Human evolution Flashcards
The order and family humans belong to
Order: Primates
Family: Hominidae (commonly called hominids)
Class that humans belong to and characteristics of this class
Mammalia: Bodies covered in hair Suckle their young Three ossicles in the middle ear
Family Hominidae includes the extant taxa…
Human
Chimpanzee
Gorilla
Orangutan
Current term for bipedal humans and our fossil ancestors
hominins
Genera considered hominins
Ardipithecus
Australopithecus
Homo
The name that refers to the orangutan, gorilla and chimpanzee
Great Apes
Shared characteristics between humans and apes
- opposable thumbs with a power grip
- no tail
- sexual dimorphism between males and females
- brain centers processing hand and eye coordination enlarged
- naked fingertips with flat nails
- long, freely rotating arms
- reduced snout and sense of smell
- stereoscopic vision with forward pointing eyes
- molars and premolars have rounded cusps
Mode of transport difference between apes and human
Apes: knuckle walkers, quadrupedal
Humans: walk on two legs, bipedal
Skull differences between apes and humans
Jawbone: Apes-large, prominent, no chin vs Humans-reduced jaw, developed chin
Cranial and brow ridges: Apes-prominent vs Humans-reduced
Brain size: Apes-smaller vs Humans-larger
Face: Apes-wider, sloping face vs Humans-narrow, flat face
Appendicular skeletal differences between Apes and Humans
Arms: Apes-longer arms vs Humans-shorter arms
Feet: Apes-flat feet, opposable big toe vs Humans-arched feet, forward thrusting big toe
Pelvis: Apes-long and narrow pelvis vs Humans-short and wide pelvis
Legs: Apes-weaker legs and smaller knees vs Humans-stronger legs and larger knees
Spine differences between Apes and Humans
Shape: Apes-C shaped spine vs Humans-S shaped spine
Foramen magnum: Apes-at back of skull vs Humans-central under skull
Evidence for hominid common ancestry
Fossils
Genetic
Cultural
A scientist who studies fossils
Paleontologist
Most commonly preserved parts of hominin skeletons studied by scientists
teeth,
jaw bones,
skull fragments,
long bones,
feet,
hands,
pelvic bones and vertebra are scarce
Particular key characteristics scientists examine in hominin fossils
- bipedalism
- dentition and palate shape
- brain size
- prognathism
- cranial and brow ridges
Prognathism
Large prominent jawbone with reduced or chin lacking
Foramen magnum
The opening for the spinal cord into the skull
Evidence for bipedalism in hominins
- Foramen magnum shifted forward, centrally at the bottom of the skull
- The spine becomes S shaped
- Longer and stronger legs
- Larger and stronger knee joint
- A forward pointing big toe, parallel to the other toes
- An arched foot
- A larger, shorter and wider pelvic girdle to support greater weight in an upright posture
Advantages of bipedalism
- bodies expose smaller surface area to the sun, reduced risk of overheating
- bodies exposed to more wind to assist cooling
- hands free to use tools etc.
- extended vision across landscape to see predators and food
Changes in brain size in hominins
Cranium size increases Chimpanzee has around 400 cm^3
Australopithecus between 440-500 cm^3
Various Homo species 640-1500 cm*3
Humans about 1400 cm^3
Changes in dentition in hominins
- Canines have reduced in size, Apes have protruding canines and they become roughly the same size as the other teeth in hominins
- Diastema (gap between incisors and canines) is reduced/disappears
- Tooth enamel has become thicker
Changes in prognathism in hominins
- From jaws that protruded (a snout) with no chin
- Jaws have become less protruding (flatter) with a pronounced chin.
- The forehead appears more vertical because of this together with the increased cranium.
Changes in palate shape in hominins
From a narrow and rectangular palate
It has become more U shaped in the hominins
In humans the palate is even wider and more curved.
Changes in cranial and brow in hominins
Apes have prominent ridges for jaw muscle attachment
These ridges begin to disappear in hominins
They are completely reduced in humans
Genetic evidence for common ancestry of apes and humans
The genetic evidence (both nuclear and mitochondrial DNA) supports the fact that humans and apes share a common ancestor.
- Comparison of DNA between living hominids to reveal shared sequences
- More shared sequences found for specific specimens, the closer the relationship
- e.g. in humans we all share 99,9% of our DNA sequences.
- humans share 98% with chimpanzees
- humans share 96-98% with other apes
Tool evidence for hominin evolution
Apes and humans share a power grip enabled by the opposable thumb.
Hominins show the development of a precision grip (fine motor grip).
This allows for more advanced tool use, first observed to be purposefully made by Homo habilis (handy man)
Main stone tool cultures
Oldowan
Acheulian
Mousterian
Oldowan tool culture
Oldest tool culture From 2,6-1,5 MYA (H. habilis)
Simple flaking of a core stone using a hammer stone. E.g. Choppers, flakes and scrapers
Acheulian tool culture
A later and more advanced culture than the Oldowan culture From 1,5 MYA to 250 000 years ago (H. erectus and H. ergaster) R
eworking of tools evident, and a repetitive flaking to better shape the edges.
Bifacial blades common.
Also made of wood and bone. E.g. Hand axes, picks, cleavers
Mousterian tool culture
A later tool culture after the Acheulian culture.
From 250 000 - 50 000 years ago (H. neanderthalensis and H. sapiens)
Mostly flakes, scrapers and points.
Greater variety in blade shapes forming a more sophisticated tool kit. e.g. spear points and awls (used to make holes)
Human tools from 100 000 years till recently
Refined spearheads and knives with improved, longer blades
Smaller stone flakes (microliths) forming a part of larger tools (tied or glued together) e.g. fishing hooks, arrow heads
Modern humans started utilizing metals in more advanced technologies (e.g. copper, bronze and iron).
Rough timing of the most recent common ancestor of humans and the chimpanzee
6-7 MYA
Rough timing of Ardipithecus and location
5.8-4.4 MYA Northeast Africa, e.g. Afar valley of Ethiopia
Human-like characteristics of Ardipithecus
Partially bipedal (when on the ground),
Foramen magnum more to the front than apes,
Smaller canines and molars,
Smaller brow ridges
Ape-like characteristics of Ardipithecus
Probably quadrupedal climbers,
Pelvis wider at top and narrower and long at the bottom,
Long arms for climbing,
Opposable big toe,
Small brain (300-350 cm^3)
Ape like teeth (though smaller) with diastema,
Narrow, rectangular palate,
Prognathism and sloped face.
Rough timing and location of Australopithecus
Between 4,5 and 1,4 MYA Africa, fossils mostly found in Eastern and Southern Africa.
Human-like characteristics of Australopithecus
Bipedalism,
Foramen magnum centrally located,
Pelvis short and wide,
Non-opposable big toe,
Smaller teeth especially canines,
U-shaped palate
Ape-like characteristics in Australopithecus
Long arms and curved fingers for climbing,
Small brain capacity, 380-500 cm^3 (though bigger than apes),
Larger teeth than humans, small diastema still present,
Prognathism with no chin,
Sloping face (though less so than in apes),
Large brow ridges.
Well known Australopithecus fossils
Taung child
Mrs Ples
Lucy
Little Foot
A. sediba
Taung child
- Australopithecus africanus (3-2 MYA)
- Found in 1924 by Raymond Dart at Taung, near Kimberly
- 3-4 year old child skull
- Small brain similar to apes
- Human like teeth
- Central foramen magnum
Mrs Ples
- Australopithecus africanus (2-3 Mya)
- Found in 1947 by Robert Broom in Sterkfontein Caves
- Skull and some bones of an adult
- Similar brain capacity as a chimpanzee
- Foramen magnum centrally located indicating bipedalism
Jaw intermediate and indicating more of a plant diet.
Lucy
- Australopithecus afarensis (3,5 Mya)
- Found by Johanson in Ethiopia (1975)
- Female showing evidence of bipedalism
- Face has ape-like characteristics
- Arms long and legs short
- Small brain
Little foot
- Australopithecus sp.
- Found by Clarke (1994) excavation still in process
- Sterkfontein caves
- Foramen magnum shows that it was bipedal
paleontology definition
The study of plant and animal fossils
anthropology definition
The study of the origin and social relationships of humankind
Archaeology definition
The study of artifacts left behind by early human populations
Palaeoanthropology defenition
The study of human evolution by studying fossils of humans and artifacts
The Sterkfontein caves
- Limestone caves found north west of Johannesburg
- Largest number of hominin fossils in the world found here
- More than 700 ape-like fossils
- Thought to be this region where humans originated: called the Cradle of Humankind
Australopithecus sediba
- A young female and boy (Karabo) (1,78-1,95 Mya)
- Found by Berger and his son in 2008 in Sterkfontein
- Considered a transitional form between A. africanus and Homo
- Small brain and large brows but shape indicates a more advance brain than other Australopithecus species
- Mostly bipedal, but good tree climbers
Homo is different from Australopithecus in…
Brain is much larger and better developed Homo can make tools, fire and develop language
Fully bipedal
Less ape like skull:
- less prominent brow
- flatter face
- smaller teeth
- rounded jawbone
Homo habilis
Handy man (2,2 - 1,6 MYA)
First found in Tanzania (1960)
Body smaller than Australopithecus and still ape-like
Larger brain (640 cm^3)
First group to use stone tools
Homo erectus
Upright man (1,8 - 0,3 MYA)
Found in Africa, Europe and Asia
Turkana Boy found in Kenya (1,5 MYA) is most complete fossil found
Large bodies with large brains (1000 cm^3)
Prominent brow ridges and no chin
Made stone and bone tools, were good hunters and used fire.
Homo neanderthalensis
- The Neanderthals (500 000 - 30 000 years ago)
- Lived in Europe and Western Asia
- Broad noses, low foreheads, prominent brow ridges
- Larger brains than H. sapiens
- Very successful hunters, built shelters, made clothes from animal skins, used fire and made tools of stone, bone and wood
- Buried their dead, indicating an advanced culture.
Homo sapiens
Direct ancestors of all modern humans (200 000 years - present)
Large brain capacity (1400 cm^3)
Reduced brow ridges, flat face and prominent chin.
Advanced use of tools, accomplished hunters and later developed agriculture.
Use jewelry, art and developed rituals.
Well developed language and communication, form communities.
Sixth mass extinction
- Homo sapiens readily changes our environment to ensure survival
- However this also negatively impacts the environment in many ways
- Many other species have become extinct due to our own destructive impact on the environment (including ourselves).
Out of Africa hypothesis
- Homo sapiens originated in Africa
- Successive range expansions (migrations) occurred to the rest of the world
- Relatively recent migrations (50 000 years ago) of more advanced cultures out of Africa out-competed other Homo species
- Homo sapiens replaced Homo erectus in Asia and Homo neanderthalensis in Europe (Replacement hypothesis)
- There is evidence of limited interbreeding between different populations, though mainly earlier populations were replaced by Homo sapiens.
