If humanity's down to 236 people, unless the advances in biology also include how to deal with recessive genes in such a way that inbreeding is no longer a concern... humanity's extinct anyway.
Species need about 4,000 genetically distinct people to maintain a stable population. As little as 1,000 extremely genetically distinct people capable of childbirth can apparently be okay for several generations, but only if they rejoin a larger population eventually, and the breeding pairs need to be picked very carefully to minimize inbreeding.
That's one of the issues with post apocalyptic settings that so many authors don't think about. The sheer amount of genetically distinct people needed to keep healthy populations alive and viable. It's one of the main reasons why there wasn't more conflict and fighting amongst humanity in the past. If you need your neighbors to keep your genetics different enough not to have inbreeding problems, you can't fight them all the time.
Peace and trade are necessary just to make it safe to have children, and for those children not to die of hemophilia or sickle cell anemia or other inbreeding diseases and such.