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Free from the archives - The origin of life I: When and where did it begin? 

Posted on 8. August, 2014.

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For decades most scientists assumed that life emerged billions of years ago in a “primordial soup” somewhere on the Earth’s surface. Evidence is mounting, however, that life may have begun deep beneath the surface, perhaps near a volcanic ocean vent or even inside the hot crust itself. Since there are hints that life’s history on Earth extends back through the phase of massive cosmic bombardment, it may be that life started on Mars and came here later, perhaps inside rocks ejected from the Red Planet by large impacts.

The traffic of intact rocks between Mars and Earth is now an established fact, and experiments confirm that microbes could survive the rigours of the journey through space if cocooned within such material.
Unfortunately, this planetary cross-contamination compromises astrobiologists’ hope of finding a second genesis in the solar system.

A pivotal event in the history of science took place in 1859 with the publication of Charles Darwin’s seminal work On the Origin of Species. Darwin gave a convincing account of how the richness, complexity and diversity of life on Earth has emerged, over billions of years, from a simpler common ancestor, through the mechanism of random variation and selection. However, Darwin pointedly left out of account any explanation of how life got started in the first
place. It has to be said that, 140 years later, the problem of the origin of life remains a deep and tantalising mystery. At its heart lies the puzzle of how nonliving chemicals can transform themselves into a truly living thing. Even the simplest bacterium is so immensely complex it strains credulity to imagine such an entity popping into existence solely as a result of the random shuffling of molecules. Yet clearly there must exist a pathway of physical processes that leads from simple chemicals to complex life; the challenge is to discover what this pathway is, and whether it is unique.

The complete article is free to download in Science Progress, Volume 84, Number 1, February 2001, pp. 1-16.

Author: Paul Davies

DOI:10.3184/003685001783239069

Image courtesy of Igor Zh