Recent research suggests that individuals who tend to be early risers may have inherited specific genetic variants from Neanderthals, influencing their preference for morning activities rather than evening ones. Despite the complexity of the human body clock, shaped by societal norms, culture, and genetics, Neanderthals, having evolved in high latitudes in Europe and Asia, may have been better adapted to seasonal changes in daylight. This is in contrast to early Homo sapiens, who evolved in Africa closer to the equator, experiencing less variation in daylight hours.
The study, published in Genome Biology and Evolution, proposes that as early humans migrated northward and interacted with Neanderthals, they may have acquired genetic adaptations to changes in daylight from their extinct counterparts. This genetic legacy could still influence contemporary variations in human chronotypes, determining whether one leans towards being a night owl or a morning lark.
According to Tony Capra, an associate professor at the University of California, San Francisco, individuals with a faster running body clock are more likely to rise early, especially in higher latitudes where adapting to changing seasonal light levels is advantageous. This adaptation may have been passed down from Neanderthals, whose circadian clocks likely adjusted to different light/dark cycles based on their diverse habitats.
To quote Capra, “At higher latitudes, it is beneficial to have a body clock that is better able to anticipate and change to match the changing seasonal light levels. Having a ‘faster’ running clock facilitates this ability and it makes individuals more likely to rise early.”
To investigate the presence of Neanderthal genetic variants in modern humans, researchers analysed the UK Biobank, a medical database containing genetic and health information. The study found a significant association between Neanderthal DNA resulting from interbreeding and a propensity to be a morning person among contemporary individuals.
This discovery is summarised by Capra: “We found that Neanderthal DNA that remains in modern humans due to interbreeding has a significant… effect. In particular, the Neanderthal DNA that associates with chronotype consistently increases propensity to be a morning person.”
This research builds on genetic studies initiated in 2010 when the Neanderthal genome was first sequenced, revealing distinct differences in circadian genes between archaic and modern humans. The study also highlights the broader impact of Neanderthal DNA on present-day health, including potential links to Covid-19 susceptibility and conditions like Dupuytren’s disease. As scientists delve deeper into our genetic past, the influence of Neanderthals on our daily lives becomes increasingly apparent.