Primates

Question 1

Order: Primates

Answer 1

• 4th largest order of mammals (after rodents, bats and insectivores)
• includes great apes, humans
• more than 250 species
• most arboreal (live in trees)

Question 2

Features of primates:

1. Plantigrade feet

Answer 2

• most mammals walk on tips of the feet (on their toes) = digitigrade
• Primates walk on their entire feet right up to the heel = plantigrade
• other plantigrade mammals = bears, hedgehogs

Question 3

Features of primates:

2. Grasping digits

Answer 3

• Primates have prehensile (grabbing) digits and opposable thumbs
• finger nails, not claws
• adaptation for arborela existence
• important in evolution of tool use

Question 4

Features of primates:

3. Binocular vision

Answer 4

• forward facing eyes
• often enormous
• increased visual sense (including colour vision) at the expense of sense of smell
• Adaptation for:
• nocturnal existence
• judging distances

Question 5

Features of primates:

4. Increased brain size

Answer 5

• particularly in great apes and humans
• visual and locomotory areas greatly enlarged

Question 6

Features of primates:

5. Shoulder anatomy

Answer 6

• a well developed clavicle (collar bone)
• very flexible rotating shoulder joint
• good for movement through trees

Question 7

Features of primates:

6. Upright posture

Answer 7

• most primates can sit upright
• some can walk short distance on hind legs
• humans do it habitually

Question 8

How do humans differ from other great apes?

1. Locomotion

Answer 8

• bipedalism - humans walk upright habitually
• great apes typically ‘knuckle walk’
• human foot become less grasping - big toe straightened

Question 9

Skeletal differences associated with upright walking

Answer 9

• big toe redued
• pelvis shortened, more bowl-like than blade-like (helps support base of spine)
• femur bends inwards, knee straightened, patella central to joint
• conneciton with spinal column (foramen magnus) on underside of skull
• less robust upper arms

Question 10

Consequence of upright walking

Answer 10

• freed hands for other purposes
• greater manual dexterity
• greater tool use
• ability to throw accurately (important in hunting)

Question 11

How do humans differ from other great apes?

2. Diet

Answer 11

• humans are highly omnivorous, but with a much higher meat intake than other apes
• also eat higher amount of processed food e.g. cooked, pickled, fermented

Question 12

How do humans differ from other great apes?

3. Brain size

Answer 12

• humans have a greatly increased brain size compared to our nearest relative

Question 13

Where did hominids originate?

Answer 13

• majority of hominid fossils found in East Africa
• most of these in sites in the Rift Valley
• Lots of lakes and human fossils found in same deposits as lake dwelling creatures e.g. fossil hippos
• early hominids must have spent some time around water

Question 14

Hominid diversity and evolutionary tree

Answer 14

• About 20 species
• 3 main genera:
• Australopithecus (about 7 species)
• Paranthropus (3 species)
• Homo (about 7 species)

Question 15

Sahelanthropus tchadensis

Answer 15

• First hominid?
• discovered 2001 in Chad
• nicknamed “Toumai”
• 6 to 7 million years old - chimps and humans may have common ancestor earlier than thought
• skull only
• location of foramen magnum on base of skull, suggests it was bipedal

Question 16

Australopithecus afarensis - “Lucy”

Answer 16

• lived 3-4 mya
• skeleton includes jawbone, part of pelvis and entire femur
• enables great interpretation of the way it lived
• first solid evidence for the transition from four to two legs = bipedalism

Question 17

A. afarensis walked upright - Evidence 1

Answer 17

• shape of pelvis very similar to modern humans

Question 18

A. afarensis walked upright - Evidence 2

Answer 18

• angle of femur and articulation with knee joint indicates bipedalism
• bones suggest A.afarensis only 1.2m tall

Question 19

A. afarensis walked upright - Evidence 3

Answer 19

• discovery of tracks in volcanic ash (3.5 mya) - walking on two feet
• A. afarensis jaw bone found nearby
• Footprints are heel to toe - walking like humans
• two individuals (parent and child?) walking side by side
• animal walking next to them?

Question 20

Was Australopithecus afarensis brainy?

Answer 20

• Facial features more chimp-like
• Complete juvenile skull - 3.3 myo suggests more human appearance (but chimp dentition)
• adult cranial capacity = 440ml (comparable with chimp)
• no increase in brain size in Australopithecus

Question 21

The earliest ‘humans’ - the appearance of Homo

Answer 21

• the earliest species of Homo was likely Homo Hability (‘handy man’)
• H. habilis lived from 2.5-1.5 mya
• often found with simple stone tools
• cranial capacity = 600ml (larger than chimps and Australopithecus but still much smaller than modern humans)

Question 22

Humans begin to travel the world: Homo erectus

Answer 22

• Lived 1.8 my - 300,000 ya
• more complex stone tools
• increased cranial capacity:
• 900ml (early specimens)
• 1100ml (later specimens)
• built simple dwellings
• used fire 300,000 ya

Question 23

When did Homo sapiens appear?

Answer 23

• first Homo sapiens fossil appear between 190-160,000 ya
• Nicknamed ‘Omo I’ found by the Omo River, Ethiopia
• Cranial capacity = 1300ml

Question 24

Neanderthals - Homo neanderthalis

Answer 24

• nearest relative of Homo sapiens
• lived between 130,000 - 30,000 ya
• found in europe and middle east
• very similar societies to Homo sapiens (hunter/gatherer)
• may have been out-competed by Homo sapiens (or may have interbred?)
• Shared up to 99.5% of genes

Question 25

Homo floresiensis

Answer 25

- discovered in 2004, on Flores, Indonesia - VERY recent (18,000 years old) - thought to have descended from Homo erectus ancestor - tiny skull and skeleton hence nicknmed the 'hobbit'