Iterated embryo selection (IES) is a reproductive technology that involves repeated cycles of in vitro sequencing and selection of embryos. Because it compresses multiple generations of selection into a fraction of one human maturation period, IES could theoretically increase heritable traits by several standard deviations in a relatively short period of time. In its current form, the technology was first described by Carl Shulman in 2009,^[1] and the idea was further developed in a 2014 paper by Shulman and Nick Bostrom.^[2] If applied to cognitive ability, IES could potentially constitute a path to superintelligence.^[3]

IES consists of the following four steps:^[4]

1. Genotyping and selecting embryos higher in desired genetic characteristics.
2. Extracting stem cells from those embryos and converting them to gametes, maturing within six months or less.
3. Crossing the new gametes to produce embryos.
4. Repeating until large genetic changes have accumulated.

Technically, the main impediment to IES appears to be the difficulty of deriving gametes from embryonic pluripotent stem cells (PSCs). The median Metaculus respondent estimates that the first live birth from stem cell-derived gametes will occur by 2033.^[5] Socially, the main impediment is apparent opposition from prospective parents and from the general public. Public approval for preimplantation genetic diagnosis for intelligence has been found to range from 13%^[6] to 19%^[7] to 28%^[8]. However, Shulman and Bostrom note that these relatively low approval ratings are comparable to attitudes towards in vitro fertilization before the birth of the first IFV baby in 1978. After Louise Brown was born, approval went up dramatically, so a similar change may be expected following a successful demonstration of IES.