“What have you been up to since we shared a womb together?”

This was one of the first questions that surfaced in the mind of Paula Bernstein when she encountered her identical twin Elyse Schein. 35 years had elapsed and never the twain had met since being separated at birth.

The twins were the unfortunate guinea pigs of an experiment headed by psychiatrist Peter Neubauer, where, in 1968, they were adopted apart to separate families. The families were not informed that their new adoptive daughters had a genetic clone somewhere else in the world. It was like that film, The Boys from Brazil, except with only one clone, not ninety-five. And the clone wasn’t of Hitler. And the adoption agency in question was in North, not South, America. On further consideration, it was nothing like The Boys from Brazil.

The point is that identical twins, by virtue of sharing all their DNA, provide a useful tool for teasing out the contribution of genes and environment to certain biological characteristics. They thus address that old chestnut in biology: nature or nurture?

The rationale behind twin studies such as that conducted on Bernstein and Schein was simple. Raise genetically identical people in widely different environments and follow them up. If they turn out to be grossly similar on a particular trait, especially when compared to less genetically similar pairs of individuals, it’s plausible that the trait in question is highly heritable. By heritable, one means that most of the variation in that trait is due to genes rather than environment. For example, height is highly heritable, with 80% of variation in human height attributable to variation in genes.

“It’s not just our taste in music or books; it goes beyond that. In her, I see the same basic personality,” Bernstein adds.

This raises the question; are complex psychological and behavioural traits such as personality and taste in music predominantly governed by genes or the environment? What about tastes in the opposite sex?

Is the apparent consensus on the physical beauty of George Clooney and Marilyn Monroe the hardwired product of thousands of years of evolution or a construct concocted by culture? To frame the question on a personal level without the cheesy alliteration: why would a girl fancy me – because of genes (hers and mine) or skinny jeans (just mine, assuming I were to buy a pair)?

Chomskying on the bit

A similar debate between hardwiring and environment/culture prevails in cognitive science. In the nativism camp, researchers claim that the mind is composed of innate, highly specialised processing units called modules. For example, renowned lefty and ostensibly less renowned linguist, Noam Chomsky suggested that the language abilities of children advance too quickly to be explained purely by learning in the environment (as is suggested by the opposing empiricist camp). Children are often only exposed to incomplete sentences, yet may produce and interpret complete sentences to which they have never before been privy.  Given that raw language data in the environment is inadequate in explaining child’s language learning, Chomsky reasoned that such a child is in possession of a LAD.

But, this is not the LAD that roams university campuses exclaiming “Banter,” trivialising rape and downing pints while already drunk on the notion that binge drinking somehow requires talent and tenacity. No, Chomsky’s LAD is the Language Acquisition Device, a hard-wired cognitive module that, operating below conscious awareness, facilitates language learning and bears some innate information about universal rules of grammar.

So there’s a module for language. What about other domains?

Well, many evolutionary psychologists such as Steven Pinker believe that the mind is composed of hundreds, if not thousands, of modules. Perhaps named by aficionados of jungle music, this view of the mind is known as the Massive Modularity Hypothesis.

The analogue analogy is that of the brain as a Swiss-Army knife but, since we’re in digital era, that analogy requires an update. Rather, modules are like apps pre-downloaded to the iOS of the brain. Just as an iPhone addict claims, for problems ranging from converting currencies to curing premature ejaculation, that, ‘There’s an app for that,” the evolutionary psychologist suggests “There’s a module for that.” Except these modules were shaped and selected for in response to the problems encountered by our evolutionary ancestors. So, there’s a cheater-detection module that tells us if someone is cheating, a face-detection module for responding to faces and even an incest-avoidance module that is apparently absent in the populace of Norfolk.

Another major problem that existed in the Pleistocene era was that of finding a suitable partner with whom to procreate, raise offspring and ultimately pass on one’s genes. Substitute the word “suitable” with “any” and you’ll generate an accurate description of my perennial dilemma today.

Evolutionary psychology suggests that modern people will be in possession of the cognitive modules that led to the selection of good long-term mates by our ancestors. Those ancestors who chose crap long-term mates would have died out. I’ll leave out short-term mate strategies for another essay.

As a heterosexual bloke apparently unable to attract any females, I’m primarily, albeit potentially myopically, concerned with female mate-preferences. In evolutionary terms, females evince different mate-preferences to males due to the fact that they bear a greater investment in a sexual choice. An act of intercourse for a woman may result in pregnancy, childbirth, lactation and so forth. As basic economics or Trivers’ theory of parental investment and sexual selection asseverates: the sex investing more in offspring (women) will be more selective about their mates. A corollary of this is that men, the less investing sex, will compete more greatly for sexual access to the high investing sex.

Great, so it seems, on an admittedly tendentious reading of the literature, that, like Germany in World War I, I’m fighting a two front war: vying for selection by choosy females and having to compete staunchly against other males.

Billy no-mates

But just what exactly is a good long-term mate to the ancestral woman? David Buss, in his book Evolutionary Psychology: The New Science of the Mind, summarises his findings in a neat table reproduced below. Reverting back to the nativism-empiricism debate, nativists contend that one or more innate modules subserve these mate-preferences.

Adaptive problem faced by Pleistocene Era females	Evolved mate preference influencing the modern day female
Selecting a mate who is able to invest in the long term	Good financial prospects Social status Ambition/industriousness Size, strength, athletic ability
Selecting a mate who is willing to invest in the long term	Dependability and stability Love and commitment cues Positive interactions with children
Selecting a mate who is able to physically protect self and children	Size (height) Strength Bravery Athletic ability
Selecting a mate who will show good parenting skills	Dependability Emotional stability Kindness Positive interactions with children
Selecting a mate who is compatible	Similar values Similar ages Similar personalities
Selecting a mate who is healthy	Physical attractiveness Symmetry Healthy

 Source: Evolutionary Psychology: The New Science of the Mind by D.M.Buss, pg 109. 

That’s all very well, but the woman I want to date isn’t from the Pleistocene era. No, the woman I desire lives in a modern culture where contraception is readily available, where children are not the endpoint of every sexual encounter, where good financial prospects and high social status are not the sole preserve of men. In the intervening 150,000 – 200,000 years since the evolution of modern humans, there has been massive cultural upheaval, a sexual revolution of the 1960s, changing notions of physical attractiveness.  Sure, the woman I desire may still possess these archaic modules underlying mate-preference, but is she purely at their mercy? Culture must be a countervailing force to hard-wired lust.

Two methods of ascertaining the role of culture include: (1) comparing mate-preference in different cultures across the world and (2) comparing populations within a single changing culture over time.

Using the first of these strategies, Shackelford, Schmitt and the aforementioned Buss surveyed approximately 10,000 people from across 37 different cultures including Zulus from South Africa, Japanese and Americans. Grossly, they found that, across cultures, men placed greater importance on a mate’s good looks and health, whereas women placed greater emphasis on financial resources and social status. Women also valued dependability, emotional stability, education and intelligence in a mate more than men, who in turn placed greater value on a mate’s desire for home and children.

Another study compared the mate-preferences of different samples in the USA at different time points: 1939, 1956, 1967, 1977, 1985 and 1996. Perhaps unsurprisingly, several mate-preferences altered over time.

• Both men and women decreased the importance placed on the virginity of a partner.

• Both men and women increased the credence given to a partner’s good looks.

• Both sexes valued a partner’s financial resources more highly, but the increase was more pronounced for men.

• Men placed less value on a mate being a good cook and housekeeper

Aha, so mate-preferences vacillate with changing cultural zeitgeist? The mind, at least with respect to whatever psychological mechanisms determine mate preference, is a blank slate, a tabula rasa, sculpted by one’s environment and culture?

This is a rather facile move, overlooking the complex entwinement of genes and environment, of nature and nurture. As both nativists and empiricists will concur, psychological traits emerge as a product of genes, environment and gene-environment interactions.

Consider again both studies of mate preferences. One sex difference remained significant; cross-culturally and temporally solidified: men place greater importance on physical attractiveness whereas women place greater importance on financial resources and social status.

Amidst this scientific quagmire then, two things weigh heavily in my mind. Perhaps I need to get fucking minted and/or increase my social standing. In the song Leader of the Pack by the Shangri-Las, protagonist Betty lists her reasons for falling in love with heartthrob Jimmy:

“They told me he was bad,
But I knew he was sad,
That’s why I fell for the leader of the pack”

 As endearing as that sounds, a robust, replicated female mate-preference for high social status intimates that Betty fell in love the with leader of the pack, precisely because he was just that: the leader of the pack. Science, debunking 60’s girl group lyrics since 1996…