what were the two first discoveries of the genus homo?
1891 - Java - 1) Java man (1.0-1.8ma)
1927 - China - 2) Peking man (0.4-0.7ma)
when first found wasnt known that they were homo erectus
describe the leakey families discovery of homo habilis
-1960 - excavate partial cranium, jaw fragments, leg, hand and foot bones from Olduvai Gorge, Kenya (1.75 Ma)
Coeval (same age) with A. boisei.
Less robust, smaller teeth, larger brain (640 cc).
They place it in the same genus as humans and name it Homo habilis (handy man- associated with lots of tools found in the same area)
what are 3 reasons for the controversy over homo habilis?
1/ It demonstrated that various genera and species of hominin co-existed
2/ It was previously considered that there was a neat evolutionary transition from A. africanus to H. erectus to H. neanderthalensis to H. sapiens. There seemed to be insufficient morphological space between A. africanus (ancestor) and H. habilis (descendent). i.e. demonstrated that various genera and species of homini co-existed
3/ It meant we had to redefine the genus Homo (accept that it could have reduced brain size).
what did the homo habilis discovery provide more evidence for?
the star wars bar scenario - lots of genera of homini living in the same area - unknown if they were ecologically separated or spatially separated
- human evolution is not a gradual progression rather it is bushy
what does it mean to be home?
combination of characters
- Upright posture and bipedal gait
- Brain size (difficult to know where to draw the boundary - when is the brain big enough to be called homo?)
- Dexterity to fashion primitive tools ( relates to brain size - however now thought australopithecines also used tools)
- ?Speech (not fossilised hard to know)
still difficult to decide on what defines home
what did Richard leakey discover in 1972 and what implication did it have?
- an even older member of Homo (H. rudolfensis) from Lake Turkana, Kenya (1.9 Ma)
- pushes back the origin of homo
- different to habilis
what evidence can you get from a cave to identify climates of different time periods?
look at staligtites and staligmites and date their layers to tell us about wetter and drier periods of time - evidence shows that most fossils build up in drier periods of time
what are taxonomic ‘lumpers’ and ‘splitters’?
- lump all new species together
- name every specimen as a new species
more specimens of H. rudolphensis and H. habilis have been discovered. There is much morphological variation within both species—causing problems with taxonomic ‘lumpers’ and ‘splitters’ - what have taxonomists decided?
- now generally accepted that they are indeed two species
why have people decided on two species despite the range of morphological difference between H. rudolphensis and H. habilis discoveries?
there is significant variation in skull and other skeletal morphology among living humans e..g Inuit, Australian aborigine etc
- people have started to quantify the differences in modern day humans to work out variation expected due to natural ontogeny and sex etc
- over relatively short periods of time modern humans have been separated to different environmental conditions and quite large anatomical differences have evolved
main morphological differences betweenH. rudolphensis and H. habilis?
H. rudolphensis - large brain case - broad flat face - flight brow ridge - broader postcanine teeth H. habilis - small brain case - small face not very flat - strong curved brow ridge - more angulated occipital bone
what did Johansen and White discover in 1986?
Homo habilis partial skeleton
1.85-1.75 Ma (Olduvai Gorge)
what were two interesting observations of lucys child?
1/ it is more ape-like than Lucy (presumed australopithecine ancestor)
2/ H. erectus is only 200,000 years younger but is much larger and more human-like
what is the trouble when trying to classify species by skull fossils?
- skulls are very delicate so are found in tiny pieces and have to be pieced together therefore there can be quite a bit of flexibility in how skulls are reconstructed so it is important not to rely entirely on casts - people often out too much emphasis on tiny differences
what did ‘lucys child’ tell us?
- dont always get progression - the direction of travel isnt always more advanced
- sometimes get reversals because the best fit to the environment at the time doesnt always have to be advancement e.g. more trees = more ape like therefore some H.habilis are more ape like than their ancestors e.g. lucy
what are the 4 recognised species of homo?
- 5-1.9 Ma Homo rudolfensis Rift valley
- 1-1.5 Ma Homo habilis Rift valley
- 9-1.4 Ma Homo ergaster Africa & Asia
- 4-0.3 Ma Homo erectus Africa & Asia
what are 4 possible homo ancestors?
- 5 Ma Kenyanthropus platyops Kenya
- 5-3.0 Ma Australopithecus bahrelghazali Chad
- 0-2.1 Ma Australopithecus africanus South Africa
- 5 Ma Australopithecus garhi Ethiopia
what is suggested about the evolution of H. rudolfensis and H. habilis?
1/ H. habilis evolved from A. garhi and led to all subsequent Homo.
2/ H. rudolfensis is an evolutionary dead end that evolved from K. platyops
what does cladistic analysis show about the early homo?
shows A.africanus to be a sister group to rudolfensis - with rudolfensis more basal than habilis
- this also fits stratigraphically with what we know
where did1/ H. habilis and rudolfensis live?
- suggested the terrain was savannah in a period of drying - they were more adapted to savannah than forest where the australopithecine’s were better adapted too
- however there is still alot of work being done trying to date the earliest homo and coincide with different climate phases based on pollen analysis
compare early homo to australopithecines?
- early Homo has a larger brain, a smaller face, smaller teeth
- Early Homo had a similar diet to Australopithecines (predominantly vegetarian), but most similar to gracile forms (general soft fruit eater). Small amounts of meat may have been scavenged.
- Not all Homo were more committed bipeds than Australopithecus (cf. H. habilis)
- Capable of very basic tool making
when did the earliest stone tool artefacts appear?
about 2.5ma - conincides with the appearance of homo
- 12 bit tool kit found in oldewan gorge
what do tools indicate about a rift valley bias?
- normally people say there is a fossil record bias to the rift valley however you could expect tools to survive anywhere and nonw have been discovered outside the rift valley
what are sites?
areas found with tools, bones, bones of food etc
- can look at where people were living
what is the issue with sites?
bones and tools can be bought in by natural processes
- need to try and understand how things got there - various evidence for this
what are the 3 hypotheses for what the early homo sites were used for?
x - take whole carcus back to a cache of stones
y - avoid competition by eating meat up trees
z- hominids cut pieces of carcusses and transported them back to a home base/central base for provisioning maybe even food sharing
how has interpretation of early hominins changed over the years?
1960s - hunter gatherer hypothesis
1970s - thought that they shared food but didnt hunt
1980s - thought they were simply scavengers
1990s - advanced scavenging hypothesis - very simple human like subsistence