Discussion Questions
Darwin on Selection

1. Darwin suggests that cultivated plants and animals "generally differ
much more from each other, than do the individuals of any one species
or variety in a state of nature."

a. What does he mean by this?



b. Do you agree with him?



c. How does he explain this greater variability?



2. Darwin, "No case is on record of a variable being ceasing to
be variable under cultivation."

a.  Using the graphs on corn oil yield explain what he means.



b. Is there some limit to the trend displayed in the graphs?



3. If selection for high oil content in corn was stopped and the parents
of succeeding generations where chosen at random, each generation, what
would you expect to happen?





4. Darwin, "One of the most remarkable features in our domesticated races is
that we see in them adaptation, not indeed to the animal's or plant's own good,
but to man's use or fancy."  How is this possible?  How is it that artificial
selection can take a species in a direction that nature would almost certainly
never take it?



5. a. What is Darwin's definition of natural selection?


b. What does he say is the fate of "variations neither useful nor injurious?"


c. What is the modern term for such "variations?"


6. Darwin, "We may conclude, from what we have seen of the intimate and
complex manner in which the inhabitants of each country are bound together,
that any changes in the numerical proportions of some of the inhabitants,
independently of the change of climate itself, would most seriously affect many
of the others."  What is Darwin talking about?




7. Do you think that natural selection might eventually produce a "super fit"
species that would be able to monopolize all resources and cause the extinction
of all other species?



8. a.  Define the word "fact."


b. Define the word "theory."


c. Does "atomic theory" qualify as a fact?  Explain.



d. Does "evolutionary theory" qualify as a fact?  Explain.



e. Explain why the statement, "evolution is just a theory, not a fact,"
is an oxymoron.




9. Some suggest that evolution has stopped in humans because of modern
medicine.  Individuals with characters that would have formerly caused
death or sterility may now reproduce.

a. Explain why you think evolution has or has not stopped in humans.



b. Using humans as an example, explain how the characteristics that determine
an individual's fitness depend on the context within which that individual
lives.


c. For humans, explain how the most fit phenotype may have changed
over the last 10,000 years.



10. A recent study finds that Icelanders and  Europeans have a vast inverted
stretch of DNA on chromosome 17.  Those with the inverted DNA tend to have
higher fertility than those with the DNA running in the standard non-inverted
direction.

a. Explain how the fitness conferred by this character may differ today
from the distant past.



b. Would you expect this character to become more common in the future?