The Primates
Our place among the primates
Homologies and analogies, primate
tendencies, human similarities and
differences.
Primatology
 Is the study of nonhuman primates-fossil and living apes,
monkeys, and prosimians, including their behavior, and
social life.
 Helps anthropologist to make inferences about early social
organization of hominids (members of the zoological
family that includes fossil and living humans to and to
untangle issues of human nature and the origins of culture.
Two kinds of primates
 1. Those whose ecological adaptations are similar to our
own: terrestrial monkeys and apes-primates that live on
the ground rather than in trees.
 2. Those that are most closely related to us: the great
apes, specifically the chimpanzees and gorillas.
Our place among Primates
 Similarities between humans and apes are evident in
anatomy, brain structure, genetics, and biochemistry.
 Physical similarities are recognized through in zoological
taxonomy-which is the assignment of organisms to
categories according to their relationship and resemblance.
 Many similarities between organisms reflect their common
phylogeny: which is their generic relatedness based on
common ancestry.
 Humans and apes belong to the same taxonomic
superfamily, Hominoidea (hominids). Monkeys are placed
in 2 other families, which means we are more closely
related to apes than either is to monkeys.
Principal classification units of
zoological taxonomy
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Kingdom
Phylum
Subphylum
Class
Infraclass
Order
Suborder
Infraorder
Superfamily
Family
Genus
Species
Subspecies
 Each lower level belongs
to the higher level unit
above it.
 Species: a group of
organisms that can mate
and give birth to viable(capable of living) and
fertile-capable of
reproducing offspring
whose own offspring are
viable and fertile.
Classification continued
 Speciation: the formation of a new species occurs when
groups that once belonged to the same species can no
longer interbreed.
 After a sufficiently long period of reproductive isolation,
two closely related species assigned to the same genus will
have evolved out of one.
 The similarities used to assign organisms to the same taxon
are called homologies, similarities they have jointly
inherited from a common ancestor. (hand out table 4.1)
 Humans are mammals that belong to the order Primates.
Homologies and Analogies
 The extensive biochemical homologies between apes and
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humans confirm our common ancestry and support our
traditional joint classification as hominoids.
It is estimated that chimps, humans, and gorillas have more
than 98% of the DNA in common.
Analogies: When similar traits arise if species experience
similar selective forces and adapt them in similar ways.
Convergent evolution:the process by which analogies are
produced. EX. Fish and Porpoises.
Table 4.2, our degree of relatedness to other primates.
Primate Tendencies
 Primates are varied because they have adapted to diverse
ecological niches. Many trends in primate evolution are
best exemplified by the anthropoids:monkeys, apes, and
humans which constitute the suborder Anthropoidea.
 The other primate suborder, Prosimii, includes lemurs,
lorises, and tarsiers. These prosimians are more distant
relatives of humans than are monkeys and apes.
 The primate trends –mostly developed in anthropoidsconstitute an anthropoid heritage that humans share with
monkeys and apes.
Primate Tendencies
 1. Grasping: 5-digit feet and hands suited for grasping. Humans and
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many other primates have opposable thumbs: meaning they can touch
other fingers.
2. Smell to Sight:Most important means to obtaining info. The portion
of the brain devoted to vision expanded, while the area concerned with
smell shrank.
3. Nose to hand:Main touch organ is the hand, specifically the
sensitive pads of the “fingerprint” region.
4. Brain Complexity: The proportion of brain tissue concerned with
memory, thought, and association has increased in primates.
5. Parental Investment: Most primates give birth to a single offspring
rather than a litter; growing primates receive more attention and more
learning opportunities.
6. Sociality: tend to be more social animals to help raise young.
Prosimians
 The earliest history of the primates is limited to prosimian-
like animals known through the fossil record, appeared
more than 40 million years ago. Some managed to survive
because the adapted to nocturnal life, which meant they did
not compete with Anthropoids, which are active during the
day.
 Examples: Lemurs: eat fruits, plant foods,eggs and insects.
 Tarsier: Confined to Indonesia and the Philippines.
 Lorises: Nocturnal prosimians found in Africa and Asia.
Anthropoids
 All anthropoids have overlapping fields of vision, permitting them to
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see things in depth. Eyes are placed forward in the skull and look
directly ahead.
Depth perception because overlapping visual fields, which with color
vision helped to distinguish edible insects, fruits, berries and leaves
and makes it easier to groom.
Grooming in one way of foming and maintaining social bonds.
Manual dexterity, including the opposable thumb, is a tremendous
advantage in examining and manipulating objects and is essential to a
major human adaptive capacity: Tool Making
A bigger brain enables monkeys, apes, and humans to store an array of
visual images in their memories, which permits them to learn more.
The ability to learn from experience and others is a major reason for
the success of anthropoids compared to other mammals.
Monkeys
 The anthropoid suborder has 2 infraorders: platyrrhines
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(New World monkeys) and catarrhines (Old World
Monkeys, apes, and humans).
The catarrhines (sharp-nosed) and platyrrhines (flat-nosed)
are named for Latin terms that describe the placement of
nostrils. (fig. 4.3)
All old and new world monkeys are arboreal.
Monkeys move different from apes and humans. Their
arms and legs move parellel to one another as dogs do and
are the same length, which contrasts to apes(when sitting)
and humans who have orthograde posture, the straight
and upright stance.
Monkeys also have tails to help with balance in trees.
New World Monkeys (NW)
 Live in the forest of Central and South America.
 Some parallels between some NW and OW.
 These are convergent evolution: has developed as a result
of adaptation to a similar arboreal niche. EX: Brachiation:
which is under-the-branch swinging. Most monkeys run
and jump from branch to branch, but gibbons and some
NW swing, using hands as hooks.
 Many NW have prehensile, grasping tails (Fig 4.4), which
sometimes have has tactile skin that allows it to work like a
hand in conveying food to mouth
Old World Monkeys (OW)
 Specializations: rough patches of skin on buttocks, adapted
to sit on hard rocky ground and rough branches.
 Both a terrestrial and arboreal species, with certain traits to
differentiate. Arboreal tend to be smaller, which can reach
a greater variety of food. Arboreal are also lithe and agile,
they escape from predators though alertness and speed.
 Another contrast is sexual dimorphism (marked
differences in male and female anatomy and temperament,
which is more marked in terrestrial.
Terrestrial Monkeys
 Example: Baboons of Africa and macaques in Asia.
 Terrestrial monkeys have specializations in anatomy,
psychology, and social behavior that enable them to cope
with terrestrial life. Male baboons are fierce-looking and
can weigh up to 100 pounds. They display long projecting
canines to intimidate predators. A male can also puff up
his mane, so they can be perceived larger.
 At puberty male baboon and macaque leave their home
troop for another, which makes females the stable core of
the group. Terrestrial core= females. Among apes=males.
 Female chimps and gorillas are more likely to emigrate out
of their group.
Apes
 Humans and apes compose the hominoid superfamily Hominoidea.
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Great apes are orangutans, gorillas, and chimps. Smaller apes are the
gibbons and siamangs of SE Asia and Indonesia.
Humans could be included here too, called “the third African Ape”
Apes live in forests and woodlands. Ape behavior and anatomy reveal
past and present adaptation to arboreal life.
Ex: Apes still build nests to sleep in trees, they have longer arms and
legs adapted for brachiation(fig 4.5) The structural collar bone of apes
and humans suggest that we had brachiate ancestor.
The terrestrial locomotion of chimps and gorillas is called knucklewalking, where long arms and callused knuckles support the trunk as
the apes amble around leaning forward.
Gibbons
 Widespread in the forests of Southeast Asia (Malaysia).
 Are the smallest of the Apes(3ft, 12-25lbs)
 Spend most of their time just below forest canopy(treetops)
 Have long arms and fingers, with short thumbs for efficient
brachiation. Most agile apes. Not knuckle-walkers,
instead they use long arms for balance.
 Eat a fruit diet and tend to live in primary groups, which
are composed of permanently bonded male and female and
offspring.
 There are hundreds of thousands of gibbons that span a
wide area of Southeast Asia.
Orangutans
 Genus Pongo. Contemporary confined to two Indonesian
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islands.
Marked sexual dimorphism, with adult male weighing as
much as twice the female(may exceed 200 lbs). Middle in
size between chimps and gorillas.
More arboreal with their size, they typically climb, rather
than swing, the trees.
Varied diet of fruit, bark, leaves, and insects.
Hard to study. Tend to be solitary animals. Tightest social
units consist of females and young. Males forge alone.
Gorillas
 One species Gorilla gorilla, with 3 subspecies.
 1. Western lowland (zoos): smallest, lives in forest in
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Central African Republic, Congo, Cameroon, Gabon,
Guinea, and Nigeria.
2. Eastern lowland: larger and lives in Congo(only 4 in
captivity).
3. Mountain gorillas: (0 in captivity) Only 650 alive.
Largest with long hair. Studied by Dianne Fossey.
Full grown males weigh up to 400lbs and stand 6ft tall.
Marked sexual dimorphism, females weigh half as much.
Little time in trees, but if they sleep in trees their nests are
no more than 10 feet off the ground.
Gorillas continued
 Most of the day is spent feeding: move through forest
undergrowth eating plants, leaves, bark, and fruits. Mainly
large quantities of green bulk vegetation.
 Live in social groups. Troop is a common unit of primate
social organization, consisting of multiple males, females
and offspring. (mostly 10-20). Stable memberships with
little group shifting.
 Each troop has a silverback male(white stripe of white hair
that extends down back) who is usually the only breeding
male in the group. “One-male groups”
Chimpanzees
 Genus Pan, which has 2 species: Pan troglodytes (the
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common chimp) and Pan paniscus (the Bonobo or
“pygmy” chimp).
Similar to gorillas: live in Africa, but live over a large area
and in more varied environments (Fig 4.6)
Common chimps live mainly tropical rain forests, also in
woodlands and mixed forest areas.
Chimps prefer to eat fruit. They are omnivorous, eating
small mammals, birds’ eggs, and insects.
Lighter and more arboreal. Adult male is 100-200 lbs.
Much less sexual dimorphism, females are about 88% of
the average male height, which is similar to humans.
Chimps continued
 Chimp communities regularly split up into smaller groups:
a mother and offspring; a few males; males, females and
young; solitary animals.
 Semiclosed communities. Social network of males is more
closed than the females, which are more likely to migrate
and mate outside their natal groups.
 Very vocal: greet one another with gestures, facial
expressions, and calls. They hoot to maintain contact.
 Exhibit dominance relationships through attacks and
displacement.
Endangered Primates
 Deforestation poses a risk for primates because 90% of the 190 primate
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species live in tropical forests(Fig 4.7).
All non-huaman primates are endangered. The apes (gibbons, gorillas,
orangutans, and chimps) are in the “most endangered category.
Habitat destruction and fragmentation can isolate small groups of
animals, leaving them vulnerable to extinction due to loss of genetic
diversity.
Another threat is hunting of primates for bush meat, skins and pelts.
Primates are also killed when they are agricultural pests.
Primates are also captured for use in labs or as pets. Chimps have been
used widely in biomedical research.
Gorrilas in the Mist???
Human-Primate Similarities
 Learning: Monkeys, apes, and humans all learn throughout their lives.
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For all, the ability to learn, to profit from experience, confers a
adaptive advantage, permitting them to void fatal mistakes.
Tools:We first thought that humans were the only primates that made
tools with a specific purpose in mind, but we have found that chimps
also demonstrate this behavior. Ex: to get water from places their
mouths can’t reach, chimps chew a leaf and then use like a “sponge”.
Chimps also make tools to probe termite hills. Pick twigs and modify
by removing leaves and bark to expose sticky surface beneath.
When chimps are trained by humans, their skills flower.
Wild chimps and orangs aim and throw objects. Hominids have
elaborated the capacity to aim and throw= without this we would have
never developed projectile technology and weaponry or baseball.
Similarities continued
 Predation and Hunting: Chimps in a large community size permits
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the formation of a large hunting parties, which contributes to hunting
success. Most hunts result in at least one prey being caught.
Hunting by chimps is both opportunistic and planned.(103)
Aggression and Resources: Jane Goodall specifically linked chimp
agression and predation to human encroachment on their natural
habitat. Gombe chimps are divided into Northern and Southern
groups(smaller). Parties from the North have invaded the southern
territory and killed. Infant victims were partially eaten.
Also, Orangs have suffered due to human encroachment-farming and
timbering. In Indonesia, in response to nearby human activities,
organs have developed a pattern of extreme sexual antagonism.
Primate behavior is not rigidly determined by genes. It is
plastic(flexible). Among humans too, aggression increases when
resources are scarce. Aggression and predation reflect environmental
variation.
Human-Primate Differences
 Sharing and Cooperation: Early humans lived in small
social groups called bands, economies based on hunting
and gathering. Men would hunt, women would gather.
When they returned they would share. Elders were
protected by the young, which would enable them to live
longer and share knowledge and experience. The amount
of info stored in a human band is far greater than that in
any other primate society. Monkeys tend to fend for
themselves. Among primates except Homo,most food
comes from individual foraging.
Mating and Kinship Differences
 Among baboons and chimps, most sexual intercourse tends to occur
when females “go into heat” or enter estrus, a period of sexual
receptivity-signaled by swelling of vaginal skin. Females form
temporary bonds with males. Among humans, sexual activity occurs
throughout the year. Because of more constant sexuality, all human
societies have some form of marriage. Marriage gives mating a
reliable basis and grants to each spouse special sexual rights to the
other.
 Ties of affection and mutual support between members of different
local groups tend to be absent among primates other than Homo.
Primates tend to disperse at adolescence.
 Humans choose mates from outside the natal group, as well as
monkeys, and usually at least one human spouse moves.
 Humans maintain lifelong ties with offspring, which is major contrast
to other primates.
Social Mobility and Fitness
 Socialbiology: studies the evolutionary basis of social behavior. Biological
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traits of contemporary organiams have been transmitted across the generations
because those traits have enabled their ancestors to survive and reproduce
more effectively than others.
Members of the same species may compete to maximize their reproductive
fitness-genetic contribution to future.
Individual fitness: is measured by the number of direct descendants an
individual has. Some monkeys kill the offspring of other males to clear a
place for their own progeny.
One’s genetic contribution to future can also be enhanced by cooperation,
sharing and unselfish behavior. Inclusive fitness: reproductive success
measured by the genes on shares with relatives. Ex: female might invest in
sister’s offspring, or male risk his life to save brothers.
Males will invest most in offspring when they are surest the offspring is theirs.