Ch 23: Human Evolution

Question 1

Primates

Answer 1

A member of the order of mammals that includes humans, distinguished by a number of molecular and morphological features, including relatively large brains, nails rather than claws, front-facing eyes, and, in some species, an opposable thumb.

Question 2

Hominims

Answer 2

A member of one of the different species in the group leading to humans.

Question 3

Ardi

Answer 3

A specimen of Ardipithecus ramidus , an early hominin, dating from about 4.4 million years ago.

Question 4

Lucy

Answer 4

An unusually complete specimen of an early hominin fossil, Australopithecus afarensis , found in 1974 in Ethiopia and dating to 3.2 million years ago.

Question 5

Bipedal

Answer 5

Habitually walking upright.

Question 6

Neanderthals

Answer 6

Homo neanderthalensis, a species similar to humans, but with thicker bones and flatter heads; present in the fossil record 600,000–30,000 years ago.

Question 7

Multiregional Hypothesis

Answer 7

The idea that modern humans derive from the Homo ergaster populations that spread around the world starting 2 million years ago.

Question 8

Out-of-Africa Hypothesis

Answer 8

The idea that modern humans arose from Homo heidelbergensis descendants in Africa before dispersing beyond Africa around 60,000 years ago.

Question 9

mtDNA

Answer 9

A small circle of DNA, about 17,000 base pairs long in humans, found in every mitochondrion.

Question 10

Cro-Magnon

Answer 10

The first known population of Homo sapiens in Europe, named for the site in France where specimens were first described.

Question 11

Neoteny

Answer 11

The process in which the timing of development is altered so that a sexually mature organism retains the physical characteristics of the juvenile form.

Question 12

Studies of the denaturation temperatures of hybrids of human and different apes’ DNA provided us with what new information, after morphological studies fell short of resolving the primate phylogenetic tree?

Answer 12

Humans are more closely related to chimpanzees than to gorillas.

Question 13

FOXP2 is the name of a gene that may be important to language, as mutations in this gene are implicated in many speech pathologies. Why does FOXP2 have such a broad impact on the development of speech?

Answer 13

FOXP2 is a gene encoding a transcription factor that controls the expression of many genes involved in the development of speech.

Question 14

What continent was the starting point for the origin of humans?

Answer 14

Africa

Question 15

T/F: The size of the human brain may be the result of “selective factors,” such as tool use.

Answer 15

True

Question 16

A young man is watching his father collect honey from beehives. He notices that sometimes a bee will “dance” in front of the other members of the hive after returning from a nearby garden. The other bees will then travel to the garden. This is an example of:

Answer 16

language

Question 17

T/F: Consider the hypothetical hominin lineage: Homo ergaster –> Homo heidelbergensis –> Homo sapiens. This is currently the accepted hypothesis because a population of H. ergaster likely speciated and evolved into H. heidelbergensis.

Answer 17

True

Question 18

Many researchers hypothesize that modern humans derived from the Homo ergaster populations that spread around the world starting about 2 million years ago. This is known as the:

Answer 18

multiregional hypothesis.

Question 19

T/F: The hemoglobin gene is the only gene that is under selection for resistance to malaria.

Answer 19

False

Question 20

There is a phenomenon called paternal leakage in which a small amount of the mitochondrial DNA from the father is found in the offspring. If paternal leakage is assumed to occur in most matings, how would it change our interpretation of studies of mitochondrial DNA in human ancestors and in groups of different modern humans?

Answer 20

If it is truly a small amount, then those deviations should not influence the conclusions generated from the study.

Question 21

There is a phenomenon called paternal leakage in which a small amount of the mitochondrial DNA (mtDNA) from the father is found in the offspring. If paternal leakage is assumed to have occurred throughout human history, how does it change our interpretation of Matthias Krings and Svante Pääbo’s studies of mitochondrial DNA in specimens of Neanderthals and modern humans?

Answer 21

If paternal mtDNA with Neanderthal sequences was found in the offspring alongside maternal mtDNA, these would have immediately indicated that the two groups interbred.

Question 22

There is some debate about whether Homo floresiensis is a separate species or an aberrant form of Homo sapiens. Regardless, what we do know is that H. floresiensis were only found on an Indonesian island, and adults were only 3 feet tall. What factors would have selected for this distinct phenotype on an island habitat?

Answer 22

The smaller body size was advantageous for living on an island, as food is often limited on islands.

Question 23

Humans and chimpanzees last shared a common ancestor around _____ million years ago, and our genomes now differ by about _____ percent.

Answer 23

5-7; 1