How viruses shape our world

COVID-19 is a reminder of their destructive power, but they’re crucial to humans’ development and survival.

Although feared as agents of disease, viruses also work wonders, shaping evolution from the very beginning. About 8 percent of our DNA comes from viruses that infected our long-ago ancestors and patched viral genes into their genomes. Some of these genes now play crucial roles in the early stages of the developing embryo and the placenta that surrounds this 13-week-old fetus.
Photograph by LENNART NILSSON, TT/SCIENCE PHOTO LIBRARY (COMPOSITE OF TWO IMAGES)

Let’s imagine planet Earth without viruses.

We wave a wand, and they all disappear. The rabies virus is suddenly gone. The polio virus is gone. The gruesomely lethal Ebola virus is gone. The measles virus, the mumps virus, and the various influenzas are gone. Vast reductions of human misery and death. HIV is gone, and so the AIDS catastrophe never happened. Nipah and Hendra and Machupo and Sin Nombre are gone—never mind their records of ugly mayhem. Dengue, gone. All the rotaviruses, gone, a great mercy to children in developing countries who die by the hundreds of thousands each year. Zika virus, gone. Yellow fever virus, gone. Herpes B, carried by some monkeys, often fatal when passed to humans, gone. Nobody suffers anymore from chicken pox, hepatitis, shingles, or even the common cold. Variola, the agent of smallpox? That virus was eradicated in the wild by 1977, but now it vanishes from the high-security freezers where the last spooky samples are stored. The SARS virus of 2003, the alarm that we now know signaled the modern pandemic era, gone. And of course the nefarious SARS-CoV-2 virus, cause of COVID-19 and so bewilderingly variable in its effects, so tricky, so dangerous, so very transmissible, is gone. Do you feel better?

Don’t.

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