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Random Thoughts on “Sapiens” Book

I am reading “Sapiens: A Brief History of Humankind“ for the second time and every time I read it or any other material with reference to evolutionary biology, I can’t help but admire the eternal wisdom and intelligence of Nature. Designing and evolving organisms as complex, efficient, and intelligent as us (humans and lions alike) is unimaginably difficult, and yet, here I am, a mere animal smart enough to ponder over its origins.

Some of the most thought provoking facts/speculations are in the first chapter under section “The Cost of Thinking”. Here are some relevant excerpts (for people who have not read the book, so that they can better relate to what I am about to say next):

[excerpt start]

“The earliest men and women, 2.5 million years ago, had brains of about 600 cubic centimetres. Modern Sapiens sport a brain averaging 1,200– 1,400 cubic centimetres. Neanderthal brains were even bigger. That evolution should select for larger brains may seem to us like, well, a no-brainer.

Why are giant brains so rare in the animal kingdom?

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 percent of rest-time energy. Archaic humans paid for their large brains in two ways. Firstly, they spent more time in search of food. Secondly, their muscles atrophied.

What then drove forward the evolution of the massive human brain during those 2 million years? Frankly, we don’t know.

The advent of cooking enabled humans to eat more kinds of food, to devote less time to eating, and to make do with smaller teeth and shorter intestines. Some scholars believe there is a direct link between the advent of cooking, the shortening of the human intestinal tract, and the growth of the human brain. Since long intestines and large brains are both massive energy consumers, it’s hard to have both. By shortening the intestines and decreasing their energy consumption, cooking inadvertently opened the way to the jumbo brains of Neanderthals and Sapiens.”

[excerpt end]

Every organism we see now is a result of millions of years of evolution, designed to survive and operate efficiently and we are still evolving (e.g. lactose tolerance in adults in regions where dairy farming is common). Just imagine the loss when we drive a species to extinction!

And to think that all these design decisions are propagated generation upon generation via something as simple as “natural selection” is astonishing. Despite being simple, it works so well that Computer Science has its own class of optimization algorithms called “Evolutionary Algorithm”, which has been used to solve many complex problems (a few years back I developed a project which attempts to solve the problem of finding optimal hyperparameters for Neural Networks using Genetic Algorithm. Smarter people have found many better applications of it). Nature truly is the greatest engineer.

Let’s pause for a second and imagine — what if Nature had decided to endow us with a larger brain (by solving the energy conservation problem in some other creative way). How different would our lives be? Could we have cured Cancer by now? Could we have solved the Unified Field Theory in physics? Would we be any closer to General Artificial Intelligence? How much more creative the Beethovens of that other species would be? How different our religions would be? Or would we have driven the entire planet to extinction even sooner? Who knows!

The book not only discusses the biological evolution of humans, it also investigates the cultural evolution of humans. Like, what drove humans to be a social animal, how do humans manage to coordinate in such large tribes (modern day religions or organizations), what role did language play in human evolution, and much more. This is one of the best books I have read.

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