I'm working on a Role Playing Game source book with the idea that players take the roles in a world drastically changed, that old chestnut. The setting's a modern world where one day nearly ninety percent of one gender was change physically. Internal biology wise they are the same, but physically completly different. Think some kind of humaniod creature. It focuses on if women changed, but with opinions to play in a world where men were the ones that changed. Oh and the event that changed everyone also effected the animals and turned many into monsters, because why not. I know monsters would make some peoples day suck, but what about the change? How would that effect society as a whole? The tone of the book is actually a comedy, a rather black one at that. The plan is to have some satire of the hard science, dark and grim, "this is the real world, only worse" (read World Of Darkness, Traveler and many more). This plan includes almost explaining how did the change happen, only to get distracted and forget, censored or just contradict oneself. In summery: Need to know how the world would react if an entire gender changed physically into human monsters, have real monsters attack and keep things tongue in cheek about it.
We'd probably go extinct if the changes were drastic like the creature from Alien. If more minor, like Klingon or Elf, many would adapt.
What kind of monsters are you talking about? "Monster" is a very vague word. The way the world would react would depend on the specific monsters people turn into.
Of those that changed, their senses, including vision, smell, hearing would be quite different, as would their physiology--cold-blooded, herbivorous/carnivorous, different sleep patterns, even hibernation. Also, I think that if their memories of being human were intact, maybe a bit of mental illness would follow. If 90% of one gender of humanity changed, that would pretty much doom humanity to extinction, especially if it became a more violent world.
I guess it depends on if your book takes place in the real-real world or in Marvel Comics world. In the real-real world this would probably mean the extinction of our species. How many of the unaffected gender would be able/willing to reproduce, honestly? The added changes you mention to other creatures doesn't help the matter. It would be a Last Drama story, in the real-real world. I won't even go into where this would take people who are serious adherents to a religion. Any religion. Also, as a gay dude, the first thing that actually occurred to me was to wonder what percentage of still-closeted gays and lesbians would use this as a convenient escape from the closet. "Yeah, man, I'm switchin' to the D because have you seen Tina? Dude, she's got a tail and twelve teats. No, not tits. Teats!"
I think a lot of manga and anime leads people of a certain generation to have a different view of things like hooking up with a furry. I recently saw a film called Wolf Children which tries to tell a heartwarming and sensitive story around an original premise of this perfectly Every Girl gal who meets and hooks up with a guy who is the Japanese version of a werewolf, which doesn't carry the same mythos as the European version of same, but regardless, she hooks with him in full-on furry form, has kids with him, has to deal with how to raise kids who are half human half wolf, yadda, yadda. The story tries to sell me all this emo (it's anime, rife with emo) and the whole time all I can think is, "Gurl, you fucked a dog. An actual dog. You fucked him. This whole story is about what happened after you took a Scooby-Do boning. That's not right." Clearly behavior in anime is not to be used as a meter by which to measure real-life behavior.