Why Are Some People Morning People? An Evolutionary Biologist Explains

InnovationScienceWhy Are Some People Morning People? An Evolutionary Biologist ExplainsByScott Travers,Contributor.Forbes contributors publish independent expert analyses and insights. I write about biodiversity and the hidden quirks of the natural world.Follow AuthorMay 18, 2026, 08:30am EDT--:-- / --:--This voice experience is generated by AI. Learn more.This voice experience is generated by AI. Learn more.The answer has less to do with morning people’s discipline than with deep evolutionary history, and a molecular clock ticking in nearly every cell of your body.gettyLong before alarm clocks, school schedules or the daily hustle of the 9-to-5, the first ever “morning people” were rising with the first light, while others were still awake when the embers died down. This wasn’t a personality quirk. It wasn’t laziness or virtue, either. It was, in all likelihood, survival.The scientific term for this variation is chronotype: an individual’s innate tendency toward earlier or later sleep timing. Formally defined, it describes a physical and behavioural manifestation of the coupling between internal circadian cycles and the need for sleep, and it sits on a continuous spectrum. Most of us occupy the middle ground. Some of us are unambiguous morning larks. Others are dedicated night owls. And all of us are more constrained by our biology than we tend to believe. What makes someone a “morning person” isn’t their iron willpower. It’s that their internal clock is phase-set slightly earlier than average — a difference measurable not in feelings, but in gene expression.The First ‘Morning People’ To Ever ExistSo, why does chronotype variation exist at all? Evolution doesn’t typically preserve traits that don’t serve a purpose. The answer may be one of the more elegant discoveries in the field of sleep science.In a 2017 study published in the Proceedings of the Royal Society B, a team of researchers studied the Hadza: a hunter-gatherer population in Tanzania, and one of humanit...