London: The human mind may have reached its limit of intelligence, as a research has suggested that the humans are presently as smart as they are ever going to be.
Scientists have said that even the cleverest people might not get any brighter since our grey matter has stopped evolving. And it is all down to physics. The structure of our brain and how much energy it uses are key to the theory, The Sun reported Sunday.
One part of the theory is that scientists reckon brain cells cannot get much smaller than they are at present - meaning there will not be any further space for more of them.
It is also thought the number of connections between brain cells cannot rise much more due to the amount of energy they consume.
Research has shown that the better connected the parts of the brain, the higher a person`s IQ.
The theory`s another part is the amount of energy used by brain cells. It states that the brain only accounts for two percent of a person`s body weight - but uses 20 percent of our overall energy.
It means if we turned any smarter - by having more brain cells or connections between them - the impact on our body`s power supply would be immense.
"We have demonstrated that brains must consume energy to function and that these requirements are sufficiently demanding to limit our performance and determine design," said Simon Laughlin, professor of neurobiology at Cambridge University.
According to Ed Bullmore, professor of psychiatry at Cambridge, all of us have "to pay a price for our intelligence".
"Becoming smarter means improving connections between different brain areas but this runs into tight limits on energy, along with space for the wiring," Bullmore said.
Laughlin also feels the brain evolution could go into reverse if human circumstances change - for instance if there were a shortage of food.
He said: "The fact that brains both expand and contract during evolution shows that the optimum balance changes with circumstances."