The colonisation of Mars is one of the most promising trends in the modern space industry. The biggest challenge, however, will not be rockets or life support systems, but humans themselves, whose bodies will have to adapt to the new conditions.
But despite the enormous resources already invested in building the technological foundations for colonising the Red Planet, we still have a rather poor understanding of the evolutionary adaptation processes that will inevitably affect humans during a prolonged stay in an alien environment. Evolutionary biologist and Rice University professor Scott Solomon knows what the long-term future holds for the colonisers and how mutations will spread through their genotype.
He believes that in about two generations, their bones will be stronger, their immune systems will have failed, pregnancy and childbirth will be much more difficult, their vision will be myopic and the average radiation dose per colony dweller will be 5,000 times higher than for the average Earth resident.
But Solomon’s main claim is that Martians will no longer need to breed with Earthlings.
“Evolution goes faster or slower depending on the benefit the species gets from the new mutation,” the professor explains. If Martians get a mutation that increases their chances of survival, that’s good, but such genes are best transmitted within a closed population. Moreover, contact with Earthlings can be fatal for Martians and vice versa. Remember Wells’ War of the Worlds? There are no disease-causing microbes on Mars, so the Martian immune system would simply learn to fight them off and would be powerless in the event of infection.
It’s worth noting that although the word “mutation” usually has a negative connotation, in this case it can play into man’s hands. Each newborn baby born on Earth is born with about 60 mutations, while the number would increase a thousandfold on Mars. By mutating, Martians gain important advantages that enable them to cope with the harsh conditions on an alien planet. In particular, their skin tone will change to protect them from the sun’s harsh rays, their bodies will be less dependent on oxygen and their bones will become denser to counteract the loss of calcium during pregnancy.
Solomon also suggested that we could use CRISPR to target such positive mutations. Remember that the astronauts on the ISS have proven that genome-editing techniques work in space too, so in the future genetic engineering could help humans colonise many other worlds. Moreover, if the Earth ever becomes uninhabitable, we will always be able to settle on other planets – even if the only way to survive in the long term is to transform humanity into a completely different species.