Human Evolution AS 3.6 (91606)

Classification of the primates  Primates are distinguished by their adaptations to arboreal (tree) life.

Primate Skeleton  Feet – pentadactyl pattern of 5 digits. They are flat on the ground in plantigrade position.

Primate Skeleton  Feet – pentadactyl pattern of 5 digits. They are flat on the ground in plantigrade position.  Bones in lower limbs (radius, ulna, fibula, tibia) are separate for greater mobility.

Primate Skeleton  Feet – pentadactyl pattern of 5 digits. They are flat on the ground in plantigrade position.  Bones in lower limbs (radius, ulna, fibula, tibia) are separate for greater mobility.  Limbs are prehensile – they can grasp objects.

Primate Skeleton  Feet – pentadactyl pattern of 5 digits. They are flat on the ground in plantigrade position.  Bones in lower limbs (radius, ulna, fibula, tibia) are separate for greater mobility.  Limbs are prehensile – they can grasp objects.  Eye sockets – forward facing and are walled off behind by bone.

Primate Skeleton  Feet – pentadactyl pattern of 5 digits. They are flat on the ground in plantigrade position.  Bones in lower limbs (radius, ulna, fibula, tibia) are separate for greater mobility.  Limbs are prehensile – they can grasp objects.  Eye sockets – forward facing and are walled off behind by bone.  The clavicle is large – from its role in transmitting body weight from breastbone to arm when the hand is holding a branch.

Primate Skeleton  Feet – pentadactyl pattern of 5 digits. They are flat on the ground in plantigrade position.  Bones in lower limbs (radius, ulna, fibula, tibia) are separate for greater mobility.  Limbs are prehensile – they can grasp objects.  Eye sockets – forward facing and are walled off behind by bone.  The clavicle is large – from its role in transmitting body weight from breastbone to arm when the hand is holding a branch.  Skin on fingertips has ridges, increasing sensitivity.

Primate Skeleton  Feet – pentadactyl pattern of 5 digits. They are flat on the ground in plantigrade position.  Bones in lower limbs (radius, ulna, fibula, tibia) are separate for greater mobility.  Limbs are prehensile – they can grasp objects.  Eye sockets – forward facing and are walled off behind by bone.  The clavicle is large – from its role in transmitting body weight from breastbone to arm when the hand is holding a branch.  Skin on fingertips has ridges, increasing sensitivity.  Nails are present instead of claws – increasing support for the soft tissue.

Primate Skeleton  Feet – pentadactyl pattern of 5 digits. They are flat on the ground in plantigrade position.  Bones in lower limbs (radius, ulna, fibula, tibia) are separate for greater mobility.  Limbs are prehensile – they can grasp objects.  Eye sockets – forward facing and are walled off behind by bone.  The clavicle is large – from its role in transmitting body weight from breastbone to arm when the hand is holding a branch.  Skin on fingertips has ridges, increasing sensitivity.  Nails are present instead of claws – increasing support for the soft tissue. 

Vision – distinctive in 3 ways 1. 3D vision – eyes face forward, overlapping visual fields give slightly different pictures. The brain compares them and judges distances.

Vision – distinctive in 3 ways 1. 3D vision – eyes face forward, overlapping visual fields give slightly different pictures. The brain compares them and judges distances. 2. Colour vision – photoreceptors are the cones. Apes are trichomatic (3 kinds of cones) = colour vision. Most other mammals are dichromatic (2 kinds) = red/ green colourblind.

Vision – distinctive in 3 ways 1. 3D vision – eyes face forward, overlapping visual fields give slightly different pictures. The brain compares them and judges distances. 2. Colour vision – photoreceptors are the cones. Apes are trichomatic (3 kinds of cones) = colour vision. Most other mammals are dichromatic (2 kinds) = red/ green colourblind. 3. Ability to see detail – monkeys and apes have a fovea (small sensitive spot at the back of the retina containing only cones). In the fovea, each photoreceptor has its own optic nerve to the brain = more detailed image.

Other characteristics  Smell – not so important as scent trails are often lost in the trees.

Other characteristics  Smell – not so important as scent trails are often lost in the trees.  Balance & kinaesthetic sense – well developed as well as the sensory position of each limb.

Other characteristics  Smell – not so important as scent trails are often lost in the trees.  Balance & kinaesthetic sense – well developed as well as the sensory position of each limb.  Brain – large in relation to body mass. Must be able to process sensory info rapidly from eyes, inner ear, and skin, as well as sending out info to the muscles.

Primate reproduction  Primates invest more energy into raising offspring than other mammals.

Primate reproduction  Primates invest more energy into raising offspring than other mammals.  Long gestation period, young are born at late stage of development = clinging onto fur.

Primate reproduction  Primates invest more energy into raising offspring than other mammals.  Long gestation period, young are born at late stage of development = clinging onto fur.  Single young are usual in monkeys and apes.

Primate reproduction  Primates invest more energy into raising offspring than other mammals.  Long gestation period, young are born at late stage of development = clinging onto fur.  Single young are usual in monkeys and apes.  Two uteri of most mammals has fused into one.

Primate reproduction  Primates invest more energy into raising offspring than other mammals.  Long gestation period, young are born at late stage of development = clinging onto fur.  Single young are usual in monkeys and apes.  Two uteri of most mammals has fused into one.  Young suckle at sitting position = mammary glands on the chest.

Social life  All social except for orang-utan.

Social life  All social except for orang-utan.  More eyes to detect predators and find food.

Social life  All social except for orang-utan.  More eyes to detect predators and find food.  Can learn from others and benefit from accumulated knowledge from group.

Social life  All social except for orang-utan.  More eyes to detect predators and find food.  Can learn from others and benefit from accumulated knowledge from group.  Easier to find a mate – inbreeding is avoided by young adults leaving the group. 