Removed requirement that a creature have a baby/child state to breed
Nice. This will make modding in creatures that undergo metamorphosis much easier.
Also, WHOA! How are you doing that?! I came up with a few ideas about it myself, but I was pretty sure it would be impossible.
The basic principle is to make a creature with two castes, a common 'child' caste and an 'adult' caste with a very low POP_RATIO (it would be nice if we could make castes with a POP_RATIO of 0 so that they never appear naturally, but that still doesn't work), and give the child caste a self-targeting interaction that transforms it into the 'adult' caste after a certain amount of time.
You can even make coral-like organisms with a mobile juvenile stage and an immobile adult stage, if they mate while they are still mobile they can give birth even as immobile adults (but only once - it would be nice if immobile creatures could breed normally, but they can't). I've made creatures like this, but they require a 2 year delay between generations since they would need to grow up first before advancing to their adult stage. Now that the CHILD tag is no longer needed, multi-stage animals with a fast reproductive cycle should work too.