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BOB HIRSHON (host):
Large noses, big brains…I’m Bob Hirshon and this is Science Update.
Most mammals have unusually large brains for their body size. A well-developed sense of smell in the earliest mammals may be responsible, according to vertebrate paleontologist Thomas Macrini of St. Mary’s University in Texas. He and his colleagues made CT scans of the brains of two 190 million-year-old mammalian fossils found in China.
THOMAS MACRINI (St. Mary’s University):
And based on these CT scans we were able to reconstruct what the brain looked like and we found that they had very large olfactory bulbs in their brain which is the portion of the brain devoted to sense of smell. Developing a really keen sense of smell which probably led to an increase in brain size.
In addition, he says areas of the brain devoted to processing tactile information were also enlarged, but that visual and hearing acuity didn’t arise until later in mammalian evolution. I’m Bob Hirshon, for AAAS, the science society.