Human Prehistory exam 3

Question 1

Model of human origins

Answer 1

Bipedalism likely came first. Then larger brains, tool use, and smaller canines came after. Whatever order is correct is up for debate.

Question 2

Bipedality

Answer 2

1. Defining characteristic of the hominins
2. Begins 6-7 mya
3. Earliest bipeds not “fully” bipedal
   a. Were likely still arboreal
   b. Likely didn’t walk as efficiently

Question 3

Hallmarks of bipedalism

Answer 3

foramen magnum facing inferiorly;
curves in vertebral column, and especially lumbar and sacral curves;
bowl-shaped pelvis;
flaring iliac blade;
high bone density of inferior femoral neck;
bicondylar angle;
horizontal tibial plateau with vertical tibial shaft;
large calcaneus; inline and large 1st toe bones

Question 4

Bicondylar angle

Answer 4

In hominins, the femur angles inward, keeping the legs more directly under the body resulting in a more efficient center of gravity.

Question 5

What are the advantages to be bipedal?

Answer 5

Increased ability to see greater distances
Greater ease of transporting both food and children
Ability to run long distances
Freeing hands for, eventually, tool manufacturing and use

Question 6

What scenario can explain the possible selection for bipedalism?

Answer 6

The change of environment from woodland to patchy forests, which lead to food availability being changed, in Africa is a likely scenario that would lead to bipedalism.

Question 7

Sahelanthropus tchadensis

Answer 7

Found in Chad, Central Africa
7.2 - 6.8 mya
Projecting face
Overlapping canine
Foramen magnum on bottom of skull
350 cc brain size
Very thick brow ridge (high supraorbital torus thickness)

Question 8

Orrorin tugenensis

Answer 8

2001: 13 fossils of at least 5 individuals found in the Tugen Hills of Kenya.
The femur shows evidence of bipedalism. Its humerus and finger bone retain evidence of arboreal adaptations.
Dated to 6 mya
No skulls have been found of this species

Question 9

Ardipithecus ramidus

Answer 9

Aramis, Middle Awash, Ethiopia
4.4 – 4 Mya
Over 300 cc brainsize
Tons of bones found

Question 10

Australopithecus anamensis

Answer 10

Lived from 4.4 – 3.8 Mya
Cranial capacity: 365-370 cc
Sagittal crest
U-shaped palate
Large, overlapping canines
Bipedal with tree climbing abilities

Question 11

Australopithecus afarensis

Answer 11

3.9-3.0 Mya
Cranial Capacity: 375 - 550 cc
Highly sexually dimorphic
Massive brow ridges
Prognathic
Large molars, smaller anterior teeth
“Lucy”
Left behind footprints in Africa
Lived in Northeast Africa

Question 12

The Plio-Pleistocene Transition

Answer 12

1. After 2.5 mya, grasslands spread thru Africa
   a. Vegetables and fruit became more scarce
2. First stone tools
   a. Adaptive strategy to scavenging meat

Question 13

Australopithecus Aethiopicus

Answer 13

2.5 mya
Found in West Turkana
Posterior sagittal crest
Post-orbital constriction
Broad cheek bones
Backward extending zygomatic arches

Question 14

Australopithecus Boisei

Answer 14

2.4 - 1.3 mya
Sagittal crest
Reduced anterior teeth
molarized premolars
Females did not grow a sagittal crest
Sexual dimorphism
Slightly bigger brains than other Au. species
About 4ft tall
Lived in Kenya

Question 15

Australopithecus Robustus

Answer 15

2 - 1.5 mya
Lived in South and East Africa
Sagittal crest
Large zygomatics
Postorbital constriction
Dished face
Postcanine megadontia w/small incisors and canines
Very thick mandible
Differences are only in the cranium
No difference in body size
Used the oldest known bone tools

Question 16

What do all the species with the genus Australopithecus have in common?

Answer 16

They all have some form of a sagittal crest and a lot of sexual dimorphism

Question 17

How do tooth proportions change from Australopithecus to Homo?

Answer 17

The teeth became smaller due to change in diet and having the ability to cook food over a fire.

Question 18

Homo Habilis

Answer 18

Smaller premolars
Bigger front teeth
Large anterior teeth and small molars
Cranial capacity around 750cc
Lived 2.3 - 1.5 mya
Used Oldowan tools (temporary tools)
About 4ft tall and weighed 80-90 Ibs
Hand reconstructions show precision and power grips
Skull has more vertical forehead than Australopithecines

Question 19

Oldowan tools

Answer 19

Stone tools used for two things: For cutting meat from bones and smashing the bones to access the protein-rich bone marrow. Only used temporarily and then thrown away. Used by Australopithecus species.

Question 20

Acheulean tools

Answer 20

Tools that are made much more effectively, are used for much longer, and are used to butcher large animals. Was used intensively by Homo Erectus.

Question 21

Benefits of stone tools

Answer 21

Wider resource exploitation
Increased meat consumption
More processing of plant materials

Question 22

Origins of Genus Homo

Answer 22

Scavenging meat with Oldowan tools should allow for:
1. Increased brain size
2. decreased molar size
3. Modern hand morphology
Changes starting with Homo Habilis

Question 23

Homo Erectus (compared to Homo Habilis)

Answer 23

1.75 mya - 690 thousand years ago (tyo)
No forehead
Wider braincase
Browridges
Occipital torus
Larger teeth
Thick cranial vault bones
Broad cranial bones
900cc for brain
Projecting nose like homo sapians
Got up to 6ft tall
Made stone tools

Question 24

Late Homo Erectus

Answer 24

600 - 300 tyo
Got up to almost 1400cc

Question 25

Homo Neanderthalensis (HEAD)

Answer 25

Long cranium
Nuchal bun (on the buck of the skull)
Brow ridge w/ sloping forehead
Big faces
Lack of chin
Projecting midface
Very wide braincase (widest in the middle)
Plenty of room for their teeth
Wide nose
Swept back cheek bones (zygomatics)
Large cranial capacity (1500cc)
Inflated maxilla - no canine fossa

Question 26

Homo Neanderthalensis (BODY)

Answer 26

Shorter than H. Erectus and modern humans
Barrel-shaped chests
Distal limb foreshorting
Radius/ulna and tibial/filula are short
Humerus and femur are long
Wide & A/P elongated pelvis
Rounded, thick femora
Robust toe bones

Question 27

Homo Neanderthalensis (MISC)

Answer 27

Cave dwellers
Were the first to live outside the tropics
Used stakes to hold down hides
Purposeful burial
Personal endorment - Wearing something to express yourself
Wore seashells

Question 28

Who has the largest supraorbital torus we’ve ever seen?

Answer 28

Sahelanthropus tchadensis

Question 29

Modern Human Origins

Answer 29

Vertical forehead
Rounded rear vault
Reduced or absent brow ridges
Originated in Africa
a. Morocco most likely
Didn’t leave Africa until 100 tyo
Likely sailed to Australia and North America

Question 30

Did Homo Sapiens and Homo Neanderthals interbreed?

Answer 30

They did. We have neanderthal dna with us still!!

Question 31

Is Skhul V a hybrid, since the parents are Homo sapian and neandertal?

Answer 31

Not exactly. Skhul V looks very normal. If it was a hybrid, then it would look very out of the ordinary.

Question 32

Denisovans

Answer 32

A very mysterious group of hominins that interbred with Homo sapiens and neanderthals.