How Women Came Before Men... and Nipples Too!

After seeing some rather disturbing misinformation earlier in the day, I thought I'd quickly cover some scientific data in a very simplified manner. Specifically, I want to explain how women existed before men.

A classic television couple -- Ralph and Alice Kramden of 'The Honeymooners'.

To my friends, both scientific and brainy; I realize this explanation will be very basic. I don't want to delve too deep into the specifics of gender determination because it would go over most folks' heads. I'm 'dumbing it down' on purpose for the benefit of the layman. Bear with me.

When a fetus begins to develop in the womb, it starts out as a simple mass of cells. Over a number of weeks, these cells slowly start to form the basis of the human body. At some point around weeks six through eight, the sexual chromosomes of the fetus determine which sex it will become. Women, in terms of a chromosome pair, are identified by XX. Men are identified as XY. To be specific, the Y chromosome is the determining factor in the sex of the fetus. The presence of the Y chromosome is what makes a fetus grow into a male. The X chromosome has no power over this choice; only the Y chromosome will produce a male child. By default, all fetuses would become female if not for the presence of the Y chromosome. Both the X and the Y chromosome are allelic mutations from ancient autosomes in mammals. What's an autosome, you ask?

A diagram of all twenty-three human chromosome pairs.

An autosome is a chromosome pair that does not determine the sex of a creature. As humans, we have a total of twenty-three pairs of chromosomes. Twenty-two of those pairs are autosomes -- meaning they do not have any influence on the gender we develop into as a fetus. The final twenty-third chromosome pair that we possess DOES control our sexual development (it's known as an allosome).

After the fetus detects the presence of the Y chromosome , it grows into a male. It couldn't be any simpler. One reflection of this shared origin between males and females are our nipples. How many times have you heard someone ask in jest "Who do guys have nipples?"

The reason behind it is simple. Men and women both have nipples because all mammals develop this feature at an early stage as a fetus. All fetuses, whether eventually determined to be male or female, develop identically before the sex is selected. The presence of nipples is one of those non-sex based factors that develop. Due to how evolution has worked in mammals, the presence of nipples (or the lack thereof) has not been a trait which was turned "on or off" by natural selection (it simply wasn't "important" enough). By default (yet again), we all get nipples. 

So there you have it my friends. I can't make this explanation any simpler. When you first started to develop as a fetus (essentially a proto-female), you were by default going to be a girl. You grew nipples (at least I hope you did). Are you a man by chance? Then your allosome had a Y chromosome in it. Congratulations!

Any questions?