Name _________________    Fill out scan sheet with name and ID (ver.2)


Humans and common chimps are sometimes described as xenophobic.  How is this manifested in their behavior?

a- both have a desire for meat

b- female parents of both species typically invest considerable time into their young offspring

c- both species are known to attack and kill members of their own species who belong to another group

d- offspring of both species are born nearly helpless and do not become sexually mature for eight or nine years –even longer in some cases depending on diet.


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- gorillas and orangs inherited the tendency for smaller testicles from a common ancestor not shared with chimpanzees.


Research on human language acquisition has shown that that among the very first complex sentences uttered by 2 year old children is something like “lookit doggie jump” .  This best illustrates a unique human characteristic of using communication to _____

a-express emotion

b- call a listener’s attention to a specific object or action.

c- engage in social relationships via social communication

d- dominate or control a peer using vocal communication


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

a- androgens

b- estrogens

c- hydrogens

d- cryogens


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

a- humans

b- orangutans

c- baboons

d- gorillas


Brain damage to the human  _____ is most likely to affect the normal use of human language.

a-Corpus callosum

b- Left hemisphere

c- Right hemisphere

d- Gluteus maximus


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 with a dominant male


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


The recent discovery of the FOXP2 gene promises to explain differences in _______ between humans and chimpanzees.

a- brain size

b- vocal communication

c- social-sexual behavior

d- testicle size


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 “motivation” 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 baboon male that leads the group

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

c- much of baboon social life is terrestrial

d- baboons 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.


Human children, even in the absence of a complete language model, can synthesize a complete language -- spoken or signed-- called  _________  from fragments of language around them.

a- a creole

b- a pidgin

c- a romance language

d- an Indo-European language


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 with her strength


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


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- common chimpanzees

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 and hiding

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- 6000

b- 150,000

c- one million

d- 3.5 million


Sperm competition usually refers to the competition between individual males’  efforts to fertilize a fertile female’s egg.  Species where this competition is strong like in chimp/bonobo society--  in contrast  to species like gorillas and humans-- tend to have sperm that _____

a- are larger

b- are fewer in number per ejaculation

c- swim faster

d- contain many more sperm with multiple copies of the Y chromosome.


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 notes and 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)

1. shocking news item about bonobo behavior

Recent research in the news reported that bonobo females were seen engaging in a very unexpected behavior.  What is were they observed doing?




2. 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?




3. Aggression

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








4.  theory of mind (ToM)

How does the “false belief test” serve as a measure of one’s ability to deal with social “objects?—i.e. other persons”




5.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 even when not nursing



6.Adult bonobo-chimp female differences

Strier (TO, 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.






7. evolve human language? 2 POINTS EACH PART

 How did bipedalism likely set the stage for the evolution of human language?  Indicate approximately the timing the appearance of bipedalism and the appearance of modern human language.



8.  Mr. Kusasi

Mr Kusasi benefited significantly  from his contact with humans.  Briefly explain, with an example, one of these benefits and how it helped Kusasi.



9.   humans cause aggression?

How might human activities cause increases in aggression among apes like orangutans or chimpanzees? (that is, aggression within each species not between species).  Give one example, either species.



essay (10 points)

Sex and reproductive differences in primate behavior

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 to make your points. IF SPECIES DO NOT DIFFER ON SOME ISSUE, SAY SO!

Hint: Make sure you identify which species you are discussing.  Don’t just say “apes” or use pronouns with unclear referents, “they …”

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?)