You are more likely to believe that a statement is true if you have heard it before - whether or not it is actually true.

As Carl Jung put it, "In each of us there is another whom we do not know." As Pink Floyd sang, "There's someone in my head, but it's not me."

At least 15 percent of human females possess a genetic mutation that gives them an extra (fourth) type of color photoreceptor - and this allows them to discriminate between colors that look identical to the majority of us with a mere three types of color photoreceptors.

Our internal life and external actions are steered by biological coctails to which we have neither immediate access nor direct acquaintance.

Some men may be genetically inclined to have and hold a single partner, while some may not. In the near future, young women who stay current with the scientific literature may demand genetic tests of their boyfriends to assess how likely they are to make faithful husbands.

Who we can be begins with our molecular blueprints - a series of alien codes penned in invisibly small strings of acids - well before we have anything to do with it. We are a product of our inaccessible, microscopic history.

Your brain is built of cells called neurons and glia - hundreds of billions of them. Each one of these cells is as complicated as a city.