This is the possible to the strange creature message:
After a few days thinking we have come to this conclusion, My friend wanted to make a new creature. The first thing he did was put the fresh totally blank creature in to the Extreme growth map. So the first ten years of its live it has learned to sleep only, and eat a little offc. So the creature has developed very strong need for sleep. Or in other words very high lethargy. Now that he has been teaching his creature when to eat, sleep, drink etc. The Creature is also learning that there is more to life then sleeping in the pen all day and night will become less lazy.