Antho week 4 quiz
Primary characteristic that distinguishes hominis from other members of the hominoidae is bipedalism is...?
1)Dental Arcade shape
2) Smaller Canines
3)No Diastemas
4)Thicker tooth enamel
5)Reduced prognathism
Why did bipedalism occur?
becoming bipedal was not nesesarilly a positive change
-more vunerable to predators
-slower, more stress on skeleton
-Had to be nessessary variability within the skeleton in order for a tansition to be made
-Not all populations evolved this way
-Bipedalism was not the only evlutionary option
Hypotheses on Bipedalism
Widely thought that significant increace in brain size and tool use evolved together
Made sence to people who thought the differnce between primates and humans was intellegence
1970s- showed that bipedalism occured at least a million years before significant increases in brain size and evidence for tool use
1970/80s- thought that bipedalism was probely an effective way to adapt to a savannah grassland kind of environment
Increasing reserch on palaenvironments showed that they were likely living in a more mixed environment
Bipedalism was chosen to free the hands (could carry things while standing or moving)
Walking in trees hypotheses
-Bipedalism evolved as a more efficent way of moving around in trees
Palaenoanthropolgy def
Many human fossils found in the Great Rift Valley of EAST?SOUTH AFRICA
Caves are really good for perservation
What do Palaeoanthropologists do ?
usually search in areas where there are sediments exposed from the time peroid of interest and good preservation of oraganic remains
Teeth tend to preserve the best, followed by bones of the skull and post cranial bones are preserved less often
IMPORTANT TO UNDERSTAND TAPHONOMY
what happens to the remains after death because its important to note weather the marks on the bone were made intentionally or by natural process
For optimal preservation, body has to be in a environment not conducive to decomposition
Ancient humans and bipedalism
No conenses definition of human or hominin
(common to consider hominins to include all members of the genus. Homo and other taxa with evidence of bipedalism)
Age:
Can be determined by looking at how many adult teeth have erupted and the degree of bore fusion
Sex
Can be dertermined by examining characteristic features of the pelvis (can be ambiguous)
Dating techniques
1-Potassium argon (K/Ar)- Best technique for sites 200,000 years old. Based on measurnment of the radioactive decay of an isotope of potassium into argon
2-Carbon 14 (C-14)- Less then 50,000 years old. Based on the decay measurnmet of carbon 14.
3-By association- two things are found in the same stratigrophc layer are likely the same age
Lumpers vs. Splitters
Lumpers- assume there is alot of variability within genera and species and therefore have relatively few taxonomic categories
Spiltters- assume there are relavetabilty little varibility within genera and species therefore recognize many differnt genera
Sahelanthropus
7-5 million years ago
Small teeth, no diastema, position of the foramen magnum indicate bipedalism
Orrorin
6 million years ago
Femur indicative of bipedalism
Relatively large body and small teeth with thick enamel
Ardipithecus
5.8-4.4 million years ago
Ardipithecus ramidus had a skeleton suggesting bipedaism and small canine teeth
Australopithecus
4.2-1 million years ago
only in Africa
Several species
Ranged in size from approx 65 pounds and 3.5 feet tall to approx 100 pounds and approx 5 feet tall
A. afarensis or A. africanus likely evolved into homo
Lucy (Dinqnesh) = A. afarensis
Found in Etheopia in 1974, showed that bipedalism was aqquired before brain size increase
Other early hominins
1- Paranthropus(1 million years ago, robust traits, became extinct)
2-Kenyanthropus (Only one skull, may be ancestral to homo)
Early Homo
Genus homo appeared between 2.5-3 million years ago
Compared to Australopithecus (had a larger brain, smaller teeth and less prognathic face)
Homo habilis/ homo rudolfensis
2.5-1.4 million years ago
only in Africa
First undisputed store tools
Homo erectus/ homo ergaster
Emerged in Africa by approx 2 million years ago
In eastern asia by 1.7 million years ago
Larger brain and body size
Many cultural developments: full-scale hunting, control of fire and cooking
Archaic Homo sapiens/ homo heidelbergensis
First appear- 8000,000 years ago
Homo neandertalensis
From a group of homo heidelbergensis in Europe
approx 400,000 years ago
Modern homosapiens evolved in Africa
approx 300,000 years ago
Piltdown man (Eoanthropus dawsoni)
Discovered in Great Brittian
Forgery discovered in 1953
Orangutan mandible/teeth and modern human skull