Credible Aliens? II

In Poul Anderson's After Doomsday (St Albans, Herts, 1975), after avians, wolverines, arachnids and humanoids, we encounter the centauroid Xoans: quadrupedal body the size of a Shetland pony with arms, comb and proboscis. How many quadrupeds does Anderson have? Xoans, Ishtarians, Donarrians, Wodenites and two sets of Jovians at least, I think.

Despite his alien body, the Xoan has familiar body language:

"The Xoan seemed nervous, shuffling his feet and twitching his proboscis." (p. 112)

It seems that a Xoan ship sold doomsday devices to two Terrestrial nations and this might explain the sterilization of Earth, the Doomsday of the title. This Xoan has an interesting opinion of humanity:

" 'The whole race was mad. Best they did die, before their lunacy threatened everyone else.' " (p. 114)

(Another parallel with comic book superhero fiction: in 1989, an Alien Alliance, deciding that Earth was a galactic threat because it had so many super-powered beings, invaded, planting a beachhead in Australia, and demanded the surrender of all superheroes, who would be incarcerated in an orbiting prison. Several superheroes on Earth are aliens and one couple continued to defend Earth although their home planet was in the Alliance.)

The idea that Terrestrials are somehow unique among intelligent species is common in Campbellian sf, having been encouraged by Campbell himself. Here we are told that:

" '...they had more individual variability than Xoans; more than any two members of one given Monwaingi Society.' " (p. 115)

- and the human leader will come to lead an alliance against Kandemir.