Peggy has an excellent discusion of the peculiar attitudes towards biology held by physicists and engineers, which includes this wonderful complaint by Jack Cohen:
In summer 2002, I was at the Cheltenham Festival of Science. Lots of biologists presenting, for sure. But… one very popular event was a presentation by three famous astronomers: ‘Is There Life Out There?’ I prefaced my first question to them by a little imaginative scenario: three biologists discussing the properties of the black hole in the middle of our galaxy. It was very clear that the astronomers really believed that they could discuss ‘life’ professionally, whereas everyone saw biologists talking about black holes as absurd.
Oh, and let’s get started on how SF treats biology…
Authors, film producers and directors, special-effects teams go to physicists, especially astrophysicists, to check that their worlds are workable, credible; they go to astronomers to check how far from their sun a planet should be, and so on. They even go to chemists to check atmospheres, rocket fuels, pheromones (apparently they‘re not biology….), even the materials that future everyday clothes (not only spacesuits) will be made of. They do go to self-styled "astrobiologists", who are usually astronomers or astrophysicists who remember some Biology 1.01 (or think they could if pressed). Between them they invent reptiloid "aliens" (who are cold-blooded enough to do all those dastardly things no warm-blooded American male could do…), feline aliens (who have the psychology of the household cat writ large, especially by more mature female authors…), dinosaur "aliens"…. Or giant ants. Or were they mut-ants, I don’t remember (but how many screen mutations have you seen that change the recipient, not its progeny?). Or a vast array of "alien" human actors with a bit of wax, as easy on the Special Effects Dept as the Pure Energy aliens, or the Aliens on mid-day TV shows who magic things out of the air and see through clothing (do their eyes emit or receive X-rays?), and which otherwise free the writers from having to produce a consistent plot. Or Vulcans who can produce viable offspring with humans (when even our cousins the fish can’t – mermaids are even less breedable than Spock). These people know that they don’t know about physics, or astronomy, or chemistry. Those disciplines are real science. So they get help. But the biology seems so ‘obvious’ to them … and they don’t realise that it feels just the same to be sure and wrong as sure and right! Of course, those of us that agree biologists can see that all those anthropomorphs can’t be alien, they’re vertebrate mammals and must share our ancestry here on Earth. They can’t see that ET can’t be e-t, that the ‘Alien’ doesn’t work – except in its primary purpose, scaring the living daylights out of the audience with the bursting-out-of-chest routine (how can a parasite pre-adapt to immune-responses, and not being felt in the chest when it’s bigger than your heart?). Biology questions don’t seem professional to the people who design these scenarios; it’s like folk psychology or philosophy – everyone has "a right to" an opinion.
There just aren’t many SF authors who do good aliens or even good biology. Sterling and Cherryh come to mind; Brin and Vinge come up with some excellently weird aliens, but sometimes they don’t seem very organic to me, but more like little black boxes of biological contrivance (it’s even worse for authors like Niven—I get the distinct impression they’re just plugging weird components together to build an alien, as if they were assembled with bio-legos). Robinson really gets into ecology, and writes more like I imagine a real biologist would do SF. Bear gets a lot of press as someone who writes about SF biology, but I find his books unreadably wrong, right there in the uncanny valley of using a lot of biological terminology while not understanding the concepts very well.
But of course it’s all because biology is easy, it isn’t a hard science, it doesn’t have any math … all ideas that are completely false, but perpetrated on science-fiction convention panels as willfully and as routinely as you’ll find in creationist tent revivals.