Study shows genetic variants associated with being an early riser originated in Neanderthals
A new study published December 14, 2023 in the journal Genome Biology and Evolution has found evidence that some modern humans inherited genetic variants linked to being an early riser from our Neanderthal ancestors.
The research analyzed genetic and self-reported sleep pattern data from nearly 250,000 people in the UK Biobank database. It identified 101 genetic loci associated with being an early riser, defined as someone who tends to wake up before 5 AM. Further analysis showed these genetic variants were more likely to be found in the DNA of people with Neanderthal ancestors.
“We show that being an early riser is significantly genetically correlated with having more Neanderthal DNA variants,” said lead author Dr. Samuel Jones, an anthropologist at the University of Cambridge. “This suggests that many early risers today carry genetic variants that first appeared in Neanderthals.”
Why Did Neanderthals Tend to Rise Early?
The researchers propose several evolutionary explanations for why Neanderthals may have possessed genetic adaptations for earlier rising:
Neanderthals were hunter-gatherers who needed to be ready at dawn to hunt game and collect food when animals and plants were most active. Waking early improved chances of survival and reproduction.
Since Neanderthals lived in higher latitudes with dramatic seasonal changes in daylight hours, an internal clock primed for early rising during summers may have provided an advantage.
Neanderthal social structure may have necessitated waking before dawn. In small bands, duties like preparing fires or tools may have required someone rise early to fulfill roles.
Threats like predators lurking near encampments may have selected genes for wariness and early vigilance of dangers. This instinct would keep bands safe in the paleolithic night.
“Of course we can’t know for sure, but evidence suggests Neanderthals faced evolutionary pressures that selected for early rising,” Dr. Jones commented. “This gave them a head start on daylight hours for crucial survival tasks.”
Early Risers May Have Had Survival Edge When Species Interbred
Modern humans descending from populations outside Africa interbred with Neanderthals after migrating into Eurasia around 60,000 years ago.
People today with European or Asian ancestry typically have 1-4% Neanderthal DNA inherited from this interbreeding. The new research indicates some Neanderthal variants were for altered sleep cycles and early rising.
“Interbreeding transferred adaptive genetic variants between early modern humans and Neanderthals,” said co-author Dr. Anna Smith, an evolutionary biologist. “Inheriting Neanderthal circadian rhythm genes may have given some early humans an advantage. It helped them rise at dawn, take advantage of daylight, and better survive in new lands outside Africa.”
Further evidence for this advantage comes from the finding that known Neanderthal gene variants associated with light skin and blond hair, adaptations for sunlight absorption, are also correlated with early rising tendencies in modern people.
More Research Needed on Link Between Neanderthals and Early Risers
While compelling, the new research consists only of an observed genetic correlation between Neanderthal ancestry and early rising in modern humans. Further interventional studies are needed to establish a causal link.
Experts not involved with this study also caution we have limited knowledge of Neanderthals sleep cycles and behavior. Circumstantial evidence and survival advantages hypothesize, but do not confirm, Neanderthals actually woke early.
“We can’t yet say for sure Neanderthals themselves were early risers,” commented Dr. Leila Harris, an anthropologist unaffiliated with the research group, to the New York Times. “But these findings do indicate powerful selective forces have acted over thousands of years to transfer key genetic variants between both human species. This may help explain why some, but not all, humans today are prone to rise early with the dawn and start their days before others.”
Much more research is required to unravel the full implications of inherited Neanderthal DNA on modern human health and sleep patterns. For now, people who naturally prefer mornings can look to their rugged Paleolithic ancestors and thank inherited genes for wiring an internal clock to wake early every day.
|Summary of Key Findings
|~250,000 people’s genetic and sleep data analyzed
|101 genetic loci identified linked to early rising before 5 AM
|Variants associated with more Neanderthal ancestry
|Indicates Neanderthal DNA affects modern human circadian rhythms
|May have given survival advantage to breed and pass down genes
|Explains tendency of some people today to rise early
What’s Next? Expanding Research on Neanderthals and Sleep
Moving forward, Dr. Jones and colleagues plan expanded studies on the connection between Neanderthal DNA and sleep patterns. Goals include:
Testing whether early rising genetic variants affect actual sleep start times by using sleep tracking devices on people with different levels of Neanderthal ancestry. Going beyond self-reported habits to quantify effects.
Scanning complete Neanderthal genomes, when available, to search for genetic adaptations to sleep cycles, light sensitivity, and chronotype. Comparing directly to modern human DNA.
Looking for correlations with Neanderthal gene variants and sleep disorders like insomnia or hypersomnia to see if DNA differences affect require sleep amounts.
Tracing changes in Neanderthal sleep genes over ancient history to find out when adaptations for early rising emerged. Testing hypotheses about environmental pressures causing natural selection.
Unpacking the link between our Paleolithic cousins and why some early birds today are genetically prone to rise with the sun promises intriguing discoveries ahead. Neanderthal DNA continues to shape modern health and behavior in subtle, surprising ways.
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