It’ll be a year to the marriage of 37-year-old Priyanka Chopra and 26-year-old Nick Jonas, but the cynics are here to stay. Their marriage has several implications for the casual observer: They are an inter-racial, inter-country, inter-faith couple… nearly a generation apart. What in the world is a woman touching 40 doing with a dude who is a former Disney star?

A quick glance at #PriyankaChopra on Twitter is a good barometer of the fact that of all the things that offend us, this “asymmetrical”, “unnatural” union with an age gap as wide as the Atlantic Ocean, has offended us the most. But what is unnatural about this union and why are so many of us opposed it? Somewhere inside us, we believe, that the laws of nature dictate that the man in a relationship is always a little taller, a little more successful, a little older than the woman. Nick and Priyanka are violating that fundamental understanding.

And we’re not wrong. This pattern, after all, is witnessed across cultures, geographies, and ethnicities, and actually has biological/evolutionary roots. For example, in the US, a nation far more liberal than most others, men are older in 64 per cent marriages and women are older in just 23 per cent, whereas they’re of a similar age in the remaining 13 per cent. This trend is true for the still more liberal Scandinavia. It’s commonplace across the world for women to be attracted to older men, and for men to eye young women.

Since evolution is designed to give us the best possible result (read maximum number of children) for any given union, it’s not difficult to see why marriage in the hunter-gatherer era happened between older men and younger women: Because women’s reproductive shelf life is much shorter than men’s, the men preferred younger women as wives to allow the birth of more children. Women, on the other hand, preferred older men because they remained fertile even at later ages and the time allowed them to rise in status and resources and thus become better protector-providers.

It’s important to note that though natural selection dictates our behaviour, it works quietly without making humans conscious of itself.

In those times, given that physical attractiveness and child-birthing capabilities were a woman’s greatest assets, a man’s marriage to an older woman was considered a waste of his genetic potential. For a woman, a younger husband usually meant a feeble protector-provider. Thus, older women and younger men mutually discounted each other as marriage prospects.

Though circumstances in the modern era might have changed drastically – women have far more to offer, marriage is hardly done only for procreation, the role of men as protector-providers matters much less and can certainly be fulfilled by younger ones – human emotions, endowed to us by natural selection in the hunter-gatherer era for the purpose of transmitting the fittest genes, haven’t undergone nearly the same metamorphosis. Seen in this light, it’s not entirely surprising that the “animal spirits” sometimes unleash themselves in ugly ways, which is what, in most cases, accounts for the behaviour of those expressing disapproval of the Chopra-Jonas relationship.

Interestingly, the animal spirits can be unleashed even against younger female and much older male pairs. One need only dig up the storm of tweets castigating Milind Soman for marrying a woman nearly three decades younger, to be sure of this. The logic behind this outrage is exactly the same as a woman marrying a much older man, nearing the end of his reproductive life, is wasting her genetic potential. Though Soman was seen as the predator in this case, men usually take only half the blame for wasting the genetic potential of much younger women because these women – now often pejoratively called “trophy wives” – have over the evolutionary past consented to such relationships, given the vast resources at the disposal of some much older men.

It’s important to note that though natural selection dictates our behaviour, it works quietly without making humans conscious of itself. In other words, most of those who outrage against Chopra’s marriage to Jonas, or against Soman’s to Ankita, don’t precisely know the reason for doing so, but act on an impulse.

This explanation counters the notion of an all-pervasive, carefully knit and sustained social patriarchy, in favour of one that’s already built into the environment – remember, natural selection doesn’t choose our environment, but only shapes behaviour best suited to the given environment – in which these people find themselves. This environment is such that natural selection, for the purpose of transmission of the maximum genes (birth of most children), promotes patriarchy over egalitarianism. That’s not at all to say social patriarchy without biological roots, doesn’t exist. It does, and significantly so – young children learn from the actions of the influential and elderly in their community. But social patriarchy has a preceding biological cousin which we may not be aware of but which is informing our reactions.

So what accounts for the behaviour of those who support the Chopra-Jonas marriage? Are these superhumans who have overcome natural selection and magically developed altruistic qualities? The answer is an emphatic no. This is simply because they’ve managed to build for themselves an environment in which natural selection promotes altruism and empathy as the emotions that help genes thrive. In other words, this environment – driven by emphasis on increasing standards of living, which has brought about participation of women in the economy and countless other associated benefits – promotes altruistic and cooperative folk over the non-altruistic and vindictive ones. Indeed, the altruistic emotions are more important to transmission of genes than the aggressive ones, which is why the arc of human civilisation bends toward peace and egalitarianism.

However, those who find themselves in the clutches of patriarchy have not been able to create this noble environment. This is not to suggest giving a clean chit to those who troll Chopra and Jonas, because some people caught in this environment have still been able to deploy their mental faculties – also a gift of natural selection – to select the right emotional response. However, it would be naïve to expect the same level of sagacity from a large number of people.

In a considerable majority of cultures, it’s highly likely that the right kind of nurture can provide the right environment, and thus bring out the right nature. It’s important to keep reminding ourselves of the considerable struggles that some of the most liberal modern societies required before they reached where they are today. This, instead of blaming everything on the apparently incurable social patriarchy and denouncing completely those suffering from it, should be the emphasis of aspiring changemakers.

As for Chopra and Jonas, natural selection or not, the celebration continues. We’re all invited, so let’s do our bit and evolve a little so that we can join in the dancing. Bollywood numbers only!