If you watch musicals from the 1950s or teen comedies from the 1990s, you find a lot of movies with different titles but the themes and plotlines barely change; two friends competing for a girl in the former or some teen wants to improve another teen, who becomes really popular, in the latter.

It's not that Hollywood lacks imagination, we are naturally drawn toward a specific set of universal narratives within cultural products, says a new paper. We have evolved to like stories about Superman saving strangers or Brad Pitt fighting zombies. 

It's evolutionary consumerism, says Concordia University marketing professor Gad Saad. Little in consumer behavior can be fully understood without the guiding light of evolution, he writes in the Journal of Consumer Psychology. It's not just films, of course, that would be silly.  Pop music lyrics are "one of the most direct windows to our evolved mating psychology", Saad says. From Bieber to Beyoncé, it's all about signaling wealth and finding a mate. 

The focus of 90% of songs is on universal sex-specific preferences in the attributes we desire in prospective mates, Saad notes Male singers show off their wealth and engage in conspicuous consumption via high status brand mentions while women denigrate men of low social status.

It's just who we are. So if the girl group Destiny's Child sings about being "Bootylicious", Darwin himself would want to get behind Beyoncé. Makes total sense when you think about it.

"The human drive to consume is rooted in a shared biological heritage based around four key Darwinian factors: survival, reproduction, kin selection and reciprocal altruism. These fundamental evolutionary forces shape the narratives that are created by film producers or song writers," says Saad, who holds the Concordia University Research Chair in Evolutionary Behavioural Sciences and Darwinian Consumption in the Business School.  "Romance novels, pop songs and movie plotlines always come back to the Darwinian themes of survival (injuries and deaths), reproduction (courtships, sexual assaults, reputational damage), kin selection (the treatment of one's progeny), and altruistic acts (heroic attempts to save a stranger's life). Movies, television shows, song lyrics, romance novels, collective wisdoms, and countless other cultural products are a direct window to our biologically based human nature." 

It's not just cultural products that demonstrate the evolutionary roots of what Saad terms "Homo consumericus." From the food we eat to the clothing we buy, we're always under the influence of evolution. That's bad news for politicians who want to ban Big Gulps. They are being anti-biology. 

For Saad, the practical implications are clear: "In order to achieve commercial success, cultural products typically have to offer content that is congruent with our evolved human nature." That means that Clark Kent will fall for Lois Lane while Superman saves the planet for a long time to come.