Where we fit in the world and how we came to be here

Study of Hominids

• Members of the family Hominidae
• Key changes during evolution
  • Bipedalism
  • Increased brain size

Hominid Chronology

• Australopithecus - 5 million yrs ago
• Homo habilis - 2 million yrs ago
• Homo erectus - 1.5 million yrs ago
• Homo neanderthalensis - 400 000 yrs ago
• Homo sapiens (modern human) - 200 000 yrs ago

Australopithecus

• Fossils found in Africa only
• Small brain (low cranial capacity)
• Bipedalism
  • Footprints were found in fossils (volcanic ash)
  • Foramen magnum positioned more forward than in apes
  • Pelvic bone was shorter and broader than in apes
• Ape-like above waist, human-like below waist (long arms compared to legs)

Homo habilis

• Brain size was slightly larger than Australopithecus (600cm³)
• Oldowan Tradition
  • Method used to make choppers (Homo habilis means "handy man")
  • Rock was hit against another which resulted in a sharp-edged flake
  • Allowed them to cut foods
  • Gained proteins from meat but still ate fruits and plants
• Had opposable thumbs that allowed power and precision grips

Homo erectus

• Travelled from Africa to Asia and Europe
• Physical appearance
  • Large cranial capacity - almost 2x of Australopithecus (1000cm³)
  • Thick bones and strong muscles for powerful movement
• Acheulian Tradition
  • New method used to make hand-axes
  • Allowed the production of a variety of larger tools
• Culture
  • Home base for social interaction
  • Control of fire
  • Prolonged childhood → prolonged learning → developed simple language

Homo neanderthalensis

• ?Not ancestors of modern humans
• ?Became extinct due to competition with modern human
• Physical appearance
  • Brain was larger than modern human (1450cm³) because of muscle attachments
  • Stronger muscles and larger-boned skeleton than modern human
  • Short stature and compact body conserved heat during ice age
• Mousterian Tradition
  • Method used to make flake tools
    • Flakes were broken off from a stone core
    • Followed by refinement
    • Edges were sharpened by pressure-flaking (can be re-sharpened over time → tools last longer)
  • Other tools made: scrapers (remove waste from animal hides), notched flakes, pointed tools (spears)
  • Combined with other materials to allow a wide range of use
• Culture
  • Build shelters (with wood, animal skin, mammoth bones)
  • Had a religion (graves)
  • Body paintings
  • Fire allowed to cook frozen meat, warm homes during ice age

Homo sapiens (modern human)

• Physical appearance
  • Globe-shaped braincase - smaller than Neanderthals (1350cm³)
  • Flat face below the front of the braincase
  • Small brow-ridges
  • Chin
  • Lighter bones and less muscle bulk
• Cro-Magnon tradition
  • Method used to make blade flake tools
  • This was done by indirect percussion and pressure flaking
  • Tools were used to make other tools
• Cro-Magnon hunting
  • Spear-hunting to kill from distance
  • Harpoons-hunting to kill fish
  • Built traps
  • Language allowed group hunting
• Culture
  • Women remained at home with children
  • Cave paintings, made sculptures, decorated tools
  • Had a religion
  • Made cloth

Evidence of diet

• Apes ate hard food, which was tough and fibrous
  • Thick enamel
  • Microwear (large numbers of small microscopic scratches)
  • Large jaws and bony crests on skull (strong jaws with powerful muscles)
• Canine teeth
  • NOT evidence for diet
  • Smaller teeth allowed side-to-side movements of the jaw required for chewing
  • But large canine teeth showed aggression

Cultural evolution and physical change

• Early stone tools
  • More efficient and less physical lifestyle
  • Caused changes in skeleton (smaller and thinner bones)
• Control of fire
  • Evidence from burned fossils (animal bones)
  • Light allowed activity at night (extends days)
  • Offered protection as animals avoid fire
  • Cooking of food → digestion requires less energy
  • Heat homes

Hunter-gather way

• Main food source was from hunting with little or no agriculture
• Moved on once food ran out in their area and build a new home base
• Food was shared
  • Women and children gathered food near home (plants, fruits, nuts, mushrooms, edible roots, ...)
  • Men were hunting animals and fish in small groups

Social groups

• The larger the brain capacity, the more energy is required
• Meat contains most energy
• Human female
  • Had to rely on her male partner to gather enough food
  • In return, she entered a pair-bond throughout the reproductive cycle (different in apes)
  • Both parents cared for the newborn (↑survival)
  • Care of both parents increased survival of newborn
• Male apes
  • Not involved in the care of their offspring
  • Did not provide food for female apes

Ramapithecus

• Features similar to humans
  • Small canines (side-to-die movement required for chewing)
  • V-shaped jaw
  • Large teeth and thick enamels (hard food)
• Early conclusion
  • Ramapithecus and humans share common features
  • Both must have split away from gorillas and chimps a very long time ago
• Conflicting evidence
  • Immunological studies showed
    • Humans and gorillas are very similar
    • Ramapithecus and gorillas are very different
  • Only humans must have split from gorillas and at a much earlier time
• New conclusion
  • Small canines must have been from a female
  • Jaw was reconstructed by using bones from different specimens
  • Thick enamel is related to diet and not evidence for common ancestors
• It was found that Ramapithecus was actually a female of the species Sivapithecus
  • Male and female had a large size difference
  • Evolved after orang-utan line split from gorilla and chimp line