Sunday, October 19, 2008

Soup's on -- Miller-Urey experiment

I caught up with an old friend today, my good buddy primordial soup. Primordial soup is a nickname for Earth’s ancient, abiotic oceans, meant to suggest the watery mix of chemicals and sediments in which life somehow began. The phrase became famous back in the 1950s, when biologists Stanley Miller and Harold Urey threw some chemicals in a beaker, zapped them with electric charges, and – it’s alive! Well, actually, it's amino acids – not quite life, but life’s building blocks. The simple but startling Miller-Urey experiments became famous, and soon found a place in every geology and biology textbook as a compelling hypothesis for the origin of life.

I encountered primordial soup decades later in college, and it was love at first hearing. The words put a vivid picture in my mind that still lingers all these years later. The aching loneliness of the empty sky and the silent sea, then a sharp crack of lightning, and in the darkness and the deep, something stirs.

The ingredients and the power of primordial soup have changed over time. Miller used a mixture heavy in methane and ammonia, but some later researchers suggested that the early atmosphere was much richer in carbon dioxide and nitrogen, gases too inert to be jump-started by a little lightning. For a time primordial soup was pushed to the back burner.

But now comes word of a new, improved recipe. Chemist Jeffery Bada recently found some old vials tucked away in a cardboard box, sealed results from one of Miller and Urey’s experimental variations. The scientists had added a jet of steam to the experiment to simulate volcanic activity. When Bada analyzed the 55-year old residue in the vials, he found all of the amino acids produced in earlier experiments, plus 10 more. This work suggests that the composition of the atmosphere as a whole may have been less important than the conditions around volcanoes. Geysers and hot springs on the flanks of active volcanoes receive frequent injections of steam and reactive gases. A lucky lightning strike into a primeval Old Faithful may have been the first link in the chain of life.

The story of primordial soup isn’t just about the origin of life, it’s a story about science. A story about how science never stops, but keeps looking and asking questions, and rummaging around in the dusty cupboards of the world. I’m thrilled to have my primordial soup back, and I wonder if some student out there right now will read those words and feel a stir on the back of her neck just like I did.

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