Evolution Pre-assessment
Question 1
Present day giraffes are believed to have evolved from ancestors who resembled horses. There
have been different theories about how this could have occurred. The two main ideas are listed below:
A. One proposed explanation is that the giraffes wanted to reach the leaves higher up on the
trees, possibly because they were greener or no other species could eat them, so the short-necked
ancestors stretched their necks trying to reach the high leaves, causing their necks to become longer.
Over many generations of stretching the giraffes’necks became longer and longer until they became the
current long-necked species.
B. Another explanation is that some ancestors of modern day giraffes had slightly longer necks
than others. These giraffes were able to reach more food, allowing them to become stronger, live longer,
and have more offspring. Over time the giraffes with slightly longer necks became the more prevalent
group and when these giraffes had offspring, their offspring had even slightly longer necks, and so on
until the current long-necked species came about.
Which of these theories do you agree with most? Explain your position in as much detail as possible.
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