The Evolutionary Effects of Testosterone on Human Society

Testosterone is a powerful hormone that has a myriad of effects on human physiology. The hormone is responsible for male sex characteristics like beards, balding, and big muscles. It's also the driver behind libido and reproduction for men (and is also important for women!)

Testosterone also has huge effects on male psychology. Carole Hooven is an evolutionary biologist from Harvard that specializes in understanding how our genetic past influences our modern behaviors. She explains that Testosterone impacts the male propensity toward aggression, confidence, and even violence. She also argues that while men are products of evolutionary biology, they are still ultimately responsible for their own actions in this life.

Nature and Nurture, Genetics and Culture

The effects of nature vs. nurture have inevitably been debated for as long as humans have been capable of philosophic quandary. It's clear when looking at data that male physiology plays a huge role in outcomes, especially related to acts of aggression and violence.

This bears out when looking at other species as well, especially mammals and animals more closely related to humans. In some species, males and females differ drastically in appearance, and this is largely the result of the influence of Testosterone. Males tend to produce somewhere between ten and twenty times the Testosterone of females. This massive disparity in hormone production activates genes that are sensitive to Testosterone, which contributes to differing primary and secondary sex characteristics.

What Is the Evolutionary Purpose of Testosterone?

Dr. Hooven argues that the evolutionary purpose of Testosterone is to encourage mating and reproduction. Testosterone, of course, leads to the development of the male genitals and machinery of fertility. It also contributes to mating and courtship rituals which have evolved over millions of years and the differing roles that females and males play during child-rearing. Competition over females has led to competitive evolution ranging from the development of antlers to complex displays, which eschew violence for elaborate displays, such as the peacock's technicolor tail-feathers.

It's essential to recognize that no matter how advanced human beings think that they are, they are still beholden to the artifacts of our genetic evolution. Environment and nurture alone cannot explain why men are so much more prone to violent displays than women.

Primates and Humans Share Behavioral Characteristics Influenced by Testosterone

Dr. Hooven's research has been largely motivated by her experiences studying chimps in Africa. She spent eight months studying Chimpanzees in Uganda. She worked with the Kibale Chimpanzee Project, researching and studying chimps in their natural environment at the Kibale National Park.

There she frequently witnessed interactions among primates that mirrored those of human beings. In one instance, she watched an extended bout of domestic violence where a male chimp continuously swatted at a female chimp for minutes as she recoiled, protecting her child. Male chimps committed the vast majority of violent and aggressive acts that she witnessed.

Testosterone is the cornerstone of male development. Testosterone activity is at its highest during fetal development and abates soon after the child is born. Testosterone Levels stay low until puberty when they spike again. In gestation, primary sex characteristics form, and during puberty, these characteristics further evolve, along with secondary features like the deepening of the voice.

Testosterone's Effects on Male Behavior

Studies have also shown that even young boys have play preferences that are influenced by Testosterone. Boys are generally more likely to be interested in rough and physical play than girls, for example. Very young children are most likely to act on instinct, and it's during this period that their preferences tend to closely mimic those of other species of the animal kingdom.

While Testosterone's effects on behavior are undeniable, they aren't always apparent at the level of the individual. Society still plays a powerful role in human activity, and different men are influenced by Testosterone in vastly different ways. Most men are taught to avoid violence, and it tends to be the minority that acts on those impulses. Furthermore, men vary greatly in confidence, strength, aggressive posturing, competitiveness, and other characteristics associated with masculinity.

The influence of Testosterone on human psychology and physiology is most notable when comparing men to women and analyzing large cohorts of males. While most men will never be charged with a violent crime, men are vastly more likely than women to commit murder, rape, assault, and other violent crimes.

The Effect of Testosterone on Men's Behavior is Undeniable

Dr. Hooven has come under criticism for her arguments regarding the influence of evolutionary biology on the male proclivity toward violence and aggression. Usually, these skeptics argue that her hypotheses could provide fuel for those that would like to say that men shouldn't be held accountable for their genetic propensity for violence.

She argues that understanding how evolution and hormones shape our thoughts and actions is critically important, in spite of the possibility that her work could be used to make spurious apologies for male behavior. The goal of her work is not to argue in favor of biological determinism, to say that our evolutionary past excuses the actions of the individual.

The best solutions to the problem of male violence will incorporate the scientific data derived from evolutionary biology. Turning a blind eye to the impacts of genetics, Testosterone, and nature on human behavior will prevent us from coming to the most effective solutions for a better society.

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