DID LIFE START ON EARTH?
by Whit Gibbons
July 23, 2006
is a lot more complex than physics or chemistry because it involves not
only physical and chemical laws but also biological processes. The ecology
of a species is governed by individual behavior and interactions with
other plants and animals, as well as the physical and chemical environment.
The added component of "life" is what makes ecology so intricate
and fascinating. Maybe life was not so complicated "in the beginning,"
but figuring out how what happened when is anything but certain.
In an article
titled “First Life” in American Scientist magazine, Michael
Russell of the Scottish Universities Environmental Research Centre stated,
“scientists don’t know for certain how life started.”
The gist of the paper is how geochemists involved in studying earth’s
mysteries 4 billion years ago are trying to find out. The refreshing part
of the Russell article is that scientists don’t know (and do not
claim to know) everything. But speculating on how life got started on
Earth, using principles of physics, chemistry, and biology that are known
today, is intriguing.
facts about Earth were that it spun on its axis half a dozen times faster
than it does now. A day would have been over between lunch and dinner.
And the moon was thousands of miles closer, which means the everyday tides
would have been like small tsunamis. Imagine the winds and waves at the
beach. Spending even one of those short days on earth would have been
more exciting than any amusement park ever designed.
To add to
the chaos, if the geochemists are correct, the planet was being rained
on constantly by enormous meteorites that vaporized when they hit the
ocean and created dust clouds that blocked out the sun. The atmosphere
was a thick, smoky blanket of carbon dioxide. Not a pleasant place for
life to begin. And indeed the author proposes that life did not begin
on Earth's surface, but far below on the ocean's floor. He suggests that
warm springs at the ocean's depths would have had properties ideal to
support life: protection from the sun's ultraviolet rays, a constant temperature,
and a chemical makeup conducive to the creation of life.
in the ocean are not uncommon. Deep ocean areas where molten volcanic
rock encounters ultracold seawater, creating unusual physical and chemical
reactions, are called hydrothermal vents. These occur where a major fissure
develops between plates making up the earth's crust. As the plates gradually
separate, underlying volcanic activity reaches the surface, warming the
ocean at the point of entry. Hydrothermal vents in the ocean were not
discovered until 1977, but the phenomenon of water being warmed by volcanic
heat has been known for centuries and is seen any time someone watches
Old Faithful erupt in Yellowstone National Park.
vents are too hot and have high quantities of heavy metals and other chemicals
uncharacteristic of living organisms. But the warm springs hypothesized
in the article would have been an excellent environment for life to develop.
The chemical explanations and hypotheses are too complex to explain here
(or maybe even for me to understand), but the point is that the proper
mix of carbon, oxygen, hydrogen, nitrogen, and other vital elements was
present to create the first nucleic acids and proteins--before actual
life was present on earth.
life originated in a warmwater spring heated below the ocean floor by
molten volcanic rock, we will never know. Whether it originated multiple
times, will also remain a mystery. In fact, barring the development of
time machines that would permit a look 4 billion years before yesterday,
we will presumably never know for certain exactly how first life began
on earth. We are left with geochemists to speculate, based on evidence
from geological records and biological events today.
seem threatened, for reasons unfathomable to me, by speculation about
how life began on earth and the scientific pursuit of answers to that
question. I repeat: “scientists don’t know for certain how
life started." Neither does anyone else. But inquiring minds are
essential for any society that wants to be an enlightened one. No question
should be deemed inappropriate for scientific investigation.
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