If you’ve just been bitten by a venomous snake and your flesh is starting to rot and you can’t breathe, you may not be in the mood to hear how beautiful snake venom can be. But from a safe distance, it really is a marvel to behold.

Snake venom is a blend of molecules, many of which are exquisitely adapted for wreaking havoc. Some are enzymes that slice muscles apart. Some grab onto proteins that normally form clots, so that a snake’s victim can’t stop bleeding. Many snake venoms attack the nervous system with molecular precision that’s so good that neuroscientists have snakes to thank for some of their biggest discoveries.

Continue reading “How a pit viper saved millions of lives: Snakes as drug factories”

I just got back from San Francisco, where I gave a keynote lecture about how our bodies are like ponds, and why doctors need to think like ecologists. It takes a lot of time for me to put these talks together, and so I like to share them afterwards with more people than those who were physically in the room with me. Sometimes the people who invite me videotape the lectures and put them online. (Example: A talk I gave about science and the media.)

Continue reading “A question for you: what should I do with my lectures?”

Here’s one of the weirder things I’ve come across in biology. When lamp shells are just tiny 36-hour-old embryos–just a clump of a few hundred cells–they can see. Many cells on their outer surface express a photoreceptor gene, and they show evidence of being able to swim towards light. In other words, these lamp shells are swimming eyeballs.

Aside from the surrealism, this discovery is also cool because it might be a model for how our own eyes evolved. Perhaps they started out in a similar way. For more details, check out my story in today’s New York Times.

[Image: Coreldraw]

Originally published March 1, 2011. Copyright 2011 Carl Zimmer.

The New York Times, March 1, 2011

Link

Charles Darwin considered the evolution of the human eye one of the toughest problems his theory had to explain. In “On the Origin of Species,” he wrote that the idea that natural selection could produce such an intricate organ “seems, I freely confess, absurd in the highest possible degree.”

But Darwin dispelled that seeming absurdity by laying out a series of steps by which the evolution could take place. Making this sequence all the more plausible was the fact that some of the transitional forms Darwin described actually existed in living invertebrates.

Continue reading “In a Marine Worm’s Eyes, the Theory of Evolution”

Strictly speaking, there should be no blue whales.

Blue whales can weigh over a thousand times more than a human being. That’s a lot of extra cells, and as those cells grow and divide, there’s a small chance that each one will mutate. A mutation can be harmless, or it can be the first step towards cancer. As the descendants of a precancerous cell continue to divide, they run a risk of taking a further step towards a full-blown tumor. To some extent, cancer is a lottery, and a 100-foot blue whale has a lot more tickets than we do. Continue reading “The Mere Existence of Whales”