Primate Studies 2

TaxonomyDevelopment

There are approximately 190 sepcies of non-human primates.

prosimians monkeys apes

Primate Development and Taxonomy Origins—where did primates

come from?A proliferation of mammalian forms from the

end of the Cretaceous period (ca. 65 Mya) opened new econiches

The major evolutionary trends that distinguish primates and their generalized mammalian form came as a result of adaptation to arboreal living.

Trees: The Primate Adaptive Niche

Adaptive niche for primates was the trees

Provided many challenges and opportunities

– Depth perception and binocular vision crucial – Climbing using prehensile hands and feet instead of claws – Varied diet led to omnivorous adaptation and generalized

dentition – Longer life span, increased intelligence and more elaborate

social system needed to cope

Other placental mammals tended to adapt to grasslands, marine or other environments

Arboreal vs. visual predation vs. mixed diet

Matt Cartmill criticized the arboreal hypothesis • He proposes a visual predation hypothesis• First adaptation was to the lower tier of the forest canopy and the

brush, as "stealthy" eaters of insects who quickly “pounce” from branch onto insect

• Needed foward-facing eyes and partially grasping hands to do so

Tarsier

Tarsier

Visual predation and the arboreal hypothesis are not mutually exclusive explanations

The visual predation traits developed as the primates moved to the trees.

Whatever the case, we know they eventually moved to the trees.

Weakness?Prosimians, considered to be closer to the ancestral form of all primates, exhibit lower reliance on visual information for locomotion and predation

Prosimians emphasize olfactory and auditory cues in the pursuit of prey.

Robert Sussman proposed the Mixed Diet Hypothesis

• Increased exploitation of angiosperms (flowering plants) selected for modern primate characteristics.

• Enhanced visual acuity, color vision, and characteristics amenable to exploiting terminal branch resources all allowed for efficient acquisition of resources.

• The emergence of flowering plants in the Paleocene roughly coincides with the emergence of the earliest primate ancestors.

Mixed Diet Hypothesis

TupaiidaeTree shrews

Indriidae

Primate Classification

Highest level: order Primates

Next level down: Prosimii (lemurs, lorises, and usually the tarsiers)

Anthropodiea (monkeys, apes and humans).

At successively lower levels (infraorder, superfamily, family, genus, and species), see chart

Linnean taxonomic system

Suborder Infraorder Superfamily Family Subfamily Common Names Distribution

Prosimii 2

(prosimians)

Lemuriformes

Lemuroidea

Lemuridae(true lemurs)  

ring-tailed, ruffed, and mouse lemurs, etc.

Madagascar and Comoro Islands

Indriidae  indris, avahis, and sifakas

Madagascar

Daubentoniodea Daubentoniidae  aye-ayes Madagascar

Lorisiformes Lorisoidea LorisidaeLorisinae

lorises, pottos, and angwantibos

lorises--India and Southeast Asia; others--Africa

Galaginaegalagos (or bush babies)

sub-Saharan Africa and Zanzibar

Tarsioidea 3     Tarsiidae  tarsiers Philippines, Borneo,

Celebes Islands, and Sumatra

Anthropoidea(anthropoids)

Platyrrhini(New World monkeys)

Ceboidea

Callithricidae  marmosets and tamarins

Panama and north and eastern South America

Cebidae 4  squirrel, howler, owl, and spider monkeys; capuchins; etc

Central America and north and eastern South America

Catarrhini(Old World

monkeys, apes and humans)

Cercopithecoidea

(Old World monkeys)

Cercopithecidae

Cercopithecinae

guenons, baboons, macaques, etc.

guenons and baboons--Africa; macaques--northwest Africa, Gibraltar, South and East Asia

Colobinae

colobuses, langurs, and proboscis monkeys

colobuses-- Central Africa; langurs-- India and Southeast Asia; proboscis monkeys--Borneo

Hominoidea(apes and humans)

Hylobatidae  gibbons and siamangs Southeast Asia

Pongidae  orangutans 5 Sumatra and Borneo

Panidae  chimpanzees, bonobos, and gorillas

Central and West Africa

Hominidae  humans throughout the world

Primate taxonomy based on morphology:Criticisms

Tarsiers have both prosimian and anthropoid traits and are biochemically closer to anthropoids.

Hominoids have traditionally included four species in one family (the Pogidae-gorillas, chimpanzees, bonobos, and orangutans), as separate from humans (Hominidae) but seem actually to have both Asian and African branches.

DNA studies have complicated it further, indicating the closeness of humans and chimpanzees, with gorillas further away. Some have even suggested that chimps be labelled Homo troglodytes.

The point is that the taxonomic system is in flux as new data are utilized. Most experts still use the traditional system.

Prosimians • The most primitive of the true primates: lemurs and

lorises• more reliance on olfaction (smell), with moist, fleshy

pad (rhinarium) at the end of the nose and a long snout

• mark territories with scent (other primates don't) • somewhat more laterally placed eyes • differences in reproductive physiology, shorter

gestation and maturation • the dental comb, formed by forward-projecting lower

incisors and canines, used in grooming and feeding

Dental comb

Rhinarium

Lemurs

Found only on the Island of Madagascar and adjacent island off east Africa, they are extremely diversified into a range of niches-22 surviving species

Size range from the mouse lemur with head and trunk length of only five inches to the indri a bit over two feet long.

Larger lemurs are diurnal and eat a variety of leaves, fruits, buds, bark and shoots; smaller are nocturnal and insectivorous

Considerable variation in behavior. Some are arboreal while others are terrestrial.

Socially several species live in groups of 10-20 animals. Some like the indri live in monogamous family units. Some nocturnal forms are solitary.

Lorises Similar in appearance to lemurs, but survived in continental areas

of India, Sri Lanka, Southeast Asia, and Africa.Five species, largely nocturnal. Galagos are included as well, with

6-9 additional species. They are slow, cautious, quadrupedal climbers who can suspend

themselves on hind limbs leaving hands for feeding. Some are entirely insect eaters while others supplement the diet

with leaves, fruits, and slugs. Food foraging is often solitary. • Lemurs and lorises are at the same adaptive level. Good

grasping and climbing abilities and well-developed visual ability, though stereoscopic ability not as developed as it is in anthropoids.

• Most have a claw-grooming claw on second toe. • Life span is about 14 years for loris and 19 years or lemurs.

Tarsiers

Three species restrcted to island areas in SE Asia. They live in a wide range of habitats.

They are nocturnal insectivores, and leap onto prey from branches and shrubs.

They form pair bonds, with the social unit being the mated pair and offspring.

Unlike loris and lemurs, they have no rhinarium and they have a eye sockets enclosed by bone t back and sides.

This is more like an anthropoid. Eyes are enormous, compared to the rest of the body.

They have taxonomically mixed traits.

Anthropoids

The traits that distinguish anthropoids from prosimians include:

• generally larger body size • larger brain (in absolute terms as well as relative to body weight) • more rounded skull • complete rotation of eyes to front of face with full binocular

vision • bony plate at back of eye orbit • no rhinarium (less reliance on smell) • increased parental care • increased gestation and maturation periods • more mutual grooming

Monkeys

• The monkeys represent 70% (about 130 species) of all primates and are the most varied.

• New species are still being discovered and there are debates about taxonomy.

• Two main groups, New and Old World monkeys, have several million years of distinct evolutionary history.

• They had a strikingly parallel evolution with similar selective pressures in tropical arboreal environments

• Some say they evolved independently while others claim a common ancestor sometime before 50 million years ago.

New World Monkey

Old World Monkey

New World Monkeys • A wide range of size, diet and ecological adaptation.

Marmosets and tamarins weigh about 12 ounces at the small end, and howlers weigh up to 20 or so pounds.

• Almost exclusively arboreal, some never coming to the ground• All but one species in diurnal, living in most forested areas of

southern Mexico into Central and South America. • Major characteristic is the shape of the nose. • New World have broad, widely flaring noses with outward-

facing nostrils—sometimes called platyrrhine or flat-nosed

Marmoset

Tamarin

Two families: Callitrichidae and Cebidae • Callitrichidae are the most primitive monkeys: marmosets and

tamarins as examples – with claws instead of nails – giving birth to twins instead of one offspring – usually insectivorous – quadrupedal locomotion with claws used in tree climbing, but

with leaping too – males heavily involved in infant care (the only primates to do

so) – family groups of mated pair and offspring.

• Cebids--at least 30 species ranging from foot-long squirrel monkey to the howler (2 ft.). – diet varies, with most eating fruit and leaves with some

insects – most are quadrupedal, but some can brachiate a bit – powerful prehensile tails used for moving and for suspending

while eating – socially live in small mixed-sex groups, but some live as

monogamous pairs with offspring

Old World Monkeys Much more variety in morphology and behavior

than New World monkeys

They have downward facing noses and are called catarrhine

                                               

                                               

Juvenile colobus (left) and

Francois's langur (right)

                                               

                                               

Juvenile colobus (left) and

Francois's langur (right)

 subfamily:  Cercopithecinae Colobinae

species:  baboonsguenonspatas monkeysmacaques

colobuslangursproboscis monkeys

Only one recognized family: Cercopithecidae Two subfamilies: cercopithecines and colobines

Old World Monkey Traits

• The most widely distributed of non-human primates, ranging from tropical forests to semi-arid deserts and seasonal snow-covered areas in northern Japan.

• Most are quadrupedal and primarily arboreal, but some (like baboons) are well adapted to the ground

• Most hold their upper bodies erect for long periods of time while feeding, sleeping, and grooming-associated with it is hard skin on the buttocks called ischial callosities-serve as sitting pads

• Most have a great deal of manual dexterityMost have tails that are used in both balance and communication.

Ischial callosities (gelada baboons)

Old World Monkey Traits

• Locomoton varies from arboreal to terrestrial quadrupedalism to semibrachiation to acrobatic leaping.

• Sexual dimorphism is typical of land species like baboons, with male weight (80 lbs.) often twice that of females

• Females often exhibit pronounced cyclical changes of the external genitalia with swelling and redness during estrus, a hormonally initiated period of sexual receptivity correlated with ovulation.

• Several types of social groups:Colobines tend to live in small gropups with only one or two adult males, whereas cercopithecines live in large groups with several adults of both sexes and offspring of all ages.

Female hamadryas  baboon in estrus

  (note the sexual skin)

Hominoids • Superfamily Hominoidea includes placed in the family• Hylobatidae: gibbons and siamangs (the "lesser" apes) • Pongidae: orangutans, gorillas, chimpanzees and bonobos (the

“great” apes• Hominidae: humans

Locations of Ape Habitats

Apes and humans differ from monkeys in many ways including:

• generally larger body size, except in gibbons and siamangs

• absence of tail • shortened trunk (lumbar area relatively shorter and

more stable) • differences in position and musculature of shoulder

joint (adapted for suspensory locomotion) • more complex behavior • more complex brain and cognitive abilities • lengthened period of infant development and

dependency

Hominoid Traits

Gibbons and Siamangs • Eight gibbon species are found in tropical areas of SE Asia. • Small, weighing 13 pounds for gibbon and 25 for saimang. • Extremely good brachiators due to very long arms,

permanently curved fingers and powerful shoulders. • Mostly a fuit diet, supplemented by leaves, insects. • Social unit is monogamous pair and offspring.

• Both males and females are highly territorial.

Gibbon

Siamang

Orangutans • Represented by two subspecies in heavily forested areas of

Indonesian islands of Borneo and Sumatra. • They face extinction due to poaching and diminution of their habitat. • The are slow, cautious climbers who use all four limbs for locomotion. • Almost completely arboreal, but do travel quadrupedally on ground for

short distances. • Very large animal that may weigh 200 lbs. for males, 100 for females. • They are frugivorous, but supplement with leaves, insects and some

meat.

Gorillas• The largest of all living primates,

now confined largely to forested regions of central Africa.

• Two varieties: lowland and highland.

• They exhibit marked sexual dimorphism with males up to 400 pounds and females at 200 pounds.

• Weight makes them primarily terrestrial, and semi-quadrupedal knuckle walkers.

• Family groups consist of one or more large silverback (due to white hair patch across back) males, a few females and subadult offspring.

• They are not the King Kong stereotype, but are gentle, shy vegetarians.

• Males will display when provoked, and may attack to defend their group.

• Probably only 40,000 lowland and 620 highland left due to poaching and habitat problems.

Chimps • Best known of the non-human primates.• Structurally similar to gorillas, but

ecological adaptations differ. • They are mostly terrestrial knuckle walkers,

but also can brachiate in trees. • May walk bipedally for sort distances. • Chimps are highly excitable, active and

noisy. • Males are about 100 pounds and females

around 80.• They tend to live in flexible communities of

as many as 50 individuals. • They are very territorial.

• They are omnivouous, and even hunt communally to kill small mammals and even

other chimps.

Bonobos • Found only in limited area of Zaire

River, they weren't recognized as separate from chimps until the 1920s.

• Least studied of the great apes. • They are "pygmy" chimps due to

small size, but some claim this is not warranted in that size can be as large as most chimps.

• They have a more linear build. They are more arboreal than chimps, but less excitable and aggressive.

• Little physical violence.

• We know little about them though

recent work by de Waal is intriguing.

Chimpanzees & Bonobos

Our closest relatives

Why are they so different?

Genetics • Karyotyping of apes has not demonstrated the evolutionary

sequence• Suggests that humans and chimps share a more recent

ancestry after splitting from gorillas.• Despite 99% similarity at the level of DNA sequence between

humans and our nearest relative, chimpanzees, the locations of DNA swapping between chromosomes, known as recombination hotspots, are nearly entirely different.

• More controlled study may clarify.

HAS=Human, PPA=Chimpanzee PPY=orangutan GGO=gorilla

Human