Which statement would neither Scientist #1 or Scientist #2 agree with?
The Pace of Evolution
Evolution is the process in which organisms change over time. Changes take place as organisms must be able to adapt
to an ever-changing environment. Scientists have long debated how evolution takes place as well as the pace at which
it occurs. Two scientists are discussing their beliefs concerning evolution and the rate at which it takes place in certain
populations. A summary of each of their viewpoints is written below.
I have always seen evolution as a slow and gradual process, taking millions of years in some cases. Take, for example, a
species such as the horse. Many millions of years ago the horse was about as tall as a fox, had toes instead of hooves,
and was a hunter and a meat eater. The species was successful, but slowly its environment was changing. Instead of
dense forests filled with small game, the horse found itself living in open areas filled with grasses and less small
animals. The horse evolved adaptations in order to survive in its new environment. He slowly grew bigger and began
to eat a vegetarian diet. We have evidence for this change in the form of many fossils showing these changes and
intermediate forms in the horse.
To me, evolution only happens in short bursts. For the most part, organisms stay the same for millions of years, then
change over time due to a dramatic shift in the environment. As an example, look at the shark. Even as their ocean
environments undergo change, the sharks, with their large size, strong sense of smell, and great hunting skills, are so
well adapted that they have not needed to evolve for millions of years. If there is some great change to the ocean,
then the shark will have to evolve in order to survive, but it will do so at a fairly quick rate when compared to the
geologic time scale.