18 - Human Evolution Flashcards
Describe the early variation in humans.
A skull and remains of 5 others from 1.8myra found in Georgia
Only in tact skull from that time
Early H. erectus
Skull has features attributed to other species
Huge variation between individuals
If not found together, presumed separate species
Is this a single evolving lineage/spp?
Describe what we know about the first Homo
2 million year old, new species of human found in 2015
Most siilar to early humans as we know
Human like foot
Buries their dead - previously only thought to be H. sapiens
Describe the dominant ecoogical trends of the last 5 million years
Stable isotopes from ancient soils used to track vegitation and climate
Decrease in temp
Increase in aridity
Amplitude and frequency of climate cycles and events changed
How did bipedalism evolve?
Full story unknown
Possible evidence of bipedalism 7 + 6 million years ago
Unambiguous evidence from 3.5 million years ago
Next evidence for brain size shows large expansion
Human body shape and life history led to the modern condition 1-2 million years ago
Modern human life history parameters appeared less than 1 million years ago
What are the costs of bipedalism?
Quadruped to biped needs many changes in bone structures
Flexible spine suffers from wear and tear
Feet vulnerable to fatigue, fractures and heel spurs
Small birth canal
Fischer and Mitteroeker: females with large heads means larger birth canals
What are the uses of bipedalism?
Frees up the hands for food gathering
Allows herd tracking
Energy efficient locomotion
How did hominid metabolic reorganisation occur?
The gut shrank a relatively short time prior to large encephalisation increase
Large brain compensated for by smaller gut - energy efficiency
Low energy intensity gut associated with higher dietary quality
However, lack of negative relationship between expensive tissue and brain size across other mammals (Navarette et al, 2011)
What dietary changes did humans go through?
2.5 million years ago, increase in meat consumption
0.75 million years ago - cooking
0.5 mya - systematic, medium sized ungulate hunting
Less than 0.25 mya : exploitation of aquatic resources, small resource collecting, domestication of plants and animals
Meat is v efficient - more iron than veg and is more easily accessible as it is not bound to fibre
How did dietary genes evolve?
FADS (fatty acid deacetylates) involved in synthesis of long chain fatty acids (O3) from medium chain precursors found in plants
Inuits low activity in this
Vegetarian countries eg. India high activity
Agriculture favoured high activity variants
In what order did behaviours develop in the stone age in Africa?
Blades, grindstones, pigment processing Points Shellfishing and long distance exchange Fishing Bone tools and barbed points and mining and incised notational pieces Microliths Beads Images Stone tools originally thought to be Homo exclusive but now thought that they were used 3.3 million years ago, pre-Homo
Describe the pattern of Hominid disersal
3mya - African australiopithecine dispersal/North and South across Africa
2mya - African early Homo dispersals
1.5mya Eurasian H. erectus and later H. heidelbergensis dispersal
0.5mya - Mode C Afro Eurasian dispersals - ‘genetically modern’ humans
30kya - further global dispersal?
What are the various views surrounding human dispersal?
Out of Africa - accepted view
Multiregional continuity: H. erectus spread worldwide from Africa with interbreeding as they travelled between regions
Leaky replacement: Neanderthal lineage split off from modern human lineage and into neandethals and denisovans, then interbred with modern humans
What is the relation between modern humans and neanderthals?
1-4% DNA sharing in European and African people
Overlap by 2.6 to 54K years
Concept: early modern humans arose in Africa and interbred with Neanderthals in Middle East before moving to Asia and Europe
What are the arguments that suggest humans won’t evolve further?
Escaped natural selection
Possible due to cultural, cognitive and behavioural flexibility
No selection, no drift
Change via non-genetic channels: culture and learning, but not traditional evolutionary mechanism
Adaptability means genetic response is unnecessary
How did humans construct their own niche?
Decide own fate Create environments and selection pressures Potential for evolution exists Occured in four major stages 1. Late pleistocene expansion 2. Neolithic spread of agriculture 3. Era of island colonization 4. Urbanization of societies that led to current anthropocene
