HUMAN EVOLUTION

Question 1

Human vs. Chimpanzees

Answer 1

Protein sequences are 98.5% similar ~6% of human genes not found in chimps, >1400 genes in humans not found in chimps
Replicate copies of some genes in humans not found in chimps
This difference in protein sequences translates a greater dissimilarity in amino acid sequences

Question 2

hominins

Answer 2

All species on the “human” side of the family tree after the split from the branch that became modern chimps.
Roughly 20 types of hominins recovered from the fossil record

Question 3

When did hominins diverge from apes

Answer 3

Earliest hominin: Sahelanthropus (ca. 7-6 Ma), bipedal, small brain
Branched off at the introduction of australopithecus into the family tree around 6.0 Ma

Question 4

foramen magnum

Answer 4

The hole in the skull where the spinal cord goes through

Positioned directly beneath the skull in hominins and enters the skull from the rear in gorilla and chimp lineage

Question 5

What does foramen magnum position at base of skull tell us

Answer 5

Indicates erect vertical posture and bipedalism when directly beneath the skull

Question 6

Age of Australopithecines

Answer 6

4.0 to 1.8 Ma, bipedal with small brain, restricted to southern and eastern Africa
Variety of species with different food niches
Most well known genus of hominins

Question 7

Australopithecus afarensis

Answer 7

(“Lucy” ca. 3.2 Ma), inward pointing femur = bipedalism

Intermediate between human and ape

Question 8

Taung Child:

Answer 8

skull of juvenile Australopithecus africanus (ca. 2.8-3.3 Ma)
Skull Included endocast of brain

Question 9

Dental arcades:

Answer 9

rectangular w/ large canines: ape-like
semi-parabolic w/ smaller canines: australopithecines
parabolic w/ greatly reduced canines: H. sapiens

Question 10

Laetoli Ash (Tanzania)

Answer 10

~3.6 Ma fossil footprints of bipedal australopithecines

Question 11

Genus Homo (H. habilis, medium-sized cranial capacity, bipedal) split from Australopithecines

Answer 11

2.5 Ma (crude stone tools)

Homo habilis: the ancestor to use stone tools

Question 12

Homo erectus

Answer 12

(ca. ~1.8 Ma)
Large brain, bipedal, and more carnivorous
Expanded geographic range to include Africa, Middle East and South Asia

Question 13

Homo neanderthalensis:

Answer 13

230 kyr to 30 kyr (Europe, West & Central Asia, Middle East)
Cold adapted with heavy built and muscular bodies

Question 14

Modern humans of non-African descent have ____ Neanderthal DNA

Answer 14

1-4%

Question 15

Anatomically modern humans (H. sapiens):

Answer 15

ca. 200 thousand years ago

Question 16

H. floresiensis (Flores Island, Indonesia)

Answer 16

94,000 – 13,000 years ago; “hobbits” only ~3 feet tall

They also used tools

Question 17

Trends in Human Evolution

Answer 17

bipedalism
dental arcade becomes more parabolic w/ reduced canines
body size increases
brain size tripled in 3 million years
less body hair

Question 18

advantages to being bipedal.

Answer 18

Good for carrying behavior
Reduction of heat stress: more surface area therefore easier to cool down
Energy efficient for travelling
Better vision
Possible defense against predators (extra hands to carry weapons)