Human evolution Flashcards
Example of Australopithecus Afarensis
Lucy (Awash valley Ethiopia)
Example of Australopithecus Africanus
Taung child (Discovered by Raymond Dart Sterkfontein caves)
Australopithecus Sediba
Thought to be a link between Australopithecus and homo
Advantages of bipedalism
Allowed bipedal animals to survey the Savannah (Early detection of predators)
Freed their hands up to either carry stuff or make tools
Cooled them down as a significant surface area was no longer exposed to direct sunlight
Economical mode of locomotion
Adaptability to a wider range of habitats
Disadvantages of bipedalism
Narrow birth canal
Puts a lot of weight on the back bone
Easier detection from predators.
Changes that occured for bidepalism
Foramen magnum shifted to be directly on top of spine
Vertebral column changed from being C-shaped in favour of being S-shaped (Flexibility, shock absorption)
Shorter arms and longer legs compared to apes
Big toe became parallel to other toes while apes have opposable big toes for climbing
Foot arch developed
Pervic girdle became larger, shorter and wider to support weight
Knee joints became larger and angled inwards to support body weight
Leg bones became longer - easier to walk
Larger brains led to
Well-developed hand-eye coordination (Make tools)
Capacity for language
The use of fire
Dentition
Teeth sized decreased
Apes have a diastema between incisors and canines to enable to close their mouths
Human canines are the same as other teeth
Diastema disappeared over time
Tooth enamel became thicker
Prognathism
Apes have large protruding without chin
Sloping face due to jaw protrusion
Prognathism became less apparent as teeth got smaller
Humans have narrow, flat face with rounded jaws and protruding chin (Development of chin accomodated a larger larynx for better vocal communication)
Forehead appears more vertical
Palate shape
Started off narrow and rectangular until slowing becoming more U-shaped
Human palate became wider and more curved
Cranial and brow ridges
Apes have more prominent cranial and brow ridges for well developed chewing muscles
Ridges decreased in size as evolution progressed
Cranial ridges began to disappear while brow ridges remained in early hominids
Both are completely reduced in humans
East African Great Rift Valley(65mya)
Australopithecus Afarensis - Lucy (3.2mya Ethiopia)
Homo erectus - Turkana boy (1.7mya Kenya)
Cradle of humankind
Adult Australopithecus - Mrs Ples (2-3mya)
Little Foot
Australopithecus Sediba
Homo naledi
Genetic evidence
Similarities in mtDNA (Which doesn’t cross over like normal DNA) shows that modern humans from all parts of the world indicate they evolved fairly recently from a single region in Africa with a common ancestor for all hominids being around 15mya. Studies show human populations in Africa have the highest levels of genetic variation.
Chromosomal DNA
All humans share 99.9% of their DNA which suggests that they originated from a very small Homo sapiens population in Africa. Closest related hominid to humans is the chimpannzee.
Y-Chrosome
Due to the Y chrosome never exchanging genetic information during meiosis thus leaving it unchanged for many generations. Hemce men sharing a common male ancestor will essentially have the same Y-DNA. Male ancestral descent can therefore be traced to a male ancestor in Africa.
Archaeological evidence
Production and use of tools, fire-making, burial rites, and hunting techniques suggest a common ancestor for liviing hominids. The development of speech and language is what differentiates modern humans from primates while improved communication and interaction were crucial for effective hunting and defence. Tool making is associated with an increase in cranial capacity and therefore intelligence as well as well-developed hands.
Similarities in primates
Enlarged complex brain
Flattened nose and reduced snout
Eyes face downward
Digits with flat nails
Molars and premolars with cusps that are low and rounded
Complex social behaviour - One offspring at a time and extended care for young
Homo habilis (2.2-1.6mya)
“Handy man” known as the first user of stone tools from Lake Turkana (Kenya) and Olduvai gorge (Tanzania)
Homo erectus (1.8-0.3mya)
“Upright man”. Likely first hominids to migrate from Africa to Europe and Asia. Disputed ancestor of Homos sapien and neanderthalensis. First to use fire.
Homo sapien
Border cave KZN, Klasies River
San
World’s oldest extant peoples
Interdependence of hominid skills
Bidepalism enabled hominids to move efficiently, carry hunted prey, see potential food sources, but needed associated tool making skills to succeed.
As they developed more complex tools, they were able to hunt larger prey and increase their protein and fat intake which would improve brain development
As brain developed due to diet, fire making skills developed which gave greater access of food and better nutrition for growth and development.
Controlling fire meant they could migrate north to colder climates
Hunting and development of culture, e.g. burial and forms of art require language and communication, thus skills could not develop independently of one another.
Palaeontology
Study of plant and animal fossils
Anthropology
Study of the origin and social relationships of humankind
Archaeology
Study of artifacts left behind by early human populations
Palaeonanthropology
Study of human evolution by studying human fossils and artifacts
Evolutionary tree
Diagram showing the different hominid ancestors and proposed relationships and the proposed times at which hominid ancestors lived.
Difference between out of Africa model and multi-regional theory
The out of Africa believes that Homo erectus gave rise to homo sapiens in Africa before migrating all over the world while the multi-regional theory states that Homo erectus ventured out of Africa and gave rise to different groups of homo sapiens independently (Even in SA) on different continents.
