The nervous system that sprouts from the brain may seem like an incomprehensible tangle. But anatomists can divide it pretty cleanly into two parts. One part is directed to the outside world, while the other is turned inward.

The somatic nerves take in sensory information from the outside world from our eyes, nose, ears, and skin. They also relay commands to move muscles. They are essential for our responding to the external world. Visceral nerves, on the other hand, detect information about our internal state. They sense blood pressure, the queasiness in our guts, even the level of oxygen in our bodies. And they also send signals to those organs, causing racing hearts, gasping lungs, and puking stomachs.

Continue reading “How Our Outside World Turned Inward” →

Nobody in my past was hugely famous, at least that I know of. I vaguely recall that an ancestor of mine who shipped over on the Mayflower distinguished himself by falling out of the ship and having to get fished out of the water. He might be notable, I guess, but hardly famous. It is much more fun to think that I am a bloodline descendant of Charlemagne. And in 1999, Joseph Chang gave me permission to think that way.

Chang was not a genealogist who had decided to make me his personal project. Instead, he is a statistician at Yale who likes to think of genealogy as a mathematical problem. When you draw your genealogy, you make two lines from yourself back to each of your parents. Then you have to draw two lines for each of them, back to your four grandparents. And then eight great-grandparents, sixteen great-great-grandparents, and so on. But not so on for very long. If you go back to the time of Charlemagne, forty generations or so, you should get to a generation of a trillion ancestors. That’s about two thousand times more people than existed on Earth when Charlemagne was alive.

Continue reading “Charlemagne’s DNA and Our Universal Royalty” →

Here’s a gruesome treat. NOVA just did a show on venom, and you can watch it online.

Ed Yong and I have written to unhealthy lengths about the evolution of venom, so if you prefer venom in text to venom in video–or if you just want some background–check these posts out.

Pythons are still a little venomous

On the Origin of Venom

Painkilling chemicals with no side effects found in black mamba venom

World’s 2nd deadliest poison, in an aquarium store near you

How a pit viper saved millions of lives: Snakes as drug factories

Venomous shrews and lizards evolved toxic proteins in the same way

Originally published May 7, 2013. Copyright 2013 Carl Zimmer.

Last year I wrote in National Geographic about the long, remarkable history of feathers. The folks at TED-Ed (the educational wing of TED) invited me to boil down that history to about three minutes–accompanied by a splendid animation by Armeilia Leung. Here’s what we came up with.

For more information, you can visit the video’s page at TED-Ed.

Originally published May 3, 2013. Copyright 2013 Carl Zimmer.