The Darwin mod only adds a mob. But the particularity of this mob is that it has chromosomes with genes. Their genetics define their color, skin, shape, behaviour...There are billions of possibilities.

In the wild you'll meet some of them inspired by existing mobs in Minecraft or other animals (even Pokémons).

You can make them mate as any pig or sheep with wheat. The child will inherit from its parents following the same biological laws than in real life including mutations. You can then obtain phenotypes which couldn't exist in the wild.
Each mob actually has the following components:
- a body (4 possible shapes)
- a head (3 possible shapes or none)
- a snout (3 possible shapes or none)
- ears/horns (3 possible shapes or none)
- a tail (3 possible shapes or none)
- 2 rear legs (3 possible shapes or none)
- 2 front legs/arms (3 possible shapes or none)
- the speed it can move depends on the size of the legs
- rotation of the body (from 0 to 90°)
- color (16,581,375 colors)
- skin (11 different skins)
- dropped item (126 possibilities)
- AI and behaviour: depending on some genes, some tasks are added like "hunt cows" for example or "flee when hit" or "look for shade".
- other behaviours: burn in sun, hurt by water, immune to fire...

Credits:
Manchou - Creator of the Darwin mod.

Godson777 - Helped port mod to 1.12.2.

This mod is an unofficial port of Manchou's Darwin mod for pre-1.7 Minecraft.