Viruses that Shaped Human Evolution

It’s COVID season and everyone’s got viruses on the brain, but I bet you don’t know just how true that is.

A couple years ago, Dr. Jason Shepherd, a neuroscientist at University of Utah Health, noticed that Arc, a protein involved in memory-making, looks remarkably like HIV, the virus that causes AIDS.

In a recent article in The Wall Street Journal, author Neil Shubin tells the story: “When the team sequenced the gene for Arc, decoding the string of molecules that make it up, they were in for an even bigger surprise. This memory gene was, for all purposes, a modified virus.”

If we hadn’t gotten that pre-historic infection sometime between now and when our ancestors first crawled out of the oceans, would we have memories no better than a fish? I shudder to think that a world without viruses is a world with very different human evolution. After all, our memory-makers aren’t the only part of our bodies whose evolution were shaped by viral infections.

Humans and large primates, mice, and cats and dogs, all have syncytin genes in the placenta that are thought to have come from different viral infections, passed down through the genome. Carrie Arnold at PBS Nova says, “Early mammals used the spare viral parts left in the junk drawers of the genome to use a viral gene to help create the placenta, and other symbiotic viruses help turn us from a ball of cells into a fully-formed squalling infant and protect us from pathogens.”

So just how prominent are these viruses of yesteryear in our DNA? Shubin says, “We have four times more viral genetic material inside our genome than our own genes,” albeit viral material with its “wings clipped.” The viral material we see—almost 8% of the human genome—is inactive and therefore can’t cause the destruction we see in active infections like today’s pandemic. We also need to remember that not all viruses behave in this way. It is the retroviruses, like HIV, that get into an organism’s DNA. Other viruses, such as the flu, simply infect cells and multiply.

Shubin’s new book, Some Assemby Required: Decoding Four Billion Years of Life, from Ancient Fossils to DNA takes readers into the world of fossils and DNA. This is both a sweeping history of evolution and insight into the latest discoveries in paleontology and genetics that seek to understand the origins of life’s immense diversity.

“An engaging, must-read for anyone with an interest in evolution.”—Library Journal, starred review

Shop: Third Place Books | Boulder Bookstore  | RJ Julia

If this topic intrigues you, please also consider these pop science books on genetics, new this season…

How to Argue With a Racist: What Our Genes Do (and Don’t) Say About Human Difference by Adam Rutherford

From the author of A Brief History of Everyone Who Ever Lived and Humanimal (being released as The Book of Humans in paperback on May 12th), this book gives fodder for “responsible, enlightened discourse” about race by explaining the most recent discoveries in genetics and clearing up misconceptions about race that have fueled hatred, nationalism, and prejudices. On sale July 21.

Pre-order: Third Place Books | Boulder Bookstore  | RJ Julia

DNA Demystified: Unravelling the Double Helix by Alan McHughen

Alan McHughen, an accomplished academic and public science advocate, brings the reader up-to-speed on what we know, what we don’t, and where genetic technologies are taking us. The book includes a brief history of DNA and genetics, DNA fingerprinting, using DNA in forensic analyses, genetic genealogy and family tree construction, genetic engineering in medicine and pharmaceuticals, and the use of those same technologies in creating GMOs in food and agriculture. On sale June 2.

Pre-order: Third Place Books | Boulder Bookstore  | RJ Julia

The Better Half: On the Genetic Superiority of Women by Sharon Moalem, MD, PhD

Using his own medical experiences, award-winning physician and scientist Sharon Moalem investigates how having two X chromosomes offers such a survival advantage.  Women live longer than men. They have stronger immune systems. They’re better at fighting cancer and surviving famine, and even see the world in a wider variety of colors. Moalem explains why genetic females triumph over males when it comes to resiliency, intellect, stamina, and immunity, and he calls for a reconsideration of our male-centric view of medical studies and how we prescribe medications, a view that still sees women through the lens of men.

Shop: Third Place Books | Boulder Bookstore  | RJ Julia

Sources: Science Focus | Wall Street Journal | UNews| PBS Nova