DURHAM, NORTH CAROLINA—A study of modern hunter-gatherers suggests that sleeping habits may have evolved to help humans avoid nighttime threats such as predators, natural disasters, and enemy attack, according to a report in Seeker. Healthy men and women of the Hadza of Tanzania agreed to wear small devices that recorded their nighttime movements. Out of the 220 hours of the study, everyone was asleep at the same time for a total of only 18 minutes. Sleep expert Dave Samson of Duke University explained someone was always awake during the night, whether it was a mother with a newborn, or an elder who got up to relieve himself or herself. He added that younger people like to stay up late, while older people tend to get up early. Occasional social rituals also disrupted sleep. “The idea behind the ‘poorly sleeping grandparent hypothesis’ is that, for much of human history, living and sleeping in mixed-age groups of people with different sleep habits helped our ancestors keep a watchful eye and make it through the night,” he said. Samson also notes the Hadza take frequent daytime naps. To read about the earliest evidence for warfare between hunter-gatherer groups, go to "10,000 Turf War."
Varied Sleep Habits May Protect Mixed-Age Groups
News July 12, 2017
Recommended Articles
Letter from Doggerland March/April 2022
Mapping a Vanished Landscape
Evidence of a lost Mesolithic world lies deep beneath the dark waters of the North Sea
Features May/June 2021
Last Stand of the Hunter-Gatherers?
The 11,000-year-old stone circles of Göbekli Tepe in modern Turkey may have been monuments to a vanishing way of life
Digs & Discoveries March/April 2021
Lady Killer
-
Features May/June 2017
The Blackener’s Cave
Viking Age outlaws, taboo, and ritual in Iceland’s lava fields
(Photo: Samir S. Patel) -
Features May/June 2017
After the Battle
The defeat of a Scottish army at the 1650 Battle of Dunbar was just the beginning of an epic ordeal for the survivors
(Mary Evans Picture Library / Alamy Stock Photo) -
Letter from Greenland May/June 2017
The Ghosts of Kangeq
The race to save Greenland’s Arctic coastal heritage from a shifting climate
(Photo: R. Fortuna, National Museum of Denmark 2016) -
Artifacts May/June 2017
Maya Jade Pectoral
(Courtesy Toledo Regional Archaeological Project, UCSD)