1.5: Characteristics of Primates

Role of Primatology in Anthropological Studies

Introduction – it has been questioned about its presence in Anthropology. Has been the black sheep of the family of anthropological studies.

likely reason for question – stems from its historical association with sociobiology during 1980s & 1990s.

Primatology – Primatology is the scientific study of behaviour, biology, evolution & taxonomy of (non-human) primates especially other than human (Homo Sapiens)

Primates includes dozen of animals such as gibbons, baboons, apes, monkeys, bonobos & many more.
Primatologist often conduct filed research – studying primates in their natural habitat o laboratory analysis.

Why it is in Anthropology – As anthropology is a holistic study of man & man is a member of order primates, study of primatology is very much essential in anthropology. As these are out close relatives, Primatologist believe that by studying primates we can come closer to understanding human evolution & behaviour.

Role of Primatology in Anthropology

To understand biological relationship b/w living & ancestral primates
Study of primate behaviour to understand human behaviour more clearly.
Anthropology is based on holistic comparitive approach
- a comparative approach in primatology can move beyong a reductionist view of speices behaviour by identifying variations of behavior b/w populations within a species.
Since primates are our closest non human relatives, their morphology & biology is highly relevant to study of human evolution.
Study of primate social intelligence, individual decision making & behavioural strategies to better understand human social & cognitive abilities.
As Anthropology stresses the significance of cultural adaptation & social flexibility, the study of primate flexibility & social commplexity can help anthropology understand human cultural / social evolution clearly.
Comparative morphological study of man & non human primates complemented by biochemical analysis provided major clones to human bipedalism, dextrin hands, bulbous head & jaw.
Wide range of adaptation of non-human primates helps in understanding human erect posture & bipedalism
Free ranging primates exhibit true of physical & behavioural adaptaions which resemble that of human Pleistocene predecessors.
Laboratory & field observations show similarities b/w cognitive abilities of great apes & Pleistocene predecessors.

Some Case Studies from Primatology

Jane Goodall – notable primatologist & Anthropologist – study of social life of chimpanzees in Tanzania.
- Demonstrated complex social life of chimpanzees, citing their emotional depth, social hierarchies & intelligence
Robert Sapolsky’s book APrimate‘s memoir
- Us vs they feel based on territorial division
- Evidences Chimp genocide & patrolling
- Understanding of Theory of Mind (1°)

Conclusion – As these primates are non human closed relatives, by studying them we can come closer to understanding human evolution & behaviour. A lot of research has been done, also significant one – how the understanding of primates behaviour – can help human to go beyond Us vs They discrimination.

Primates

Primates – The order primate is mainly tree dwelling or arboreal. As a result they have experienced changes in almost all organ systems which has been modified due to arboreal life such as locomotary organs, nervous system, sense organs etc. All these changes are unique to them which can’t be found anywhere in the animal kingdom.

Primates belong to subclass of mammals that show the presence of placenta

Example & Distribution – Primates includes dozen of animals such as gibbons, baboons, apes, monkeys, bonobos & many more.

Tree shrews are found in India & east Africa
Lemurs of Madagascar
Lorises of Tropical Africa & Asia
Tarsiers of East Indians
The new world & Old world monkeys, the anthropoid apes & Man.

Features of Primates

General Mammalised Features : – These features are present in all mammals

Physiological & Anatomical
- Warm blooded – homeothermy
- Four chambered heart
- presence of sweat & sebaceour glands
- Differentiated teeth – 4 types
- +nc of diaphragm which separates body cavity into anterior thorax & posterior abdomen
- +nce of external ear pinna
- Aeucleated & circular RBCs
- vivipary, the development of young ones take place in uterus
Behavioural
- A pair of pectoral mammae & suckling of young ones with breasts
- Learn by trail & error.
- Social relation b/w mother & offspring

Ancestral Features – Are those that were posed by the ancestors common to all primates

Pentadactlism – Five Fingered hand & five toe foot
Generalised Forelimb structure – Classical radius & ulna
Dentition – simple cusp pattern on the molar teeth
Flexible generalised skeleton
Pendulous Penis

Derived/ specialised Features – anatomical and behavioural features that have undergone change from ancestral state & that distinguish primates from members of other mammalian orders I.e Present in primates only

include a lack of strong specialization in structure;
Progressive development of truneal uprightness leading to habitual bipedalism.
Ability to grasp objects
- the hand & feet are prehensile for arboreal life. mainly b/c of independent mobility of digits & opposability of thumbs & large toe to varying degree (i.e great toes) (except in humans)
- Due to grasping habit – flattened nails instead of claws on the digits;
- +nce of planter pad on the sole of their limb provide larger friction for better grasping power.
- Well marked power grip & precision grip
Use of Forelimbs for exploration – for knowing objects, for gathering food & for putting food into mouth.
Present of Simple stomach d/t – Herbivorous & Frugivores nature & some are carnivores
Reduced use of smell
- As mostly arboreal & sense of smell is most imp on ground. So → Decreased size of olfactory centre
- Muzles & Snouts have also been smaller & dry nose
Development of great visual acuity : Grater decency on eye than upon nose ;
- acute vision with some degree of binocular vision; As in arboreal life precise info of direction, distance & depth is crucial.
- Most primate’s eyes are encased in bony socket, feature not found in any other mammalian skull
- in primates the eyes have become larger & orbits have become shifted from the comparatively lateral position to the front. consequently in anthropoida the optical axis is more or less parallel resulting in steroscopic or 3D vision.
Changes in the skull & Brain
- ↑ eye -hand coordination & manual dexterity has effect on brain & skulls.
- High brain to body ratio, highly developed & convoluted brain exciting a degree of cortical folding
- Why ?
  - Primates sit on branches & use forelimbs for a exploration resulting in shift of foremen magnum in downward & forward direction.
  - The frontal, parietal & occipital bones have greatly increase in size. D/t selective development of different lobes of brain.
  - arboreal life requires sound balance, for that cerebellum has increased greaty in size
  - ↑ in sensation & intelligence → ↑ cerebral hemisphere & associated lobes (differentiation of cerebral cortex)
Increased ability to adoption to diversified ecological conditions.
Longer growth & maturation period compare to others. Also Sexual maturity takes longer time to achieve
Year Round Sexuality
Testies descended into scortum
With some exception presence of two pectoral located mammary glands.
Longer gestation period (from 45 days in tree Shrew to 9 months in humans)
Reduction in no. of offspring at birth Primates don’t give birth to more than 2-3 offspring at a time. – In many cases a single offspring si born.
Post natal dependence – ↑ in period of infant dependency
- In primates, due to haemochoreal placenta & long uterine developemnt, after birth they are dependent upon maternal care
transmission of learned behaviour resulted in social organisation & is significant in most primates
Marked increase in life span.

No primate exhibits all these features, and indeed the diversity of primate forms has produced disagreement as to their proper classification.

Conclusion – Thus primates have some unique biological function which are the result of selective pressures of arboreal life. These features are unique to primates which are not found in any group of organism in kingdom animal. Among primates man is a cultural animals which can be rooted ot human biology.

Primates Evolutionary Trends

Introduction – What makes a primate a primate ? Defining primates like other taxonomical groups on the basis of morphological or anatomical characteristics is extremely difficicult b/c

Primates lack distinguishing bodily specializations like other mammalian groups
Primates exhibit amazing variety of forms & grades of organization – size, Habitat, Behavior etc.

The best & most useful solution to the problem of a definition was devised by one of the foremost primate anatomists, Sir Wilfred E. Le Gros Clark

he proceeds to characterize the order by a series of evolutionary trends.

Nature of Trends

Though there are ten trends , they are related to 3 principle areas
1. Limbs & extremities (1-3)
2. Head – eyes, brain & dentition (trends 4-8)
3. Life Cycle-reproduction, growth & longevity (trends 9&10)
These are trends not characteristics. Hence are not uniformly present, but are expressed to varying degrees among the members of the order.
As a rule, except for the first one, these trends are less well developed in the living prosimians & in fossil forms than in the more advanced, modern Higher Primates
They are all interrelated & adaptive to a mode of life which has been the outstanding factor in primate evolution – the arboreal habitat.
Other mammals have taken up arboreal life but none have done it in exactly the same way
Many of man’s characteristics are simply refinements of a basic primate pattern that evolved millions of years ago in response to the necessities of arboreal living.

Evolutionary Trends

The preservation of a generalized structure of the limbs like primitive pentadactyly, & the retention of certain elements of the limb skeleton ( Such as clavicle) which tend to be reduced or to disappear in some groups of mammals
- these features contributes to the great mobility of the limbs needed in climbing & grasping.
An enhancement of the free mobility of the digits, especially the thumb & big toe ( which are used for grasping purposes)
- most advanced digits in this respect are the thumb & great toe that are not only independent, but opposable in majority of primates.
The replacement of sharp compressed claws by flattened nails, associated with the development of highly sensitive tactile pads on the digits.
The progressive abbreviation of the snout or muzzle
The elaboration & perfection of the visual apparatus with the development to varying degree of binocular vision
Reduction of the apparatus of smell
The loss of certain elements of the primitive mammalian dentition ( 3:1:4:3), & the preservation of a simple cusp pattern of the molar teeth.
Progressive expansion & elaboration of the brain, affecting predominantly the cerebral cortex & its dependencies.
Progressice & increasingly efficient development of those gestational processes concerned with the nourishment of the fetus before birth
Prolongation of postnatal life periods.

Classification of Primates & Primate Taxonomy

Outline of primate classification is following

Kingdom : Animalia
Subkingdom : Metazoa (Multi-cellular)
Phylum : Chordata (Possess Notochord)
Sub Phylum : Vertebrata (notochord is covered by bones)
Class : Mammalia (Mammary Gland)
Subclass : Eutheria (having true placenta)

Primate Taxonomy (Order : Primates)

Primate Adaptation : Arboreal & Terrestrial

Primate adaptions Reveals their adaptations to territorial & arboreal life & survival.

Forelimbs –
- all primates have retained clavicle, radius & ulna in lower arm & pentadactlism.
- This permit a grater flexibility in the shoulder, forarm & hand
- Which faciltate movement thr the trees.
Flexible Skelton – Facilitate wide range of locomotive pattens both on treess & on ground.
Grasping by Toe – place an important role in arboreal insect predation.
- serves to differentiate early primates from early mammals.
Grasping Thumb – in many primates thumb has become truly opposable. It is important for manipulating objects (strength to hold)
Tactile Pads – it confers refined sense of touch that helps to convey information about the environment
Nose – In terrestrial mammals olfactory sense place a crucial role. But in arboreal env it doesn’t give useful information (exact direction & distance b/w two branches) → olfactory region of brain is reduced.
Eye
- Location of Eyes – On the front of the face permitting 3D -Steroscopic vision → helps in rapid movement
- Bony Eye Socket – To protect from physical damage due to arboreal life
- Vision –
  - most early mammals have 2D- Black & white vision with increased dependency on olfactory sense.
  - 3D & coloured vision developed in response to selective pressure of arboreal environment where precise information of direction & distance is crucial.
- Vision plays key role in primate communication.
Means of Communication
- They frequently used facial expressions, body postures as a means of communication apart from vocalisation,
Teeth – primates have fewer teeth than ancestral mammals. Primates teeth are relatively simple in structure.
Placenta – through placenta blood vessels of foetus & mother come into close contact & nutrients & other substances are supplied to foetus for growth & development.
Longer Life Span – It helps primates to adoption to different environmental cycles & to transfer the knowledge.
Longer gestation period & decency of offspring – helps in proper nutrition & development of offspring
Intelligence & Learning –
- place a important role in their great awareness about env & their abilities to manipulate their environment
- Much of primate adaptability is the result of behavioural adaptations that are learned thr large social units & long childhoods
Quadrupedalism – shown by monkey & ape when moving on ground and on branches. It is possible due to
- Small to moderate body size
- Prehensile big toe & opposable thumb

These helps them to be agile on tress.

Bipedalism – found exclusively in humans
- Adoption to terrestrial life due to drought in Miocene Period (lack of forest)
- It is achieved thr several changes in the skull & skeleton.
- Bipedalism helped man to use/ develop tools

Locomotory Adapaiton

The primates exhibits varied form of arboreal adaption & locomotory variation

Such as Vertical clinging, quadrupedlism & brachiation
Bipedalism is a terrestrial adaptation.

Why study Locomotion Adaptaion

Man’s full time, bipedal, upright locomotion is unique among the primates & its origins are unclear from the fossil recors
Further, most of the evolutionary developmentscan’t be fully understood by studing skeletons alone → so supplement by observation of living primates
A major contribution of studying living primates is functional anatomy
Two functional complexes that have received maximum attention are hands & feet – not very different as except man, every other primate uses both for locomotion.

Types of Locomotory Adaptation

Arboreal Adaptation

Vertical Clinging & Leaping
- Found – among Prosimians i.e Tarsier, Lemurs, Galagos etc.
- What – Leaping from one vertical support to another, using only hind limbs for propulsions . Ex
  - When animal is on rest, it is clinging to a branch keeping his body in vertical position.
  - While moving it leaps( jumps) landing on a second branch vertically.
  - On the ground they move by hooping. However vertical clinging & leaping are dominant locomotions.

Adaptations which made it successful
- tarsal bone of the foot – extremely long in Tarsiers.
  - The tarsal bone acts as an added spring in them
  - it is very small in man is
- Long hind limbs give extra edge.
Brachiation
- It is arboreal adaption ; found in lesser apes (only modified in orangutan)
- is a suspesory behaviour in which hands & arms as main locomotory organs.
- Primary adaptation for feeding at terminal ends of branches
- Adaptations
  - Relatively light body weight
  - Long arms with long fingered hands
  - Long opposable thumb is in the way & hence all brachiators have some means of getting their thumbs out of way during locomotion
    - Gibbon tucks away the thumb – since hands function as hooks.
- It is of two subtypes
  1. Primitive Brachiation
    - Progression is accompanied by swinging the body from one handhold to another : Use both hands alternatively
    - Turn 180° While moving through a branch.
  2. True Brachiation
    - found in lower apes i.e Gibbon & Siamang
    - In this case there is flight in air. → animal jumbs from a branch to another branch of tree.
    - In such cases both hands are used.
  - Modified Brachiation
    - Found in Orangutan
    - Involves arm swinging with feet used for support, climbing & hanging
    - The orangutans are really cautious climbers than brachiators & climb using any combination of their four grasping extremities.
Quadrupedalism
- Found – in monkey & ape – on ground & on branches of trees
- It involves both fore & hind limbs
- Types – differ mainly in the degree to which climbing, leaping & swinging are employed in addition to quadrupedal running or walking.
  - Arboreal Quadrupedalism
    - Adaptations
      - Reduction in index finger / thumb
      - Big toe splayed out at a wide angle – forceps to enclose a branch
      - Short and broad trunks – COG
      - Fore and hind limbs are of equal length
      - Prehensile hands & feet – to grasp branches
      - N.W.M. – Long Prehensile tails
    - Subtypes
      - Slow Climbing – these combine slow climbing & deliberate movement with a powerful gri
        
        eg. Lorises, Pottos
      - Branch Running & Walking – walking or running along the tops of branches ; climbing & leaping also seen (for gaps)
        
        tree shrew & marmosets (hold branch by claws), some Lemurs etc
      - Old World Semi – Brachiation – Arm swinging combined with climbing, quadrupedal walking & leaping
        
        Colobus monkeys, Langurs
      - New World Semi – Brachiation
        
        Along with OW Characterises + also used to suspend prehensile tail.
        
        Howler, spider, wooly & wooly spider monkey 🐒
  - Terrestrial Quadrupedalism – Apes
    - Two subtypes
      1. Ground Running & Walking – Baboons & patas Monkey
        
        Quadrupedal walking & running on soles & underside of fingers
        
        limbs of equal length
        
        all fingers of equal length – allows more precision grip
      2. Knuckle Walking – Chimpanzees & Gorillas
        
        2° adaptation to ground living – quadrupedal walking & running on soles & backs of curled fingers.
        
        Adaptation b/c of large body size but at the same time retaining arboreal features like long arms & long fingers & short thumbs like their brachiating ancestors.
        
        Elongation of pelvis
        
        Head of femur – not forming an angle with shaft – restricts the movement of the leg
        
        habitually bent knee
        
        whole foot making contact with surface

Examples

Monkey – Arboreal & terrestrial quadrupedalism
Apes – terrestrial Quadrupedalism
Chimpanzee do climb & brachiate in trees while feeding, but return to the ground & knuckle walk when traveling.
In Orangutan 🦧 – Palm & fist 🤛 walking

Terrestrial Adaptation

Bipedalism
- Evolved some 4 mya due to drought in Miocene period ; The reasons for this adaptation are unknown & speculative
- What – Hind limbs alone support the body weight & propel it along the groud
- Exclusively found in Human, in adaptation to terrestrial life,
  - Other primates have come to the ground but none taken to bipedalism
  - though the tendency to occasional bipedalism can be seen in other primates, the structural adaptations seen in human is extraordinary
- The essential factors in upright posture
  - reorientation of the body with respect to gravity & this necessitates many skelatal, muscular & visceral changes.
- Changes to support bipedalism in human anatomy
  - involved a number of structures – head, foot, pelvis, knee, leg, vertebral column, musculature etc.
- Modifications for adaptation
  - Flexible skeleton – give wide range of locomotive patterns both on trees & grounds
  - Grasping big toe & opposable thumb – important for manipulating objects & gives strength to hold
  - Claws have evolved into nail in most primates
  - Tactile pads : Fingers of primates have tactile pads. act as frction pads while walking & offer refined senee of touch that help to convey info. about the env.
  - Nose ; in terrestrail mammals , olfactory sense plays a crucial role. Smell is relatively unimportant in the trees
  - Eyes ;
    - On fron of face, they provide 3D vision (Stereoscopic)
    - Mostly encased in bony eye sockets
    - 3D vision improves accuracy during movement in trees.
- main advantages
  - it frees hand , so can be used in carring & manipulating objets such as tools.
  - it give rise to culture in human beings which distinguishes it from other primates.

Primate Behaviour

Study of Social behaviour of non-human frimates gives us an idea about behaviour of our ancestral hominid before emergence of culture.

Non human primates have a wide ranging behaviour depending upon the composition of their social groups and on the environment in which they are inhabiting
Social Organisation
- Except orangutan and some prosimians, most of the non-human primates live in stable group
- The basic pattern of Social group compositions:
  - Single female and her offsprings group
    - found among Orangtun in this group are adult male normally lead their lives alone..
  - Adult male, female and offsprings
    - It is common pattern. among gibbong, titi monkeys.
  - One female, many adult male & offspring
    - extreamly rare type, reported in tamarins.
  - One male, Several female group.
    - Can be called as Polygynous grioup
    - most common in Baboons, Langurs, Gorillas 🦍
Distribution of food and the threat of predators influenced the extent of Society and Social interaction.
Primates confine their day to day activities to a particular area called home range
- It is divided based on the need of the group. Ex – Dietary needs.
- most primates defend their home range when other groups of their own species entered their home range.
- Ex -Specialised territorial defensive behaviour found among Hawler monkeys & gibbon.
- Lemurs mark their woodland territory with Chemicals produced by wrist glands.
Apes Spend time for grooming, playing and even fighting apart from feeding and resting.
Grooming apart from serving as hygienic function by removing dirt & Parasite, Provides friendly Contact and reinforces Social bonds among primates.
Sitting close to each other, touching and mutually grooming also reduces group tensions. (allogromming)
Communication
- Apes and even monkeys are capable of Symbolic Communication and hence not dependent on Language.
- They Communicate through.
  - Sound (vocalization)
  - Visual message (facial expressions, gesture)
  - Olfactory Signals
  - Touching & grooming
- Facial expression of non-human primates convey to other members their psychological state such as fear, threats, grinting, danger, pain, hunger & Courtship.
- Displays like yawning, ground slaping, branch shaking, Screaming, hoops, head bobbing and bouncing also been noted in case of non-human primates.
- Communication by Smell is prevalent among Prosimians as they have excellent olfactory Sensing ability.
  - Olfactory Signals come from urine, feces, Saliva, genital and other glands.
- Lemurs mark their woodland territory with Chemicals produced by wrist glands.

Tertiary & Quaternary Fossil

Introduction: The fossil remains of Tertiary Period were studied by various anthropologists and palaeontologists as it threw light on the understanding of the origin and evolution of primates. On the basis of these fossils, gross structure of the body of human being can be reconstructed, but at the same time its behavioural patterns can also be suggested. The fossil primates of the Tertiary period are mostly represented only by teeth and fragments of jaw and in some cases parts of skull.

It is extremely important to interpret primate evolution within the context of the earth’s changing environment (changing geography & climates

K-T Extinction took place around 65 mya

Adaptive Radiation in Primates –

The first radiation of the primate order has its roots in the beginning of the explosive adaptive radiation of placental mammals in general.

Fossil primates & Tertiary Period are classified as follows.

late Cretaceous & early Paleocene Primates

The earlies discovered traces( Several teeth & jaw) – in Dakota area of North America of Puragatorius
bulbous cusp pattern in molar teeth, instead of sharper cusps (which is seen in insectivores)
indicate early primates were adapting to fruit & leaf eating diets or perhaps a diet also including insects exploited in an erboreal niche.
by reconstruction – dental formula is still of primitive mammal : 3-1-4-3

Paleocene Primates (Middle) (65my-53my)

first clearly recongizable primates begin to diversify -i.e middle of palaeocene epoch.
Geographical Distribution – Mountainous regions of North America(Most) & France in Europe (Few)
Most of the remains consist of teeth & frgments of jaw
grouped into three families
1. Carpolestidae
2. Phenacolemuridae
3. Plesiadapidae (Best Known)
  - fossils comprise of whole fossil skull & other parts of limb skeletons
  - found in Europe & America known from the late Paleocene
  - they ranged from from that of a squirrel to domestic cat.
  - on basis of the dental characters these Palaeocene fossil animals have been included under the order primate
  - show definite primate tendencies
    - dependence on vision (not completely binocular)
    - flexible wrists & akles (though still probably with claws
    - unusual specializations of their front teeth
      - large & procumbent (angle forward)
      - also show dental oddities.
  - but retain numerous primitive charactersistics
    - lack of postorbital bar – (Pb serve to form a bony division b/w the orbit & Brain case.)
they are more primitive than any living primate & can be described as prosimian or even proto prosimian

Eocene Primates (53 my- 37my)

primates of modern aspect & were true primates , can clearly c/a prosimians & closely resemble the loris/lemur & tarsier evolutionary grade.
Geographical distribution : N. America & Parts of Europe & Asia.
primate characteristics in anatomical traits
- show complete postorbital bar,
- large brain & larger, rounder brain-cases
- bigger eye than Palacocene time, rotated forward & enlarged orbits , alllwoing operlapping filed of perception & thus binocular vision.
- reduced snout
- nails instead of claws
- foramen magnum was situated toward the front of base of the skull
- prehensility is suggested in limb skeleton
they were like lemurs in anatomical plan but don’t show the same specialization seen in contemporary lorises & lemurs, such as dental comb
- Projecting lower incisors & canines forming a str. used for grooming & hence c/a dental comb.
Five families
1. Adapidae (Best Known)
  - first discovery in France in 1821 by Cuvier
2. Anaptomorphidae
3. Microsyopidae
4. Omomyidae
5. Tarsiidae

Oligocene Primates (37-35 my)

very few fossil remains have been discovered from oligocene epoch
Geographical distribution
- most from Africa, & in it all from Egypt
- none from Europe, speciments from America are also rare.
Egyptian Varieties include Parapithecus, Propliopithecus, Macropithecus, Oligopithecus, Aeolopithecus, Aegyptopithecsus etc.
Parapithecus( Apidum): Features
- represented by lower jaw & some teeth found
- Location : Fayuro, Southwest fo Cario in Egypt
- The owner of the jaw was very small animal attaining the size of a little squirrel monkey of today.
- The shape of the jaw is more or less like that of a Tarsier.
- The teeth dental fomula was 2,1,3,3. – reveal an extra premolar not found in contemporary Old world anthropoids.
- the teeth suggest a diet composed of fruits & perhaps some seeds.
- limbs remains indicate that this creature was a small arboreal quadruped, adept at leaping & springing.
- Parapithecus is considered as an intermediate form b/w prosimians & anthropoids
Propliopithecus
- represented by incomplete lower jaw with its teeth but without the ascending ramii.
- location : Fayum, southwest of Cario in Egypt
- considered to be primitive anthropoid ape & to be closely related to the gibbon.
- the jaw was somewhat deeper, shorter & more pointed than the jaw of modern gibbon. The canines were not so big. the jaw was about the size of that of a small gibbon.
- Dental formula 2,1,2,3 – The reduction in the no. of the premolar suggests shortening of muzzle & jaw.
Aegyptopithecus
- most complete & evolutionarily most significant fossil from the fayum
- It is largest of the Fayum anthropoids & of size of modern howler monkey
- it bridges the gap b/t the Eocene prosimians on the hand & Miocene hominoids on the other & it brain(40 cc) is also in b/w two.
  - visual cortex was large compared to prosimians.
  - with concomitant reduction of the olfactory bulbs
  - but frontal lobes were not especially expanded.
- dental formula 2-1-2-3 (old world anthropoid pattern)
- skull (primitive than teeth) resembles the skull of monkey in some detail.
- from analysis of limb proportions & muscle insertions, → short limbed, heavily muscled, slow moving,arboreal quadruped
- anatomy -speculation about social behaviour
  - dental remains from different individuals, vary greatly in canine size
    - implies male/female differences (sexual dimorphism)
  - male may be competing for female
  - mating pattern was probably polygynous.

Miocene(22.5 -5 my) – Pliocene Primates

considered together, there seems continuity of certain lineage of Anthropoidea during these two epoch
from this period fossil remains of several Hominoid forms, besides that of Cebidae, Cercopithecidae & Lorisidae have been found from different part of Asia, Europe & Africa (old world 22-7 my)
E.L Simons & David Pilbeam lumped the vast majority of the Miocene forms into only two genra ; one presumably quite Pongid like & other hominid like.
form East African Miocene deposits : Limnopithecus, Epipliopithecus & Prohylobates
Pliopithecus
- fossil ape represented by an incomplete mandible discovered in Europe
- it is a gibbon like animal in respect of ,- teeth, narrow snout portion, wide set eyes
- but resembles like monkey in some proportions – upper limb, spinal column & general body proportions
Dryopithecine
- time period : Miocene & Pliocene epochs
- G. D: Europe, East Africa, Middle East, China & some site of India
- as, in most of the cases lower jaw & teeth of this extinct type have been discovered.
- Their phylogenetic relationships are determined on the basis of dental anatomy mostly .
  - Gregory & Hellman studies their dental characters
  - they believed that they were the common ancestory of the living anthropoid apes & man.
  - but some of them show such dental characters which would require a slight modification to produce human charactersitics of dentition.
  - Gregory, Hellman & other are of opinion that Dryopithecine primates were on a distinctly infra-human grade of evolution.
- can be grouped under two major headings
  - Dryopithecinae (Sub-family of the pongidae) – include two groups
    - Dryopithecus
    - Gigantopithecus
  - Ramapithecus (group assigned to family Hominidae) also includes
    - Brahmapithecus
    - Kenyapithecus
- Dryopithecus
  - known from some teeth & jaw bone
  - from Miocene & Pliocene deposits of Europe & the siwalik hills of India.
  - Now remians from different parts of Europe, Africa & Asia( India & China)
  - there is definite pattern, k/n as Drytopithecus pattern(Y5), in the arrangment of the cusps of the lower molar teeth. total 5 cusps
    - 2 towards tongue side & 3 towards cheek side.
    - these are so separate that it forms a Y
  - anthropologist are of opinion that Dryopithecus are most likely ancestors of the modern ponginae i.e gorialla & chimpanzee
- Proconsul
  - time : Early Miocene
  - G.D : East AFrica & Uganda
  - remain discovered by Leakey , show considereable variation in size & features.
  - 3 species
    - Procosul africanus,
    - P. major
    - P. nyanzae
  - it may be regarded as African variety of Dryopithecus b/c close resemblance.
  - Simons & Bilbeam prefer to call them by the names Dryopithecus africanus, D.major & D. nyanzae respectively
  - they are regarded as ancestral to both the pongidae & Hominoidae.
    - D. africanus thought to be ancestory of chimpanzee
    - D. major of gorilla
- Sivapithecus
  - fossil remains of Sivapithecus from Tukery & India-Pak are the most clearly derived large-bodies hominoids we have from whole Miocene
  - Sivapithecus has several derived features of the face, linking it evolutionarily with the Orang.
  - except face & jaw they are not like Orangutan.
  - these differe morphologically from Proconsul or Dryopithecus in its dentition & facial anatomy.
  - they were probably fruit eater.
  - Researchers now simpy lumb Ramapithecus(earler thought as first hominid of middle miocene k/n from mostly from India & some bits from East Africa) with Sivapithecus.
- Other example
  - Kenyapithecus (Ramapithecus of East Africa)
  - Gigantopithecus (Hong Kong, South China)
  - Oreopithecus (Tuscany, North Italy)

Separation of the Asian large bodied hominoid line from the African stock (leading ultimately to gorillas, chimps & humans) thus occured at least 12 mya

The Thickness of the enamel cap has played a significant role in recent interpretations of Miocene hominoid evolution.

enamel is also seen in early hominids(4-1mya) in Proconsul & Dryopithecus
Among livign hominoids, relative to body size, humans have by far the thickest enamel caps.
Gorillas & chimps have thin enamel
Orangs descived as moderately thick

Conclusion – If the Eocene was the age of prosimians & the Oligocene the time of great diversity for early anthropoids, the Miocene was certainly the epoch of hominoids.

Living Major Primates

Comparative Anatomy of Man & Apes

Both apes & humans belongs to same order primates. Both belong to the saborder anthropoidea. However, they belong to different families. Following are the differences between

Skeletal Changes Due to Erect Posture & its Implications

The morphological alterations to the human skeleton that have occurred since the first bipedal hominid include changes in foot bone arrangement & size, hip size & shape, knee size, leg length & vertebral column shape & orientation.

Quadrupedal Ape Skeletons & Adaptations for Bipedalism

The Human Foot

Redesignes as a platform to support entire body weight rather than a grasping structure
Reduction in size of toes
Development of two arches to support weight
Axis of the human foot lies between big toe & first toe
Transference of weight from the heel, along the outside of the foot, across the ball of the foot, and finally through the big toe – conserves energy during locomotion

Hip

Shorter & broader than quadrupedal ancestors – to support more weight
Pelvic region has become basin shaped to support vertical weight transference
The alteration in shape brought the VC closer to the hip joint, providing a stable base for support of the trunk while walking upright.
Three muscles, gluteus maximus, gluteus medius & gluteus minimus stabilize pelvis
Ischium, a pelvic bone, flattened allowing humans to sit comformtably
The shape change of the hip may have led to the decrease in the degree of hip extension, an energy efficient adaptation.

Kness

Knee joints have enlarged to support increased body weight
Degree of knee extension – angle b/w thigh & shank reduced ( hence no bend knee posture)
Double Knee Action reduces energy during walking – when we walk, the thigh is bent inwards & knees straight so that knees are almost directly under the body, rather than out to side.

limbs

Femur orientation
increase in leg length
puss in walking comes from the leg muscles acting at the ankle.
A longer leg allow the use of the natural swing of the limb,

Skull

Skull balanced on vertebral column
Foramen magnum located inferiorly, which puts weight of the head behind the spine
Flat human face helps balancing on two occipital condyles
Thus, without strong supraorbital ridges & muscles of forehead ( occipitofrontalis), we are able to balance the head
We use these muscles only for facial expressions

Vertebral Column

The vertebral column of humans takes a forward bend in the lumbar ( lower ) region & a backward bend in the thoracic ( upper) region.
Typical S-curve
The curves help conserving energy while also help transferring the weight & CoG directly over the feet
Also, the degree of body erection ( the angle of body incline to a vertical line in a walking cycle) is signigicantly smaller to consrve energy
Fusion of Sacral Vertebre
Vertebrae from top to bottom gradually increase in size for better load bearing giving human column its characteristic cone shape

Evolutionary Consequences of Bipedal Functional Anatomy

Some features of humans are still poorly adapted to bipedalism leading to negative implications
lower back & knee are susceptible to osteological malfunction
This is because the human body weight is now supported by joints of two legs rather than four legs
Vertebral arthritis was discovered in paleolithic hunter gatherers too – shows its not a civilization problesm

Why Bipedalism

Tool Use – Darwin & Washburn
Energy Efficiency – Isbell / Young
Body Temp – Wheeler
Habitat Varibility – Potts
Reproduction – Lovejoy
Canine Reduction – Jolly

Name & Picture	Distribution	Features	Behaviour
Lemurs	Madagascar, Africa, South & East Asia & South India Eg. – Aye- Aye, lemur & Tree shrew	❖ Lateral eyes ❖ forelimbs shorter than hind limbs ❖ Duplex uterus	❖ Arboreal ❖ diurnal ❖ Live in groups
Loris	Sri Lanka, Africa, South India E.g Slow Loris, Bush baby	❖ No tail, ❖ 2nd toe with claw ❖ First premolar looks like canine	❖ Arboreal ❖ Nocturnal ❖ Solitary & shy PIc – Slow Loris
Tarsiers	Philippines, Celebes E.g Tarsius	❖ Large pinna ❖ Large eye ❖ Elongated tarsal bone → so the name❖ Size of rat ❖ Non prehensile tail ❖ Eye heavier than Brain	❖ carnivores ❖ solitary ❖ Nocturnal ❖ Arboreal ❖ It can rotate head by 180 degree
All the above three belong to Prosimians sub order. They are lower primates with small body size like squirrels, mostly have tail & live in small bushes.
New World Monkey	Tropical forests of central & South America, Mexico E.g Cebus, spider monkey, wooly monkey	❖ Flat nose ❖ Fave prehensile tail❖ Thumb is either completely absent or vestigial	❖ Usase hands for swinging on threes❖ tail as 5th limb ❖ Arboreal ❖ Diurnal
Old world Monkey	Asia, Africa & absent in Europe E.g colobus, langurs, baboons, Rhesus monkey	❖ Prominent nose❖ Have check pouches For storing food for later mastication ❖ Baboons sexual dimorphism	❖ arboreal ❖ Territorial ❖ Lives in group
Apes
Gibbon – swift swinger	Tropical rain forests of south east Asia Gorilla – largest & most powerful Chimpaanzee – arms & legs of same length	❖ smaller apes (< 3 feets) ❖ Arms are extremely long for swift swinging	❖ Monogamous family ❖ Arboreal ❖ They walk on two legs
Oranguta 🦧	mostly in islands of Borneo & Sumatra	❖ height – ~ 5 feet ❖ Prominent beard & mustaches ❖ filthy cheek, reddish brown hair	❖ Arboreal ❖ Marked sexual dimorphism ❖ Diffused social org.
Chimpanzee	tropical forest of Africa	❖ Height ~ 5 feet❖ Body is covered By course hair❖ Semi -quadrupedalism	❖ intellectual skills & ability for planning ❖ Sometimes bipedalism ❖ Arboreal ❖ Grooming & social commutation ❖ Organised hierarchy of dominance
Gorilla 🦍	only in Africa (equatorial region)	❖ largest of all primates ❖ Massive skull ❖ enormous supraorbital	❖ terrestrial ❖ Semi – quadrupedalism ❖ Group living ❖ Diurnal ❖ Dominance hierarchy ❖ vegetarians
Man			❖ Bipedal❖ Omnivores ❖ Live in group ❖ Has culture & Lang❖ Vertebral column ❖ Tool making etc `

Features	Human	Apes (🦍 & Chimp)
Geographical Distribution	All over the world	From above for respective species
Skull 💀 – Anatomical
Diagram
Cranial Capacity Range	1300 – 1450 cc	128 cc – 600 cc ❖ Chimp – 400 cc❖ Gorilla – 500 cc
Cranial vault	is arched & dome like	is flattened
Sagittal Crest (attachment for jaw muscles)	Not much developed – i.e segittal region is flattened	very well developed
Occipital Region	bulging	Flat & Receding
Foramen Magnum	placed anteriorly on the base of skull – exactly in centre	placed posteriorly towards dorsal side
Facial Skeleton	Cranial more developed than facial skeleton	Facial skeleton is more developed than cranial skeleton
Types	is Orthognathous, Jaw are reduced	is prognathous type, lower jaw protruded
Facial Ange	is 90°	less than 90°
Forehead	well developed – vertically high & whole	poorly developed – small & receding box
Frontal Bone	– well arched & have tube tuberocities	I.e not well ached & tuberocities are not well marked
Orbit	larger, Eyes are close together	smaller, eyes are placed apart
Supraorbital Ridge	Reduced & separated	Prominent & like torous (fused) – massive
Cheek bones	Prominent	Poorly developed
Nuchal Bones	are reduced	are well developed
Jaw Muscles, Supra Orbital Muscles, Sigittal muscles, Nuchat Musscels	are well developed d/t bipedalism	are well developed d/t quadrupedalism
Nasal Bone	Prominent & Elongated	Depressed & Broader
Zygomatic Arch	Moderately developed	Well developed
Nasal Bridge	well developed	faintly developed
Jaw	Brain has developed at the expense of jaw	jaw developed at the expense of brain
size of Jaw	small	moderaly large
Maxilla	Is reduced	is protruded
Premaxila	is absent / Reduced	is present
Mandible	slender & light	large & massive, protruded
Chin	present	Absent
Teeth	Smaller	larger
No of teeth	32	36
Dental Formula is	2,1,2,32,1,2,3	2,1,3,3 2,1,3,3
Incesrors	are vertical & not broad	Are broad & slant
Canines	are normal	are longer & sharper
Canines Interlocking System	is absent	Present
Premolars & Molars : cusps	are blunt	have conical cusps
Dental Arch	Parabolic shaped	U- Shaped
Diastema	absent	present
Vertebral Column
curve	Pronounced	Little
No. Of curve	4 curves with 32 segments	curves are leaking
lumber curve	pronounced	little
Neck – Anatomy
Neck	Prominent	neck is Not properly prominent
Neck Muscles	are weak due to which humans can rotate neck up to 180°	Well developed & strong neck to proved balance to the skull
Thorax	is laterally compressed into “V” shape	is cylindrical & broad
Limbs
Arms	shorter than legs i.e Hind limbs are larger & also stronger d/t terrestrialisation	longer than legs & stronger due to arboralism
Linea aspeara	Present	Absent
Hand
Fingers	are shorter than palm b/c of bipedalism	Are longer than teh palm b/c of amoralism
Finger terminals	are round & smooth	are pointed & sharp
Phalanges (Finger bone)	are straight & cylindrical	are bend & curved
Thumb	is long & strong	is short
Angle b/w Thumb & index finger	Greater – very high	Lesser
Thumb muscle	are well developed	are weak
Hind Limbs
Femur	is bent/curved & platymeric	is straight & cylindrical
Femur angel b/w Head & shift	is 120°	Is very narrow in apes
Foot	Biarched	flatten
Heel	well developed	poorly developed
Toes	are short b/c of T –	Are very long b/c of A
Alignment of toes	all toes are towars the front	four toes are towards the front & great toe is separated
Big/ greater Toe	Non – opposable & very strong & well developed	opposable, but normal life other toes
Grasping power of Toe	human can’t hold branch with foot	Apes hold branch with foot
Ligaments	strong ligament are present b/w foot bones (meta tarsal)	either weak or absent
Pelvic girdle
Shape	Is short & bowl like (basin like)	is long & elongated one
Ilium	Ilium is reduced & fan like in humans	illim is long palte like
Morphological
No. Of species	1
Sexual Dimorphism	Marked	Lacking
Hairs	Coarse hairs	coarse Hairs
Behavioural
Locomotion	Terrestrial locomotion	Arborealism