Without a stable breeding population, surviving “protovector” race fades out after three generations.

This is really only a minor blip in Sol’s history, there likely weren’t many protovectors left as the breed was made illegal before they built up any numbers, likely wiped out completely by AE -10 or -20 or so. It’s only a suggestion in the text that there were any left, but it’s a possibility, and it’s possible there were some on Mars as well, used as companions and helpers. There was a lot of biotech on Mars, after all, and some experimentation must have happened when the “Help Them” memo was delivered.

But as cultural background, this period may go a ways toward answering the question of “why do Lateral vectors wear clothes?” There was a time when the two species existed side by side. It was a period where the Gen One vectors were trying to distinguish themselves and get respect, and the comparison to what are likely only somewhat uplifted animals…if even that, there’s no suggestion that the protovectors had any unusual intelligence…would likely be grating, at least. Imagine being asked to sit at the monkey table, with the chimps. Didn’t necessarily happen, but it seems likely that the feeling was there.

Reference: HSD 1.0 p.13, HSD 2.0 p.7)

Date Notes: Thirty years after creation of race (three 10-year generations)