Old World Monkey Skull Reveals Primates Had Tiny But Complex Brains (VIDEO)

First Posted: Jul 06, 2015 01:32 PM EDT

It turns out that brain complexity can evolve before brain size in primates. Scientists have discovered that the brain hidden inside the oldest known Old World Monkey was tiny but remarkably wrinkled.

The monkey, in this case, is known as Victoriapithecus. It was first discovered on an island in Kenya's Lake Victoria, and is estimated to have lived about 15 million years ago.

Now, researchers have used high-resolution X-ray imaging to peer inside the cranial cavity of the skull. More specifically, they created a three-dimensional computer model of what the animal's brain really looked like.

"When Lauren finished analyzing the scans she called me and said, 'You won't believe what the brain looks like,'" said Brenda Benefit, co-author of the new study, in a news release.

In fact, the researchers calculated the brain volume to be about 36 cubic centimeters, which is less than half the volume of monkeys of the same body size living today. Despite these tiny proportions, though, the brain was surprisingly complex; the CT scans revealed numerous distinctive wrinkles and folds. In addition, the olfactory bulb was three times larger than expected.

"It probably had a better sense of smell than many monkeys and apes living today," said Lauren Gonzales, one of the researchers. "In living higher primates you find the opposite: the brain is very big, and the olfactory bulb is very small, presumably because as their vision got better their sense of smell got worse. But instead of a tradeoff between smell and sight, Victoriapithecus might have retained both capabilities."

The findings may reveal important new clues about how primate brains changes over time. More specifically, it may show how humans also evolved over time.

"In the part of the primate family tree that includes apes and humans, the thinking is that brains got bigger and then they get more folded and complex," said Gonzales. "But this study is some of the hardest proof that in monkeys, the order of events was reversed-complexity came first and bigger brains came later."

The findings are published in the journal Nature Communications.

Want to learn more? Check out the video below, courtesy of YouTube.