Editing Generation ship (section)

===Biology and society===
Generation ships would have to anticipate possible biological, social and morale problems,<ref name="Malik20020319">{{cite web|last1=Malik|first1=Tariq|title=Sex and Society Aboard the First Starships |url=http://www.space.com/scienceastronomy/generalscience/star_voyage_020319-1.html |url-status=dead |archiveurl=https://web.archive.org/web/20020407132242/http://www.space.com/scienceastronomy/generalscience/star_voyage_020319-1.html |archivedate=2002-04-07 |work=Space.com |date=19 March 2002}}</ref> and would also need to deal with matters of self-worth and purpose for the various crews involved.

Estimates of the minimum reasonable population for a generation ship vary. Anthropologist John Moore has estimated that, without [[genetic testing]] of people before boarding the ship, [[social control]] and / or [[social engineering (political science)|social engineering]] (such as requiring people to wait until their thirties to have children), nor [[cryopreservation]] of eggs, sperm, or embryos (as is done in [[sperm bank]]s), a minimum of 160 people boarding the ship would allow normal family life (with the average individual having ten potential marriage partners) throughout a 200-year space journey, with little loss of [[genetic diversity]]. If the people who board the ship are couples, presumably in their early twenties, and everybody who lives in the ship is required to wait until their mid to late thirties before having children, then the minimum would be just 80 people. However, many variables are not accounted for in the estimate, including the higher chance of health problems for both the woman who is pregnant and the fetus or baby because of the [[advanced maternal age|pregnant woman's age]].<ref>{{cite web |url=https://www.newscientist.com/article/dn1936-magic-number-for-space-pioneers-calculated/ |title="Magic number" for space pioneers calculated |date=15 February 2002 |author=Damian Carrington |work=[[New Scientist]] |access-date=6 August 2019}}</ref> In 2013, anthropologist Cameron Smith reviewed existing literature and created a new computer model to estimate a minimum reasonable population in the tens of thousands. Smith's numbers were much larger than previous estimates such as Moore's, in part because Smith takes the risk of accidents and disease into consideration, and assumes at least one severe population catastrophe over the course of a 150-year journey.<ref>{{cite journal|title=Smith, C.M., "Estimation of a genetically viable population for multigenerational interstellar voyaging: Review and data for project Hyperion" |journal=Acta Astronautica |volume=97 |pages=16–29 |date=2013-12-13 |doi=10.1016/j.actaastro.2013.12.013|bibcode=2014AcAau..97...16S|last1=Smith |first1=Cameron M. }}</ref>

In light of the multiple generations that it could take to reach even our nearest neighboring star systems such as [[Proxima Centauri]], further issues on the viability of such interstellar arks include:

* the possibility of humans dramatically [[evolution|evolving]] in directions unacceptable to the sponsors
* the minimum population required to maintain in isolation a culture acceptable to the sponsors; this could include such aspects as
** ability to learn scientific and technical skills needed to maintain, operate and pilot the ship
** ability to accomplish the purpose (planetary colonization, research, building new interstellar arks) contemplated
** sharing the [[values]] of the sponsors, which may not be likely to be empirically demonstrated to be viable beyond the home planet unless, once the ship is away from Earth and on its way, survival of one's offspring until the ship reaches the target star is one motivation.