Is Human Evolution an Inevitable Race Toward Bigger Brains?

Is Human Evolution an Inevitable Race Toward Bigger Brains?

“Some scholars believe,” writes Yuval Noah Harari in his book Sapiens, “there is a direct link between the advent of cooking, the shortening of the human intestinal tract, and the growth of the human brain.” Harari argues that technologies around cooking allowed human intestinal tracts to evolve toward simplicity. Cooking food broke down compounds in foods that were harder to digest and neutralized pathogens that could have made us sick. As we learned to use fire, boil water, and create stone or dirt ovens, we made food more healthy, safer, and easier on our digestive systems which meant that we didn’t need to have such a robust digestive tract.
Harari continues, “Since long intestines and large brains are both massive energy consumers, it’s hard to have both.” When our intestines didn’t need to be so beefy, it was advantageous for humans to evolve with shorter, more streamlined guts. The energy saved in the gut could go toward other organs. Specifically, in the view Harari explains, the extra energy could be used to maintain a larger brain.
This makes me wonder, is all of human evolution a race toward a bigger brain? It is true that taller men are more likely to be elected president in the United States and that the typical image of a sexy man is a taller and more muscular individual (like Thor or Captain America), but for how long in human evolutionary history have tall bodies and large biceps been the most advantageous features for survival? Perhaps our desire for big brawny genes is leftover from our super quick ascendancy to the top of the food chain. Perhaps, as Harari’s quote eludes to, bigger brains have been the most advantageous feature for human survival for most of our history. Perhaps that truly is still the case.
An argument that Harari makes throughout the book is that humans have come to dominate the planet through our improved cognitive, reasoning, and social skills, which are all dependent on our brains. In this sense, evolutionary pressure has been toward larger brains, so all of human evolution is in some ways a race toward bigger brains. Shortening our gut allowed for bigger brains, giving up musculature allowed for more brain energy, standing on two feet allowed us to better survey the land – to provide our big brains with more data. We are not evolving to be better fighters, faster runners, or to physically occupy new niches. We are (and have been) evolving to better support better brains.
An Over-Hasty Food Chain Jump

Climbing the Food Chain Too Quickly

Evolution usually takes a very long time. Genetic and epigenetic factors tend to be the driving forces behind evolution, and changes to the genome or expressions of genes are usually quite slow. Over thousands to millions of years certain traits in species change, certain genes end up with errors that turn out to be beneficial for survival, and species slowly evolve. In most ecosystems across Earth’s history, predators, prey, and everything living have co-evolved in a slow but steady manner.
However, evolution does seem to have its shocks. This can be seen in theories of punctuated equilibrium, where things are stable with small changes occurring at relatively constant frequencies punctuated by periods of rapid and dramatic changes. Perhaps a volcano erupted and changed the landscape of an ecosystem. The genetic changes that were previously advantageous might not be advantageous now, and perhaps a whole new set of genetic mutations become advantageous. Or perhaps an invasive species has moved into the ecosystem and is upending a balance that evolution and natural selection had settled upon, reshaping the ecosystem and what traits are the most beneficial for the survival of all creatures.
In his book Sapiens, Yuval Noah Harari describes the quick ascension of humans as a force toward punctuation in the history of evolution on planet Earth. We are similar to a volcano or invasive species in terms of our destructive and disruptive power. For over a million years humans evolved slowly, positioned in the middle of the food chain, but  relatively rapidly, we rose to the top of the food chain and became the most dominate animal on the planet.
Harari writes, “Other animals at the top of the pyramid, such as lions and sharks, evolved into that position very gradually, over millions of years. This enabled the ecosystem to develop checks and balances that prevented lions and sharks from wreaking too much havoc.” Most apex predators evolved over a long period of time alongside the same prey and other living creatures, allowing animals to find their niches and natural defenses to live in a type of balance within an ecosystem.
Harari continues, “humankind ascended to the top so quickly that the ecosystem was not given time to adjust. Moreover, humans themselves failed to adjust. … Many historical calamities, from deadly wars to ecological catastrophes, have resulted from this over-hasty jump.” When humans went from mid-food chain to the top in only a few thousand years, we created a punctuation in the evolutionary course of the planet. Tool use, advanced social tribes, and coordination and cooperation among humans allowed us to disrupt the slow and steady process of evolution that allows living creatures to steadily evolve together. Other species couldn’t adapt quick enough, and a mass extinction is the end result.
Further, Harari argues that our quick jump in the food chain didn’t allow humans to evolve and adapt – in terms of our psychology – to our new position. We possess fears and insecurities that are tied to our tribal ancestry. We live as if we are still in the middle of the food chain, and not  the top. Our quick ascent was so fast that we still haven’t caught up with exactly what the change means and where we are, and as a result we still live with the same fears that our ancestors had when they were in the middle of the food chain. This insecurity, Harari argues, has contributed to wars, deliberate decimation of other animal species, and various negative things that humans have done to each other and the planet since becoming the most dominant species.
Are Humans Really Hunters?

Are Humans Really Hunters?

One skill that I have is the ability to see the narrative in the way that people understand the world. I think there is some level of an objective reality in the world, but it is often hard to see and understand because we layer so many narratives together to define the reality around us. I think I do a pretty good job of seeing the narratives that people tell themselves and of understanding why people are attracted to certain narratives. One such narrative that I think deserves to be questioned is the idea that humankind are natural hunters, that we are apex animals, and as such, our men (in particular) should be dominant and should exercise their natural urge to hunt and kill.
This is a narrative that has lost a lot of appeal in the United States and other WEIRD – Western, Educated, Industrialized, Rich, Democratic – countries, but still has a lot of power. People who gravitate toward such a narrative tend to be described as more traditionally conservative than people who eschew such a label in cultures like ours. In other cultures across the globe, the narrative is still a lot stronger, and countries like China are cracking down against sissy men who seem to violate the narrative. But are humans natural hunters? Are we really such powerful apex predators with urges to hunt and kill? Yuval Noah Harari argues that this narrative doesn’t seem to fit the evidence and leading scientific thoughts on exactly where humans have fit within the food chain for most of our evolutionary past.
“Humans who lived a million years ago, despite their big brains and sharp stone tools, dwelt in constant fear of predators, rarely hunted large game, and subsisted mainly by gathering plants, scooping up insects, stalking small animals, and eating the carrion left behind by other more powerful carnivores,” writes Harari. What is important to note is that for humans, who date back about 2 million years, a majority of our evolutionary past was not spent at the top of the food chain. There was a very long evolutionary past where humans were vulnerable, and rarely did any hunting that we would like to associate with early humans if we hold the narrative of humans being natural hunters and the most powerful animal on the planet. Harari continues, “one of the most common uses of early stone tools was to crack open bones in order to get to the marrow.” For much of human evolution, we were more scavengers than hunters, waiting for more dangerous predators (lions, hyenas, and such) to clear a carcass before we came along with our smart brains, deft hands, and insightful tool use to access the bone marrow the animals couldn’t easily get to.
I think it reveals a lot to note that the narrative of man as tough, aggressive, hunter-killers is common, while the narrative of man as a ingenious scavenging coward is not a narrative that anyone adopts. It may be more accurate to say that we are clever and find ways to pick up the scraps that other animals left behind, but no one wants to view themselves or humans broadly as scavengers. No one considers it “natural” to eat road kill, yet many diets are based on eating “natural” caveman diets that are based around the idea of hunting and killing our food.
“Genus Homo‘s position in the food chain was, until quite recently, solidly in the middle. For millions of years, humans hunted smaller creatures and gathered what they could, all while being hunted by larger predators,” writes Harari. The idea that man needs to hunt, that men need to be aggressive and kill, and that our survival is dependent on how tough our men are, is largely a narrative. I realize I am leaving out inter-human conflict and combat, but at least in terms of what humans evolved to eat, it is more narrative than objective reality that we need to eat lots of meat and kill animals for our diets. Humans evolved as scavengers, and only recently jumped to the top of the food chain.
Early Births and Socialization

Early Births & Socialization

“Compared to other animals,” writes Yuval Noah Harari in his book Sapiens, “humans are born prematurely, when many of their vital systems are still under-developed.” Harari explains that humans are born so early because humans walk upright. As humans evolved, we began to stand and walk on two legs, rather than walk on four legs or primarily walk on two legs while greatly supporting ourselves with our arms. A consequence is that female hips narrowed to support an upright gait, which in turn restricted the birth canal, meaning that infants born sooner were more likely to survive because they were smaller and less of a risk to a female human with a relatively more narrow birth canal than other species.
In evolutionary terms, earlier births had additional consequences for the direction in which humans evolved. Harari continues, “since humans are born underdeveloped, they can be educated and socialized to a far greater extent than any other animal.” Raising a child is difficult work, and raising infants who are born under-developed and then develop slowly takes the work of many. Harari’s suggestion is that raising human infants was not possible for our female ancestors to do on their own – at least it was incredibly difficult compared to females raising their infants within a tribe. It would have been hard for a lone female to forage for sufficient food and to provide defense for herself and the infant. As a result, “evolution thus favored those capable of forming strong social ties,” writes Harari.
I find this explanation of the evolution of human social skills pretty convincing, even if I can imagine particular instances where it may not necessarily fit. I think it is reasonable to assume that there was a dual feedback mechanism, where evolving brains shaped our physiology, and where our evolved physiology in turn shaped our brains. As we got smarter and as evolution favored larger brains and increased cognitive capabilities, our bodies changed to adapt to our brain, and certain physiological traits were more advantageous to a species with increased cognitive abilities. Those physiological traits and characteristics, like narrow hips and birth canals, changed the size of the brain at birth, changing the cognitive capabilities of human infants. This allowed infants to be socialized at a younger age and favored individuals who were better at being part of a community, changing the dynamics for what type of cognitive abilities were favored by natural selection.
There was no clear evolutionary path and no way to predict where the future would go based on the past. Social factors, physiological factors, environmental factors, and other factors we have not identified all likely shaped the evolution of humans. We adapted to fit the circumstances and evolution favored different ways of being human at different times. I think this is a lesson we can still learn lessons from today. We can learn that we will evolve and that different ways of being human will be favored at different times based on many factors unique to our time, space, cultures, and environments.
Increasing Brain Power, But Little to Show

Increasing Brain Power With Little to Show

I recently listened to Gastropod’s episode about barrels, and the hosts said that we don’t know a whole lot about the development of barrels throughout human history. One reason why we don’t know too much about ancient barrels is that barrels are made of wood, which decays and disappears over thousands of years.  We can study pottery and containers for food and drink made of earthenware because it can be more easily preserved than wooden vessels. Barrels can only be studied tangentially, since original specimens are hard to come by after a thousand years of decomposition.
Gastropod’s episode about barrels represents a challenge faced in all ancient history studies and sciences. How do we learn about things that don’t leave permanent remnants behind? What is reasonable to conclude from the absence of physical artifacts? What inferences are reliable and reasonable, and what inferences are biased because we don’t have something physical that could tell a story?
Yuval Noah Harari ran into this problem in his book Sapiens. About the evolution of early human species and the development of big brains he wrote, “for more than 2 million years, human neural networks kept growing and growing, but apart from some flint knives and pointed sticks, humans had precious little to show for it.”
He explains that our brains allow us to make many marvelous things today, from laptops to skyscrapers, that give us a clear advantage over the rest of the world. Our brains use a lot of energy and our species evolved away from big muscles, claws, and teeth to support our big brains. This payoff doesn’t really seem worth it if it took more than 2 million years to get from no tools to where we are today. A few flint knives and pointed sticks, Harari argues, is hardly worth the costs of developing big brains which left us vulnerable to more threatening animals.
A problem I think that Harari runs into is that we can’t look back at 2 million years of human evolutionary history and see the things that nature wasn’t able to preserve for us. For all those years of evolution we may have only been developing rudimentary physical tools, but we may have been developing new tools that we can’t look back and see, mainly mental tools and institutions.
This is an argument Robin Hanson and Kevin Simler might make. In their book The Elephant in the Brain, they argue that social interactions, in particular complex political interactions between humans, drove the evolution of our brains. Increasing our brains so that we could better work together and develop political groups would not leave a trace we could identify through physical artifacts like stone tools.
Additionally, early evolving humans with their increasing brains may have been developing more physical items than we give them credit for. Because many of the things they created may have disappeared due to natural decomposition, we might not have a record of them. I am sure this is something that people in the field know much better than me, and I’m sure something that Harari is aware of as well, but it is not well presented in Sapiens. His argument that the evolution of the brain did not have immediate payoff in terms of physical tools that would help the species survive is still valid, but it is narrow and leaves out other important advantages that the evolution of big brains brought to humans.
Why Giant Brains Are So Rare

Giant Brains Are Rare

In Sapiens, Yuval Noah Harari explains that Homo sapiens means wise man. It is a term we have given ourselves as a species because we have large brains and use those large brains to set ourselves apart from the rest of the animals and creatures on the planet. There are some other species with big brains, but in general large brains are rare, and no other species has been shown to use their brain to the same competitive advantage as humans.
But if large brains have made us so competitive across the globe, why are they so rare? Harari writes, “The fact is that a jumbo brain is a jumbo drain on the body. … in Homo sapiens, the brain accounts for about 2-3 percent of total body weight, but it consumes 25 per cent of the body’s energy when the body is at rest. By comparison, the brains of other apes require only 8 per cent of rest-time energy.”
Our brains are incredibly active and use a lot of sugars for fuel, even when we are not doing anything. This is great news for those of us who are trying to go on a diet to lose some weight today, but it was not great news for our ancestor hunter-gatherer humans and proto-Homo sapiens species of the past. According to Harari, large brains essentially have a high up-front cost. There is a large energy up front energy cost that goes into maintaining the brain before a species can really use the brain to a competitive advantage, and that has been a barrier to other species developing large brains and using them in a way that could give them a competitive advantage.
Harari continues, “Archaic humans paid for their large brains in two ways. Firstly, they spent more time in search of food. Secondly, their muscles atrophied. … A chimpanzee can’t win an argument with a Homo  sapiens, but the ape can rip the man apart.” Strong thinking and reasoning skills are helpful today and are the reasons we live in houses, build rocket ships, and are able to develop vaccines to end global pandemics. However, our big brains are not always the best tool to bring to a fist fight. It is not obvious that better reasoning skills will help a species survive better than sharp claws and teeth, thick hides, or spiky spines. Evolution doesn’t have an end goal in mind, and for all species besides the human species that evolved into Homo sapiens, the big brain payoff simply wasn’t the evolutionary rout that provided the best chance of survival and spread. It wasn’t until the big brained human species began to live and interact in clusters and tribes, communicating and working together, that big brains and reasoning skills could begin to pay off and become competitive against larger animals with bigger muscles and more ferocious claws, teeth, and tusks.
The Most Durable Human Species Ever

The Most Durable Human Species Ever

In recent years our DNA sequencing techniques and abilities have become dramatically better. We are able to get DNA from ancient sources in a way that we previously had not been able to, and we are then able to sequence that DNA more accurately are carefully than ever before. What this has started to reveal is a greater diversity of ancient human species, a greater spread of various human species, and more diversity and intermixing of human species than we had previously thought. A lot of this research is cutting edge and evolving daily, but for the last decade this research has been shifting how we view ancient humans, which in turn shifts the way we view ourselves.
In Sapiens, published in 2011, Yuval Noah Harari writes, “the more eastern regions of Asia were populated by Homo erectus, ‘Upright Man’, who survived there for close to 2 million years, making it the most durable human species ever.” It is somewhat strange to think that one species of human existed for 2 million years, or close to that figure, and eventually was outcompeted by a different species of human. Homo sapiens, our modern human species, eventually outcompeted all the other species of humans, including those which existed for hundreds of thousands to millions of years before our species evolved and began to spread.
Since Harari’s book was published we have learned more about species he briefly mentions such as Homo denisova and how widely those species managed to spread across the Earth. Additionally, research during the COVID-19 Pandemic suggested that some individuals may have genetic mutations stemming from the genome of Homo neanderthalensis, which changed their immune response to the disease. To me, research on ancient humans through DNA is a powerful and humbling reminder that my life and experiences are not unique just to me and this moment. It reminds me that human evolution has been a long and complicated process, with many Homo Sapiens and other human species that could think, talk, and experience the world in similar ways coming before me. Harari also stresses that Homo Sapiens may not be the final version of humans to evolve and dominate the planet, or last the longest on the planet. He continues, “this record [the estimated 2 million years that Homo erectus survived] is unlikely to be broken even by our own species. It is doubtful whether Homo sapiens will still be around a thousand years from now, so 2 million years is really out of our league.”
Three Major Revolutions

Three Major Revolutions

Yuval Noah Harari explains the evolution of humankind through three major revolutions in his book Sapiens. Harari takes a long view of humanity, trying to understand our very origins as a species and how we became who we are today. The three revolutions he identifies changed the course and direction of the evolution of humankind, and might lead to us becoming something unrecognizable in the future.
Harari writes, “the Cognitive Revolution kick-started history about 70,000 years ago. The Agricultural Revolution sped it up about 12,000 years ago. The Scientific Revolution, which got under way only 500 years ago, may well end history and start something completely different.”
This quick quote shows that the development of humans has been long and slow, but that recent changes have been dramatically quick in comparison. Human brains began to change dramatically during the Cognitive Revolution, but those changes did not spark instant societies and further tool use or manipulation of nature. 50,000 years of evolution took place before an Agricultural Revolution, which marked another change in human behavior, thinking, social structures, and life. What it meant to be human and the experience of living humans changed little in the 50,000 years between the Cognitive and Agricultural Revolutions, even though our minds were evolving dramatically.
But in the last 500 years, with the Scientific Revolution, the human experience has changed dramatically. It is possible that these dramatic changes and advances will continue, to the point where humans will no longer be recognizable as human when compared to the species that kicked off the Cognitive Revolution or the Agricultural Revolution. The Scientific Revolution put us on a new path that may end up with humans fusing with computers and machines to be human in a way, but not in a way that a human from 12,000 years would recognize.
Why Equality of Opportunity is a Myth - Ezra Klein - Star Wars - Yuval Noah Harari - Thrawn - Ahsoka - Sapiens

Why Equality of Opportunity is a Myth

I used to listen to the Ezra Klein show on a regular basis, and Klein was frequently critical of the idea of equality of opportunity. In our country, the idea of equality of outcomes is looked down upon, but the idea of equality of opportunity is praised. However, Klein argued that equality of opportunity was actually a much more difficult and radical idea to achieve  than equality of outcome. When you really consider all the advantages the children of millionaires or billionaires have over middle class children, and the subsequent advantages those children have over children raised in poverty, you can see that equality of opportunity is little more than a myth.
This idea is reflected in Yuval Noah Harari’s book Sapiens: A Brief History of Humankind. Harari writes, “most abilities have to be nurtured and developed. Even if somebody is born with a particular talent, that talent will usually remain latent if it is not fostered, honed and exercised. Not all people get the same chance to cultivate and refine their abilities.”
Our country believes that everyone can pull themselves up by their boot-straps, but the reality is that we almost all need someone outside of ourselves to help encourage us, coach us, and aid us in developing our skills, even if we are born with a natural talent. As I write this, I am reminded of two Star Wars books I recently listened to through Audible. In Star Wars: Ahsoka, the titular character explains to the parent of a force-sensitive child that if the child is not brought up by a Jedi and her force abilities are not nurtured, then they will eventually fade away. The force, and the ability to tap into the force, in Star Wars is a god-like power, but even those born with a special proclivity toward the force will lose that power if not properly trained. The child in the book, born on a planet on the outskirts of the major center of the galaxy, was not likely to have a chance to harness and maximize her force powers. She did not have the same opportunity to develop her natural talent as the Jedi Ahsoka did.
In another Star Wars title, Thrawn by Timothy Zahn, the titular character Thrawn meets a young cadet named Eli Vanto who is exceptionally skilled with data and strategic analysis, but who is also from a planet on the outskirts of the galaxy. Despite his exceptional skill, his rural and low status upbringing slotted him into a relatively minor career path within the Galactic Empire. Thrawn recognizes his talent by chance and continually encourages and challenges Eli to maximize his abilities (often against Eli’s own desires). In the end, Eli raises to a military rank he never expected, and while his own talent played a huge role, it was largely thanks to Thrawn that Eli had the opportunities to maximize his abilities.
The two Star Wars novels may be fiction, but they reflect a reality in our society that we are all aware of, but prefer not to think about. Instead of acknowledging that our talent needs to be cultivated, and that cultivation and the opening of doors often has to come from beyond ourselves, we imagine that we can get where we want through hard work and determination alone. Those are certainly important character traits, and can be seen clearly in the story of Eli Vanto, but alone they don’t mean that we are really going to maximize our potential.
In Sapiens, Harari continues, “even if people belonging to different classes develop exactly the same abilities, they are unlikely to enjoy equal success because they will have to play the game by different rules.” We like to believe that talent, hard work, and grit are all one needs to succeed to the greatest extent possible, but where we are born, who we know, and the opportunities that our birth, appearance, and upbringing provide can overwhelm the advantages that talent, hard work, and grit give us. Equality of opportunity is a myth, because we are playing different  games by different rules, and because we all rely on assistance from outside of ourselves to  get to where we want to be. For some, that assistance comes more easily than for others, and for some there are exceptional hurdles that make it difficult to get onto a path toward great success.
Shift Work

Shift Work

“For the past four decades, submarines have run on a watchbill known as sixes, which divides sailors’ time into six-hour chunks: six hours on watch, six for other duties and studies, six for personal time and sleep, then back on watch. The creation of an 18-hour day saw each sailor putting in six extra hours of watch time every 24-hour period. The problem is that his activities ceased to align with his biological rhythms,” writes Mary Roach in her book Grunt.
For many humans, shift work doesn’t align with our biological rhythms. Not all of us are sailors working sixes, but when our shift work doesn’t align with our biological rhythms, it can still throw us off, diminish our performance, and cause all kinds of problems for our daily lives. To me, it seems that shift work is a leftover of the industrial revolution, and something we are more or less stuck with, especially in a globalized world that seems to be increasingly moving toward an always on – 24 hour schedule.
Studies have shown that shift work among nurses is bad for performance and healthcare, but getting nurses to give up 12 hour, three/four workday shifts is difficult. Roach writes about the problems submariners have with shifts that don’t align with their circadian rhythm, and force them to work when their bodies need sleep. And all of us have probably felt the challenge of working in the mid afternoon when our minds can’t seem to concentrate on anything important. We force ourselves to push through times when we are not at our best because our shifts demand that we be on when our bodies would prefer us to be off.
But none of us really seem to want to do anything about changing our shifts. Some people who are creative and work for themselves, like my uncle or Tim Ferris with his Four Hour Workweek, can build a schedule that is flexible and aligns with their body and performance, but most of us are stuck working a schedule driven by our customers or our bosses. “As flawed as it is, we’d perfected it,” Commanding Officer Bohner is quoted by Roach as saying in the book. Making changes to nursing schedules, adjusting the expected daily working hours for everyone in the country, and adjusting our hours of operation is hard. It is easier to simply perfect working in imperfect conditions, even if that means putting up with bad performance.
I hope in the future we will be able to change this for many people. I hope we can find ways to get people into a work rhythm that better aligns with each individual’s circadian rhythm. The benefits would be important. Nursing and hospital safety could be better. Daily performance and happiness for workers  could be better. This could translate into real improvements in people’s lives, and I think it is worth striving toward, even if it would be hard to shake up all the pieces and start over without the same shift work.