Did Our Ancient Relatives Prefer Early Mornings? New research from Oxford University Press reveals that Neanderthal genes might hold the key to why some people are early risers.

In a recent study published in Genome Biology and Evolution by Oxford University Press, researchers explore the fascinating connection between Neanderthal genes and the propensity of some individuals to be early risers.

The research, led by John A. Capra, delves into the impact of ancient DNA on modern human circadian rhythms.

Genetic basis of being a morning person

All modern humans trace their roots to Africa approximately 300 thousand years ago, where environmental factors played a pivotal role in shaping biological features.

As our ancestors migrated to Eurasia around seventy thousand years ago, they encountered diverse environments, including higher latitudes with varying daylight and temperature patterns.

In contrast, Neanderthals and Denisovans had already inhabited Eurasia for over 400,000 years, diverging from modern humans around 700,000 years ago. Interbreeding occurred when humans arrived in Eurasia, allowing for the transfer of genetic variants adapted to the new environments.

The Influence of Neanderthal Circadian Clocks

The study focuses on circadian adaptation, a relatively understudied aspect of human evolution.

Neanderthals and Denisovans, having lived at higher latitudes with more variable daylight, potentially developed distinct circadian clocks.

The researchers identified 246 circadian genes, revealing hundreds of genetic variants specific to each lineage.

Morningness and Neanderthal Legacy

Using artificial intelligence methods, the team pinpointed 28 circadian genes with variants capable of altering splicing in archaic humans and 16 genes divergently regulated between modern humans and archaic hominins.

Examining genetic variants in a large cohort from the UK Biobank, they found introgressed variants—those transferred from Neanderthals to modern humans—associated with sleep preferences.

Notably, these variants consistently increased morningness, indicating an evolutionary adaptation.

Evolutionary Advantage of Morningness

Increased morningness, linked to a shortened circadian period, appears to be evolutionarily advantageous at higher latitudes.

The ability to align sleep/wake cycles with external cues more rapidly would have been beneficial for our ancestors living in Europe.

This Neanderthal genetic characteristic, preserved in modern humans, sheds light on the evolution of circadian adaptation.

Looking Ahead

Lead author John A. Capra emphasizes the significance of combining ancient DNA, large-scale genetic studies, and artificial intelligence in uncovering substantial genetic differences in circadian systems.

“By analyzing the bits of Neanderthal DNA that remain in modern human genomes we discovered a striking trend: many of them have effects on the control of circadian genes in modern humans and these effects are predominantly in a consistent direction of increasing propensity to be a morning person.

“This change is consistent with the effects of living at higher latitudes on the circadian clocks of animals and likely enables more rapid alignment of the circadian clock with changing seasonal light patterns.”

Future steps include expanding analyses to diverse human populations, exploring Neanderthal variants’ effects in model systems, and investigating other potentially adaptive traits.

Stay tuned as science continues to unravel the intricate relationship between our genes and the daily rhythms that shape our lives.

Image Credit: 1920’s artistic reconstruction of Le Moustier’s Neanderthals. – WIKIPEDIA