Dating, the Leakeys, Laetoli, and Lucy

Question 0

Paleolithic

Answer 0

Crudely divided into several periods (relative dating)

• 1.8 million years-200,000 years: lower paleolithic
• 2-5 million years: middle paleolithic
• Upper paleolithic = humans

Question 1

Dating

Answer 1

5-7 million years ago: humans and chimps diverge

4. 4 million years ago: Hominin bipedalism
5. 3 million years ago: first evidence of tool use
6. 8-7,000 years: absolute dates

Question 2

Absolute Dating techniques

Answer 2

Dendrochronology, radiocarbon, optically stimulated luminescence, therma-luminescence, electron spin resonance, geomagnetism, and radiopotassium

Question 3

Dendrocchronology

Answer 3

Annual growth bands in tress

Question 4

Radiocarbon

Answer 4

Decay of C14

Question 5

Radio-potassium

Answer 5

K-Ar dating

• Requires volcanic layers of ash (ash, basalt, etc.)
• Measures 40K and 40Ar
• Range of 100,000 to >5 million years old
• “Setting the Clock”= heating vent releases Argon from molten lava; when the lava solidifies it means it has a lot of radioactive potassium; constant decay or Argon leads to accumulation in rocks

Question 6

Stratigraphy and K-Ar

Answer 6

Soil -> volcanic ash -> soil -> volcanic ash -> soil

• Find two dates; first layer is under the spot human remains would be found second layers pile up (very important)
• Can provide date range for non-volcanic sediments

Question 7

Early Hominins

Answer 7

Teeth were the only part of early Hominins found by archeologists (other parts destroyed by local animals; teeth too hard to digest)

Question 8

Thomas Huxley

Answer 8

Published Man’s Place in Nature (1863); similarities between human and ape skeleton’s
-Coined the concept of “missing link”: a species which links apes and humans (now there is many links)

Question 9

What makes humans?

Answer 9

Obligatory bipedalism, large brains, highly dextrous hands (opposable thumbs), non-divergent toes, enhanced verbal communication, and tool use

Question 10

Obligatory Bipedalism

Answer 10

Walking straight

Question 11

What makes apes?

Answer 11

Non-obligatory bipedalism, small brains, limited mobility in thumb, divergent toes, limited verbal communication, and limited tool use

Question 12

Non-obligatory Bipedalism

Answer 12

Walking bent

Question 13

Family “Bush”

Answer 13

Divergence, split offs, and a lot of common ancestors/relatives
-Hominin, lumpers, and splitters

Question 14

Hominins

Answer 14

All modern and fossil human species since the split of chimps

Question 15

Lumpers

Answer 15

Collapse species into one category

Question 16

Splitters

Answer 16

Split fossils into new species of genes (in between)

Question 17

Ardipithecus Ramdidus

Answer 17

Mixture of human and chimp features, bipedal walking, aboral adaptations (indication of climber due to long arms), divergent toes (grasping and climbing, not running), and reduced sexual dimorphism (females aren’t smaller than males)

Question 18

“Ardi”

Answer 18

Tim White (2009), Aramis, Ethiopia

• Most complete early Hominin
• 4.4 million years old
• Female; weight: 110 lb (50 kg) height: 4 ft (120 mm)

Question 20

“Lucy” (Lucy in the Sky with Diamonds)

Answer 20

Donald Johanson discovered complete specimen (1974), Hadar, Ethiopia)

• 3 million years old
• Most complete specimen of A. Afarensis
• Pelvis designed for bipedal locomotion; bowl-shaped pelvis

Question 21

Laetoli footprints

Answer 21

Mary Leaky, Tanzania (1976)

• Evidence of bipedalism
• 3.8-3.5 million years old
• Footprints discovered by A. Afarensis

Question 22

Australopithecus Afarensis

Answer 22

Pronounced Sexual dimorphism (females smaller than males), long arms (climber) relative to legs, smaller cranial capacity (compared to chimps),

• Females = weight: 55 pounds (25 kg) height: 3.5-4 ft (1-1.2 mm) brain: 380 cc
• Males = weight: 110 lb (50 kg) height: 5 ft (1.5 m) brain: 480 cc (similar to chimps)