Why the penis tip is mushroom shaped?

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 women live longer than men?

Why do we have different blood types?

Why do have four seasons?

Why do we yawn and is it contagious?

Why Finland is the happiest country in the world?

Why did human brains decrease in size?

Why are we the only human species left on the planet?

Why physic laws respect mathematics?