A recent research paper reveals that genetic material inherited from Neanderthal ancestors may have influenced the tendency of certain individuals today to be “early risers,” meaning they are more comfortable waking up and going to bed earlier.
All modern humans can trace their origins back to Africa approximately 300,000 years ago, where various environmental factors played a role in shaping their biological characteristics. Around 70,000 years ago, the ancestors of present-day Eurasian humans began migrating to Eurasia, encountering diverse new environments, including regions with higher latitudes that experience greater seasonal variations in daylight and temperature.
However, other hominins, such as Neanderthals and Denisovans, had already inhabited Eurasia for over 400,000 years. These ancient hominins diverged from modern humans around 700,000 years ago, resulting in our ancestors and the archaic hominins evolving under different environmental conditions. Consequently, lineage-specific genetic variations and phenotypes accumulated. When humans arrived in Eurasia, they interbred with the archaic hominins on the continent, creating the potential for humans to acquire genetic variants that were already adapted to these new environments.
Prior research has shown that much of the archaic hominin ancestry in modern humans was not advantageous and was eliminated through natural selection. However, some archaic hominin variants that remain in human populations exhibit signs of adaptation. For instance, archaic genetic variants have been linked to differences in hemoglobin levels at high altitudes in Tibetans, immune resistance to new pathogens, variations in skin pigmentation, and fat composition.
Changes in light exposure patterns and levels have biological and behavioral consequences that can lead to evolutionary adaptations. While scientists have extensively studied the evolution of circadian adaptation in insects, plants, and fish, its study in humans is not as well-explored.
2023-12-14 08:41:02
Link from phys.org rnrn
