Friday, December 7th, 2007

Did Life Start in Mica?

This sketch shows Hansma's hypothesis for the evolution of different types of biological molecules in the many spaces between mica sheets. Image width is ~50 nm. Helen Greenwood Hansma, UC Santa Barbara

How did life begin on Earth? Once, a commonly held belief was that the first building blocks of life formed in a primordial soup of chemicals in an ancient, warm ocean. In a famous experiment in 1953, chemists Harold Urey and Stanley Miller cooked a flask of water, methane, ammonia, and hydrogen, and sparked it with electricity. After only a few days, Urey and Miller found fragments of amino acids -- needed to form proteins -- in the water. The experiment, many people felt, proved the old assumption. But later research revealed that perhaps the gases Urey used in his experiment weren't as common in the early atmosphere as he had thought - and that the sheer size of the oceans might have made any amino acids formed much too dilute to form into anything useful. So how did life on Earth get started? In a presentation at a meeting of the American Society for Cell Biology, one researcher presented her hypothesis that the spaces between sheets of mica rock may have had just the right characteristics for the development of those essential compounds. Rather than just 'primordial soup,' says Helen Hansma, life may have developed in a 'soup and sandwich.' In this segment, Ira talks with Hansma about the idea and what research might be needed to explore it further.