Common-Sense I would think it is something that is just known! Instinctively known.

I heard on the news the other day, these scientist after years of experience  came to

the conclusion human nostrils are different because of climate conditions.

This is common sense, adaptation takes place in order for survival. Skin color for another example,

Humans living in hot climates develop dark skin which absorbs the rays of the Sun for their

protection. I find Common Sense is no longer common. People are losing their ability to think!