Why is universe expanding?

Why does the moon glow?

Why does the conductivity of a solution decrease with dilution?

Why is world map not to scale?

Why do we shake in the cold?

Why does the brain need so much power?

Why is diffusion insufficient to meet the oxygen requirements of multicellular organisms like humans?

Why do we have different blood types?

Why do we yawn and is it contagious?

Why did human brains decrease in size?