What will the inhabitants of Mars look like?

  Many people care about how these people will survive on Mars, and how they will reproduce their offspring and establish a permanent Martian colony. But we know that on Mars, there is a world of difference between the low gravity, strong radiation, and lack of microorganisms. This means that settlers not only have to consider how to adapt to the Martian environment, but the isolated Martian environment will also accelerate the offspring of settlers. Evolution. So, what will these future Martian residents look like?
Founder effect

  Due to technological limitations, the number of terrestrial colonists who initially arrive on Mars will be very small. In such an isolated and closed alien environment, settlers will be affected by the founder effect. The founder effect refers to the fact that after a small number of new individuals multiply in a solitary environment, although the number of this group will increase in the future, the genetic difference between them is very small because they have not mate with other biological groups.
  If we only send 100 immigrants to Mars, the probability of their height, hair color, diabetes or breast cancer probability, etc. often cannot represent the commonality of human beings. In the isolated new Martian environment, no matter what characteristics they have, they may be passed on from generation to generation. For example, if all the astronauts sent to Mars are red-haired, Martian residents will become red-haired residents. After generations of evolution, the loss of genetic diversity will expand the genetic defects of the population. Eventually, these new humans will not only differ in appearance and voice from ours, but may even be another species completely different from ours.
Martian inhabitants will be more robust

  The founder effect can occur in any solitary or isolated environment. So, what impact will the unique Martian environment have on the human body?
  Since Mars has only one third of the gravity of the Earth, without the pull of gravity, pregnancy and childbirth may be more difficult on Mars. A study of mouse embryos found that in a simulated microgravity environment, the survival rate of pups born to a mouse mother is lower than that in a gravity environment. Although in vitro fertilization and IVF are not affected by the drop in gravity, in some cases they can still cause embryonic dysplasia. Researchers do not yet know why. Other research results also show that mammals, including humans, may experience more pregnancy complications on Mars than on Earth. These studies indicate that the evolution of Martian inhabitants will face many unknowns.
  Low gravity can also cause bone density to be lost at a rate of 1% to 2% per month. Settlers may lose half of their bone mass after two to three years, and pregnant women’s bone density declines faster because pregnancy requires a lot of calcium. Loss of bone density makes people more vulnerable to injuries, especially hip and spine fractures.
  In a microgravity environment, because the activity of “osteoblasts” is inhibited, the blood supply of bones is also reduced accordingly, and broken bones will be more difficult to heal. Such fractures may be fatal. Therefore, those Martian residents with higher bone density will have a higher chance of survival and pass on their genes. Therefore, after many generations, Martians may end up with stronger bones and a more robust appearance than their earth ancestors. Compared with modern humans, these people will be more similar to ancient human ancestors.
Skin color will change

  Martian residents also have to adapt to the high concentration of radiation environment. As everyone knows, Mars has no magnetic circle or atmosphere, and is continuously bombarded by high-energy cosmic rays, strong ultraviolet radiation, and solar particles. After a person has lived on the surface of Mars for 500 days, the radiation dose received is 6 times the minimum safety standard in the United States. Although spacesuits or underground structures will protect astronauts to a certain extent, there is no doubt that if astronauts want to grow crops, build buildings, etc., they still have to move on the surface of Mars.
  Radiation can damage DNA, and the resulting mutations can cause cancer. For Martian immigrants, this may mean a higher incidence of cancer. But under environmental pressure, it can also promote genetic mutation, accelerate the evolution process, and produce characteristics that are conducive to the survival of Mars.
  For example, on the earth, our skin produces melanin, a pigment that acts as a natural sunscreen. The skin pigments that appeared in human evolution play a balanced role, because if the amount of radiation is too high, it will destroy the production of DNA, and the amount of radiation that is too low will hinder the normal formation of bones. Many organisms use melanin to protect themselves from radiation. For example, at the site of the Chernobyl nuclear disaster, it was discovered that a dark fungus was multiplying there.
  For us humans, one type of melanin that protects most humans from solar radiation is eumelanin, which makes the skin appear dark brown or black. Therefore, those humans with more eumelanin in their skin will be better able to survive in extreme radiation environments, so future Martian inhabitants may have darker skin than on Earth.
  In addition, the intense radiation on Mars may facilitate the evolution of new skin pigments. Carotenoids, which are orange pigments, determine the color of carrots. Many plants and microorganisms produce this pigment in order to protect them from solar radiation. Many animals also have carotenoids, but most of the carotenoids in animals need to be obtained from the food they ingest. However, the pea aphid is an exception. This piercing-sucking insect is usually green, but when it gets the gene for carotenoid production from the fungus, it turns red. This shows that in rare cases, animals can borrow genes from other organisms to produce their own skin color. Therefore, the researchers speculate that if orange skin is beneficial for humans to resist the high radiation environment of Mars, then humans may also, like pea aphids, obtain genes for carotene from the environment and evolve bright orange skin.
Brain genes will also change

  High radiation dose not only affects the color of human skin, recent studies have shown that it also affects the brain. In experiments on mice, researchers found that high doses of radiation can damage brain nerves, reduce the spatial memory and learning ability of some mice, and make their behavior bolder and more adventurous.
  Martian residents must be able to drive spacecraft or maintain infrastructure on Mars. These activities have high requirements for space learning capabilities, and if Martian residents behave more adventurously and regardless of the consequences, they will undoubtedly be fatal in the dangerous outer space. of. Therefore, these brain changes may be an unfavorable factor for humans to successfully colonize Mars.
  However, this experiment also showed that the sensitivity to radiation varies from individual to individual, because not all rats are affected by radiation. If humans are in the same situation as mice, then natural selection will be more biased towards individuals who are less susceptible to radiation, and their offspring may evolve brain genes that are better at resisting harmful radiation in order to better adapt to the Martian environment. Moreover, these future generations of Martian inhabitants may have stronger space exploration capabilities, and are more suitable to travel to remote and habitable planets such as Proxima b to become true multi-planet inhabitants.