Ah, the Abh. I think the back-story was that they were a genetically-engineered labor/slave class set up centuries ago to do the nasty space work and they revolted and formed their own civilization. They had elvish-looking ears and blue hair. There was a funny scene where the (ethnically Abh) heroine has crash landed on a hostile world with a boy and he (having Abh citizenship but not being genetically Abh) goes into town and buys a bottle of hair dye, comes back with it, and our heroine throws a fit about not wanting to wreck her blue hair.
I can’t remember if they were engineered by modifying the genes of human embryos or whether or not they were synthesized ab initio in a lab (which, arguably, could make them non-human). Anyone remember?
Harry Harrison’s Deathworld Trilogy - no intelligent aliens as far as I remember; only humans.
In Deathworld 1:
The protagonists at one point think that intelligent aliens are strirring up the hellacious local lifeforms against them - but they are mistaken: it is them doing it to themselves, by being so damn deadly in return!
Deathworlds 3 and 2:
Involve humans who have “devolved” into dragon-beast-riding mongol-types and clannish tech-hoarding technocrats, respectively
They get mentioned several times in the very first book, The Engines of God. There was a faction back on Earth which wanted to colonise their planet despite it already having an intelligent race on it.
iirc, the warring alien race was referred to as the Nok (short for something much longer).
The fact that adopted members (ground dwellers who of sufficient nobility to be allowed to join) have to have their children genetically modified gives me the impression that they were modified embryos. And, anyways, even if they weren’t, they were still made on Earth, which makes them not aliens. We don’t call dogs aliens, now do we?
I don’t recall them in the mainstream “future history” series but obviously Podkayne of Mars, Red Planet and Stranger In A Strange Land all had Martians.
The Past Through Tomorrow series had the Venusians, as noted, and it also had a species in Methusaleh’s Children - the godlike beings that had the “pets”. Those were never referenced again, however.
I remember one Asimov novel – I don’t remember which, but I think it was one of the later Foundation books – theorizing that, since Earth was the only known planet in a habitable zone that had a satellite of significant mass, the tidal forces generated when the planet was molten caused heavy radioactive minerals to solidify in the crust instead of all settling into the core. The increased radiation at the surface caused mutations, resulting in a faster rate of evolution than on planets without a large natural satellite. That’s supposed to be the reason that Earth was the only planet with such a wide variety of species, including intelligent ones.
The Past Through Tomorrow is the Future History (even though there’s a couple of stories that I think don’t quite fit).
There are three intelligent alien species in “Methusaleh’s Children” - the god-like beings, their intelligent pets, and the “Little People”. The godlike aliens are mentioned briefly in “Time Enough for Love” I think.
