Topic 13 Flashcards
distinguishing features of mammals
- three bones in middle ear
- some teeth made of canines, incisors, premolars and molars
- lower jaw a single bone
- milk producing mammary glands
- fur or hair over body surface
- diaphragm separating chest cavity from abdomen
primates characteristics
- bony brow ridge- increased sight
- large eyes at front of head- pointing forward- 3 D vision
- colour vision-increased perception of environment
- round face/short snouts- reduced smell dependence
- large brains compared to body, small area for smell, large area for vision- reduced dependence on smell, more on vision
- variation in tooth size- omnivorous diet
- well-developed collarbone- brachiation- swinging movement
- long bones of forelimbs not fused- wide range of arm movement
- five digits on hands and feet with nails- exposed fingertips allows increased sensitivity
- opposable thumb- grasping hands
- tendency to upright locomotion- free hands for other activity
- long gestation period/ parental care- large brain development and extended learning
- well developed communication and behaviour- well developed social grouping- complex hierarchies
humans as hominoids
- shared taxon with lesser apes or gibbons and great apes such as orangutan chimps and gorillas
anatomical features of all hominoids
-large brains
-broad pelvis and nasal region
-distinctive molars in lower jaw
-relatively long upper limbs
-rib cage creates large chest
-absence of tail
shoulder joint can rotate
human with other taxa
hominoids- greater apes, lesser apes and humans- superfamily
hominids- greater apes and humans (chimps, gorillas, orangutans, human and all immediate human ancestors
hominin- humans and extinct close relative ( homo, Australopithecus and Paranthropus)
anatomical features and habitats common to all hominins
bipedal- modified feet, thighbone, pelvis and spine
large cerebral cortex
reduced canines and other teeth
nose and chin are prominent, reduced brow ridges
highly sensitive skin
body hair short- very reduced to assist cooling
complex social behaviour
skull of ape vs man
ape- sloping forehead, pronounced brow ridge, variable and large teeth, has diastemic gap, no chin, box like jaw, smaller brain case, present crest, position of foramen magnum towards back of skull
man- vertical forehead, reduced brow ridge, small, non-varying teeth, no diastemic gap, present chin, parabolic shape jaw, larger brain case, absent crest, foramen magnum in centre of skull
skeleton of ape vs man
ape- curved vertebrae, large scapula, longer pelvis, feet turned outwards
man- s shaped vertebrate, forelimbs are free, shorter, broad pelvis, longer feet and shorter toes point forward
evolution of primates
- done by comparing structure in terms of composition of particular proteins, and DNA sequences
- no universal agreement on precise evolutionary history- varying interpretations of fossil record/molecular evidence
Australopithecus
- direct ancestors of first human species
- taung child- ape like/human like features
- foramen magnum closer to front- probably bipedal walking
- australopithecus africanus
- Lucy from afar- most complete fossil skeleton found to date
- skeletal structures suggest upright walking due to angled slant of femur relative to tibia
- belongs to Australopithecus afarencis
bipedalism
- may have evolved due to changing climate, changed habitat
- walking on ground in shrinking forest snd forage for food on ground had selective advantage over other phenotypes
-allows carrying of offspring, seeing over grass, holding tools and weapons, efficient locomotion, carrying food
-thermoregulation- smaller surface area presented to sun
and greater air flow across body when lifted high off the ground- assists cooling
cranial changes
-size of brain has tripled in hominin evolution
-increase took place as part of complex interrelationship that included fire use, tool making and other learned skills- allowed increasing ability to live in variety of environments.
skull- cranium increased, increased in height/ vertical slope of forehead, increased width, smaller brow ridge, large brain capacity- distinguishing feature of homo- result of natural selection favouring greater intelligence
jaw and teeth- moved from large canine teeth and jaw, v shaped dental arcade, thin enamel, tougher material diet
-moved to shortened jaw- allows large effortless bite force, chin reinforces jaw, thick tooth enamel, small molars- adapted to chewing cooked/soft food, parabolic dental arcade
homo habillis
- first tool maker
- greater brain size and smaller teeth than Australopithecus
- used tools to cut thick skin off animals, scrape flesh and extract marrow out of bone
- probably first meat eaters- provided nutrients for increase brain size
homo rudolfensis
- rudolfensis and habillis existed in Africa at same time
- rudolfensis had larger brain size and smaller brow ridge than habillis
homo erectus
- first emigrant
- fossils found out of Africa, suggesting migration out of Africa
- had larger brain than habillis, smarter hominin
- manipulates fire for cooking meat and keeping warm
- made more elaborate tools
- systematic hunting
- make sounds for communication
- increased brain capacity gave ability to plan/act intelligently
