Early Risers: Tracing the Neanderthal Signature in Human Sleep Patterns
Recent work suggests that the habit of waking early may be passed down from Neanderthal ancestors. The study appears in the journal Genome Biology and Evolution. It connects modern daily rhythms to the genetic legacy left by ancient human relatives who interbred with early Homo sapiens. The key finding shows that some circadian rhythm genes linked to morning activity were inherited from Neanderthals, a memory etched in our DNA that still influences how people experience dawn each day.
Humans are members of the species Homo sapiens, but other human lineages such as Neanderthals and Denisovans existed in the past. Genetic exchange between these groups means contemporary humans carry traces of their ancestors. Researchers analyzed genetic data from hundreds of thousands of individuals in the UK Biobank and discovered a clear association between early-morning awakening and Neanderthal-derived genes. This discovery helps explain why certain people feel more energized at sunrise while others prefer later hours.
In humans as in model organisms like fruit flies, a shortened circadian period appears to favor alignment with extended daylight during longer days. When days lengthen, an internal clock that runs a bit faster helps wakefulness and daytime activities better match the new light environment. This could have offered a selective advantage to early human groups living at higher latitudes in Europe, where summers bring longer daylight. The ability to synchronize sleep and activity with the seasonal light cycle would have supported efficient foraging, social interaction, and survival during critical periods.
Researchers emphasize that this line of inquiry opens doors to exploring how ancient gene transfers shape a broader range of human traits. The same approach used to link Neanderthal DNA with circadian timing has already contributed to understanding high-altitude adaptation among Tibetans, immune responses to infections, skin color variation, and body fat distribution. By studying these genetic exchanges, scientists aim to map how ancient interbreeding events continue to affect health and behavior in modern populations.
Historical accounts and early studies offer cautionary context for interpreting genetic findings. Some old assertions about ancient societies, such as tooth modification practices attributed to Vikings, have been questioned by later research. Modern investigations rely on careful genetic and fossil evidence to build a coherent narrative about how our species came to exhibit the diversity of sleep patterns seen today. This evolving story underscores the importance of cross disciplinary work that blends genetics, anthropology, and chronobiology. Attribution for these insights is provided by researchers and institutions contributing to Genome Biology and Evolution and related genomic resources.