Ok, here's a REALLY simplified version taken from the LiveScience website. More complex/detailed explanations are available!

Brace yourselves for a low blow, tough guy. Nipples remind us that gender is anything but clear-cut, especially in utero. Whatever your sex, everyone starts off as a woman in the womb.

For the first several weeks a developing embryo follows a "female blueprint," from reproductive organs to nipples. Only after about 60 days does the hormone testosterone kick in (for those of us with a Y chromosome), changing the genetic activity of cells in the genitals and brain. But by then those mammary papillae aren't going anywhere.

So the real question is: why do male nipples come equipped with nerves and blood vessels? In many male mammals nipple formation is stunted by hormones, but not in humans. Did prehistoric men nurse their young? The lack of evidence suggests not. More likely, full-grown nipples — being harmless — don't get weeded out by natural selection.

Nagy: Nagy: More misstatements: no scientist said there was no reason for the Big Bang. The reason is currently unknown. As to the arrangement of particles into matter, with further refinement, that has specific reasons; the laws of chemistry, physics, and mathematics.

Rac: You are assuming that physics, laws of chemistry and mathematics existed before nothing even existed. What came first, nothing or physics? That is where the BIG whole is in your statement. In order for the big bang to happen when there was absolutely nothing, there were no such things as physics or mathematics. You have to ask yourself, what came first the big bang or physics...or maybe what came first the chicken or the egg??? Where did physics come from?? who invented physics??? did physics all of the sudden pop out of nowhere for nothingness???