HUMAN EVOLUTION Where we fit Primate family tree Hominoids Primate features Ape features Ape vs. Human - skeletal Ape vs. Human – skull Ape vs. Human – brain Ape vs. Human – other Selection Pressures Bipedalism

WHAT WE’LL COVER Biological evolution, Cultural evolution, Dispersal of hominins Main Menu Body changes, genetic change Learning, language, tools, clothing, fire, agriculture From Africa to the world: When? How long did it take? Where do neanderthals and “cavemen” fit?

PRIMATE FAMILY TREE Evolutionary speaking… Apes branch off here Main Menu

WHERE HUMANS FIT IN Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Primates Family: Hominidae Genus: Homo Species: sapiens Fur wearin’, warm blooded, young bearin’, milk sucklers. Adapted to arboreal life (living in the trees). Man-like. Let’s include our ancestors and great apes. Man The thinking man! To find our place it’s worth studying our taxonomic position… Main Menu

HOMINOIDS Chimps Gorillas Gibbons siamangs Humans Old classification New classification Hominidae Hominidae/ Homininae Pongidae/ Paninae Hylobatidae Hominoid = human-like (apes and humans) Hominid = humans, recent ancestors and great apes. Hominin = only man’s ancestors Recent DNA analysis has changed views of family/subfamily classifications: As our DNA is 98.6% the same as chimps, it has also been suggested that chimps be placed in our Genus, Homo. Orang- utans Pongidae/ Ponginae Hominidae/ Ponginae Manual pg 342(&3) Main Menu

APE FEATURES Features of apes: No tail Rib cage is flattened Molars have 5 cusps (monkeys have 4) Locomotion is brachiating, knuckle-walking, or bipedalism. Posture partly (or fully) erect… leaving the hands free Main Menu The Y5 molar pattern

SKELETAL DIFFERENCES For walking: S –shaped spine Pelvis is wide F Valgus angle; feet under COG Buttressed knee Big toe not opposable Foot arched Main Menu Manual pg 373/4 Thumb fully opposable Fingers are less curved – for tool use rather than brachiating

SKULL DIFFERENCES Foramen Magnum vertical – balanced Brow ridge Protruding muzzle Sagittal crest (jaw muscle attachment) Zygomatic arch (jaw muscle passes through) Forehead slope Canine size Molars (indicates diet) Nuchal crest (neck muscle attachment) Nose width Cranial capacity (as a proportion of body size) Manual pg 345/54Main Menu

BRAIN & SKULL DIFFERENCES Human have a large brain (1400cm 3 vs. ~ 450cm 3 ) Well-developed cerebral cortex (folded) - memory - speech (Broca’s area) - understanding of language (Wernicke’s area) Cerebellum (balance and coordination) more developed – bipedal locomotion and tool use Manual pg 375/6 Main Menu Cerebellum Wernicke’s areaBroca’s area

APES vs HUMANS More sweat glands Finer, and shorter, hair Larynx is lower and pharynx longer – for complex sounds Other things Smaller teeth – ‘cos we used tools instead, as well as having a more refined diet Rounded jaw – not rectangular Main Menu

SELECTION PRESSURES Environment: In Africa around 6 m.y.a. forests were receding, replaced by grassland. This reduced arboreal habitat driving primates onto the ground. Bipedalism: is more energy efficient than knuckle walking – these species can travel further for scarce food. It allows tool use and carrying of young. The body is also kept cooler (less surface area hit by the sun and greater airflow around the body). Height advantage: gained by being upright and being more able to see food and predators. Dentition: due to the nutty and vegetable diet canines reduced and molars enlarged. Hairlessness: reduces parasites, assists cooling. Brain size: increases correlate to tool use 2.5 m.y.a. and more recent developments are thought to be parallel to communication improvements. Main Menu

BIPEDALISM The change to bipedalism is thought to have been explosive – within 2 million years or less. What could cause such a rapid evolution? More time standing and walking Increased air currents over body Infant less able to grasp mother Infant held more by mothers arms Less body hair beneficial More sweat glands beneficial More forwardly directed big toe Infant less able to grasp mother Main Menu Warmer, dryer climate Manual pg 372/377-8

PRIMATE FEATURES What are the adaptations for arboreal life that set primates apart? Dexterous hands – for clutching branches (maybe opposable thumb) – see pictures on 347 Sensitive fingertips with skin ridges with nails, not claws Eyes front – need to be good at judging distances Colour vision – recognise ripe fruit Poorer sense of smell, but emphasis on fine vision Single offspring and extended parental periods - importance of learned behaviour Mobile hip and shoulder joints Unspecialised dentition – omnivorous diet Big bwain we got Strong social organisation Main Menu Manual pg 344