Good news: You survived the nuclear war. Bad news: Earth’s population has been decimated, and all that remains is you and a 22-year-old supermodel. It’s up to you to save the human race!

THE BIRDS & BEES

In due time, after a catastrophic event, the Earth could reasonably be repopulated, so long as you carefully promote genetic diversity.

Experts estimate that every person carries the genes for around 5-10 genetic diseases. Luckily, these are recessive traits, so they only manifest when we mate with a partner who carries the same trait. In a diverse population, these diseases are rare. But when everybody is marrying his or her cousin—as in closed communities like Appalachian hill people, European royalty, or your personal postapocalyptic wasteland, they become more common. For example, hemophilia was pervasive among the ruling classes of Europe.

MAKIN’ WHOOPEE

You and—depending on your gender—Miss America or Captain America are hopefully genetically distinct going in, so the outlook for your kids is pretty good. But that next generation, beyond the weirdness of having to mate with a sibling, will be at a very high risk for whatever genetic disease traits are present. The old story about inbreeding leading to messed-up kids? It’s true. One study found a 20-36% rate of mortality or major disability among children of siblings. If a serious disease manifests itself, it’s quite possible that the population could be wiped out in the “genetic bottleneck” of those first two to three generations.

After those first few generations, the risk decreases significantly as long as people procreate with partners separated as far from them as possible. First cousins share only 13% of the same genetic material, and the ratio continues to decrease the further out you go. Bottom line: You’re going to want to implement a system of arranged marriage, or at least arranged procreation.

FAMILY TREE

Whether you’re starting with a base population of 2 or 10 or 100, you’ll want to map it out (perhaps on a cave wall) and pair up newlyweds with partners as far removed, genetically, as possible.

With some careful arrangement of mates and a little luck getting through that initial bottleneck, you’ll have the world overfilled, drained of natural resources, and ruled by nations with nuclear stockpiles again in no time!

SOCKS FOR FOX

One wild animal you don’t need to much worry about: the fox. Rarely, if ever, do they attack humans. If threatened, they simply run off. However, if you’re sleeping under the stars, be warned that curious foxes are known to gently nibble on exposed human toes.