Human brains are getting smaller
Human brains are getting smaller, not exactly as we speak, but at an alarming rate nevertheless.
For the first two million years of human evolution, human brains steadily got bigger, as you might expect. However, over the last twenty or thirty thousand years - the blink of an eye in evolutionary terms- human brains have actually reduced in size by about 150 cubic centimetres or about the size of a tennis ball. In Fact, the Cro-Magnons who huddled around fires in caves and bashed flints together to make axe heads had more gray matter than our college professors.
Fortunately, this doesn’t impact much on intelligence. The surface “grey matter” essentially determines intelligence while the interior of the brain, the “white matter”, is more concerned with metabolic support. So women have generally smaller brains than men, but because of increased folding the surface area, intelligence is not consequently reduced. In fact, women often ghave a larger brain surface area owing to deeper convolutions of the brain surface.
Smaller heads may the result of natural selection as the likelihood of the death of the mothers of smaller headed babies in natural childbirth is less. This is, of course, less of an issue nowadays because of advances in modern medicine.
It has also been suggested that having too large a head would affect balance in a bipedal animal such as ourselves. Remember the Mekon? He was an extra terrestrial in the space comics of my childhood – Dan Dare I think – with a massive head and tiny body. I thought at the time that he was implausible from a purely engineering perspective. It is also suggested that we are as smart as we need to be at the moment.
Dr. Solar Wolff has another suggestion: “Let's face it folks, it doesn't take a big brain or a high IQ to survive and reproduce today. There is probably very little survival value in our society for high IQ or a big brain.”
It is also known that there is a dramatic increase in Humanoid brain size as meat consumption increases. People are eating less meat these days.
Again, intelligence has more to do with how much of the brain is utilized and we supposedly only use ten percent of our current brain potential. A massive superhuman brain is useless if the owner can only make use of as small percentage of it.
Then, of course, there is the comment of John Hawks, anthropologist at the University of Wisconsin at Madison: "What do we need these brains for? We've got iPods."