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10. The Evolutionist

Name: David Samson
Title: Evolutionary biologist at The University of Toronto
Why they're interestingExamining how human sleep has changed since Homo erectus dozed in trees

A common refrain in the sleep conversation is that our modern-day rest is broken. But David Samson, who studies the evolution of human sleep, has a different take. "Short, fragmented sleep isn't just a byproduct of electricity and smart phones," said Samson. "Humans have been trading off nighttime sleep for other activities (i.e., finding food, partying, searching for a mate) since we mastered the use of fire."

Samson makes the case that every change to human sleep, from the time of Homo erectus all the way to iphone addictus, has played a role in our cognitive development. The logical question underlying Samson's work is: Why would humans have evolved to put themselves in the defenseless position of being unconscious all night long for no reason? His answer is that, of course, they wouldn't. Early humans started sleeping in one, long chunk, Samson hypothesizes, because it enabled them to get the deep sleep and REM sleep necessary for the development of higher-order cognitive capabilities. In turn, these cognitive boosts promoted survival. 

One focal point of Samson's research is comparing human sleep with that of great apes (our six closest primate relatives) to figure out what makes human rest unique. Through these cross-species comparisons, Samson hopes to "discover how evolution shaped the relationship between sleep, cognition, and health."

Samson also looks at sleep in industrialized societies vs. modern-day hunter-gatherer tribes. The idea here is to understand how people sleep in the absence of technology and other modern practices, such as the 9-to-5 workday. From his work with both primates and traditional populations, Samson has found evidence that human sleep is inherently flexible — far more so than the sleep of other great apes. Long story short: We've evolved to go with the flow.

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