Absolutely. Why? Because,

Evolution never stops.

Our environment is always changing, and so our brain is also evolving, but so slowly (take home message #1) that we cannot see it unless several thousand generations have passed. And recent scientific evidence suggests this too. Our ancestors had to adapt to the altered conditions of ground-based threats, which triggered the brain size growth. How is the environment changing today?

After agriculture began about 12,000 years ago, and particularly the industrial revolution of late 1800s and early 1900s, rapid advances in technology have considerably improved our life style, and made it fast-paced. Today a teenager’s brain processes more information in an hour than our forefathers did in their entire lifetime. Such increased demand on brain efficiency is likely to favor (Evolution point #2) a stronger brain in the foreseeable future.

Does “stronger” mean “bigger”? Posed another way,

Is our brain still getting bigger?

The best answer that I, or anybody else, can give you today is: Not necessarily. Even though we know how our environment has changed in the last few thousands of years, we  still do not understand our brain well enough to know how exactly this change is driving its current evolutionary course.

We all agree, though, that modern human intelligence depends as much on the size of our brain as on its complex internal structure. And so, with each new generation getting smarter, it is possible that our brain is evolving internally, without getting bigger. Experts also seem to divide along these lines on their interpretation of the latest scientific evidence.

A quick peek at our brain:

If you cut open a human brain vertically in the middle, it looks like the picture here (click to enlarge). Our brain  is packed with many internal organs, each connected to the others in intricate arrangements, and each  performs a variety of complex tasks (much of which is still unknown).

For example, Prefrontal cortex(PFC) is the chief executive of our brain, because it is responsible for forethought, planning, impulse control, and decision making. Likewise, Limbic system(LS) is made up of a number of component organs that together govern our emotion, memory and behavior. Not surprisingly, proper functioning of PFC and LS is vital to develop a normal personality. (People with ADD often differ from others in this aspect, as I will talk about in detail elsewhere.)

It sure looks dramatic when we compress the vastness of 3.5 million years – about 110,000 generations – in a single picture, as shown here (click to enlarge). We see that our brain capacity, measured by “cranial volume” (upper part of the skull that houses our brain), has grown more than two-fold during this time.

What could have happened back then that triggered this growth? Or, in the language of Evolution, how did the environment change millions of years ago that favored the “trait” of large brain size?

To make a complex story overly simple, after the hominids decided to come down from treetops (favored hangout of their ancestor – apes) and live on ground, they faced serious danger from large land animals with sharp tooth and claw. Being no match physically, only those with superior alertness and skill – signs of a healthy brain – survived, and passed on this trait to their offsprings. As the younger generations perfected these survival skills, their senses and intelligence continued to improve, and brain got bigger.

Thus, the new threat on survival of hominids favored the trait of a bigger brain, which continued through the next hundreds of thousands of generations, and has now become the 3lb mass of ganglion inside our head.

Next up: Is our brain still evolving?