HUMAN EVOLUTION

Question 1

Human vs. Chimpanzees

Answer 1

• Human vs. Chimpanzees
○ 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

What are “hominins”?

Answer 2

• What are “hominins”?
○ 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

• When did hominins diverge from apes?
○ 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

What is the foramen magnum?

Answer 4

• What is the foramen magnum?
○ 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 its 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

• Age of Australopithecines: ~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

• Australopithecus afarensis (“Lucy” ca. 3.2 Ma), inward pointing femur = bipedalism
○ Intermediate between human and ape

Question 8

Taung Child:

Answer 8

• Taung Child:
○ skull of juvenile Australopithecus africanus (ca. 2.8-3.3 Ma)
○ Skull Included endocast of brain

Question 9

Dental arcades:

Answer 9

• Dental arcades:
○ 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

• Laetoli Ash (Tanzania): ~3.6 Ma fossil footprints of bipedal australopithecines

Question 11

Genus Homo

Answer 11

• Genus Homo (H. habilis, medium-sized cranial capacity, bipedal) split from Australopithecines ~2.5 Ma (crude stone tools)
○ Homo habilis: the ancestor to use stone tools

Question 12

Homo erectus

Answer 12

• Homo erectus (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

• Homo neanderthalensis:
○ 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

Answer 14

• Modern humans of non-African descent have 1-4% Neanderthal DNA

Question 15

Anatomically modern humans (H. sapiens):

Answer 15

• Anatomically modern humans (H. sapiens): ca. 200 thousand years ago

Question 16

H. floresiensis (Flores Island, Indonesia):

Answer 16

• H. floresiensis (Flores Island, Indonesia): 94,000 – 13,000 years ago; “hobbits” only ~3 feet tall
○ They also used tools

Question 17

Trends in Human Evolution:

Answer 17

• Trends in Human Evolution:

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

Question 18

Name some advantages to being bipedal.

Answer 18

• Name some advantages to being bipedal.
○ 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)