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BIOLOGY CHAPTER 12
Question | Answer |
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Humans are Primates | members of the order Primates of class Mammalia |
Identify a primate part 1 | • hands and feet have five digits that can grasp or curl around objects • thumbs or big toes (sometimes both) are opposable- that is they can be brought into contact with the other digits • Flat nails on digits |
Identify a primate part 2 | • digits have touch receptors able to gain information. • large forward-facing eyes that give 3D vision • colour vision |
Identify a primate part 3 | • protective bone at outer side of eye-socket. • Rotate the arm in the shoulder socket. • Larger brains relative to their body size |
Hominoids | Collective term for various human-like species and their erect-walking close relatives, collective term for species within the genus Homo and the genus Australopithecus • Lack a tail • Similar skeletal and skull features |
Characteristics of humans as Homo sapiens 1 | • are bipedal- walks fully upright • has fewer, smaller teeth than apes. • have a flat face and lack heavy brow ridges |
Characteristics of humans as Homo sapiens 2 | • have a large cranial capacity, which is a measure of brain size, ranging from 1200 to 1500 cm3 compared with 350-500 cm3 in apes. • makes tools • uses language and is self-aware. |
Hominin Evolution - from Australopithecus to Homo genius (characteristics) 1 | • marked increase in brain size, with an accompanying increase in size of the cranium, including height and vertical slope of the forehead and width of the skull. Inclusion of meat in the diet and later use of cooking allowed for greater brain growth |
Hominin Evolution - from Australopithecus to Homo genius (characteristics) 2 | • Position of the foramen magnum more forward- indicates bipedal locomotion • Vertical forehead • Smaller lower jawbone • the pelvis is more bowl-shaped and the hip bone is shorter- indicating bipedal locomotion |
Hominin Evolution - from Australopithecus to Homo genius (characteristics) 3 | • Space for spinal cord in neck region is larger- increased fine muscle control of breathing that is necessary for speech. • Size of teeth decreased (particularly size of canine teeth). • Jaw became less parabolic |
Hominin Evolution - from Australopithecus to Homo genius (characteristics) 4 | • Absent gap in tooth rows (diastema) that were previously present • use of fire • flattening and shortening of the face. |
Cognitive changes of Homo part 1 | • burying the dead • caring for the aged and ill members of the species • development of art, language and music • increasing the use of technology beginning with the use and creation of tools made from stone |
Cognitive changes of Homo part 2 | • systematic hunting • making and wearing clothes • development of speech and communication. • use of symbols • development of religion and ritual |
Cultural evolution | refers to changes in human societies over time where those changes are socially transmitted, not genetically transmitted |
Homo Neanderthalensis | Coexisted with modern humans in some regions Comparisons of the nuclear genomes of modern humans with those of Neanderthals reveal that about one to four per cent of the DNA of all non-African modern humans living today came from Neanderthals |
Homo denisovans | Coexisted with modern humans and Neanderthals Interbreeding probably occurred when the ancestors of these present-day humans were migrating across southern regions of Asia |
Homo heidelbergensis | Modern humans, Neanderthals and Denisovans all descended from a common ancestor that lived many hundreds of thousands of years ago which then diverged to form a separate branch of Homo sapiens, the modern human |
The origin of modern humans | All human mtDNA sequences can be traced back to Africa and support the conclusion that small groups of Homo sapiens dispersed from Africa about 100 000 years ago |
The origin of modern humans Recent DNA evidence | • the genome of living humans of African descent does not contain Neanderthal DNA • the genomes of living humans of European, East Asian and Australian Aboriginal descent all contain small amounts of Neanderthal DNA (1–4%) |
Out of Africa (replacement) theory | Proposal that modern human populations originated from modern humans who evolved in Africa and migrated from there to the rest of the world |
Multiregional evolution model | Modern humans evolved in different regions from existing Homo erectus populations in each region Genetic drift has led to the DNA of the other species being lost from the genome of homo sapiens |
Assimilation (partial replacement) model | Proposes that all modern humans had an African origin and that when people migrated out of Africa there was occasional interbreeding with archaic humans who were already living in other parts of the world, resulting in hybrid populations (assimilation) |