Class Session 14>
Biological Diversity – What Good Are the Neighbors?
The diversity of biological
species is the Earth's most important natural resource. Without this diversity,
life on earth and the ability of the human species to sustain itself, would
have been greatly limited. Biological diversity is important for:
1. Agriculture - The most
important sources of such genetic material for plant breeders are the wild or
locally cultivated relatives of these crop species, which are found where they
were originally domesticated. Just 20 plant species provide more than 80
percent of the world's food. Three of them -- corn, wheat, and rice --
constitute 65 percent of the food supply. Second, insects are important as pollinators
for crops. Nearly 100 of the most important
2. Medicine - Over 40
percent of the prescription drugs sold in the
3. Industry - Many raw
materials and products used in industry are derived from wild plants and
animals. Among the most economically important category of industrial products
derived from living resources include timber and other wood products, such as
lumber, paper, and wood-based chemicals like rayon.
4. Psychological Benefits
- We often value natural resources based on their economic contribution.
Biological diversity, however, also confers many non-economic or qualitative
benefits. These include the psychological and spiritual benefits that human s
derive from being out in nature.
5. Philosophical Values -
Natural resources are usually valued from a human based perspective - how
important such resources are to the economy or our well-being. While this
approach is understandable, we being humans, the biological kingdom also has
values and rights which are non-human in context. The ethical and legal debates
over the value and rights of non-human, biological life are complex, but
increasingly many of the world's religions and philosophies are addressing such
issues and are working to foster a reverence for all life forms.
Are the Neighbors Moving Out?
The biosphere faces a multitude
of threats which are serving to greatly decrease biological diversity. In
addition to the species that will be lost outright, many others are being
reduced to populations teetering on the edge of extinction. What does it mean
to become extinct? Extinction means gone, forever -- not just rare or a few --
but gone…..forever. If current trends continue, and all evidence is that they
will, our children’s children will inhabit a world that is much less abundant
than we have and this lack of abundance could affect the quality of their lives
in various ways. This section focuses on the changes that are underway in the
biosphere. While the biosphere has undergone change since the beginning of the
earth, the changes that are of the greatest concern are those that are
occurring today as the result of human activity.
For starters, it is important to
recognize that species extinction has occurred down through the millennia.
While it is difficult to piece together with any accuracy the pattern of
species extinction down through the ages, most scientists agree that there have
been five major mass extinctions. Remember the dinosaurs? They were wiped out
at the end of the Cretaceous period – the last really big period of mass
extinction – which occurred about 65 million years ago. What’s different about
the previous periods of mass extinction from the one underway today is that all
the previous extinctions took place “naturally”, without our (human) help since
humans date back as an identifiable species to only around 4 million years.
Interestingly, climate change does seem to have played a role in each of the
previous mass extinctions, possibly due a sudden change in climate as a result
of an asteroid striking the earth.
Second, it’s also important to
clarify some terminology.
1. Extinction - Complete
disappearance of a species.
2. Critically Endangered –
A species is considered “critically endangered” when it is facing an extremely
high risk of extinction in the wild in the immediate future without some form
of human intervention such as the establishment of a nature preserve or
relocation.
3. Endangered - Species
are those who are not critically endangered but still face a very high risk of
extinction in the near future.
4. Threatened – A species
that is not yet endangered, but whose numbers are declining in such as way so
that it could become endangered.
5. Rare - Species not
presently in danger, but of concern because of low numbers
Significant loss of biological
diversity is underway today. The difference between the current period of
extinction and the ones that came before is that, instead of changes in climate
or natural events causing wipeout, one single species is driving other species
to the brink of extinction and beyond. How fast are species becoming extinct
today?
My original intention was to provide
an update on the latest figures regarding extinction, so I did a website search
for “global species extinction” and found the site below. When I went to the
site, I was BLOWN AWAY!!! I’ve taught environmental science for the past 20
years and have been aware of the fact the world is losing species but even
I, as an environmental science prof, am staggered
by the amount of recent evidence about species extinction, much of this information
which has become available since September 2001, when world attention has
been on terrorism and security issues. So, this is what I want you to do.
I want you to check this site out for yourself. Go to http://www.well.com/user/davidu/extinction.html
and scroll down the page, slowly, just looking at the headlines. We will discuss
this in class on Thursday.