The fact that humans and other primates share many characteristics means that other primates provided valuable insights about early humans
Humans are more closely related to nonhuman primates than we are to any other animal species
Anatomical similarities among monkeys, apes, and humans led Swedish naturalists Carolus Linnaeus to place humans in the order Primates in the first scientific taxonomy, Systema Naturae (1735)
Humans were later placed in their own order because of out distinctive mental capacities and upright posture.
We share many aspects of morphology, physiology, and development with primates. I.e. Visual Abilities and Grasping Hands and Feet
Also, share an extended period of juvenile development and rimates as a whole have larger brains in relation to body size than members of most other taxonomic groups
Homologies in behavior as well b/c of physiological and cognitive structures that underlie human behavior are more similar to those of other primates than to members of other taxonomic groups
Nonhuman primates, therefore provide useful models for understanding the evolutionary roots of human morphology and the origins of human nature.
Primates Are a Diverse Order
Diversity within the primate order helps us to understand how natural selection shapes behavior
There is great morphological, ecological, and behavioral diversity among species within the primate order
Primates range in size from tiny mouse lemor (30 grams) to male gorillas weighing (350 lbs)
Some species live in dense tropical forests, others in woodlands and savannas
Some eat only leaves, other on an omnivorous diet, including fruits, leaves, seeds, gum, nectar, insects, small animal prey
Some actively defend their territory from intruders, others don’t
Some have only females that provide care, others have males help out
Evidence of diversity among closely related organisms living under different ecological conditions helps scientists understand how evolution shapes behavior.
Animals that are closely related to one another phylogentically tend to be very similar in morphology, physiology, and life behavior.
So, differences among organisms indicate adaptive responses to specific ecological conditions and similarities among more distantly related creatures living under similar ecological conditions are likely to be product of convergence.
Sexual Dimorphism- the observation that there are substantial differences in male and female body size-suggests that highly dimorphic hominids in the past were not monogamous.
Features that Define the Primates The primate order is generally defined by a number of shared, derived characters, but not all primates share all of these traits.
Animals in primate order typically similar: thick coat of hair, four limbs, five fingers, but share these with all mammals.
So define in terms of DERIVED FEATURES
Definition of Primate Order:
Big toe on foot is opposable and hands are prehensile, so primates can use their feet and hands for grasping. Opposable big toe has been lost in humans
There are flat nails on the hands and feet in most species, instead of claws, and there are sensitive tactile pads with fingerprints on fingers and toes
Locomotion is hind limb dominated, meaning the hind limbs do most of the work and the center of gravity is nearer the hind limbs than the forelimbs.
There is an unspecialized olfactory (smelling) apparatus that is reduced in diurnal primates
The visual sense is highly developed, the eyes are large and moved forward in the head, providing stereoscopic vision
Females have small litters, and gestation and juvenile periods are longer than in other mammals of similar size
The brain is large compared with the brains of similarly sized mammals, and it has a number of unique anatomical features
The molars are relatively unspecialized, and there is a maximum of two incisors, one canine, three premolars, and three molars on each half of the upper and lower jaw
There are a number of other subtle anatomical characteristics that are useful to systematists but are hard to interpret functionally
Many primate species can perceive color and their eyes are set forward in the head, providing them with binocular, stereoscopic vision.
Binocular vision means that their fields of vision of the two eyes overlap so that both eyes perceive the same image
Stereoscopic vision means that each eye sends a signal of the visual image to both hemispheres in the brain to create an image with depth.
Trends are not uniformly expressed within primate order, some play more important roles in prosimian primates than in anthropoid primates
Prosimians include lorises and lemurs, and the anthropoid primates include monkeys and apes
Primates as a group have longer pregnancies, mature at later ages, live longer and have larger brains than other animals of similar body size do. These features reflect a progressive trend toward increased dependence on complex behavior, learning and behavioral flexibility within the primate order
“Intelligence as a way of life”
Teeth play a very important role in lives of primates: allows primates to process food and use as conflict when facing other animals.
Primatologits use tooth wear to gauge age of individuals, and use features of teeth to assess the phylogenetic relationships among species.
Paleontologists rely on teeth to identify and make inferences about the developmental patterns, dietary preferences, and social structure.
1) None of these traits makes primates unique (ie. Dolphins)
2)Not every primate possess all of these traits
Primate Biogeography
Primates are generally restricted to tropical regions of the world
The continents of Asia, Africa, and South America and the islands that lie near their coasts are home to most of the world’s primates.
Primates are mainly found in tropical regions of the world where fluctuations from day to night greatly exceed fluctuations in temperature over the course of the year.
A Taxonomy of Living Primates
Primates are divided into two groups: the prosimians and the anthropoids
Many of the primates Prosimii are nocturnal and have adaptiations to living in darkness including a well-developed sense of smell, large eyes, and independently movable ears.
By contrast, monkeys and apes who make up Anthropoidea evolved adaptations more suited to a diurnal lifestyle. In Anthropoidea, traits related to increased complexity of behavior are most fully developed
Classification of primates into prosimians and anthropoids does not strictly reflect the patterns of genetic relationships among the animals in the suborders.
More traditional division into prosimians and anthropoids is an example of evolutionary taxonomiy in which overall similarity and relatedness are used to classify species.
The Prosimians
The Prosimians are divided into three infraorders: Lemuriformes, Lorisformes, and larsiiformes
Lemuriformes include lemurs and underwent adaptive raditation because faced with a diverse set of available ecological niches
Quadrupedal , arboreal, travel by jumping in a n upright posture from one tree to another known as vertical clinging and leaping
Some lemurs are nocturnal, some are diurnal
Female lemurs control male lemurs, dominant.
Lorisiformes comprises small, nocturnal, arboreal residents of the forest of Asia and Africa. Galagos are active and agile, leaping through trees and lorises move with deliberation (have adaptation of with specialized network of blood vessels that allows them to remain immobile for long periods of time)
Tarsiiformes includes tarsiers which are enigmatic primates who live in the rain forests of Bronea and the Phillipines.
Tarisers are small, nocturnal, and arboreal and move by vertical clinging and leaping.
Tarsiers are only primates who rely exclusively on animal matter, deeding on sects and small vertrbrate prey.
The Anthropoids
The suborder Anthropoidea contains the infraorders Platyhrrhini and Catarrhini
Platyrrhini-New World monkeys
Catarrhini- Old World Monkeys and Apes
The infraorder Platyrrhini (New World Monkeys) is divided into two families: Callitrichidae and Cebidae
New World monkeys encompass considerable diversity in size, diet, and social organization, but they do share some basic features. All except aotus are diurnal, all live in forested areas, and all are mainly arboreal.
Most new world monkeys are quadrupedal, moving along the tops of branches and jumping between adkacent trees. Some species of Cebidae can suspend themselves by their hands, feet, or tail and can move by swinging by their arms beneath branches.
Family Callitrichidae is composed of marsomets and tamarins.
They are extremely small, largest weighing less than 1 kg, they have claws instead of nails, only 2 molars, while all monkeys have three and frequently give birth to twins, and sometimes triplets
Polyandry
Cebid monkeys are generally larger than marmosets and tamarins .Family cebidae is divided into six subfamilies that encompass considerable diversity in social organization, deeding behavior, and ecology. The subfamiliy Aloutatinae is composed of several species of howlers
Subfamily Callimiconinae is compsed of just one species, Goeldi’s monkey.
Apotinae and Callimiconinae monkeys are small bodied fruit eaters and live in monogamous groups.
The infraorder Catarrhini contains the monkeyts and apes of the Old World and HUMANS
Cattarhine primates share number of anatomical and behavioral features that distinguish them from the New World Primates.
Most Old world monkeys and apes have narrow nostrils that face down, while New World Monkey have round nostrils.
Old World Monkeys have two premolars on each side of the upper and lower jaws, New World monkeys have 2 premolars on each side of the upper and lower jaws, New World Monkeys have 3. Most Old Wolrd Primates are larger than most new world species, and old world monkeys and apes occupy a wider range of habitats than new world species do.
Catarrhine primates are divided into two superfamilies:Cercopithecoidea (Old World Monkeys) and Hominoidea (Apes and Humans)
The Superfamily Cercopithecoidea encompasses great diversity in social organization, ecological specializations, and biogeography
Colobine monkeys are found in forests of Africa and Asia and are perhaps the most elegant of the primates
Slender bodies, long tails, and often beautifully colored coats
Colobines are mainly lead and seed eaters, and spend most of time in trees
Also, have complex stomachs which allows them to maintain bacterial colonies that facilitate the digestion of cellulose
Colobines are often found in groups composed of one adult male and an umber of adult females
Cercopithecine monkeys are found in Africa and more variable in size and diet than the colobines are. The cercopithecines consist of baboons, macaques, and ververts (just a few)
Typically remain in their natal groups, groups where they were born
The superfamily Hominoidea includes three families of apes: Hylobatidae (gibbons), Pongidae(oranguatans, and chimpanzees_ and Hominade (HUMANS)
Hominoids differ from cercopithecoids in a number of ways. Most readily observed difference b/t apes and monkeys is that apes lack tails.
Apes share some derived traits, including broader noses, broader palates, larger brains…
But they retain some primitive traits, such as relatively unspecialized molars
Old world monkeys: the prominent anterior and posterior cusps are arranged to form 2 parallel ridges.
Apes: five cusps on lower molars are arranged to form a side turned Y shaped pattern of ridges
Hylobatidae includes lesser apes (gibbons and siamangs) and living members are now found in Asia
Family pongidae includes larger bodied great apes (orangutans, gorillas, baboons, and chimpanzees)
Orangutans are found in Asia, while chimpanzees, bonobos, and gorillas are restricted to Africa
Humans in own family, *Hominade* but many taxonomists believe humans belong with other great apes in Pongidae
Lesser apes are slightly built creatures with extremely long arms in relation to their body size
Gibbons and siamangs are strictly arboreal and they use thei long arms to perform acrobatic feats
Gibbons and siamangs are the only true brachiators (propel themselves b their arms alone in free flight between handholds)
All of lesser apes live in monogamous family groups, vigorously defend their home ranges, and feed on fruit, leaves, flowers, and insects
Orangutans are among the largest and most solitary species of primates and feed primarily on fruit, leaves and bark
Gorillas, largest of apes are in isolation and live in small groups that contain one or two adult males and a number of adult females and their young. Eat a lot of plants and bamboo, and eat little fruit because fruiting plants are scare in their mountainous habitats
Adult male mountain gorillas called silverbacks play a central role in structure and cohesion of their social groups.
Males sometimes remain in their natal groups to breed, but most males leave their natal groups an acquire females by drawing them away from other males during intergroup encounters.
Humankinds closest living relatives are chimpanzees
Play an important role in study of human evolution.
Observations about chimps to be important bases for hypotheses about behavior of early humans
Bonobos are less well studied because they live in inaccessible areas
Chimps and Bonobos form large multimale, multifemale communities
Female chimps normally disperse from their natal groups when they reach sexual maturity, while males remain in their natal groups throughout maturity
Split up into smaller parties that vary in size and composition from day to day
In chimps, the strongest social bonds among adults are formed among males, while bonobo females form stronger bonds with one another and with their adult sons than males do
Chimpanzees modify natural objects for use as tools in the wild
Primate Conservation
Many species of primates are endangered by 1) habitat destruction, 2) hunting, or 3) live capture for trade and export
Nearly 100% of primate species are considered to be endangered or critically endangered, or are in real danger of extinction
Efforts to save endangered primate populations have met with some success.
Reading: B&S, Chapter 10
Evolution of the first mammals
Apes came from shrew-like ancestor
Important to understand geological climate and biological conditions under which evolutionary changes took place to understand why unique human traits were favored by selection
On major environmental change is the shifting of the continents (continental drift) - important for two reasons
Oceans serve as barriers between species
Position of continents affects climate
Much of our knowledge of evolutionary history comes from the fossil record
Radiometric methods for estimating the age of fossils
Potassium-argon dating: used to date volcanic rocks, potassium decays into argon at a known rate
Carbon-14 dating: carbon 14 decays into carbon 12 at a constant rate (measure ratio)
Thermoluminescence dating: (they better not test us on this)
Electorn-spin-resonance dating - used to determine age of apatite crystals in material like tooth enamel
Absolute radiometric dating supplemented by relative dating method based on magnetic reversals of the earth's poles and other fossils
One of driving evolutionary forces was the evolution of flowering plants, which created a new set of ecological niches. Primates evolved to fill these niches.
Angiosperms and gymnosperms
Ancestors of modern primates were small-bodied nocturnal quadrupeds like a modern shrew
Discovery of C. simpsoni with an opposable big toe with a flat nail, helps explain why natural selection favored the basic features of primate morphology
Likely that evolution of grasping hands and feet precede the movement of the eyes to the front of the face
Primates then radiated during the Oligocene, swampy forest
Primates appear in South America for first time in Oligocene, but unclear how they got there
Miocene period was warm and moist, then became cold and dry.
First evidence of adaptations for suspensory locomotion comes from Miocene fossils
Apes and monkeys differ in some features of their skeletal anatomy, dentition, brain size and life history patterns
Middle Miocene saw a new radiation of hominids and the expansion of hominoids throughout much of Eurasia
No clear candidates for the ancestors of humans or any modern apes, except perhaps orangutans
Ape species abundant during middle Miocene, monkeys were not. Many ape species became extinct and replaced by monkeys during the late Miocene and early Pliocene
Reading: Wrangham (African apes as time machines)
Evolution from chimp-like common ancestor
Based on cranial ontogeny, ancestor more chimp-like
Implications for behavior
Relevant relationship in phenotype and morphological evolution
Morphological evolution not always correlated with molecular clock
Reduction in aggression leads to reduction in sex dimorphisms and juvenile features in bonobos
Lethal raiding began 6 mya
Concealed ovulation 1.9 mya
Reading: Ruvolo (Hominoid genetic diversity)
Why compare humans to primates?
Human genetic diversity – no races or subspecies
Subspecies exist within primate species
Look at mitochondrial DNA because it’s maternally inherited and evolves faster
Genetic diversity within humans and how it arose – molecular clock
Gene flow after isoloation
Common ancestry – not enough time to develop differences
