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Wednesday, July 07, 2004
An op/ed by David Suzuki
Scientists often lament about the loss of biodiversity occurring
worldwide as a result of human activities. It's an important
issue because humans rely on this diversity of life to maintain
the natural services that we depend on: things like clean
air and water. But protecting life diversity is exceedingly
difficult if we don't even know what we're trying to protect.
Scientists are still a long way from pinning down the number
of species on our planet. Most common estimates range from
10 million to 20 million species, although we have identified
only 10 to 20 percent of those. Researchers are hard at work
finding and identifying new species, and they discover them
all the time. But the largest number of unclassified species
are also the most difficult to find because we can't even
see them.
In an impassioned plea for more studies into the invisible,
Dr. Sean Nee of the University of Edinburgh, U.K., points
out in the journal Nature that today's most important and
interesting discoveries about biodiversity are being found
at the microscopic level. Yet the vast majority of scientists
are fixated on the visible world, he says.
He makes a strong argument. Life on Earth would not exist
at all if not for the actions of microscopic creatures who
pumped first methane and then oxygen into the atmosphere billions
of years ago. Indeed, for more than half of the time that
life has existed on this planet, there were only microorganisms.
Over some 2 billion years, they evolved all of the basic mechanisms
that multicellular creatures like us depend on.
The majority of life on the planet still exists at microscopic
levels. The soil that we depend on for our food is a community
of microorganisms who not only constantly recreate soil but
feed trees of the forest, filter water, and fix nitrogen from
the air. Both in terms of biomass (the weight of living matter)
and individual numbers, microscopic organisms far outnumber
life forms in the visual world. Four out of five animals on
the planet are actually microscopic nematodes.
On the tree of life, visible creatures are but "barely
noticeable twigs," Nee says.
In fact, we still owe our breathable atmosphere to microscopic
creatures. While most people think about trees and plants
as the source of the oxygen we breathe (and they do produce
50 percent of it), terrestrial plants also absorb much of
that oxygen again through the process of respiration. It's
actually invisible phytoplankton practicing photosynthesis
in our oceans who add enough oxygen to our air to prevent
the world's supply from dwindling.
Some of the most fascinating recent discoveries of new life
forms have not been of mammals or birds but of unusual microscopic
organisms. From creatures who breathe uranium to those who
thrive in hot acid or solid rock, new discoveries about microscopic
biodiversity have raised new questions and challenged some
of our views about the basic requirements for life to exist.
Life, it seems, is extremely tenacious. Given a chance, it
will evolve and flourish in the most unlikely of places.
If we are to truly begin to understand the diversity of life
around us, Nee argues, biologists must rid themselves of their
bias towards the visible world. We are too emotional in our
study of life diversity, focusing on cute creatures and virtually
ignoring the majority of life on Earth, he says. Humans must
think more rationally, like Mr. Spock of Star Trek fame, and
less emotionally in our study of biodiversity.
He has a point, and not just in regard to microscopic organisms.
Our insistent focus on threatened "charismatic megafauna"
or "cute critters" has in some ways blinded us to
the rapid degradation of entire systems. The fact that animals
like tigers, gorillas, and whales have been held back from
the brink of extinction gives the public a false sense of
security.
But popularizing the microscopic world is no easy task either.
Humans are emotional creatures, and we naturally feel more
affinity to creatures who are more like ourselves. People
just might not be ready to relate to things they can't even
see.
Most of us are already so cut off from the natural world
that we don't even recognize how dependent we are on healthy
ecosystems. We need to reconnect with nature at all levels
if we are to protect the diversity that underpins the basics
of life we now take for granted.
Related Link
Take the Nature Challenge and learn more at http://www.davidsuzuki.org/.
Source: David Suzuki Foundation
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