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Year 10 Evolution – Evolution in Action
Name: ____________
Why Does Evolution Matter?
Grains, such as wheat and corn provide 75% of the food the world eats.
Today, a corn plant produces twice the grain it did 30 years ago, and
probably 10 times what it could a century ago. Why? Because we know -we have found out -- that living things are changeable. Over many
generations we can change them into things that serve us better. Nowadays
we do it very systematically and on purpose. We've done it more
haphazardly for thousands of years. Somewhere in our dim past we
discovered that if we mate our best plants and animals, or save the best
seeds, and destroy or eat the less perfect ones, each generation will get
slightly better -- more fit, by our standards. But corn, for instance, is still
being improved, and still has enemies. One way we could improve it is to find its wild ancestor, the native grass that
our ancestors started cultivating. The problem is that we have changed corn so much that it now looks very different
from any wild grasses. But understanding that corn has evolved has allowed agricultural researchers to find its wild
cousin. Now, using the science of genetics, we can "borrow" genes from that relative to improve corn. We are making it
more resistant to disease and insects, and more tolerant of salt and drought.
That's one thing we can do with a knowledge of evolution and genetics:
feed a hungry world. Research into improving animals - livestock - is
just as dependent on modern evolutionary biology. How could we even
conceive of using ancestral genes to improve breeds if we thought all
plants and animals were just created, in their present forms?
If you want to see evolution in action, all you have to do is look for
things with very short times between generations: insects, for instance. A
major problem with bugs (from our point of view) is that their
generations are so short that they can evolve fast. So what? So every
farmer must be painfully aware that he has to be very careful about how
he uses pesticides. If he uses too much, too often, he may force bugs to
evolve rapidly and become resistant, so that the poison no longer kills
them. This isn't "just a theory" -- it happens.
There are many pesticides that are now useless, because the bugs they were used on have evolved into something that is
no longer bothered by those poisons. They may not be new species yet, but they are no longer the same insects, either.
The U.S. Department of Agriculture and the multi-national, multi-billion-dollar agribusinesses take evolution very
seriously .
Consider those other "bugs": germs. Modern hospitals have learned the hard way just how fast bacteria can evolve.
They have accidentally "created," by using too many antibiotics, new breeds of super-germs that have evolved
resistance to antibiotics. It's now a race: can we find new antibiotics fast enough to keep up with the mutation-andnatural-selection rates of killers like resistant staphylococcus? And if we do find something that kills it, do we run the
risk of forcing it to just evolve again into an even more unstoppable form?
Our first step in understanding AIDS was to figure out what it had evolved from -it didn't just appear magically. We have also discovered that it will be very difficult
to make an AIDS vaccine, because the HIV virus has developed the trick of
evolving so fast, that something that prevents it this year, probably won't next year.
Another of its tricks is to mutate (evolve) into many different strains within each
victim's body, so that the immune system can never find and eliminate all the
viruses. If researchers didn't know that life has always changed, and continues to
change -- if they didn't believe in evolution -- how could they deal with the turbocharged evolutionary rates of these tiniest and deadliest life forms?
Finally, a (true) horror story. A few years ago there was a little girl, known to the
concerned public as "Baby Fae," who needed a heart transplant. Human donors
are hard to find, especially for infants, so a daring surgeon convinced the parents
to let him implant a baboon's heart. A hopeful world held its breath, while
skeptical biologists scratched their heads (a baboon's heart?), but everyone hoped
for the best. Sadly, Baby Fae died after a few weeks. Among the contributing
factors may have been that her immune system had recognized the heart as
something foreign, and attacked it. After the sensational news stories had died
down, it was reported that a biologist asked the surgeon why he had chosen a
baboon donor, which is a much more distant relative of ours (in evolutionary
terms) than a chimpanzee, which is our closest relative. Wouldn't there have been
less danger of rejection with a heart from a closer relative? The surgeon's answer:
he hadn't even taken that into consideration, because he didn't believe in
evolution! To him, no creatures were related to each other, since they had all been
created at once, in their present forms. Maybe a chimpanzee's heart would not
have saved Baby Fae either, but the chances might have been better. One would
think that a doctor or scientist would want to use the best available knowledge,
such as what we understand about evolutionary biology and the relationships of
organisms.
Answer the Questions:
1. What is the main point of the article?
a. evolution is an important and useful theory
b. evolution is a theory that has not been proven
c. we should improve crops to feed more people
d. we should not tamper with nature
2.
a.
b.
c.
d.
Why must farmers be careful about the pesticides they use?
they could poison the land and harm other organisms
they crops may die
insects may become resistant
so that they can produce better crops
3. Why is it difficult to create a vaccine for AIDS?
a. the virus is too well hidden in the body
b. the virus is constantly changing
c. vaccines only work on bacterial infections
d. not enough research money
4. Years ago, doctors would prescribe antibiotics for many symptoms of a common cold. Today, it is much more
difficult to get a prescription. Why has the medical industry changed its procedures?
a. too many antibiotics can create resistant bacteria
b. pharmaceutical companies objected to the amount of prescriptions
c. antibiotics can make people sick
d. doctors are against prescribing medicines
5.
a.
b.
c.
d.
To see evolution in action, you should look at organisms with:
short lifespans
complex body systems
large populations
short amount of time between generations
Short Answer (use complete sentences!)
1. Describe two ways in which the evolution of organisms can have a harmful effect on humans.
2. Name two ways that the Theory of evolution is currently being used to improve the quality of human life?
3. Why did the doctor NOT choose a chimpanzee heart to donate to Baby Fae? Do you think the baby’s chances would
have been better if he had?
4. What do you think is the main message the author wanted to get across with this article?