lecture 11 - origin of the hominoidea

Question 1

what did uncovery of the piltdown hoax initiate?

Answer 1

systematic excavation in Africa - scientists rediscover Huxley/Darwins contention that humans are most closely related to african apes and evolved in Africa

Question 2

what did Dart and Broom discover?

Answer 2

that there is two forms of australopithicene

Question 3

what are the two formss of australopithicene?

Answer 3

1) gracile - A.africanus - Taung boy

2) Robust - A.robustus - thick jaws and prominant teeth

Question 4

who are the Leakey family?

Answer 4

family of scientists who have dedicated their lives to studying the rift valley in Africa and human fossils found there

Question 5

what did Mary leaky discover in the olduvai gorge, Tanzania

Answer 5

Australopithecus boisei (1.75ma)

• prominent cheeks and jaw
• big and strong
• eat a heavy diet (ridge on head where jaw muscles attach)

Question 6

describe Homo habilis (1.75ma) discovered by the Leakeys in Olduvai gorge

Answer 6

• first to be put into the same genus as humans
• dating showed that autralopithecens co-existed with homos (until then it was assumed that the ancestor -australopithecus- evolved into the descendent -homo erectus

Question 7

what did the homo habilis discovery signify?

Answer 7

that evolution wasnt a linear progression it is actually a bushy evolutionary tree
- realised there was actually multiple hominid species around at the same time

Question 8

describe Lake turkanya, Kenya

Answer 8

classic rift valley lake - changed size regularly depending on the climate (expanding and contracting)

• sediment piles up on the side in terraces
• well dated by layers of ash from volcano explosions also layered in the lake
• can look at pollen and reconstruct vegetation at the time

Question 9

what was the major breakthrough discovery in 1970?

Answer 9

‘lucy’ A.afarensis(3ma) - found 40% complete - pelvis intact, limb dimensions - tell how she walked etc
- found in Ethiopia

Question 10

what did the A.afarensis footprints tell us?

Answer 10

• two animals recorded walking

- both bipedal

Question 11

what are 2 major fossil findings which stand out on the timeline of discoveries?

Answer 11

1) 6.0-7.0 ma - Sahelanthropus tchadensis - chad (2002)

2) 3.0-3.5 ma - Australopithecus bahrelghazali - chad (1995)

Question 12

what is significant about the two findings in chad?

Answer 12

• chad is beyond the rift valley (rift valley is often seen as the cradle of human kind) - but these finds prove humans moved out the rift valley
• sparked the thought that the rift valley is influencing our thinking by a huge bias n the fossil record due to its sediment deposits

Question 13

what is the issue with working out relationships in human evolution?

Answer 13

• people tend to come up with non scientific phylogenies based on hunches while other people take a more cladistic approach - however its very hard to prove anything
• lots of different scenarios have been proposed - inexact discipline with a bad fossil record

Question 14

what does the rift valleys environment indicate about Australopithicenes?

Answer 14

• pollen cores show the rift valley had a constantly changing environment - so they must have been adapted to a variety of different conditions e.g. life in trees, life on savannah etc

Question 15

between 3-2ma how many homini species coexisted?

Answer 15

6 - either australopithecine’s or homo

- inhabiting a mixture of environments

Question 16

summary of australopithecines

Answer 16

• essentially bipedal apes with modified dentition (ape like from the neck up and human like from the neck down)
• walked in a bent knee bent hip style
• thought they spent alot of time climbing trees - mixture of characteristics for climbing and walking
• evidence of sexual dimorphism and lived in groups

Question 17

what do you observe when comparing chimps, humans and australopithecines?

Answer 17

• australopithecines have long fingers and good rotation adaptations for tree climbing - also short hindlimbs and long forelimbs with alot of movement in should joints - all indications that they were tree dwellers but could walk better than chimps

Question 18

what are the main differences between gracile and robust australopithecines?

Answer 18

• lies mainly in their dental and facial adaptations to chewing
• robust forms = robust jaws, more bulky chewing muscles and more prominent muscle attachments - thought that meat was only scavenged, mainly ate vegetation and nuts
• little difference in size or brain size

Question 19

what is the debate over tool use in homo and australopithecines?

Answer 19

tools found - debate wether australopithecines copied homo or stole tools
- recent evidence of tools found in sites where only australopithecine’s have been found
BIG DEBATE