We are all sure we know what life is, but if you try to actually define it, things get tricky fast. I wrote a feature about the scientific struggle to define life in 2007 for Seed, and I’ve been keeping tabs on the evolution of this metaphysical quandary ever since. I was particularly intrigued to discover recently that one scientist thinks he can define life–and do so in just three words. I’ve written an essay about his short and sweet definition for the web magazine Txchnologist. Check it out.

Originally published January 11, 2012. Copyright 2012 Carl Zimmer.

Over on Facebook, David Hillis, an evolutionary biologist at the University of Texas, took up my question as to whether anyone can define life in three words. His short answer was no, but his long answer, which I’ve stitched together here from a series of comments he wrote, was very interesting (links are mine):

Continue reading “Life with a capital L? (Like Zimmer with a capital Z?)” →

I’ll be on National Public Radio’s Science Friday this week to talk about Science Ink. Host Ira Flatow and I will be chatting during the 3 pm EST hour. In the meantime, the folks at Science Friday have set up a slide show preview.

Originally published January 11, 2012. Copyright 2012 Carl Zimmer.

Today , a company called Ion Torrent announced they were going to start selling a DNA-sequencing machine that can sequence an entire human genome for $1,000. It’s just the latest milestone in the long-term crash in the cost of gene-reading. There are lots of benefits that will flow from this ongoing transformation. For one thing, as I wrote in 2010 in the New York Times, it’s getting easier to identify new viruses that could turn to be the next HIV or SARS.

Continue reading “Any deadly viruses to declare?” →

This is a story of about how the parts of a puzzle locked into place 800 million years ago. The puzzle is an ion pump that you can find in any mushroom, mold, or yeast. I’ve reproduced a picture of it here.

Fungus cells, like our own cells, have lots of little pouches inside of them for carrying out special kinds of chemical reactions. In order for those reactions to work, there have to be a lot of positively-charged protons inside the pouches. To get those protons into the pouches, ion pumps like this one force them through membranes.

Continue reading “Resurrecting Evolution to Solve an 800-Million-Year-Old Puzzle” →