Deck 20: Human Evolution

Question 1

The accompanying figure shows that humans have thicker thumb metacarpals than chimpanzees or bonobos,with broader heads.This is directly correlated with humans' ________.

A) bar-shaped central portion of the hyoid bone
B) increasing dependence on meat in the diet
C) more elaborate thumb musculature and better precision grip
D) loss of the ability to knuckle-walk
E) loss of an arboreal (tree-based) lifestyle

Answer 1

C

Question 2

Short sequences of nucleotides (typically 4 to 8 bases)that are repeated a variable number of times at a locus are known as ________.[three words]

Answer 2

short tandem repeats (STRs)

Question 3

The accompanying figure shows how levels of a microRNA called miR-320b change with age in the prefrontal cortex of the brains of humans,chimps,and macaques (African monkeys).This may be important for understanding the genetic features that make us human,because microRNAs ________.

A) are found only in primates
B) are translated into short polypeptides
C) influence gene expression by binding to messenger RNAs
D) are transcribed from "selfish DNA" sequences such as Alu elements
E) are known to increase neuronal connectivity and therefore intelligence

Answer 3

C

Question 4

Although attempts to date the divergence between humans and chimpanzees using molecular sequence data do not perfectly agree,a rough consensus from multiple analyses would place the divergence date at ________.

A) 175,000 years ago
B) 6,000 years ago
C) 5 to 7 million years ago
D) 3.14 million years ago
E) 65 million years ago

Question 5

Which genus or genera of hominin is/are most consistently associated with stone tools?

A) Homo
B) Paranthropus
C) Australopithecus
D) Sahelanthropus
E) All of the above.

Question 6

The accompanying figure shows the percentage of pairwise genetic comparisons within sample populations of living hominids,graphed against the percentage of sequence divergence for each pair.We can conclude from the figure that ________.

A) any randomly selected pair of humans in the world should differ in their mitochondrial DNA sequences by less than 6%
B) humans are more genetically diverse than Western chimpanzees
C) hominid species do not differ significantly in levels of genetic diversity
D) humans share a more recent common ancestor with bonobos than gorillas
E) All of the above.

Question 7

Which piece of evidence BEST supports the "out of Africa" model of the evolution of modern humans?

A) African populations show the greatest diversity in numbers at a short tandem repeat (STR) locus on chromosome 12.
B) African Homo ergaster/erectus appear almost simultaneously with Asian Homo erectus, 1.6 to 1.9 million years ago.
C) Both Indonesian fossil Homo erectus and modern Australian aboriginal populations (which probably reached Australia by way of Indonesia) have unusually prominent and straight brow ridges.
D) In most regions, there does not seem to be a rapid replacement of earlier hominins by Homo sapiens.
E) There is no solid evidence supporting the "out of Africa" hypothesis.

Question 8

"Robust australopithecines," now classified in the genus Paranthropus,are distinctive as compared to other hominins because of their ________.

A) great height
B) unusually large brains
C) knuckle-walking ability
D) cave paintings and other artwork
E) huge teeth, faces, jaws, and jaw muscles

Question 9

Your textbook,and many (but not all)paleoanthropologists,refer to a species more closely related to humans than to chimps as a(n)________.

Question 10

All non-African humans today show evidence of a limited amount of past interbreeding with ________.

A) Denisovans
B) Paranthropus boisei
C) Homo ergaster
D) Neandertals
E) Australopithecus sediba

Question 11

The fossil Sahelanthropus tchadensis from the Djurab Desert of Chad,dated at 6 to 7 million years ago,may be a hominin (i.e.,share more recent common ancestry with humans than with any other ape because of ________.

A) its relatively large brain
B) the shape of its thighbones
C) its sophisticated use of stone tools
D) fossil footprints showing bipedal locomotion
E) its relatively flat face

Question 12

Most DNA-based phylogenetic analyses place humans and chimpanzees (including bonobos)as each other's closest relatives,but a persistent minority of studies place gorillas and chimpanzees as sharing a common ancestor that was not a human ancestor.The reason is incomplete lineage sorting,which simply means that ________.

A) the ancestral species of all great apes was genetically variable at some loci, and each descendant species lost different random combinations of ancestral alleles
B) the labs that sequenced great ape DNA made a simple procedural error
C) mitochondrial genes can become unlinked and be inherited by independent assortment
D) primate lineages are not completely reproductively isolated and can hybridize
E) coding regions of the primate genome are more likely to give false results than noncoding regions such as SINEs

Question 13

Which of the following organisms is NOT considered a great ape?

A) human
B) baboon
C) orangutan
D) bonobo
E) gorilla

Question 14

Modern humans have lost the system of air sacs that other great apes have.Whatever the reason for this loss,one resulting effect on human behavior was ________.

A) restriction of modern humans to low altitudes
B) loss of the ability to make loud calls
C) improved ability to swallow
D) increase in the sizes of Broca's and Wernecke's areas
E) the ability to pronounce sounds more clearly

Question 15

The first close human relative known to have dispersed out of Africa was ________.[two words]

Question 16

Chimpanzees and gorillas share the trait of knuckle-walking,which humans do not generally have.Why do most scientists NOT classify chimpanzees and gorillas as each other's closest relatives?

A) The majority of genetic evidence places chimpanzees closest to humans, not to gorillas.
B) Fossil evidence suggests that knuckle-walking was present in ape ancestors and is not a uniquely derived trait for chimpanzees and gorillas.
C) Chimpanzees and humans share more unique features in common than either share with gorillas.
D) Fossil apes that are thought to be closest to humans show adaptations for knuckle-walking, implying that humans have secondarily lost the trait.
E) All of the above.

Question 17

Which piece of evidence BEST supports the "multiregional evolution" model of the evolution of modern humans?

A) Molecular clocks date the last common ancestor of modern humans to about 171,500 years ago.
B) Present-day human populations from Africa have greater genetic diversity than non-African populations.
C) African Homo ergaster/erectus appear almost simultaneously with Asian Homo erectus, 1.6 to 1.9 million years ago.
D) Both Asian fossil Homo erectus and modern Asian human populations show a high frequency of shovel-shaped incisors.
E) There is no solid evidence supporting the multiregional hypothesis.

Question 18

Judging by the nature of modern humans,chimpanzees,and bonobos,which of these traits did the last common ancestor of all three probably NOT show?

A) some form of culture
B) tool use to get and process food
C) a broad diet including plenty of fruit
D) strictly heterosexual mating patterns
E) some degree of hunting

Question 19

Vincent Sarich and Allan Wilson estimated that humans diverged from their closest living primate relatives about 5 million years ago.What line of evidence did they use initially?

A) cladistic analysis of DNA sequences from living primates
B) chromosomal banding patterns, fusions, and fissions
C) radiometric dating of fossils
D) DNA denaturation and re-annealing temperatures
E) reactions between primate serum proteins and antibodies to human serum

Question 20

All of the following traits are shared by all great apes,except ________.

A) increased flexibility of the wrist and thumb
B) spoken language
C) absence of a tail
D) increased flexibility of hips and ankles
E) relatively large brains

Question 21

The peoples of Africa have often been negatively stereotyped by Europeans and Americans as "primitive" and "less advanced" than other peoples.Recent genetic analyses show that Africans make up the earliest branches of the human family tree.But do these two statements mean the same thing? Does genetic research imply anything about the relative "advancement" (or lack thereof)of different human groups?

Question 22

Human populations vary genetically,but the variation is subtle and not easy to find without large data sets.Most of the genetic variation in the human species exists between ________.

Question 23

________ are fragmentary hominids 30,000 to 50,000 years old,found in a Siberian cave,who astonishingly appear to have interbred with the ancestors of modern Melanesian human populations.

Question 24

In 2003,fairly complete remains of what was claimed to be a new species of hominin were described from the Indonesian island of Flores.The species,Homo floresiensis,may have lived between 100,000 and perhaps as recently as 12,000 years ago; because of its small stature,about three feet (1 meter),it was perhaps unfortunately nicknamed "hobbit" (it didn't help that film The Lord of the Rings: The Return of the King came out the same year).If Homo floresiensis is a real species,it lived at the same time and general area as fully modern humans.However,some scientists are convinced that the bones belonged to a fully modern human who suffered from a growth disorder of some kind.Devise a detailed hypothesis for the origins and relationships of Homo floresiensis,and come up with the best test that you can,given that it has not yet been possible to extract DNA from the fossils.

Question 25

Both the "out of Africa" hypothesis and the "multiregional evolution" hypothesis agree that the last common ancestor of all modern humans lived in Africa.Overwhelming fossil and genetic evidence confirms an African origin for modern humans―but that isn't enough,by itself,to decide between the two hypotheses.Explain one of the lines of evidence that does tend to support one or the other of these hypotheses.

Question 26

The earliest style of stone tools,dating as far back as 2.6 million years,is called ________.

Question 27

In 1912,parts of a skull and jawbone were found in a gravel pit near the English town of Piltdown,about 40 miles south of London.These were claimed to belong to a human ancestor with a brain about two-thirds the size of a modern human brain,and a large,protruding jaw."Piltdown Man," or Eoanthropus dawsoni as it was named,was conclusively shown to be a hoax in 1953―pieces of a human skull braincase and an orangutan jaw,stained to look old and to have the same color.(The perpetrator's identity is still not certain.)However,almost from the start,a growing number of scientists were skeptical of Piltdown Man.Discuss two facts about Piltdown Man that would have been increasingly difficult to reconcile with the emerging picture of human evolution in the first half of the twentieth century.

Question 28

Green and colleagues assessed the degree of past interbreeding between modern Homo sapiens populations and extinct premodern populations by looking at an aspect of genetic diversity known as ________.[three words]

Question 29

The only hominid skeletal feature that is fairly clearly correlated with the ability to speak is the shape of the ________.

Question 30

In humans and possibly even in chimpanzees,there seems to be a neurological correlation between ________ and ________.