Can simulating evolution on a computer explain our enormous brains? Scientists believe so

Compared to the rest of the animal kingdom, the human brain is way out of whack.

Our brains are roughly six times larger than what you would expect for a placental mammal of our stature, scientists say.

And no other animal has a brain as large as ours relative to body size.

So why did humans evolve to have such large brains when other animals did not?

It’s a question that evolutionary biologists and anthropologists have been trying to answer for decades.

Our giant brains must have helped our ancestors survive in the African savannah where the first modern humans evolved, but they also came at a metabolic cost.

The human brain represents just 4 percent of our body weight, but it consumes 20 percent of our energy, said Mauricio Gonzalezforero, a mathematical evolutionary biologist at the University of St. Andrews in Scotland.

“It’s a very expensive organ,” he said.

Determining what social and environmental conditions caused our predecessors to develop such disproportionately large, energyhungry brains has turned out to be a hard problem to solve.

Human brain evolution is not something you can test in the lab. It would take hundreds of years, A reconstruction of 300,000-year-old Homo sapiens fossils from Morocco. A computer simulation of evolution suggests that ecological factors were the biggest factor in the evolution of our large brains.

if not thousands, to reveal how evolutionary pressures shaped the modern human brain. And even if you could do those experiments, they would probably not be ethical.

Instead, previous research has generally focused on the relationship between the brain size of different animals and their ability to find food, learn new skills, and live in groups. Scientists use those correlations to make inferences about why the human brain might have evolved as it did.

But this strategy has limitations, Gonzalez-forero said. For example, some researchers have found a correlation between large group size and large brain size, he

said. But it is not clear what came first – the living in large groups, or the development of a large brain.

In a paper published Wednesday in Nature, Gonzalez-forero set out to approach the question of why our brains got so big in a different way – by attempting to simulate evolution in a computer.

To do this, he started by considering how much energy an adult human female needs to sustain her brain, body tissues and the energetic cost of reproduction.

He also included previously determined data on how the energy requirements of an organism shift depending on its body size and the size of its brain.

For example, a bigger brain might have helped our ancestors find and consume food more efficiently by allowing them to be more adept at tracking and by learning to cook over fire, but that bigger brain also requires more energy. The same holds true for body size.

Next, Gonzalez-forero identified four challenges that early humans might have faced that could have influenced the evolution of their brain size. These were ecological (me vs. nature), cooperative ecological (us vs. nature), competition between individuals (you vs. me) and competition between groups (us vs. them).