Stephen Hawking is wrong. Colonizing space will not save the human race from extinction. And the only thing that really matters is the manner in which we Homo sapiens go extinct.
If we stay on Earth, we risk annihilation by the homogenization of humanity, weapons of mass destruction (WMD), and Extinction Level Events (ELE). And even if we do end up colonizing the stars, our descendants will eventually cease to be human anyway.
Humans colonized most inhabitable niches of the globe (except Antarctica) by around 10,000 years ago. Separated by thousands of miles, each pocket of humans slowly adapted to whatever unique environment they happened to occupy. Humans adapted to colder northern climates by evolving shorter limbs and thicker bodies. A smaller surface area allowed them to retain more heat. In sub Saharan Africa, people developed longer limbs and thinner bodies. More surface area allowed them to radiate more heat, which helped to keep their internal body temperature low. While humans from southern climates are better adapted to fight parasitic infections than viruses, northerners are better able to stave off viruses than parasites.
In Scandinavia, where a sunset can last for the better part of a day, nature selected persons with blue eyes who could better distinguish between shades of red. Blue-eyed people are far more adapted to hunting caribou during long Arctic sunsets than brown-eyed people like me. Each population of humans became specialized in its own unique way to survive in various hostile environments.
Today however, due to globalization and mass migrations, humans are beginning to homogenize. It may take some time before people from one continent are indistinguishable from another, but the trend looks like it’s here to stay. The question is, when (not if) a global calamity strikes, does our species stand a better chance of survival if we remain specialized, or if we become homogenized? Whether global warming takes its toll, or Ice Age glaciers once again cover the continents, some survival strategies will be more effective than others.
If every individual of a species is equally homogenized to the same environment, when the environment disappears it takes the entire species with it. Specialization, on the other hand, increases the odds of a species’ survival.
Bear in mind that 98% of all species that ever existed on planet Earth are now extinct. Some of them couldn’t adapt to new situations and simply died off. Others adapted and became entirely new species. But the important thing to remember is that nothing lasts forever.
As noted above, a global calamity will eventually strike. Whether it’s caused by pollution, WMD or an ELE beyond our control – like a rogue asteroid, super volcano, solar storm, or even a supernova in our galactic backyard – humans will face global extinction at some point in the future. Extinction Level Events occur, on average, every 26 – 30 million years (depending on which scientist you listen to). Again, specialization increases the odds that some individuals will be better able to survive plagues, chemicals, nuclear winters and natural disasters than others.
Many scientists believe the Earth is experiencing an extinction level event right now. Human-induced pollution and destruction of natural environments is not only causing the extinction of thousands of unique species, but they may also send our own species spiraling into the abyss.
This is why Hawking is adamant that humans need to colonize space. But colonizing space will not actually save Homo sapiens from certain extinction. And I really wish my favorite genius had worded things differently.
Because even if we succeed, we will still go extinct as our species slowly adapts to new environments on space stations and on alien worlds. If space-faring arks should successfully transplant our species on distant and remote planets, and each colony remains separated from the others by hundreds of lights years of space, over time our descendants will eventually cease to be Homo sapiens altogether and evolve into completely different species. After millions of years of unique selection processes, our descendents would barely recognize one another. And they would probably view their human ancestors with the same kind of quaint nostalgia we afford Australopithecines and Neanderthals.
Therefore, whether we stay or go we’re still doomed to extinction.