The human being is the primate that sleeps the least. Science is clear that it is a “radical evolutionary experiment”

We spend a third of our lives sleeping, yet the most common complaint in modern society It’s the lack of rest. We tend to blame screens, work stress and artificial light for robbing us of hours of sleep, but here evolutionary anthropology has a much more forceful answer: human beings are genetically designed to sleep less than any other evolutionary relative.

It is studied. It is not something that we see from afar as a mere hypothesis, but researcher David R. Samson, professor of Evolutionary Anthropology, recently published a book that includes the results of his research. And the truth is that, after living with hunter-gatherer tribes like the Hadza in Tanzania and the BaYaka in the Congo, their conclusion is resounding: humans are an absolute biological anomaly.

We are the great early riser. If we take out the calculator and the meter, a primate more or less of our same average body mass, brain size and diet should sleep about 9.5 hours a day. But this figure is limited to a fairly select few people, since we actually sleep around 2.5 hours less than our evolutionary biology predicts, making us the primates that sleep the least of all.

This is a pretty clear conclusion. if we compare ourselves with other species that have very high sleep rates, as can be seen in the following list:

• Chimpanzee: between 9.5-11.5 hours a day.
• Gorilla: 10-12 hours.
• Pig-tailed macaque: 14 hours.
• Night monkey: 17 hours.

Because? How is it possible that with the most complex and energetically demanding brain in the animal kingdom we sleep so little? The answer seems to lie in the “deep sleep” hypothesiswhich suggests that evolution forced us to have a much deeper and more efficient sleep to sleep much less than the rest of the hominids.

For example, humans spend approximately 25% of our rest time in the REM phase, which contrasts with species such as African green monkeys, which They only dedicate 5% to this phase. But in addition, human sleep has a lower proportion of light sleep, since in return, it has a higher proportion of deep sleep.

A necessity. Having a much shorter rest was not a whim of ours, but rather a matter of survival, since by leaving the safety of the trees, where our ancestors slept safely, and descending to dry land, the risk of predation skyrocketed.

Regarding shorter sleep, evolution promoted several mechanisms to guarantee our survival, such as sleeping next to the fire and in large groups for greater security. But in 2017 a study showed that natural variation in chronotype allowed someone to always be awake standing guard during the night.

Don’t blame the screens. It is tempting to think that we sleep for about 7 hours because electric lights and smartphones have altered us in this modern life. But this is not the case, because after analyzing the sleep of the Hadza, who are a hunting community in Tanzania without access to electricity or mobile phones, it was shown that their patterns are identical to ours, sleeping 6.25 hours a night and maintaining a sleep efficiency of 68.9%.

Images | MediaEcke

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