Legion of super-heroes stories involve a lot of alien planets peopled by super-powered folks whose crazy abilities are a perfect fit for their environment (Polar Boy's people being able to "project" cold on a very hot world, for example). These people are, for the most part, human beings: they have no problem breeding with ordinary Earthlings.

The original concept for all these races was apparently that we shouldn't overthink such things, that evolution must have given them their abilities, and that aliens traditionally look like us anyway the same way they all speak English. While all acceptable for funnybook purposes, these "explanations" are nonsensical. However, in the course of the 5YL era of the Legion, it was established that all these aliens were originally humans experimented on by the Dominators. Their extraordinary gifts are not the result of unlikely evolutionary processes, but of genetic engineering (explaining how they can remain essentially human while also being changed enough to have superpowers). The suitability of their powers is not an adaptation to their planet, but rather the factor that dictated the choice of planet they eventually colonized. 

That was an elegant and simple explanation, and while most superpowers in a human being are still a stretch, they are more easily explained by conscious tinkering than by evolutionary processes that would doubtless involve a lot more biological changes that just the ability to eat a car. I'd expect a naturally-evolved Matter-Eater Lad to look nothing like a human anymore.

I enjoyed the Official Handbook of the Marvel Universe and Who's Who in the DC Universe (and DC's Who's Who in Star Trek); while some writers would go to great lengths to explain how a power or device worked, the general purpose of both titles was the same. Some explanations were absurd, as their application of certain scientific principals were dodgy at best, laughable at its worst (e.g., Wolverine). If I recall, DC's guide had the occasional heavier explanation for the way certain devices worked, but again, both Big Two titles served a good purpose, and to be honest, they were almost as enjoyable to read as the other titles I bought at the time.

Obviously this was a brilliant twist in storytelling first and foremost, but Alan's Moore's "Anatomy Lesson" reveal with Swamp Thing was based on a scientific explanation and a clever one at that.

One "least favorite" explanation is one a friend always brings up: In JLA 31, Hawkman gets into the JLA by figuring out that a bunch of crooks is using hoops that project them 10 minutes into the future. Hawkman stops them by planning to sprinkle tacks over their getaway route in 10 minutes, so when they drive over the roadway in the present, their tires blow out.



Makes sense to me... I guess.

OHOTMU got ridiculous with the channeling energy from another dimension as a source of energy powers and the Hulk drawing mass from another dimension to explain how Banner can grow to the Hulk's side without transforming energy to matter in massive doses. It got to be a cliche, after one issue of entries. Might as well have said "Wizard!"



Who's Who was more interested in the character history and background. OHOTMU was a fine character reference and was a great swipe file for poses, if you were trying to draw your own characters; but, Who's Who was a better encapsulation of the company history, in my opinion. I also preferred how various artists were recruited/assigned, in Who's Who, especially some classic artists returning for a special treat. marvel had other artists working on entries; but, there was a very 'house" look to a lot of it.

In regards to scientific explanations, the Guardians of the Galaxy convention that the alien colonies established by Earth, with genetically engineered colonists, made a bit more sense than the Legion "evolved in the environment" explanation. The Legion's worked for some characters; but, ones like Matter-Eater Lad were a bit hard to swallow, so to speak. Martinex, Charlie 27 and Niki's people were modified to be able to survive in their environments and then bred from there, while Yondu's people were an actual alien race.

Adam Strange usually had some pretty good science at the heart of his adventures

The Golden and Silver Age artists, even with hokey comic book science, tended to have a better grasp of scientific principles and research, compared to the later generations, who were fans of comics first and barely ever cracked open a science book. A lot of the early crowd were sci-fi fans and were exposed to more real science and toyed around with things like crystal radio sets and such, instead of just piles and piles of comic books. By a similar token, more of them could craft mysteries than a lot of the modern crowd. Ones that don't require the hero to be a moron for most of the story, until he suddenly figures it out, in the climax (or is told, by the villain).

What I recall from the DC comics of the 60s was explanations like, "Superman can fly because flight is a superpower that he has."

Marvel's pseudoscience back then was equally unrealistic, but it had more verisimilitude. It felt more real, more consistent.

And magnets worked on everything.  Not just every metal...literally everything.