My, Grandma, What a Big Brain You Have!

"The findings are intriguing because they suggest that some aspects of social complexity are more likely to be consequences rather than causes of our large brain size, and that the large human brain is more likely to stem from ecological problem-solving and cumulative culture than it is from social manoeuvring."
Dr Mauricio González-Forero, School of Biology, University of St Andrews, Scotland

Human brains are about three times as large as those of our early australopithecines ancestors that lived 4 million to 2 million years ago, and for years, scientists have wondered how our brains got so big.  Credit: NIH, NIDA

"Compared to almost all other animals, human brains are larger as a percentage of body weight. And since the emergence of the first species in our Homo genus (Homo habilis) about 2 million years ago, the human brain has doubled in size. And when compared to earlier ancestors, such as australopithecines that lived 4 million to 2 million years ago, our brains are three times as large. For years, scientists have wondered what could account for this increase."
Rachael Rettner, Senior Writer, LiveScience

There are various hypothesis over the conundrum posed by the fact that humans have huge brains for the size of their bodies. Huge in comparison to other animals. The scientifically unschooled might simply point out that of all other animals that exist in this world of ours, it is humans that exhibit the most profound capabilities of thought, observation, reasoned action and response to environmental stimuli, among other attributes. We alter our environment in ways no other animal does, using the raw natural resources surrounding us for shelter, food and protection.

Other animals, however, do all of these same things, responding to their environment, seeking out food, shelter and safety specific to their species. Scientists speculate and have the evidence to point to, that the human brain evolved from being less physically prominent to what it is today in response to humans' primal encounters in survival, indicating the need to use resources, negotiate social interactions, acquire speech and language, and manipulate their environment, particularly as waves of hominids migrated from one geographical location to another.

The human brain typically weighs around three pounds and utilizes a full twenty percent of the energy the body requires to furnish all its needs. It is the evolution of the brain in response to various stimuli over time that piques the interest of scientists hoping to find definitive answers -- the ultimate reason why this transformation has taken place, why the human brain is roughly six times greater in size than it logically should be, contrasting it with other mammalian brains. 

And in the hope of finding answers it occurred to Mauricio Gonzles-Forero and Andy Gardner of St.Andrews University in Scotland that computer simulation might just produce the elusive answer. For their study they created a hypothetical population comprised only of females for simplicity purposes in facing their challenge in existence. Data was fed into the program relating to brain size and energy costs of maintaining the brain and reproductive organs Tasks were simulated to resemble environmental and social challenges held in brain evolution theories.

The task of the computer in assessing all these variables was to determine how pressures of specific challenges could lead to changes of brain size over time. The program was set to calculate the amount of energy females would invest in growing the brain as opposed to other organs and tissues, drawing on evolutionary theory. More robust mental demands had a tendency, predictably, to produce larger brains. 

According to computer results, some 60 percent of the effect boosting brain size resulted from an individual focusing on how they would react to environmental challenges singly, to find, store and prepare food and produce stone tools. An additional 30 percent was assigned to social cooperation in dealing with the environment; group activities such as hunting. The final ten percent was ascribed to competition between groups of people. The results of the study was published in the journal Nature.

A brain-evolution expert at Florida State University felt the work failed to assess the hypothesis of long standing that the development of language may have driven expansion of the brain. (Which feeds right into the present-day acknowledgement that learning more than one language expands brain power.) This was acknowledged by Gonzalez-Forero, explaining the language factor represents a cultural factor to be addressed in further studies on the enlarged brain size. 

Tough conditions are responsible for making the human brain disproportionately large, new research at the University of St Andrews has found.