来源：《新科学家》
原文见刊日期：2023年2月25日
Genetic variants inherited from Neanderthal and Denisovan ancestors may increase the odds that some individuals are morning rather than evening people. “This was really exciting to us, and not expected,” says Tony Capra at the University of California, San Fransisco.
从尼安德特人和丹尼索瓦人祖先那里遗传的基因变异可能会增加一些人早起而不是晚睡的几率。加州大学旧金山分校的托尼·卡普拉说：“这对我们来说真的很令人兴奋，这是意料之外的。”
Following a split from our common ancestor with archaic humans such as Neanderthals and Denisovans around 700,000 years ago, our species spent hundreds of thousands of years evolving in Africa, while other archaic humans adapted to higher-latitude regions in Europe and Asia.
在大约70万年前，我们与尼安德特人和丹尼索瓦人等古人类的共同祖先分离后，我们这个物种在非洲进化了数十万年，而其他古人类则适应了欧洲和亚洲的高纬度地区。
Around 50,000 years ago – and perhaps much earlier – some members of our species migrated and interbred with other species of humans. As a result, Neanderthal DNA makes up roughly 2 per cent of the genome in people of European or Asian descent and Denisovan DNA comprises up to 5 per cent of the genome in people from Papua New Guinea.
大约5万年前——也许更早——我们物种的一些成员迁徙并与其他物种杂交。结果，尼安德特人的DNA在欧洲或亚洲人的基因组中约占2%，而丹尼索瓦人的DNA在巴布亚新几内亚人的基因组中占5%。
Previous studies have revealed that genetic variants from Neanderthals and Denisovans give some modern humans higher fertility or a better tolerance for low oxygen levels at high altitudes.
先前的研究表明，来自尼安德特人和丹尼索瓦人的基因使一些现代人具有更高的生育能力，或者对高海拔地区的低氧水平有更好的耐受性。
Capra and his colleagues wondered if archaic DNA may have affected the evolution of our circadian clocks, which set the rhythm of our sleep-wake cycles and are driven by dozens of genes.
卡普拉和他的同事们想知道，古老的DNA是否影响了我们的生物钟的进化，生物钟决定了我们的睡眠-觉醒周期的节律，由几十个基因驱动。
The researchers compared the genomes of three Neanderthals and one Denisovan with those of thousands of modern humans, 80 per cent of whom were of European descent. They found that, of the genetic variants that the modern humans had inherited from archaic humans, more were linked to regulating the circadian clock than would be expected by chance. This suggests there was a survival benefit to inheriting them. People with these variants from archaic humans were more likely to describe themselves as being a morning person.
研究人员将三名尼安德特人和一名丹尼索瓦人的基因组与数千名现代人的基因组进行了比较，其中80%是欧洲血统。他们发现，在现代人从古人类遗传的基因变体中，与调节生物钟有关的基因变体比随机期望要多。这表明遗传它们对生存有利。具有这些来自远古人类的变体的人更有可能将自己描述为一个早起的人。
This doesn’t mean that being a morning person is itself advantageous, says Capra. People with these variants might have a biological clock that responds more quickly to changes in light-dark cycles, which may be beneficial for living at high latitudes.
卡普拉说，这并不意味着早起本身就有优势。携带这些基因的人可能有一个对明暗循环变化反应更快的生物钟，这可能有利于生活在高纬度地区。
“Faster clocks help other species like fruit flies adapt to higher latitudes where there is higher seasonal variation in light-dark cycles and ultraviolet exposure,” says Capra. “We think it was the same case for Homo sapiens.”
卡普拉说：“更快的生物钟有助于果蝇等其他物种适应高纬度地区，那里的明暗周期和紫外线暴露有更高的季节性变化。我们认为智人也是如此。”
One limitation of the study is that it only included four archaic genomes, but this is what was available, says Capra. The study also focused on modern humans of European ancestry, so further work should look at more diverse populations, he adds.
卡普拉说，这项研究的一个局限性是，它只包括四个远古人的基因组，但可用的只有这么多。他补充道，这项研究还集中于欧洲血统的现代人，因此进一步的研究应该着眼于更多样化的人群。