ACTIVITY 8: Try This!
Analyze and answer the following questions.
1. What feature of the environment enabled the development of long neck of the giraffe
according to Lamarck’s theory?
- In Lamarck’s theory is the view that acquired characteristics are inherited. With our
present understanding of the control of inheritance by the genetic apparatus, we realize
that only changes in the makeup of genes could lead to permanent alterations in the
offspring. However, at the time of Lamarck’s formulation, little was known of the
mechanism of genetics. Even Darwin incorporated some of the Lamarckian views of the
inheritance of acquired characteristics into his own thinking. Lamarck’s theory of
evolution should not be regarded as being merely a conceptual error. Rather, it should be
viewed as a necessary step in a continuing development of greater exactness in the
description of a natural process. Science moves in slow, tentative steps to arrive at greater
certainty. The truths of today’s science are dependent on the intellectual forays of earlier
investigators. They provide the shoulders on which others may stand to reach for more
fruitful explanations.
2. Lamarck’s idea lacked evidence at that time. What do you think it was? Why do you think this
evidence was missing?
- Lamarck's theory suggested that the giraffe's original short-necked ancestor repeatedly
stretched its neck to reach the higher branches to eat. Lamarck believed that the
stretching elongated the giraffe's neck, which became a useful characteristic and was
passed onto future generations. This resulted in the length of the giraffe's neck increasing
over time. It is now commonly accepted that Lamarck's ideas were wrong. For example,
simple organisms are still detected in all varieties of life, plus it is now known that
mutations can create variation such as neck length.
3. How did Darwin disprove Lamarck? Explain why Darwin still thought that Lamarck’s idea
was very important?
- Lamarck's Theory of Inheritance of Acquired Characteristics has been disproved. The
other way that Lamarck's theory has been proven wrong is the study of genetics. Darwin
knew that traits are passed on, but he never understood how they are passed on. Darwin
and Lamarck were both scientists who tried to understand evolution. Lamarck's theory of
evolution was based around how organisms change during their lifetime, and then pass
these changes onto their offspring. Darwin's theory became accepted because it had more
evidence that supported it.
ACTIVITY 9: True or False
Write True if the statement is correct, and False if not.
1. Darwin developed the concept of natural selection from his observations on the Galapagos
Islands. True
2. Evolution is a scientifically a valid theory.
True
3. Darwin took Mendel’s idea on inherited traits into account in his work on natural selection.
False
4. Lamarck thought that giraffes developed long necks in stretching their necks to reach leaves
on the branches of trees.
True
5. An individual with lower fitness has a lower reproductive success in comparison to those
with higher fitness.
True
6. Individuals with variation tend to survive longer.
False
7. Wallace, like Darwin, also advanced the concept of “evolution by means of natural selection.”
True
8. The possible site of the origin of life is the ocean floor.
True
9. Structures like the human tail bone are called vestigial structures.
True
10. Scientists divide the history of life into large geologic time sections called eras.
True
