Name _________________    Fill out scan sheet with name and ID for exam 3


Frodo – one time leader of Goodall’s F-troop—attained his position as alpha chimpanzee on the basis of

a- his mother’s rank

b- his size and brutality

c- his ability to persuade several other high ranking chimps to support him,

d- his support of most of the females in  the group


What seems to best explain the smaller testicles of gorillas and orangutans in contrast to their cousins the chimpanzees?

a- larger testicles would hinder locomotion on the ground

b- larger testicles would hinder contests with intruding males

c- due to their social-sexual structures, there is very little direct sperm competition with other gorilla and orangutan males

d- they inherited the tendency for smaller testicles from a common ancestor not shared with chimpanzees.


Competition among primates for mates in some species such as baboons, orangutans, gorillas, involves a strong male from outside the group physically challenging the current dominant male.  The winner takes over the group, the loser____

a- is typically dismembered – even eaten -- by the winner

b- leaves the group taking several females with his offspring with him.

c- rarely is severely wounded but can become seriously infected during the fight

d- typically stays with the group as second in command.


In order for the brain to become appropriately sexually differentiated, males in particular need exposure to _____________ during the prenatal period of development.

a- pryogens

b- estrogens

c- hydrogens

d- cryogens

e- androgens


Which of these species appears to have the least male parental investment (MPI) in their offspring?

a- humans

b- orangutans

c- baboons

d- gorillas


Many have suggested, including Bard (1995) in her paper on parenting and contributors to the Gorilla video, that what seems like "intuitive parenting" is primarily:

a - based on instinct

b- based on "hands on" experience of the young females with infants before they become mothers themselves

c- based on social priming within the group

d- based on the mother receiving good parenting as an infant by her mother.


What is the best definition of concealed ovulation?

a- females are born with all their egg cells' DNA determined though the eggs are not matured

b- females engage in mating with many males so the father is unknown

c- cyclic (e.g. monthly) changes in fertility do not correspond to overt sensory changes in the genital area

d-  an immature female who is unlikely to conceive even if she mates has concealed ovulation


The dominant male in a multi-male chimpanzee troop tends to have relatively more offspring than the less dominant males. This is most likely because

a- females always prefer to mate with him

b- he has a longer penis

c- he is intolerant of attention toward females in estrous by other males and tries to drive them away

d- he is better at detecting the moment of ovulation and thus timing of mating


Which of these primates is the least sexually dimorphic?

a- baboon

b- gorilla

c- gibbon

d- orangutan


Darwin discovered and wrote about this important evolutionary process:  males have a trait, females like it and mate with them. Females then have sons with the trait and daughters with the preference. The trait and the preferences are inherited together over and over co-evolving with each other.

a- sexual dimorphism

b- sexual selection

c- sexual coercion

d- the theory of the inheritance of acquired traits


There is a lot of speculation that bonobos might be the best model for our human ancestors.  Yet one of the following bonobo characteristics, ___,  seems to be very different from any recent human ancestor.

a- sexual activity is varied, and often related to tensions during feeding

b- female bonobos are sexually receptive for extended time beyond the few days each cycle they are fertile.

c- bonobos appear to walk on two legs more easily than other apes

d- female bonobos give birth and care for their young much on their own, picking them up at birth and moving through trees supporting their clinging newborn infant.


Wrangham and others have proposed that one factor was perhaps initially responsible for the differences between bonobo and chimpanzee aggressive behavior toward females.  This is that ___.

a- male chimpanzees are larger than male bonobos

b- because of their preferred diet and competition for that diet by other species, female chimpanzees tend to forage by themselves or in smaller groups than do bonobo females

c- female bonobos "advertise" ovulation much more than do female chimpanzees and the male bonobos respond to the ad!

d- female bonobos have greater physical strength than female chimpanzees


All primate social structures have one or another sex, sometimes both sexes, migrating out of their birth group into other groups. The primary evolutionary advantage for this is thought to be that:

a- it reduces sibling rivalry

b- adolescents don't get along with their parents

c- it increases genetic variation in the species

d- it spreads cultural diversity


Baboons differ most from chimp social-sexual structures in that:

a- there is no dominant male that leads the group

b- young adult males must leave their natal (birth) group

c- much of baboon social life is terrestrial

d- they are among the few nocturnal primates


Mr Kusasi, known for his brief date with Julia Roberts as well as being the dominant male orangutan in his region for many years, got his start as _____

a- firstborn son of the dominant female in that region

b- an orphan brought to Galdikas’ orangutan refuge when he was very young

c- one of a rare set of twin orangutan males born in captivity at Galdikas’ refuge

d- as the first son of a young orangutan who was sexually assaulted by a sub-dominant male.


Like many dominant male apes, Mr Kusasi achieved dominance largely due to _____.

a- the status of his mother in the rainforest

b- the bright color of his fur

c- his unusually large size and strength

d- his persuasive vocalizations


What factor seems to be the most important in determining the rank of an adult female bonobo entering into a new group?

a- her success in ingratiating herself into her new group using her social skills and sexuality

b- the rank of her father

c- the rank of her mother

d- her ability to physically dominate the males of her group


Which of the following is NOT one of the situations in which primates might be expected to display aggression?

a- competition for mates

b- xenophobia

c- self-protection

d- all of the above are situations where aggression might be expected


Male baboons (and some other male primates) have been seen to kill young infants of their own groups.  The explanation suggested in our recent video of this ugly behavior is that ___.

a- it serves no function and is psychopathic behavior

b- it serves to enable the group to travel faster to new feeding grounds

c- it serves to hasten the return to fertility of the nursing mother

d- only the very weakest infants are killed for the good of the group


Male bonobos have not been observed to engage in most of the more aggressive and violent activities of their very close relatives, the common chimps.  One reason for this is, not surprisingly perhaps, is their  _________.

a-  diet with very little meat

b- overindulging in penis fencing

c- relatively low levels of testosterone compared with common chimps

d- dominating female mates, who display most of the aggression in bonobo society


Which of the following characteristics appears to be the most significant difference between humans and the great apes?

a- parenting

b- ability to share knowledge across many minds

c- sensory abilities

d- reproductive processes


Female apes vary in the extent of time during each menstrual cycle that they are interested in sexual activity (sexual receptivity).  Which species appears to have the longest period of sexual receptivity?

a- bonobos

b- chimps

c- gorillas

d- orangutans


One biological/behavioral feature that plays a role in attraction and mate selection across a large number of species including birds, apes, and humans is ________.   

a- genital color

b- that the dominant male doesn’t allow a fertile female to get out his sight

c- body symmetry

d- waist-hip ratios


In many species of animals, competition among males leads to _____ in the losers.

a- decapitation

b- embarrassment

c- increased desirability to females

d- lowering of their levels of testosterone


In chimpanzee and bonobo social structure, it is _______ that will leave their birth group and move to another group.

a- infants b- females c- males d- both sexes


Various apes, dogs, and birds have been taught to communicate with humans to varying degrees using a "human based code."  How is this different from the way humans communicate using human language?

a- human language is acquired by children normally without explicit training

b- the formal structure of human language differs from human based codes.

c- children can create novel expressions about idea or events that they haven't heard anyone talking about previously.

d- all of the above distinguish human language from human based code use by non-humans.


If human language resulted from the same evolutionary processes that produced the earliest modern humans according the "out of Africa" hypothesis, modern human language would have appeared for the first time approximately ________ years ago.

a- 3 million

b- 1 million


d- 6000


Hollywood has occasionally made primate research a topic for popular films. We saw a segment from the 1951movie "Bedtime for Bonzo" starring Ronald Reagan as a psychology professor who raised a chimp in his home.  The main themes of that film illustrated in the clip we viewed was the possibility that ____

a- chimps do not belong in human society

b- chimps and humans can fall in love with Hollywood stars

c- behavior was a reflection of environment rather than fixed by heredity.

d- chimps can talk if exposed to human speech


Sexual reproduction seems to be an awkward and costly procedure, say compared with cloning or asexual reproduction.  Several reasons have been suggested to explain this basic biological process.  What of the choices below seems to be the most plausible explanation for sexual reproduction?

a- it provides one source of variability necessary for Wallace and Darwin's theory of evolution

b- it just happened by chance first and seemed to work ok.

c- the biochemistry of life requires two different types of DNA

d- none of the above is even close to plausible


What best captures the idea of "erotic imagery" as discussed in class?

a- dreams may stimulate sexual arousal

b- the cognitive abilities of humans enable us to become sexually aroused even in the absence of potential mates – unlike any of the apes.

c- an erotic image essentially defines a potential mate and may stimulate sexual arousal via any of the sensory modalities, depending on the species and individual experiences

d- a unique human cultural artifact designed to arouse viewers

short answers (only do 3;  4 points each)

facial symmetry

A recent study reported in the “news” found that facial symmetry was more attractive than asymmetry across both hunter-gather cultures and in the modern English population.

What appears to be a plausible reason for this preference?




Harlow’s research

What is one significant fact Harlow found about the importance of a primate infant's early relationship with its mother?




 What, if any, was the impact of this early relationship on the mature primate?





Briefly describe two different situations where you might expect aggressive behavior from any of the large apes.  Be specific about species and situations.









survival of great apes?

Describe two problems that face survival of the large ape species in their natural habitats.  Be specific about species and situations.



















Adult chimp-human female differences

Human females differ from chimpanzees notably in having concealed ovulation and prominent breasts when not nursing.  For each of these two features, give a plausible story in a sentence or two -- about why those features are useful or adaptive to humans --if they are.


Concealed ovulation




Prominent breasts



Adult bonobo-chimp female differences

Strier (p.85) and others have suggested that the longer period of sexual swelling in bonobos is responsible in part for the lesser aggression among bonobo males – both toward the females and between males themselves compared with male chimpanzee behavior.  Briefly explain how more days of sexual swelling per monthly cycle might have this effect.






 Apes acquire human language? 2 POINTS EACH PART

One of the earliest thoughts in explaining ape's lack of language was simply that they had not had the experiences necessary to develop language.


a) How was this evaluated (1 POINT) and what was the outcome (1 POINT)?




b) Briefly suggest two reasonable possibilities that might explain the lack of language in apes. (2 points)




essay (10 points)

Sex and reproductive differences in primate behavior

A. We have read about and seen many examples of how male and female primates differ within a species as well as across species. Focusing upon three species: humans, bonobos, and orangutans, discuss the following 3 topics, using examples—at least one -- to make each of your points.

Hint: Make sure you identify which species you are discussing.

1.sexual dimorphism in body.


How do the sexes differ in general body features in these species? (Do not ignore the obvious sexual features!)


2.  sexual and social relationships:

 How do these 3 species compare and contrast in regards to the sexual relationships and related social relationships --  e.g. aggression, dominance, mating patterns?


3.  Parenting -- How do these 3 species compare and contrast in regards to basic reproductive functions, parental investment, and development (that is, how might parenting affect the development of offspring into adults in both individual cases and differentially in these three species?)