Lecture 15 - evolution of modern humans Flashcards
what big effect do the glacial cycles have?
- the sea levels vary significantly depending on whether glacias have expanded out or contracted
expanded = reduced levels
contracted = raised levels
how did people first migrate to australia?
- requires island hopping even though the gap between the islands and Australia was much more reduced than it is now
- longest boat trip to be made was 52 miles
what do glacial events tell us about the migrations that could have happened to populate homo sapiens in Australia and America?
the glacial event lowered sea levels to expose the shallow continental shelf - left a corridor linking north America and Siberia and narrowing the gap between the islands and Australia facilitating migrations
when was it thought that people first went to Australia and why?
about 50,000 years ago - debate over whether they went out intentionally looking for it or is they got blown unintentionally of course when fishing etc
what do paleovegetation reconstructions tell us about Australia?
- the environment used to be very different to what it is now
e. g. savannah joined australia and new guinea on the continental shelf
what was it believed Europeans found when they rediscovered Australia?
two main groups
1 had come down from china/ eastern asia
1 from a more western area down
this was entirely based on anatomy
what is now thought about the people that invaded Australia?
now know that anatomical comparisons are less robust because on intraspecific variation - now thought there was just one invasion but possibly several waves
what is ‘mungo man’ ?
homo sapien (50ka) found in burials in Australia - australians also had the first cremations - pots found with ash in
what evidence do we have of just one group that invaded australia?
Evidence from archaeology
Evidence from molecular biology
Megafauna- alot of megafauna is often wiped out when humans first arrive
Evidence from anatomy is now discredited
what is more evidence for aggression in early humans?
pattern of evidence that when h.sapiens invade a place they wipe out any existing humans and megafauna
how did humans invade the americas?
invaded across beringia when it was land between siberia and alaska
- was thought they followed mammoths
how is it thought they invaded south america?
used the coast as a guide because evidence suggested they spread through south america very quickly and it would have been very difficult to battle through the rainforests
when is it thought the americas were invaded and describe the population numbers?
now generally considered the americas was invaded about 30,000 yrs ago . in low population numbers - spread throughout the whole of north and south america
- then there was cultural increase in population numbers when clovis culture appears (form of tools)
describe archaelogical evidence for the america model?
- bones, rock shelters, tools (prodominantly clovis but some odd ones have been found which are much older so the model has changed slightly in recent years
describe anatomical evidence for the americas model?
- alot of distinctive tribes around the americas - in general quite good evidence that people came from the north as they were well adapted for the cold e.g. short and stocky
- main idea = a few waves through beringia and then a population explosion linked to clovis culture
describe evidence of language in the americas model?
- cladistic analysis of language and look at basal words that have changed and so on
describe what evidence megafauna shows for the americas model?
all wiped out when humans first moved in - is thought in africa humans evolved in tandem with the megafauna and then when the humans moved out and came into contact with new fauna they were more scared and destroyed it
- is why africa is one of the only places you still find megafauna
evolution and migrations require a larger brain size - what is brain expansion related to?
mother’s metabolic rate
gestation time and litter size
what are the problems with a big brain?
- requires stable, high energy food supply
- birth problems - larger heads are harder to fit through a birthing canal - so brain and skull have to be born not fully developed therefore length of pregnancy is artificially reduced which results in an extended childhood which needs more division of labour as mothers are out of action for longer
describe the brain sizes of early homo species
Australopethicine -400cc (EQ 2.5)
H. rudolphensis/habilis 650-800cc (EQ 3.1)
H. ergaster/erectus 850-1000cc (EQ 3.3)
Archaic H. sapiens 1000-1400cc (EQ 5.5)
speech/language is related to brain size - what is evidence for speech?
- Endocasts of the brain (know the parts of the brain that habe been developed for speech in modern humans and see if they are expanded)
- Larynx/pharynx structure ( n humans babies have a modified pharynx which is similar to chimps - it stops them from choking but prevent speech - loose when they get older)
- Tongue nerve hole (lots of nerves in tongue to use it for speech)
- Spinal canal (gets bigger with speech )
- Tools, art etc (need to be able to conceptualise things )
- FOXP2 gene (if its damaged people cant speak - trace back homologs of this gene in the great apes when they diverged)
Overall speech is not a bery satisfactory area of study - difficult to come to conslusions
what evidence do we have of art?
- Ochre found from 100,000 from South Africa (used for painting or painting bodies)
- Paintings in caves from 33,500-10,000- Reported from Europe (but also China and South Africa - very little human representation mainly animals - stopped about 10,000 yrs ago when the ice retreats
what is it thought the carvings of figurines from 35,000 yrs ago represent?
fertility symbols - found all over the place - either they are converging or the technology spread
describe the Sungir man found in russia (28-30ka)
found in a burial with 2936 ivory beads (probably adorning clothes)
- shows they must have had time on their hands - complex societies
describe the timeline of creativity?
- 100,000 Jewelry (shell beads) from the Levant and North Africa
- 40,000 Flutes (music) discovered in Europe
- 30,000 Wild flax used (?to manufacture clothing)
- 20,000 Pottery
How did early humans transfer from being hunter-gatherers
- learnt how to grow their own food and take animals for use
- Mese-America : Maize , Squash , Cotton (9000 yrs ago)
- China : rice, miller, soybean, pigs (7000 yrs ago)
- Plant and animal domestication occurred independently and at different times in many different parts of the world
in how many places did animal+plant domestication occur
- three major centres of origin existed, influence spread geographically , eventually coming to dominate local innovations
- with domestication came settlements - requirement to stay in one place
when did the agricultural (neolithic) revolution start
- 12,000 KA
what happens following the agricultural revolution
- population explodes from 10 million to 100 million (neolithic supernova)
what example records a transition from hunter-gatherers to farmers
Abu Huregre (syria) is a series of villages continuously occupied from 13,000 to 9,500 and records a transition from hunter- gatherers to farmers.
when was the earliest walled city
Jericho (trading post) 10,000 years ago
when did the bronze age begin
5300 years ago
