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About life's origin and its many forms
Tongyun
9/22/2002



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Nature and human nature
 
An article titled “How Life Began” published in Time magazine on July 29th, 2002 revealed some of the most inconceivable forms of life. Scientists have recently found that microbes can survive in the most extreme of environments. They can thrive in boiling heat, freezing cold, radiation, and toxic chemicals. These findings have triggered a revolution in biology. (Time)

It's hard to imagine a more inhospitable place on earth than the hydrothermal vents that cover the ocean floor. These cracks in the sea bottom spew water that is superheated by rising magma to as high as 750 degrees Fahrenheit and is contaminated by toxic substances such as hydrogen sulfide, cadmium, arsenic, and lead. Unbelievably, even in these lethal conditions there exists life that not only survives but even thrives.

The frozen continent of Antarctica is almost equally deadly, but it sits on the other end of the temperature spectrum. Drilling into a thick ice cap three miles below the surface, scientists reached a body of underground water known as Lake Vostok that rivals Lake Ontario in size. Although Lake Vostok hovers near the freezing point, cut off from light and outside nutrients, it is teeming with microorganisms. Scientists studying the samples marveled at this discovery because no one believed that life could exist down there.

Remarkable as these discoveries might have once seemed, they have become almost commonplace. Over the past few years, scientists have continued to find microbes thriving in extreme environments. Scientists have been finding life in all sorts of places where biology textbooks say it should not exist, such as at high temperatures, deep under ground, in highly concentrated salt water, with near toxic metals, and even with radiation. In the past, these findings seemed little more than a biological oddity, but the new collective body of evidence has triggered a scientific revolution, forcing researchers to reexamine biology's most basic assumptions about how life began.
In addition, when biologists looked carefully at microbial genes, they realized that while these microbes share bacteria’s key feature --- the absence of a distinct nucleus --- their genes more closely resemble those of more advanced cells. The implication of this discovery is that life on earth may not have first arisen in a warm tidal pool as Darwin theorized. Consequently, some scientists have started to reexamine Darwin’s theory of evolution.

These findings have also inspired scientists to explore the possibility of life beyond Earth. People once believed that life could only exist in habitable environments as defined by biology textbooks. The recent discoveries of life in extreme environments have transformed biology. It is now humbling to find microorganisms where you never imagined they could exist.

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