Abiogenesis & The Origin of Life: Ideas, Research, and Myths
Traditionally, scientists have thought that life began billions of years ago in a muddy pool on the Earth’s surface. Recently, though, evidence has begun pointing to the possibility that life might have started deep under the surface within geothermally heated rocks in hot, high-pressure conditions. If it turns out that the formation of life is not only not unusual, but in fact occurs under extreme conditions, then it is much more likely that we will discover life on other planets.
According to many religious believers, and especially by proponents of Intelligent Design, there can't be any scientific explanation for the beginning of life. Fortunately scientists aren't listening to such nonsense and are actively engaged in an effort to discover how life began. They've made a lot of progress in recent decades and we have every reason to think that progress will continue.
As if evolution and evolutionary theory were not already confusing enough, many creationists complicate matters even further by promulgating the mistaken idea that evolution is the same as abiogenesis. One common way this is done is to argue that evolution cannot explain how life began while creationism can and, therefore, creationism is superior to evolution.
A common criticism of abiogenesis is the alleged improbability of life developing by natural means. Often cited is Sir Fred Hoyle, a British astronomer and mathematician, who calculated the odds at 1 in 10 to the 40,000 power against the proteins serving as enzymes in a cell all forming by chance. Is this a valid argument against life developing naturally?
What is life, anyway? Despite how often it is used, biologists have had difficulty coming up with a coherent definition which would distinguish between life and non-life. The line between the two is not nearly so clear and easy to find as people often assume.
The nature of the earliest forms of life on our planet are unknown and may remain that way, but we keep coming closer to understanding what they may have been like. Whatever they were like, it seems clear that they arose out of a process of molecular self-assembly. This process is commonplace in our universe. If you look up into the night sky, you’ll see countless stars and galaxies which arose spontaneously by a process of self-assembly.
Some organisms which make their homes on - and in - the earth can be far stranger than most can realize. Thiobacillus thio-oxidans feed upon sulfur and can exist in concentrations of sulfuric acid strong enough to kill all other creatures or dissolve metal. Hyperthermophiles grow in temperatures approaching 350 degrees Celsius. Chemotrophs produce nutrition independent of the sun’s energy - complete ecosystems exist without ever seeing the sun and would die if exposed to the surface.
Can life survive a journey through space? Experiments offer a resounding yes. For example, Japanese scientists sealed up Bacillus subtilis spores and other various organisms in a vacuum chamber and simulated the conditions of space exposure over a period of 250 years. In the end. half the sample survived, with the tobacco-mosaic virus doing the best at an 85% survival rate. It should be noted that these were normal organisms, not extremophiles which thrive in the nastiest conditions.
