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.

Compartmentalizing our Experiences is Impossible

Recently I have been thinking a lot about the present moment and I have been working on making the present moment its own moment in time, unconstrained by the past. I am working to remember lessons from Marcus Aurelius and to remember that all I control is my mind and reactions to the world at this moment. At the same time, however, I have recently ready Daniel Pink’s book When and I’m currently reading Cal Newport’s book Deep Work. Aurelius encourages us to be focused on the present moment, and to leave the past in the past and let the future come without thinking too far ahead. He stresses the importance of separating ourselves from the past in order to do the most that we can with the present moment.
Research by Pink and Newport, however, suggests that this might not be possible, and that even if we try our best to stay mentally focused on the present, the past unavoidably impacts the way our brains operate in the present. Pink studied the science of timing and examined the ways that the body and mind react to the world as we move through the day. He finds that the time of meetings, of intellectually challenging work, of exercise, and sleep all impact the way we think, feel, and move about the world.
Newport in his book looks for a way to perform at his best and seeks to understand how habit, performance, attention, and experience are all linked. He finds evidence to suggest that our minds are not very good at switching between tasks, and that what we have done in the past directly shapes our brains and our performance in the present. The habits we build and the effort we put toward developing our attention either enhance or limit our ability in the future to think deeply and focus on a given thing. What his research, along with Pink’s, finds, is that our current experience and state of mind is directly linked to our past and to rhythms and experiences throughout the day and throughout our lives.
The insight from Pink and Newport comes from scientific study of reality, but has also been discovered by those who meditate. Thich Nhat Hanh wrote about the inseparability of the world in his book The Miracle of Mindfulness. He states, “The great body of reality is indivisible. It cannot be cut into pieces with separate existences of their own.” the experience we have at one moment can not be compartmentalized and separated from another moment. At any given time we may be doing one thing and not another, but our experience of that moment is to some degree shaped by the experiences we have had throughout the day and in our past. In stoic philosophy, there can be a tendency to want to split what we do and how we experience the world into separate categories, but Pink, Newport, and Hanh suggest that this would be a mistake and may not be possible at all.
I don’t think we have to throw out the ideas of Aurelius and stoicism, but we must understand as we focus on the present moment how it relates to our past and to our future. We can perform our best if we think, moment to moment, about how we are connected to other times in our lives and how we can maximize our performance and experience given the time of day and the activities we have been involved with or will be involved with. This drives greater intentionality in our lives which in turn drives better experiences and a better connection to the present moment.