In the future of evolution, the brain and mind – the most prominent characteristics of humans – will undergo significant development.
What Causes the Brain to Shrink?
Over the past 6 million years, the brain size of hominids has nearly tripled, indicating that the evolution of larger brains was driven by tool use, complex social communication, and particularly language. It is easy to think that this trend will continue inevitably, but perhaps that will not be the case.
Instead, the human brain is becoming smaller. In Europe, brain size peaked around 10,000 – 20,000 years ago, just before humans invented agriculture. After that, brain size began to reduce. Modern humans have smaller brains compared to ancient people or even those from the Middle Ages. The reasons for this shrinkage are unclear.
The human brain once developed robustly but is now shrinking after the agricultural revolution.
It may be due to the scarcity of fats and proteins when humans transitioned to farming instead of hunting, making the development and maintenance of a large brain more costly. The brain is also very energy-intensive, burning about 20% of the body’s daily calorie intake. In agricultural societies with frequent famines, a large brain could become a burden.
Life as a hunter-gatherer may have required skills that agricultural work does not. In civilization, humans no longer need to worry about dealing with lions and antelopes or memorizing every fruit tree and watering hole within a thousand square miles. Manufacturing and using bows and arrows also requires good motor coordination and tracking abilities; the parts of the human brain dedicated to those skills may have shrunk with the cessation of hunting.
Alternatively, living in a populous society with the presence of specialists may require each person to use less intellect than living in a tribe where everyone had to manage everything. Stone Age humans had to master many skills to survive: hunting animals, foraging for plants, crafting herbal medicines, identifying toxins, making tools, and combat skills. Modern humans perform fewer roles, specializing as part of a vast social network with a division of labor. In a civilization, individuals focus solely on their specialization and rely on others for everything else.
Interestingly, domesticated animals have also evolved with smaller brains. Sheep lose 24% of their brain mass after domestication; cattle lose 26%; dogs lose 30%. This raises a concerning risk. Perhaps the inclination to be more passively agreeable (even potentially lazier in thinking) has affected all species, including humans.
Humans Becoming More Docile
Human personality must also evolve with life circumstances. The lives of hunter-gatherers demanded aggression. They hunted large animals, fought to the death for women, and waged wars against neighboring tribes. Now, we simply pay for everything, including purchasing meat from a store; we have developed a habit of turning to the police and courts to resolve disputes. Although war has not disappeared, it now causes a lower mortality rate relative to population size than at any time in history. Aggressiveness has become a maladaptive trait, facing elimination.
Changing social patterns will also change personality. Early humans lived in significantly larger groups than other primates, but still formed tribes of about 1,000 hunter-gatherers. In today’s world, people live in vast cities with millions of residents. In the past, human relationships were few and often lifelong. Now, we live among crowds, frequently moving for work and forming thousands of relationships, many fleeting and increasingly tenuous. This environment encourages humans to become more extroverted, open, and inclusive. However, navigating such vast social networks may also require us to be more compliant rather than resistant.
Not everyone adapts psychologically well to this existence. Human instincts, desires, and fears are largely inherited from our Stone Age ancestors, who found meaning in hunting and gathering for their families, waging wars with neighboring tribes, and praying to ancestral spirits in the night. Modern society meets our material needs well but struggles to satisfy the psychological needs of our primitive brain.
Perhaps this is why more and more people are suffering from psychological issues such as loneliness, anxiety, and depression. Many turn to alcohol and stimulants for relief. Choosing to combat vulnerability to these conditions may improve mental health and make us happier as a species. But that may come at a cost. Many great geniuses had their flaws; leaders like Abraham Lincoln and Winston Churchill battled depression; scientists like Isaac Newton and Charles Darwin faced similar struggles; artists like Herman Melville and Emily Dickinson also contended with mental health issues. Some, like Virginia Woolf, Vincent Van Gogh, and Kurt Cobain, took their own lives. Others, like Billie Holiday, Jimi Hendrix, and Jack Kerouac, were ruined by substance abuse.
Scientists Einstein and Newton.
A troubling thought is that these psychological conditions may lead us to eliminate them from our gene pool. In return, this could come at the cost of removing the mutations that have produced visionary leaders, great writers, artists, musicians… Future humans may be better adjusted but less joyful at parties and less capable of sparking scientific revolutions. In other words, from the current perspective, our future lives may be stable, happy, but boring.
The Risks of Trying to Control Evolution
One of the more extreme possibilities is controlled future evolution, where we actively adjust the evolution of humanity. We have been selectively creating generations by choosing partners with desirable appearances and personalities. For thousands of years, hunter-gatherers have arranged marriages, seeking skilled sons-in-law for their daughters. Even when children reach marriageable age, they often still need their parents’ permission to marry. Similar traditions persist in various places today. In other words, we are self-adjusting our genes for future generations.
In the future, we will do this with more knowledge and control over the genes of our offspring. We have already been able to screen ourselves and embryos for genetic diseases. We have the ability to select embryos for desired genes, just as we do with crops. Directly editing human embryo DNA has been shown to be feasible. Moreover, if such technologies prove safe, we can envision a future where parents compete to select the best genes for their children.
Computers also provide a completely new selective pressure. As more compatible results are produced on smartphones, we are delegating decisions about the appearance of the next generation to computer algorithms, which suggest outcomes that align with our desires. Current digital codes are aiding in selecting which genetic codes are passed on to future generations. This may sound like science fiction, but it is already happening. Human genes are being managed by computers. It is difficult to predict where this will lead, but it is worth questioning whether it is entirely wise to entrust the future of humanity to iPhones, the internet, and the companies behind them.
Discussions about human evolution often have an optimistic outlook, as if the greatest victories and challenges are far behind us. But as technology and culture enter a period of rapid change, human genes are also evolving. It can be argued that the most interesting parts of the evolutionary process are not the origins of life, dinosaurs, or Neanderthals, but what is happening right now, in the present and future of humanity.
