An interesting study, just out by Stanford University professor Gerald Crabtree, says that humans are indeed getting dumb and dumber. According to Crabtree, this unfortunate process began when humans switched from hunter-gatherers to a sedentary agrarian culture. Advances from that point onward made survival less stressful, but also negated the process of natural selection pressures which acted on genes responsible for intellectual and emotional development.
To me this is a bit scary in light of how technologically advanced we have become, especially in the area of deadly weaponry.

…With the development of agriculture, came urbanization, which may have weakened the power of selection to weed out mutations leading to intellectual disabilities. Based on calculations of the frequency with which deleterious mutations appear in the human genome and the assumption that 2000 to 5000 genes are required for intellectual ability, Dr. Crabtree estimates that within 3000 years (about 120 generations) we have all sustained two or more mutations harmful to our intellectual or emotional stability. Moreover, recent findings from neuroscience suggest that genes involved in brain function are uniquely susceptible to mutations. Dr. Crabtree argues that the combination of less selective pressure and the large number of easily affected genes is eroding our intellectual and emotional capabilities….

I would say that with the discovery of petroleum, Homo Sapiens really hit their stride with the ‘dumbing-down’ effect of circumventing evolutionary pressures. As someone named Reality Broker at the Huffington Post commented:

Why should they need to think when there is a vast wealth of ‘knowledge’ on the web? They don’t need to think, there’s an app for that, or a blog full of people who’ll nurture their ‘beliefs’. Humans are becoming more like the Borg, with their collective Twitter feeds…their smart phones attached to their heads like some Cybernetic implant.

It is unfortunate that for many its getting harder to select the raisins from the rabbit manure.

Crabtree’s study dovetails with biologist Ernst Mayr’s belief that intelligence is a “lethal mutation”. At some point our intellect allowed us to make the jump from mere survival to living with all the creature comforts surrounding us today, but at the cost of avoiding the natural selection process which weeded out those deleterious genetic mutations to our brain.

However, hope springs eternal and Professor Crabtree has confidence that we will be able to overcome the ill-effects of this little deviation from natural selection:

…But not to worry. The loss is quite slow, and judging by society’s rapid pace of discovery and advancement, future technologies are bound to reveal solutions to the problem. “I think we will know each of the millions of human mutations that can compromise our intellectual function and how each of these mutations interact with each other and other processes as well as environmental influences,” says Dr. Crabtree. “At that time, we may be able to magically correct any mutation that has occurred in all cells of any organism at any developmental stage. Thus, the brutish process of natural selection will be unnecessary.”

Unfortunately, the brutish process of natural selection won’t be avoidable with mankind having surpassed the bio-capacity of the planet, putting us irrevocably into environmental overshoot. The fact that there’s something like 19,000 nuclear weapons in the hands of an emotionally and intellectually stunted species does not make me sleep any better, either.