The establishment of a Mars colony is a big step for humankind
The #Mars One Project (MOP) has the goal to establish a permanent human colony on Mars launching in 2025 with the first four human beings. In 2027 the crew will arrive Mars and start a colony. In the following years after the first landing all two years another group of four humans will arrive. With this eager project the humankind does the first step into an interplanetary age to colonize other planets than earth. This is a very important step in our development, our understanding of us as species and for our biological evolution.
To find settlers for Mars the MOP was calling for voluntaries worldwide and 200.000 people applied to be part of this big step in our history. Recently the last 100 possible future Mars settlers were selected. I want to take now a closer, more detailed look into the biological possibilities of the planed human Mars colony.
To establish a stable Mars colony the colonists have to reproduce
Each kind of isolated colony has to grow or keep at least a stable number of individuals to prevent its extinction. So does the Mars One colony, too. It has to grow to secure their existence and ability of action. That means the Mars colonists have to reproduce to increase their number and to replace died colonists. The MOP is aware of this necessity. See here here. The MOP plans reproduction on Mars, but not in the first years (see link), because in the first years the colony housings are just too small to shelter children. Scientifically at this point it is unknown, if the human reproductive organs work in the lower gravity of Mars as good as on earth.
For these thoughts let us assume they work and the Mars colonists are able to increase their number by reproduction. Logically, but important to understand, this means the colonists produce more offspring in each generation, than in the existing one. In other words, each female on Mars now and in the future has to give birth to at least 3 children to guarantee an increasing population or to 2 children to keep the number of colonists stable.
A Mars colony has to be genetically independent
The main purpose of any colony is to be 100% independent of energy, food/water, medical care and supplies/tools like spare parts for machines and housing to keep the ability to surpass at least a couple of hundred years if not thousands of years. To achieve the long term survival of a human population on Mars, the colony needs to own an additional independence, the independence of genetics.
Genetically independence means, that the gene pool of a group of individuals contains a certain level of genetic variability to prevent heritable diseases over time.
Actually, it seems the first settlement will consist of 40 human beings, 20 males and 20 females. If we assume, that the MOP does not plan to send more people to Mars, and even if each female gives birth to 3 children to keep a stable number of individuals, Mars One will run into a genetic bottle neck, because a population size of 40 possesses not enough and creates not enough genetic variability to establish a genetic independence. Following, the population on Mars will dramatically increase genetic diseases in their gene pool and will lose their ability of action over time and at the end it will face its extinction. In fact with the actual colonization plan Mars One will not be able to sustain a healthy genetic population!
For a genetic independence are 14K to 44K human beings necessary
In order to create genetic independence and to prevent this bottle neck problem Mars One has to reach a critical number of individuals. This critical number, is the number of individuals in a population to guarantee genetic independence. In case of a human population the anthropologist Dr. Cameron M. Smith came up in his publication with a range of 14.000 to 44.000 individuals. This number of human beings is necessary to establish a completely genetically from earth independent Mars colony!
With the 3 children reproduction strategy it would need at least 15 generations (25yr. = 1 generation) or 375 years to surpass the minimum of 14.000 individuals (17.515) (Figure 1.)
Figure 1. Mars population growth curve
with a 3 children reproduction strategy
With a starting population of 40 human beings it is impossible to keep the population in a time period of 375 years genetically healthy on the other hand it is also impossible to send so many humans to Mars.
Creating genetic independence with genetic donor material
To achieve this critical number of individuals on Mars a different reproductive strategy than planed is necessary. Mars One needs a high amount of genetic variety represented by at least 14.000 individuals. To reach this number of individuals, two strategies are imaginable 1) by sending 14.000 humans from earth to Mars. This strategy is financially impossible. Nevertheless, there would be enough volunteers.
The second strategy to reach the critical number of individuals for a genetic independence is by additional stored genetic donor material from earth.
For this strategy each female still has to give birth to at least 3 children, but only one children’s father is originated from Mars. For the other two pregnancies, donor material from earth will be used. With this strategy it can be ensured that genetic disorders would not increase until the critical
number of 14.000 individuals is achieved.
The amount of different genetic donor material samples has to cover at least two thirds of all offspring born on Mars until the fifteens generation. With a total number of 54.427 individuals born on Mars until the fifteens generation, the amount of donor material has to be 34.951 genetic samples.
All these assumptions were made with an ideal Mars One crew, where all females are able to give birth to at least 3 children in lower gravity.
Thanks for reading this article. I would be happy for any feedback and I am open for discussions.
Dr. Christoph Lahtz