Evolution of the Eye

A possible sequence of such changes begins with simple eyespots made of light-sensitive pigment, as seen in flatworms. The skin then folds in, forming a cup that protects the eyespot and allows it to better localize the light source. Limpets have eyes like this. In the chambered nautilus, we see a further narrowing of the cup’s opening to produce an improved image, and in ragworms the cup is capped by a protective transparent cover to protect the opening. In abalones, part of the fluid in t...

 Why the Brain Takes So Much Time and Effort

The brain’s chief job description—yours, mine, and your hopelessly adorable children’s—is to help our bodies survive another day. The reason for survival is as old as Darwin and as young as sexting: so we can project our genes into the next generation. Will a human willingly overcome self-interest to ensure the survival of his or her family’s genes into the next generation? Apparently, yes. Enough of us did hundreds of thousands of years ago that we grew up to take over the Seren...