Virus hiding in our genome protects early human embryos

We may owe our survival and complexity to a stowaway virus that springs to life in the very first cells of human embryos. Not only does the virus seem to protect embryos from other viruses, but it also assists genes when the groundwork is under way for the body plan of a new human. The finding backs the controversial idea that viruses which took up residence in our DNA millions of years ago may be playing the role of puppet master, quietly influencing our existence and evolution.

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