Human Evolution

Question 1

Where do humans fit into mammalian diversity? How far back does the primate lineage go? What are some of the major events in primate evolution during the Cenozoic?

Answer 1

Split off from closest order during Cretaceous period, last common ancestor of all primates lived approximately 66 mya, split from tarsiers 55 mya, new/old world monkeys split 40 mya, 25 mya apes diverge from old world monkeys, orangutans 15 mya, humans split from chimps 5-6 mya

Question 2

Who are our closets living relatives and how do we know that?

Answer 2

The genus Pan (chimps and bonobos) because the fossil and molecular evidence shows a more recent common ancestor with this genus

Question 3

What is incomplete lineage sorting? How does it complicate phylogenetic trees?

Answer 3

Variation present within an ancestral population segregates differently among ancestors and different loci

Question 4

What have the underlying patterns of human evolution been? Are we the result of a smooth, continuous “improvement” of a single lineage?

Answer 4

l

Question 5

What do Sahelopithecus and Ardipithecus tell us about the order of some trait changes in the transition from ape-like bodies to our current form?

Answer 5

These species show evidence that there was an early shift towards bipedalism in human evolutionary history

Question 6

Who were the first members of the genus Homo and where did they live?

Answer 6

Homo habilis, found in Africa

Question 7

Who were the first members of the genus to leave Africa?

Answer 7

Homo erectus

Question 8

What are the two recent hypotheses for the transition from H. erectus to H. sapiens. Which one is best supported by data? What are some implications of this for relationships among current human populations.

Answer 8

Homo sapiens evolved from Homo erectus independently in different locations globally, or Homo erectus gave rise to Homo sapiens in Africa and H sapiens then also migrated, with the latter being largely supported by DNA evidence

Question 9

What was the 19th century version of the “multiregional hypotheses?” Why did it persist in some circles long after evidence mounted to the contrary?

Answer 9

Different races of people evolved separately, an idea that persisted because it fit racist/imperialist views