For the rest of the world who preferred to obtain their nutrition in ways that didn't involve sucking on a cow's tits, their lactose intolerance remained just as it was. So if you've enjoyed some cheese recently, you know who to thank.
Fleas Might Save Us from HIV
Centers for Disease Control and Prevention
Because of their willingness to bite human and animal alike, fleas are extremely good at spreading disease. Countless human deaths can be attributed to their two most lethal gifts, the Black Death and smallpox. But here's the kicker -- by infecting us with these horrors back in a more classical period of history, fleas helped a bunch of us develop an immunity to HIV, and in doing so might help us find a cure for good.
Larry Busacca/Getty Images Entertainment/Getty Images
"All in a day's work."
HIV is a virus that destroys the immune system by infiltrating immune cells, which it can only do by going through a very specific opening in the cell wall, kind of like how Luke blew up the Death Star. Once all your body's Death Stars have been destroyed, you have the disease known as AIDS, which means that you have no immune system, and that's really bad. Really bad.
What's this got to do with fleas? Well, it turns out that the Black Death and smallpox infiltrate your cells in the exact same way. Back when these diseases ravaged the globe and killed almost everyone, there were a few people who, through random chance, had a genetic immunity (i.e., their little Vaders remembered to shut off the damn exhaust ports). Eliminating vast numbers of people who weren't immune allowed the resistance to spread through natural selection -- which, incidentally, also made them resistant to HIV. That's why today 10 to 18 percent of humans of European descent are either immune or resistant to HIV.
Carl Zimmer, via Berkeley.edu
Probably not you, though, so keep wearing those condoms, please.
The discovery of this mutation has led researchers to the creation of an antiviral medication called maraviroc and is helping them create the first ever HIV cure. So thanks, fleas; your murderous, infection-spreading lifestyle might just cure one of the worst human diseases ever.
Zac Eckstein is a writer, web designer, and circus employee in Seattle. You can find him on Facebook or, if you like art, you can visit his website at theseattlevine.com.
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