• Primates are social
animals and most
species live and travel
in groups.
• A community is a unit
of primate social
organization composed
of 50 or more
individuals who
inhabit a geographical
area.
• Males and females can be organized into dominance
hierarchies, an observed ranking system ordering
individuals from high (alpha) to low standing
corresponding to predictable behavioral interactions
including domination.
• The ritual cleaning of
another animal to remove
parasites and other matter
from its skin or coat is a
common pastime for both
chimpanzees and
bonobos.
• Grooming can be a
gesture of friendliness,
closeness, appeasement,
reconciliation, or even
submission.
• Primates have elaborate systems of communication based
on vocalizations and gestures.
• Bonobos employ trail signs to communicate their
whereabouts to others.
• Chimpanzees use facial expressions to convey emotional
states.
• It is now clear that all of the
great ape species can develop
language skills to the level of
a 2-to-3 year-old human child.
• A tool may be defined as
an object used to facilitate
some task or activity.
• From adults, juveniles
learn to use a variety of
tools and substances for
various purposes.
• Innovations made by one
individual may be adopted
by other animals,
standardized, and passed
on to succeeding
generations.
• A wild chimp is using
a long stick stripped of
its side branches to
fish for termites.
Chimps will select a
stick when still quite
far from a termite
mound and modify its
shape on their way to
the snacking mound.
• Brain Complexity (the brain
areas devoted to thought,
memory and association are
more elaborate and
proportionally larger).
• Parental Investment (single
offspring births combined
with longer development
periods).
• Sociality (strongly associated
with parental investment,
cooperative social groups are
selected for in part because of
the needs arising from
primate parenting).
• Adaptive Flexibility
Through Learning
• Neotony and life in
cooperative social groups
allows primates to learn
behavior from their
fellows, rather than
relying only on
genetically encoded
behaviors.
• Learned behavior has
been observed in
monkeys as well as apes.
• Predation and Hunting
• Hunting is a regular and normal component of wild
chimpanzee behavior.
• Hunting by chimps is both opportunistic and planned.
• Wild chimpanzees have been observed hunting
consistently, using cooperative techniques, with some sex
specialization (males hunt more than females).
• Tools
• Tool use allows primates to adapt to a wider range of niches more
quickly than physiological adaptation alone (although primates are
not the only animals that use tools).
• Wild chimps have been observed constructing tools.
• Aggression and Resources
• The capacity for hunting
exists among many different
primates, but expression of
this capacity can depend
upon environmental
pressure and opportunity.
• Observations of chimps and
orangutans indicate that
aggressive behavior
(“warfare,” in some chimp
cases) may increase when
territorial encroachment
occurs.
• According to evolutionary
theory, when the
environment changes,
natural selection starts to
modify the population’s
pool of genetic material.
• Natural selection has
another key feature: the
differential reproductive
success of individuals
within the population.
• Behavioral ecology studies
the evolutionary basis of
social behavior.
• It assumes that the genetic
features of any species reflect
a long history of different
reproductive success (that is
natural selection).
• In other words, biological
traits of contemporary
organisms have been
transmitted across the
generations because those
traits enable their ancestors
to survive and reproduce
more effectively than their
competition.
• Natural selection is
based on differential
reproduction. Members
of the same species may
compete to maximize
their reproductive
fitness- their genetic
contribution to future
generations.
• Individual fitness is
measured by the
number of direct
descendants an
individual has.
• Illustrating a primate
strategy that may
enhance individual
fitness are cases in
which male monkeys
kill infants after
entering a new troops.
• Destroying the
offspring of other
males, they clear a
place for their own
progeny.
• Besides competition,
one’s genetic
contribution to future
generations also can be
enhanced by
cooperation, sharing,
and other apparently
unselfish behavior.
• This is because of
inclusive fitness –
reproductive success
measured by the genes
one share with relatives.
• By sacrificing for their kin – even if this means limiting
their own direct reproduction – individuals actually may
increase their genetic contribution (their shared genes) to
the future.
• Inclusive fitness helps us understand why female might
invest in her sister’s offspring, or why a male might risk
his life to defend his brother.
• If self-sacrifice perpetuates more of their genes then
direct reproduction does, it makes sense in terms of
behavioral ecology.
• Such a view can help us understand aspects of primate
behavior and social organization.
• Maternal care always makes sense in terms of reproductive fitness
theory, because females know their offspring are their own. But it is
harder for males to be sure about paternity.
• Inclusive fitness theory predicts that males will invest most in
offspring when they are surest the offspring is theirs.
• Gibbons, for example, have strict male-female pair bonding, which
makes it almost certain that the offspring are those of both members
of the pair.
• Thus we expect male
gibbons to offer care and
protection to their young,
and they do.
• However, among species
and in situations in which
a male can’t be sure about
his paternity, it may make
more sense to invest in a
sister’s offspring than a
mate’s, because the niece
or nephew definitely share
some of that male’s genes.
• “Sociobiology is the study of the evolutionary basis for behavior.”
• Types of Fitness
• Individual fitness is the number of direct descendents an
individual organism has.
• Inherent in this notion, as seen in terms of natural selection, is
the implication that any individual’s fitness competes with that
of its conspecifics.
• A model attributing a drive to protect one’s individual fitness to
all organisms could not explain altruistic or self-sacrificing
behavior.
• Inclusive fitness is a theoretical concept developed to account
for unselfish behavior and is defined as “reproductive success
measured by the representation [in succeeding generations] of
genes one shares with other, related animals”.
• The fossil record
offers evidence for no
more than 5% of
extinct types of
primates.
• Such small numbers
provide the merest
glimpse of the diverse
bioforms – living
beings- that have
existed on Earth.
• Based on fossils found in
Stratigraphy sequence, the history
of vertebrate life has been divided
into three main eras:
• The Paleozoic (544-245 m.y.a.): was the
era of ancient life –fishes, amphibians,
and primitive reptiles.
• The Mesozoic (245-65 m.y.a.): was the era
of middle life – reptiles, including the
dinosaurs.
• The Cenozoic (65 m.y.a. – present) is the
era of recent life – birds and mammals.
Each era is divided into periods; the
periods, into epochs.
• Anthropologists are
concerned with the Cenozoic
era, which include two
periods:
• Tertiary and Quaternary.
• Each of these periods is
subdivided into epochs.
• The Tertiary had five
epochs: Paleocene, Eocene,
Oligocene, Miocene, and
Pliocene.
• The Quaternary includes just
two epochs: Pleistocene and
Holocene, or recent.
• Sediments from the Paleocene epoch (65-54 m.y.a.) have
yielded fossil remains of diverse small mammals,
including, by the late Paleocene, the earliest known
primates.
• Hominoids became widespread during the Miocene (23-5
m.y.a.). Hominins first appeared in the late Miocene, (5-2
m.y.a.)
• When the Mesozoic era
ended, and the Cenozoic
era began ,around 65
million years ago, North
America was connected
to Europe but not to
South America (The
Americas joined around
20 million years ago.)
• Over millions of years,
the continents have
“drifted” to their
present location.
• During the Cenozoic, most
landmasses had tropical
or subtropical climates.
• The Mesozoic era had
ended with a massive
worldwide extinction of
plants and animals,
including the dinosaurs.
• Mammals eventually
replaced reptiles as the
dominant large land
animals.
• Trees and flowering plants
soon prolifered.
• According to the
arboreal theory,
primates became
primates by adapting to
arboreal life.
• The primate traits and
trends discussed
previously developed as
adaptations to life high
up in the trees.
• A key feature was the
importance of sight over
smell.
• Changes in the visual apparatus were adaptive in the
trees, where depth perception facilitated leaping.
• Grasping hands and feet were used to crawl along slender
branches, Grasping feet anchored the body as the
primates reached for foods at the ends of branches.
• Early primates probably had omnivorous died base on
foods available in the trees.
• A tiny, complete skeleton from China, first described in
2013, represents the earliest known primate.
• The creature was smaller than today’s smaller primatethe pygmy mouse lemur of Madagascar. Named
Archicebus archilles.
• Archicebus Archilles
weighted no more
than 1 ounce, and it
had a 5-inch tail that
was longer than its 4inch body.
• It lived 55 million
years ago, when Earth
was a natural
greenhouse.
• This finding supports the view
that the first primates evolved
in Asia – not too long after the
extinction of dinosaurs 66
million years ago.
• Somehow primates crossed
open water to reach Africa by
38 million years ago (Africa
remained an island continent
until 16 million years ago).
• Archicebus achilles had the
feet of a small monkey; the
arms, legs and teeth of a very
primitive primate; and
primitive skull with very small
eyes.
• During the Oligocene epoch (34-23 m.y.a.), anthropoids
became the most numerous primates.
• Most of our knowledge of early anthropoids is based on
fossils from Egypt’s Fayum deposits.
• This area is a desert today, but 34-31 million years ago it was a
tropical rain forest.
• The anthropoids of the
Fayum lived in trees
and ate fruits and
seeds.
• Compared with prosimians,
they had fewer teeth, reduced
snouts, large brains, and
increasingly forward-looking
eyes.
• Of the Fayum anthropoid
fossils, one group is the more
primitive and perhaps is
ancestral to the New World
monkeys.
• These proto-monkeys were
small (2-3 pounds), with
similarities to living
marmosets and tamarins,
small South American
monkeys.
• Another Fayum group
seems ancestral to the
catarrhines- Old World
monkeys, apes, and
humans.
• In 2013, researchers
working in Tanzania’s
Rukwa Rift Basin reported
their discovery of two
finds that may be the
oldest known fossils from
two major primate
groups.
• hominoids (apes and humans)
and Old World monkeys.
• Geological dating shows the fossils to be 25.2 million
years old, several million years older than any other
confirmed example of an ancient ape or old monkey.
• Hominoid fossils become abundant during the Miocene
epoch (23-5 m.y.a.), which is divided into three parts:
• Lower or earlier
• Middle
• Upper or later
• The earlier (23-16 m.y.a.) was a warm and wet period,
when forests covered East Africa. The earliest hominoids
are here called protoapes, or simply apes. Although some
of these may be ancestral to living apes, none is identical,
or often even very similar, to modern apes.
• Proconsul is the name for a group (three known species) of
early Miocene protoapes.
• These ancient apes, which lived in Africa, had teeth with
similarities to those of living apes.
• Below the neck, however, their
skeleton was more monkeylike.
• The Proconsul species ranged in
size from that of a small monkey to
that of a chimpanzee.
• During the early Miocene (23-16 m.y.a.), Africa had been
cut off by water from Europe and Asia.
• During the middle Miocene, Arabia drifted into Euroasia,
providing a land connection between Africa, Europe and
Asia, were various animals, including hominoids
migrated in and out of Africa.
• The most remarkable Miocene
ape was Gigantopithecusalmost certainly the largest
primate that ever lived.
• Confined to Asia, it persisted
for millions of years, from the
Miocene until 400,000 years
ago, when it coexisted with
members of our own genus,
Homo erectus.
• Some people think
Gigantopithecus is not extinct
yet, that we know it today as
the yeti or Bigfoot (sasquatch).
• With a fossil record consisting of nothing more than
jawbones and teeth, it is difficult to say for sure just how
big Gigantopithecus was.
• Based on ratios of jaw and tooth size to body size of other
apes, various reconstruction have been made.
• All reconstructions agree, however, that Gigantopithecus
was the largest ape that ever lived.
• There were at least two species of Gigantopithecus: one
coexisted with H. erectus in China and Vietnam, and the
other, much earlier (5 m.y.a.), lived in northern India.
• In 2004, Spanish anthropologists announced their
discovery of what may be the last common ancestor of
humans, chimpanzees, gorillas and orangutans.
• This ape species, named Pierolapithecus Catalaunicus,
lived around 13 million years ago, during the middle
Miocene.
• The fond comes from a rich fossil site near the village of
Hostalets de Pierola in Catalonia, Spain.
• The find appears to represent a single adult male that
weighted about 75 pounds. Like chimps and gorillas,
Pierolapithecus was well adapted for tree climbing and
knuckle-walking on the ground.
• Several features distinguished Pierolapithecus from the
lesser apes (gibbons and siamangs) and monkeys.