Botkin Environmental Science Earth as Living Planet 8th txtbk

272 CHAPTER 13 Wildlife, Fisheries, and Endangered Species
A CLOSER LOOK 13.2
Reasons for Conserving Endangered Species—and
All Life on Earth
Important reasons for conserving endangered species are
of two types: those having to do with tangible qualities
and those dealing with intangible ones (see Chapter 7 for
an explanation of tangible and intangible qualities). The
tangible ones are utilitarian and ecological. The intangible
are aesthetic, moral, recreational, spiritual, inspirational,
and cultural. 18
Utilitarian Justification
Many of the arguments for conserving endangered species, and
for conserving biological diversity in general, have focused on
the utilitarian justification: that many wild species have proved
useful to us and many more may yet prove useful now or in
FIGURE 13.12 Sowbread (Sow cyclamen), a small flowering
plant, was believed useful medically at least 1,500 years ago,
when this drawing of it appeared in a book published in Constantinople.
Whether or not it is medically useful, the plant illustrates
the ancient history of interest in medicinal plants. (Source: James
J. O’Donnell, The Ruin of the Roman Empire [New York: ECCO
(HarperCollins), 2008], from Materia Medica by Dioscorides.)
the future, and therefore we should protect every species from
extinction.
One example is the need to conserve wild strains of
grains and other crops because disease organisms that attack
crops evolve continually, and as new disease strains develop,
crops become vulnerable. Crops such as wheat and corn
depend on the continued introduction of fresh genetic
characteristics from wild strains to create new, diseaseresistant
genetic hybrids. Related to this justification is the
possibility of finding new crops among the many species of
plants (see Chapter 11).
Another utilitarian justification is that many important
chemical compounds come from wild organisms. Medicinal
use of plants has an ancient history, going back into human
prehistory. For example, a book titled Materia Medica, about
the medicinal use of plants, was written in the 6 th century
A.D. in Constantinople by a man named Dioscorides (Figure
13.12). 19 To avoid scurvy, Native Americans advised early
European explorers to chew on the bark of eastern hemlock
trees (Tsuga canadensis); we know today that this was a way
to get a little vitamin C.
Digitalis, an important drug for treating certain heart
ailments, comes from purple foxglove, and aspirin is a
derivative of willow bark. A more recent example was
the discovery of a cancer-fighting chemical, paclitaxel, in
the Pacific yew tree (genus name Taxus; hence the trade
name Taxol). Well-known medicines derived from tropical
forests include anticancer drugs from rosy periwinkles,
steroids from Mexican yams, antihypertensive drugs from
serpentwood, and antibiotics from tropical fungi. 20 Some
25% of prescriptions dispensed in the United States today
contain ingredients extracted from vascular plants, 21 and
these represent only a small fraction of the estimated
500,000 existing plant species. Other plants and organisms
may produce useful medical compounds that are as
yet unknown.
Scientists are testing marine organisms for use in
pharmaceutical drugs. Coral reefs offer a promising area of
study for such compounds because many coral-reef species
produce toxins to defend themselves. According to the National
Oceanic and Atmospheric Administration (NOAA),
“Creatures found in coral ecosystems are important sources
of new medicines being developed to induce and ease
labor; treat cancer, arthritis, asthma, ulcers, human bacte-