Monday, September 23 -- Film: The
Baboons of Gombe
[Topic List] | [Next
Lecture] | [Previous Lecture] |
Film about a troop of baboons who live on the shores of lake Tanzanyka,
narrated by Jane Goodall and featuring her, her husband, and their child,
endearingly nicknamed "Grub." Showed such behaviors as male-male
competition, males befriending females and h elping protect their young,
males using their friends' young to protect themselves from attacks by
other males, the insinuation of a new male into a troop, young being
carried underneath their mother's bellies and then learning to ride on
of them as t hey age, childless females showing an extreme interest in
newborns, and so on.
Wednesday, September 25 -- Old
[Topic List] |
[Next Lecture] | [Previous
Lecture] | [Discussion]
Infraorder Catarrhini (Old World Monkeys)
Geographic Distribution of the Catarrhines
Old world monkeys are found throughout tropical Africa and Asia. The only
exceptions are the macaques- some species live in Japan and others in
Differences between Platyrrhines and
Remember that these classifications represent two different evolutionary
branches, so they are actually pretty distinct.
The most obvious difference is the shape of the nose:
platyrrhine means flat-nosed, whilecatarrhine means
hook-nosed. In platyrrhines, the nostrils are farther apart and they
outward, while in the catarrhines, they're closer together and they point
The number of teeth in each type is distinct, but we don't have to
memorize their dental formulas for a test. The old world monkeys have
sharp canines with a diastema (gap between canines and incisors), and the
upper canines are kept sharp by being honed against the first premolar on
Old world monkeys are larger on average than the new world
Baboons are the biggest of the old world monkeys, especially the males.
The Catarrhine family includes more folivores. Among the new world
monkeys, the howlers are exceptions cause they're folivores, too.
Catarrhines are also more terrestrial.
Catarrhines tend to have a narrower range of niches. They share
their habitats with prosimians and apes, so there're a lot of niches
around which aren't filled by the old world monkeys since some other
primate filled it first.
Taxonomy of the Infraorder Catarrhini
There are two superfamilies; Cercopithecoidea
world monkeys) and Hominoidea (apes)
Today we will cover the old world monkeys, and next
time we'll do the apes.
The Differences between Cercopithecoids and Hominoids
These aren't phyletic groups; apes are just a subset of the old world
monkeys in terms of evolution. However, they're traditionally classified
as a parallel family.
Cercopithecoids have a narrow nose and palate, and smaller brains
relative to body size than Hominoids.
Cercopithecoids' molars are bilophodont (two cusps) but Hominoids'
have several cusps.
Cercopithecoids have tails (often long), while Hominoids have no
Cercopithecoids are laterally compressed, with a narrower thorax
and pelvis, and a longer trunk. Compare this to hominoids like the
gorillas, who are pretty wide in the chest.
Cercopithecoids' back legs are at least as long as or longer than
their front legs, while Hominoids tend to have longer arms than legs.
In Cercopithecoidea superfamily we have only 1 family,
It has 2 subfamilies:
Cercopithecinae, also called cheek-pouch monkeys,
Colobinae, also called leaf-eating monkeys.
The Differences between Cercopithecines and
Colobines have more space between the eyes, and their incisors are
narrower than in the cercopithecines.
Colobines have a deeper jaw which extends father below the joint.
Colobines' molars have high sharp cusps, while cercopithecines' have
lower, more rounded cusps.
Colobines have a complex stomach, which is atypical for primates.
It is divided into four chambers kind of like a cow's stomach, and it
works the same way too; The first chambers are less acidic fermentation
chambers. Full of bacteria, they break d own the leaves, digest the
cellulose, and make it available for absorption.
Cercopithecines, on the other hand, have a simple stomach with no
chambers but they do have cheek pouches (and thus their name). These
pouches open inside the cheek at the base of the teeth and extend down
into the neck. Also called buccal pouches, they are used to stuff food
into for storage. The two pouches together can hold about a stomachfull.
The pouches are good for grabbing food quickly and then getting out of
there. Then the monkey can eat it somewhere safe. Also, since they live
groups, there's competition over food so if you can grab a whole meal and
get away you won't have to share it.
Colobines have long tails, while cercopithecines' tails are
variable but often short.
Colobines have longer hind legs, related to being more arboreal;
They do more leaping and climbing. This is also probably the reason for
the long tail. Cercopithecines have similar arm and leg lengths.
Colobines have short thumbs. (Brachiators generally have short or
no thumbs, probably since they tend to get caught when swinging through
foliage at great rates of speed.)
Superfamily Cercopithecoidea - The Facts
1. African cercopithecines
a. Cercopithecus: Numerous arboreal species, and
one (C. Aethiops) that is highly terrestrial. Dispersed widely
throughout Africa. This genus includes the red forest monkey, the blue
monkey, and the vervet monkey (aethiop s). They play a lot since
that teaches them about social interactions and they need to exercise
their brains. As a secondary sexual characteristic, the males have blue
testes and red penises. They live in grassy savannah, and to look for
predators the y'll stand on their hind legs to see over the brush.
b. Erythrocebus: This genus is the Patas monkey,
specialized running monkey found in W and N central African savannahs.
Their societies are made up of one male with several females. Living in
the savannah as they do, they can't c limb trees to escape. They can run
at speeds up to 35 mph.
c. Papio (baboons): Savannah dweller, but found
also in forests and in arid land, throughout West East Central and
Southern Africa, as well as the southern tip of the Arabian peninsula. We
will say there are 5 species, but this is subject to debate. Some
characteristic species are the yellow baboon and hamadryas baboon.
form 'friends;' male-female long term social relationships which do not
imply exclusive breeding. Papio also includes the drill and
mandrill, who hav e a distinctive face. This is a mixture of pigment and
d. Cercocebus: (mangabeys): Arboreal. 4 species,
but again subject to debate. They are found variably throughout Africa.
Their society varies from one-male groups to mutimale-multifemale
e. Theropithecus (geladas): Arid high country
dwellers, mostly in Ethiopia and in arid parts of E Africa. They form
hierarchical groups with troops, clans, and and one-male units like the
hamadryas baboons. They have manes and red eyes.
f. Macaca: There are several species; 12
to Smuts et al. Macaques have a wide distribution and a wide range of
habitats. Some are arboreal, others terrestrial. They are used in
biomedical research a lot. They can be seen mostly in S and SE Asia, but
there's one in Japan and one in N Africa (Barbary macaques). They live in
large multimale-multifemale groups. As in many old world monkeys, females
get genital swellings when they're in estrus. This occurs especially
in multimale groups. This way, all the males are aware she's ready so
they'll compete and she'll get the stronger ones' sperm.
2. Asian cercopithecines
a. Macaca: Many species spread across Asia,
including the north Japanese islands. As we saw happen in the baboon
other females often want to pet babies. Also, males want to see newborns
sometimes. Macaques are omnivorous or frugivorous, and their societal
structure is variable. Rhesus macaque has been used the most in
biomedical. We might also see radiata, called the bonnet macaque, or the
pigtail macaque which is solidly built.
1. African Colobines
a. Colobus: Found in African forests, there are
six species (subject to debate). They are mostly folivorous but some eat
seeds too. Colobus monkeys live mostly in one-male groups, but some form
multimale groups. Examples are the re d colobus and the black and white
colobus who has a spectacular long white tail.
2. Asian colobines
a. Presbytis (langurs or leaf monkeys): This
includes numerous species dispersed widely through forested areas in
and Southeast Asia. Their society is variable, with one-male or multimale
groups. Langurs are known for t heir practice of infanticide.P.
entellus, the hanuman langur, is atypical in several respects. Some
examples of this genus are the grey langur, the banded leaf monkey, and
the silver leaf monkey which has a long tail!
b. Nasalis (proboscis
monkeys): Limited to
areas of Borneo and the Mentawai islands west of Sumatra, there is just
one species. The big nose is a secondary sex characteristic of males. In
females, the nose is just a little pinocchio nose. In males, the bigger
the nose is, the sexier the monkey is. This is an example of the effects
of sexual selection which we'll speak more of later. Proboscis monkeys
folivorous seed predators. Nasalis has multilevel groups.
c. Rhinopithecus (golden monkeys): Three species
who all live in the forests of China, with some species in the mountains.
They even get some snow sometimes. Golden monkeys live in large groups up
into the hundreds. They seem to ha ve a hierarchical society like
They're rare and obscure and they're just beginning to be studied. Golden
monkeys are highly endangered so it's a race to study them before they
Friday, September 27 --
[Topic List] | [Next Lecture] | [Previous Lecture] | [Discussion]
At 10 million years ago, our ancestral species split into 3. At 5 million
the first branch split into the gibbon and the siamang (which used to be
a different genus but is now recognized as a gibbon). The second branch
split into chimps/bonobos (who split
apart at 2mya), humans, and gorillas. This branch is known as the
apes). The third branch split into orangutans. Thus, biologically
speaking, humans should be in the same family as gorillas, but when the
current taxonomic system was set up, they wanted humans to be in a
The way we actually do it is: hominoidea has hominidae (Homo),
hylobatidae (Hylobates), and pongidae (Pongo, Pan,
There's more info about apes than prosimians. This is partly
because they're more interesting to us since they're more closely
and partly because nocturnal, arboreal little beings are really hard to
study but land-living big creatures are easier.
Taxonomy of the Hominidae
Two families for us to study: Hylobatidae and
Some characteristics which
distinguishHominoidea from Cercopithecoidea
Many of their differences in anatomy are related to differences in
locomotion- apes brachiate. Gibbons and orangutans brachiate the most,
the other apes also show adaptations for it.
- Long arms
- Apes have long arms relative to
their leg length.
- Broad pelvis and thorax
- Apes tend to be
compressed front-to-back instead of side-to-side like the monkeys.
- Short lumbar segment
- Apes have short lumbar
segment (the spine from ribs to pelvis.)
- High limb mobility
- They have a reduced ulnar
styloid, a short olecranon process, and spool-shaped trochlea. These all
mean a greater surface area in the joints so that they have a wider range
of movement. Compare your arm to a dog' s forelegs which really don't
such a broad range of movement.
- No external tails
- No explanation necessary!
- Distribution of body sizes
- Apes as a group are
the largest primates. The exception is the gibbon, who is not quite so
- Large brains relative to body size
- This is a
general trend, not an absolute difference.
- Sexual dimorphism
- Most marked in orangutans and
gorillas. Some difference in chimps and bonobos, less in gibbons and
|| Male: Female |
In Africa, the chimp is distributed widely, the bonobo is found only in
Zaire south of the Zaire river, and the gorilla has widely-scattered
patches. In Asia, gibbons are widely spread while the orangutan has
patches in Borneo and Sumatra. Mostly they liv e in rainforests but
are in savannah sometimes and gorillas are up in mountains usually. Apes
are mostly frugivorous. The exceptions are gorillas who eat more leaves
and stems, and chimps who eat lots of things besides fruit, but still eat
a fair a mount of fruit too. Almost every social variation that we have
seen so far exists in the apes.
And now, may I present the Apes...
Family Hylobatidae (gibbons)
This family includes only one genus, Hylobates, with 9 species
distributed through the forests of South and SE Asia. Besides man,
are the most successful apes measured in abundance and diversity of
species. They're all pretty much the same size, about 5 kg, except the
siamang, who is about 10kg. Highly adapted for brachiation, gibbons have
extremely long arms and fingers. Their fingers are like hooks. They can
move really, really fast by swinging through the branches by their arms.
Most gibbons are frugivorous. They like small amounts of fruit
scattered around in trees, even though there are some trees which will
produce a lot of fruit at once. By looking for the trees with smaller
harvests, they compete more with birds and small ma mmals for food rather
than with other primates.
Examples from this family include the siamang, the lar gibbon, and the
silvery gibbon. Gibbons show a lot of variation in coat color but that's
not good for distinguishing between species; some species have different
coat colors for each sex, while others just have two different color
distributed randomly. It is easier to distinguish gibbon species by their
song because their songs are more distinctive.
Most of the species don't overlap. They're found in S India, down the
Malay peninsula, in Borneo, and in Sumatra. They do not live outside of
tropical rainforests. It is surmised that they were originally one
which radiated out from a single area. As sea level went down, different
groups got isolated and then became separate species and now they don't
interbreed any more.
Gibbons form small, monogamous groups, more like birds than typical
primate. A family is usually 5-6 individuals because the kids stay until
they're about 5 or 6 but the parents have another kid every year. A
cooperates in defending their territory , and males cooperate in parental
care. Indeed, in the siamang, the males do most of the parental work
the first year. This is unusual for primates. When they reach maturity,
juveniles of both sexes go off and find a mate and establish their own
territories. Usually they develop a new territory, but sometimes they
establish theirs on one of their parents' property. Although they have
direct encounters from time to time, gibbons mostly defend their
territories by going around the boundaries and singing often. They have
throat pouches that inflate which helps the sounds resonate better. (We
listened to tapes of these calls in class.)
Family Pongidae (the great apes)
Genus pongo (orangutans)
Orangutans are highly arboreal. This is shown anatomically in the
structure of their hips and shoulders. Although they have really mobile
joints, they don't really swing like the gibbons. It's more like they
climb around with four hands. They just hang out because they're too
heavy to fling themselves around like gibbons. Adult males get so big
sometimes have to get down and walk from one tree to the next! Orangutans
also exhibit size dimorphism. When they reach adulthood, males get throat
sacs and face flanges filled with fat.
Orangutans are found a little bit on Sumatra and a little on Borneo.
They're really endangered, and found strictly in the rainforest. Being
fruit eaters, they need to move around a bit to find their food. They
don't move too quickly, so they rely on knowi ng a lot about where and
when fruit can be found. They know when which trees are ripe, etc. They
may only move a few hundred meters in a day, but they cover a lot of
territory in a year. They'll do things like watch the birds and other
animals to figure o ut where food is good. Orangutans have little social
organization- the maximum group size is mom with baby. A couple may have
brief associations while the female is in estrus, and maybe a few
orangutans will congregate at a good fruit tree, but they tend to ignore
each other when they're eating together. However, there's evidence that
they recognize people whose ranges are near theirs. Females have smaller
rages than males. Their ranges overlap extensively but they don't defend
Sometimes females will copulate with young males who
don't have secondary sex characteristics yet. Also, young males will
sometimes rape females which is unusual in primates other than humans.
Males probably move house more than females; Females come into estrus
every several years since they keep their young around for so long, so if
all of the females in a male's range have babies, he may move on to
Genus Pan (bonobos)
Bonobos are a recent find. They were only first described in 1929 from
specimens in museums. Not studied much in the wild until recently, they
are similar to chimpanzees in a lot of anatomy and habits. Bonobos are
more slender and lighter in build, but th ey're actually not much
even though they're also called pygmy chimpanzees. Pretty terrestrial,
bonobos live in Zaire in a small patch of the rainforest south of the
Zaire river. Less carnivorous than chimps, they eat more leaves and
Like c himps, they have a fission-fusion type of society, but bonobos
larger groups than chimps. Bonobos are also less violent; no one has seen
organized aggression between communities like you see in chimps.
is also unusual is that there's a lot of sexual activity among all
individuals, of any age and of any gender combination. Females remain
sexually active even when they're lactating or pregnant. Sex seems to
become more a social activity and less a reproductive one. Bonobos
copulate missionary style, whereas most primates do it doggie style.
Females will engage in genital-genital rubbing, and even look like
climaxed. This behavior is involved in reducing tension, and mediating
social rela tionships. For instance, a group will come upon a tree with
lmited amounts of food left, and you know that there's going to be some
competition for food resources. Two females will suddenly turn to each
other and do some g-g rubbing until everyone is happ y and mellow again.
(New idea for world peace?)
Genus Pan (chimpanzees)
Chimps are knuckle-walkers, and are terrestrial. Most primates walk on
flats of their hands, but chimps walk on their knuckles with their hand
turned over. Chimps exhibit less size dimorphism than other apes, but
chimp and bonobo females have pro minent genital swellings when they are
in estrus. (Why do some females advertise it and other don't? Answers
later.) Chimps have quite big testicles relative to body size, especially
compared to gorillas, for example.
Chimps are found a little in
western Africa and across the equatorial belt in mid-Africa. They've only
been closely studied in their eastern ranges - in Kibale forest and in
Mahale mountains in Tanzanyka. So how much variation there is across the
populati on, we don't really know.
Although they're mostly frugivorous, chimps eat termites and ants too.
Chimps exhibit tool use for gathering ant and termintes, especially the
females. The males tend to hunt more. They'll eat monkeys, antelope,
anything young and easily catchable. They're pretty opportunistic about
it- they won't chase things who are likely to escape easily, but if they
happen across some noctural animal who is asleep, they'll start right in
on it. They do hunt in groups but there doesn't seem to be extensive
ration about it.
Socially speaking, they have a fission-fusion society; there'll be 20-100
chimps who defend a common territory, but within this group they're
up into smaller-sized groups. The female tends to be more solitary, with
range where she spends most of her time, while the male is more sociable
and tends to go around with other guys. Females usually leave their natal
territory when they reach sexual maturity, so they end up living with
non-relatives. Males stay, so they've got their brothers and uncles e tc.
around them. Females do, however, maintain close relationships with their
offspring, even after they're grown. If they're in the same community,
they'll spend time together. Males do social grooming with a wider range
of individuals than females do. M ales hanging out together and
associating together is also a good thing because there is a lot of
hostilities between communities. If a male were wandering around alone,
he'd probably get attacked because males from one community will attack
given the chance. Males will patrol the border together, and they'll even
go on a raid. Researchers will see them all getting excited, riling each
other up, and gathering together. Suddenly, they'll get quiet, sneak to
the neighboring territory, and invade! If the y encounter a lone male,
they'll gang up in a frighteningly organized way; some will hold him down
while others hit him. Chimps are the most violent primates besides us
Genus Gorilla (gorillas)
This family has 1 genus, gorilla, and one species, g.
gorilla. Gorillas are the largest primate. They exhibit extreme
sexual dimorphism, males being more than twice the size of females.
Mostly terrestrial, gorillas are knucklewalkers. Their distribution is
limited; they're found only in tropica Africa. The eastern mountain
gorillas are high enough that the climate isn't really tropical, but
geographcially it is tropical. Gorillas live in open canopy places 'cause
they eat vegetation that grows on the gound. They also like it in wet
places. Gorillas have been studied mostly in the Bururi forest.
Gorillas eat mostly terrestrial vegetation such as leaves and stems. This
is not high quality food compared to fruit, insects, or meat, since
there's not a lot of calories in the food. There's no competition for
food, but you have to eat a lot to get your daily requirements.
The gorilla's social system is usually composed of a single adult male
with multiple females. There are usually about 5-10 animals in a group.
All of the social organization centers around the male; the females
aren't generally related to each other and their only link is that they
like the same guy.
[Topic List] | [Next Lecture]
Today I wasn't in class but I heard that we played a sort of quiz game
with teams, testing our knowledge of primates.
Let me know your thoughts: firstname.lastname@example.org
Last modified: October 6, 1996