The Seven Skulls

We are taking a break from Of Spice and Men today, in order to let our germs grow for an extra day. We will continue the project tomorrow.

The final evolution topic we’ll be covering is perhaps the most famous and most relevant topic in Unit 6, and that is the evolution of humans. Today in class, students examined replicas of seven different skulls that were in some way related to the human skull. They examined the size, the thickness, the bone structure, and even finer details like the eyebrow ridges and the lines. After examining all of the skulls, students made a hypothesis about the order in which the skulls had evolved.

But all of the hypotheses were wrong. And I mean way wrong. I mean the not-even-close, better-luck-next-time kind of wrong. And that’s because our students assumed, like most people tend to assume, that evolution happens in a straight line… nice and organized… one species at a time. But it doesn’t.


Real evolution more closely resembles a tree. Over time, the species grow and change, sometimes quickly, sometimes slowly. At some point, most of the branches reach a dead end and die. After all, no species will stay on this Earth forever. It takes just the right environment, and a little bit of luck, to allow a species to evolve from some ancient forest ape, into a bipedal organism with two free hands, into the primitive tool-using homo erectus, into a human.

April 11 – The Seven Skulls Lab (pg615)

Your homework tonight is to watch a YouTube video about evidence of
evolution that can still be found on our bodies. Click here to access the video. 

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