, of how a species that has led a hunter/gatherer life for the majority of its existence made the leap to class society, civilisation, and the technologically advanced societies we have today.

The funny thing is you probably think you're being original. Unfortunately for you, your argument was resolutely pooh poohed about 200 years ago.