现在,肤色通过新的人群融合而进化,不同种族的人聚集在一起,于是后代拥有新的肤色基因混合。
Today, skin color is evolving via new mixtures of people coming together and having children with new mixtures of skin color genes.
少数情况下,动物冠状病毒会进化并在人群中传播,如中东呼吸综合征和严重急性呼吸综合征(SARS)。
Rarely, animal corona-viruses can evolve and then spread among people, such as Middle East respiratory syndrome and severe acute respiratory syndrome (SARS).
而那种变异基因没有被生物进化所淘汰,仍然存在于人群之中,其原因在于它也有益处——它能保护人体抵御疟疾的侵袭。
It remains in populations because the mutation has a flip side—it helps to protect against malaria.
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