Ancient monkey skull reveals tiny but complex brain

In 1997 a 15 million year monkey skull was discovered, and for the first time researchers have peered inside to see what secrets it holds. What they found was surprising — the brain was small but very complex. The skull comes from an ancient monkey known as the Victoriapithecus, and it was examined using X-rays and a 3D computer model based on the X-rays. The brain is said to have been "tiny" in relation to the monkey's body size, coming in at more than 50-percent smaller than comparable modern monkeys. The level of complexity, however, was surprisingly high.

Scans of the skull show the brain had many folds and wrinkles, and that the monkey likely had superior smelling abilities compared to modern monkeys. This was due to an olfactory bulb that turned out to be thrice the size researchers had anticipated.

In comparison, modern monkeys have "very small" olfactory bulbs, something believed to have been a trade-off that came with improvements to their vision. Victoriapithecus may have had both, however — an excellent sense of smell and good vision.

The discovery also turns a long held belief about primate brain evolution on its head. Researchers have thought that primate brains likely became larger before forming folds and wrinkles, but this latest discovery — which comes from the oldest Old World skull so far discovered — shows that the brain had such characteristics while still tiny.