Theories of Evolution Assignment - Karen Burke | Library

Instructions

If you had been a biologist in the 1800s, you would have had to decide between two main theories about how evolution occurred. Consider the long neck of a giraffe. How did that evolve? Read the two explanations below, and answer the questions that follow.

Theory One
      The ancestors of giraffes had short necks, and there was great competition for plant food near the ground. Some giraffes kept trying to stretch their necks to reach leaves higher in the trees. As they stretched and stretched, their necks became longer. As their necks became longer, they were able to reach more food. Those ancestral giraffes survived to reproduce, while the giraffes that had not stretched their necks died. The offspring of giraffes with stretched necks inherited the longer necks. This process continued generation after generation. In this way, giraffes evolved with longer and longer necks.  

Theory Two
      The ancestors of giraffes had short necks, and there was great competition for plant food near the ground. Some of the ancestral giraffes were accidentally born with slightly longer necks than others. The individuals with longer necks could reach leaves higher in trees and therefore, could eat more food. Because those ancestral giraffes ate more food, they survived to produce offspring with longer necks. At the same time, the individuals with shorter necks died and did not produce many offspring. The offspring of giraffes with longer necks inherited the longer necks. This process continued generation after generation. In this way, giraffes evolved with longer and longer necks. 

Required

1

In Theory 1, what caused the giraffe species' neck to become longer over time?

Required

1

In Theory 2, what caused the giraffe species' neck to become longer over time?

Required

1

According to what scientists know now about heredity, could the giraffes’ offspring have inherited longer necks, as described in Theory 1?

Required

1

According to what scientists now know about heredity, could the giraffes’ offspring have inherited longer necks, as described in Theory 2?

Required

6

Which of the two theories matches more closely with Darwin’s theory of evolution? Explain your answer using the RACE response strategy.
Restate the question
Answer the question
Cite evidence from the text to support your answer
Explain your reasoning

Your answer should be 3-5 COMPLETE sentences.
Before submitting your response, check for spelling and grammar errors.