The Facebook addiction that has been enveloping humans is hardwired in the brain, a psychologist says.

This means that human brains are compelled to be addicted and genetically determined to end up this way as manifested by the evolution of human brain sizes over the years.

Brains Getting Bigger, Brains Getting Smaller

Since time immemorial, human brains are thought to increase in size as time passes. However, about 20,000 years ago, this trend stopped, even paving the way for brain size shrinkage.

Scientists were not sure how this happened. Hypotheses start to spring up as they try to investigate fossil records. Some say the evolutionary changes are linked with climate change.

Others think that it may have something to do with the different diets and nutritional modifications that people practice. From being berry-eating to meat-divulging predators, humans have turned into hunter-gatherers that seem to have changed how life used to be lived.

From Needing To Survive To Needing To Socialize

American-born psychologist Bruce Hood believes that the changes in brain sizes persist to occur until now. All because humans are increasingly becoming domesticated.

In the past, the big brains of humans are required for them to process what they need to do in the face of complicated social situations. They have so much to deal with and they have to deal with it all from scratch.

Fast forward to today's society, people no longer need to think hard to survive. While humans in the past had nothing in mind but to think of ways to stay alive, people of today do not think about that at all anymore.

Humans have evolved into so-called "natural gossips" whose constant craving is to socialize with other people. With the rise of social media, people are all more given a larger platform to fulfill that urge, backing up the generation's growing Facebook addiction.

Human Brain Taking A Back Seat

While it may seem like the social media age may pave the way for people to have exposure to diversified views and become more open-minded, that is not exactly the case.

"What we see in reality of course is the opposite," says Hood. "People seem more likely to slot into niche groups of thought online than in real life."

Hood says humans' brains began decreasing in size when humans started transitioning from being hunter-gatherers to farmers.

As our ancestors began living in their permanent settlements, their brains also took a back seat. They do not need to think constantly about how to outwit their competitors for survival anymore.

The Ripple Effect

People then began passing this so-called "group intelligence" to the succeeding generations, which is something other species are able to do in a great extent.

The intelligence of humans grew from generation to generation thus, people of more advanced time periods need not to think heavily or learn from scratch.

Professor Hood will present more information about this topic during the latter part of this month at the Bristol Festival of Neuroscience.