Brain of 15-million-year-old monkey found to be small yet complex

Over the millennia, primates' brains have become both larger and more complex, leaving the scientific community at odds over which development occurred first. A computerized brain model recently made from scans of a 15-million-year-old monkey skull suggests intricacy over size may win that argument.

The 3D likeness shows that the brain of the Old World animal was decidedly small, being about the size of a plum. Similarly sized primates today have a cerebral mass that's about twice as big.

Nonetheless, the model of the ancient monkey's brain had numerous folds and wrinkles, which are benchmarks of a more elaborate network. Further, its olfactory bulb was 3 times the anticipated size, indicating a highly developed sense of smell that may have been sharper than what modern primates possess.

The specimen studied is the oldest one of its kind found. The information it's provided has helped in learning how brain development occurred over time. According to one of the study's authors, "...this study is some of the hardest proof that in monkeys...complexity came first and bigger brains came later."

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