Current technological level. (in the setting there is an awful tech stagnation, so waiting for better DNA engineering technology is considered as waste of time) Possibility to use all contemporary known assisted reproductive technology. No problem in hiring surrogate mothers.

Limits issued by local ethic committee equivalent:

No serious health damage to those kids or any seriously excessive risk. (excessive means: "many times higher than during a normal pregnancy"; yes, it's only a moderate dystopia)

At which age it would be possible to collect gametes that could be used for in vitro fertilization?

  • $\begingroup$ Are you willing to use surrogates? And if not, why IVF? Also, what traits are you selecting for, and how will you test them? This may be more of a limiting factor than procreation biology $\endgroup$
    – Mołot
    Dec 26, 2016 at 22:37
  • 3
    $\begingroup$ What's the question? At what age can women carry a pregnancy to term without "excessive" risk? $\endgroup$
    – AlexP
    Dec 26, 2016 at 22:41
  • $\begingroup$ What is an IVF? $\endgroup$ Dec 27, 2016 at 5:50
  • $\begingroup$ @XandarTheZenon: In vitro fertilization. $\endgroup$
    – AlexP
    Dec 28, 2016 at 11:28
  • 1
    $\begingroup$ Selective breeding? How long are you going to wait to determine which ones to breed? That's a major limitation in time. $\endgroup$
    – Mary
    Dec 15, 2020 at 22:45

2 Answers 2


In girls, the gametes are ready very early, so you could in principle induce ovulation in young children and harvest the egg cells to be carried by an adult surrogate. In boys, sperm do not mature until puberty, and from a quick googling this seems to be at the age of 11-13 years. You might be able to trigger this somewhat earlier, again via hormones.

If you are willing to trigger puberty early in both boys and girls, you could probably get away with generation cycles under 10 years. You would obviously need surrogate mothers to carry the pregnancies.

Some factors speaking against this:

  • Triggering puberty early is somewhat harmful to the child. If you want these children to be useful to society in ways other than by their gametes, you better wait until natural puberty.
  • Some heritable defects don't show up until after puberty. If you're able to screen for these defects very effectively, you can probably also just genetically modify the embryos to be what you want, and don't need generations at all.
  • You probably also want to avoid breeding for traits that make natural reproduction impossible.
  • In the same vein, you'll want to see what your generations are like as adults, so you don't accidentally breed for the wrong traits.
  • There is some evidence that the birth mother has some influence on a developing fetus, so for optimal results you'd want your genetic mother to also carry the fetus.

In conclusion, your best bet would be to wait until the generation has gone through puberty and is able to procreate normally, which should take you around 15-20 years per individual.

  • $\begingroup$ How do you trigger ovulation or puberty? $\endgroup$
    – kingledion
    Dec 28, 2016 at 13:22
  • $\begingroup$ Is it possible to harvest eggs from females before puberty? $\endgroup$
    – Tobe
    Dec 15, 2020 at 17:37

Currently, the average female is fertile around 11 or 12. There are examples of fertility as early as 8 months which resulted in a pregnancy at 6. It is very possible to medically induce fertility. This may introduce unforeseen complications is viability. Therefore, the short answer is: very early, within the first year of life. However, what is truly limiting is observing for the desired trait. If it requires more physical maturity, then you are going to have to waiting longer to see if the trait presents itself in the new generation. If your genetic testing is sufficient enough to test for the desired trait then your generations can be around two years.

  • $\begingroup$ A pregnancy at age six? I'm sorry, but that seems a little far-fetched to me. Do you have any references for that, and if so what on earth happened to that poor girl? Was that even a survivable pregnancy or childbirth (if it got that far)? $\endgroup$
    – Palarran
    Dec 15, 2020 at 22:03
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    $\begingroup$ @Palarran See Lina Medina $\endgroup$
    – StephenS
    Dec 16, 2020 at 3:33

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