Because we need to get basic knowledge for our futher future survival in this life.
Why dick becomes red when it's horny?
:ps: To James Alterlis and others: Please, stop fooling around with answers like " lulz, dunno " or "I dunno, ask them lololol". If you really can't give an answer, then press cross at the right corner of the screen. The game is based on giving RIGHT answers, not bullshit.
Thanks for attention.