Lecture 10 - Case study - human evolution Flashcards
what are the 6 stages of studying human evolution?
1) temporal framework
2) reconstructing paleogeography
3) reconstructing environment
4) evidence from living organisms
5) evidence from fossil organisms
6) evidence from archaeology
when is is thought the start of human evolution was?
7 million years ago when the chimp-human split occurred
top of miocene just before pliocene on geological column
why have we gotta a much better understanding of humans than dinosaurs?
much more recent so can use a variety of dating methods - accuracy of dating is getting better with time
how else is the fact that human evolution was relatively recent useful?
better knowledge of geology stratigraphy - the rocks still exist - therefore can subdivide the 7 million years much better
what is an added complication when studying human evolution?
glacial events - sea levels changing - temps changing - unstable environments
- need to understand where we are in the glacial cycles to understand human evolution
when were sea levels last lowest?
last glacial maximum - 18,000 yrs ago
when were sea levels at their highest?
middle miocene 14ma - before humans split from chimps (greenhouse world)
what are rainfall patterns effected by?
by which part of the glacial cycle the worl is in
what are the study of pollen cores in the East African rift lakes useful for?
- they can give you a chronology of the dramatic environmental changes as humans were evolving and what effects they have
how can you date sediments by drilling cores in the ocean crust?
study oxygen or boron isotopes from forams (single celled organisms that live in the ocean with a carbonate shell - so remain in ocean floor for years)
what can fine details about oxygen isotopes reflect?
how much ice was at the poles and therefore sea temperatures
what does boron show?
how much co2 was in the atmosphere and how acidic the ocean was
how can we get evidence from living organisms to help study human evolution?
1) look at nearest living relatives e.g. chimps
- look at their history, anatomy, genomics, physiology and behaviour
2) look at other human societies that havent advanced as much e.g. sandbush people in south Africa (still practice hunter-gatherer societies)
describe the human fossil record
- terrible fossil record - few terrestrial deposits
- human skulls are very delicate - mostly find teeth and body bones with cranium smashed too pieces
- get some footprints
what evidence can you find from archaeology?
- tools (very robust)
- charcoal (work out when fire was invented)
- find burials (instantly fossilises the bodies)
what are the 4 groups that 200 extant species of primates are classified into?
1) promisians (lemurs, lorises, bushbabies)
2) new world monkeys (spider monkeys, marmosetts)
3) old world monkeys (baboons , colobus monkeys)
4) hominoids (apes, includins humans (hominins - new term))
what are anthropoids?
collectively the monkeys and apes
when did primates appear in the fossil record?
85ma
when was the KT mass extinction?
65ma
what happened in terms of primate evolution 50ma?
- primates of modern aspect appear
- adaptive radiation of primates
- anthropoids evolve din Africa
when did hominoids appear in Africa?
20ma
when did hominoids migrate into Asia as Asia/Africa collide?
18ma - adaptive radiation of hominoids in Asia
what happened 10ma in terms of primate evolution?
as asian hominoid migrates back to Africa and is ancestral to all later hominoids (including hominins)
when was the earliest hominoid?
proconsul - 22ma from Africa
there is debate over whether lemurs+lorises or tarsiers are more derived - what now solves alot of theses issues?
molecular studies - solve issues that used to be decided by morphological studies
over the history of research into human origins, human remains discovered in caves were often interpreted, depending on where they were found, as either …..
- soldiers from the horde of gengis khan The
- remains of Cossacks that had died on the way back from their victory over Napoleon
what is it now know that the fossils found in caves actually are?
remains of Neanderthals, Cromagnon Man etc
what significant book was published in 1859?
Darwins - origin of species - evolution became accepted
what book did huxley publish in 1863?
“Evidence as to man’s place in nature”. Based on comparative anatomy and embryology he concludes that humans share a close evolutionary relationship with great apes (particularly African apes)
what did darwin publish in 1871?
“Descent of man”. He concurs that humans are most closely related to African apes and suggests that humans originated in Africa
describe Dubois discovery ‘java man’
java man (homo erectus) - huge animal, heavily muscled, thick skull etc
what was the issue with dubois discovery?
people thought the java man was just ape fossils - this annoyed dubois so he locked the fossils away never to be seen again
describe the piltdown man (1908-1913)
- supposed discovery of a human ancestor from England - people started to forget that humans evolved just in Africa and actually evolved everywhere
what discovery was made in 1925?
Taung boy (australopithecus africanus 3.5-2.5ma) - found in south africa at the end of the rift valley - very small with small brain - he was neglected by the rest of the world
what discover was made in 1927?
peking man - homo erectus (0.4-0.7ma) - very big so was brushed to one side and thought to be more on the ape side
- fossil destroyed in world war however more similar ones have been found from the same area
what did Robert Broom continue today between 1925-1935?
continued his search in johannesburg despite Tuang boy being neglected and fins more fossils such as A.africanus(3.5-2.5ma) and A.robustus (2.0-1.0ma)
what is the difference between africanus and robustus?
robustus has a much thicker jaw
what happened in 1953 regarding the piltdown man?
was accepted as a hoax
- had set back human evolution for 50 years
- Brooms discoveries were started to be taken more seriously and people started to search more in Africa
