Neurology of Brains

Neurology of Brains

Less than ten million years ago, the first creatures who closely resembled human beings evolved, accompanied by a spectacular increase in brain size. And then, only a few million years ago, the first true humans emerged, who grew up in forests.

As our ancestors evolved in forests, we have a natural affinity for them. Indeed, how lovely a tree is, straining toward the sky. Its leaves harvest sunlight to photosynthesize, so trees compete by shadowing their neighbors. If you look closely you can often see tow trees pushing and shoving with languid grace. Trees are great and beautiful machines, powered by sunlight, taking in water from the ground and carbon dioxide from the air, converting these materials into food for their use and ours.

Neurology of Brains. Illustration by Elena

The plant uses the carbohydrates it makes as an energy source to go about its planty business. And we animals, who are ultimately parasites on the plants, steal the carbohydrates so we can go about our business. In eating the plants we combine the carbohydrates with oxygen dissolved in our blood because of our penchant for breathing air, and so extract the energy which makes us go.

In the process we exhale carbon dioxide, which the plants then recycle to make more carbohydrates.

What a marvelous cooperative arrangements – plants and animals each inhaling the others’ exhalation, a kind of planet-wide mutual mouth-to-stoma resuscitation, the entire elegant cycle powered by a star 150 million kilometres away.

(By Carl Sagan, Contact)