maybe now we'll grow an exoskeleton

There's an interesting review in National Geographic by James Owen [LINK] about evidence that early human species probably evolved along with changing regional climate in Africa. The studies cited tie the evolutionary stages of humans to changes in rainfall and vegetation in the Great Rift Valley in East Africa. The idea seems pretty straightforward. As the climate dried out, tropical vegetation gave way to grasslands, making the ability to run an advantage in finding food and staying alive. Then a series of climate shifts made eastern Africa wetter and drier over a few millennia, which made early humans adapt several times. That favors bigger brains that can cope with a variety of climates, as well as a host of other physiological traits that may have helped early humans.

This kind of study shows some of the potential for very multidisciplinary studies among biology, geology, and atmospheric and oceanic sciences, and even including anthropology, etc. It warms my heart.