Open course ware

PROFESSOR: Continue today. We're still in the spirit of origami. And we're going to do some origami design and foldability again. There are two main topics here on the design side we're going to talk about-- universal hinge patterns, which are the things that make underlying this robot, which I showed in lecture one. You may recall. So it's called a box pleat pattern. It's a square grid with alternating diagonal creases. And the idea with the robot is you're constrained to only-- you have to build the creases ahead of time. You can't say, you can't build one sheet that can fold anywhere at anytime. You want to build a sheet that can fold at any of the crease lines, at the built crease lines whenever you want. And so whereas with something like Origamizer, every design has a completely different crease pattern and it's difficult to control that, here we wanted to make one. It's not exactly a crease pattern, because you're not usi...

So we're shifting gears today. We're going to talk about molecular evolution, i.e. how do we understand how species evolve, how do we understand a lot about ourselves, how human evolution is taking place over the last couple hundred thousand years. And traditionally, evolution has been the purview of people who study the morphology of organisms, and when I talk about morphology, obviously I'm talking about shape and form. And by comparing organisms, starting already 250 years ago, one began to develop hierarchies of how different organisms on the planet are related to one another. You've seen this, undoubtedly, in high school biology. This is the study of phylogeny, and phylogeny has traditionally been figured out by comparing the phenotypes, the morphologies of adults, sometimes embryonic development, and on that basis, attempting to extrapolate back in evolutionary time, about the relatedness of different organi...