HUMAN EVOLUTIONA Look Into Our Past
“It has often and confidently been asserted, that man's origin can never be known: but ignorance more frequently begets confidence than does knowledge: it is those who know little, and not those who know much, who so positively assert that this or that problem will never be solved by science.”
- Charles Darwin
WHAT IS HOMININ?
A taxonomic group that includes humans and their sister taxa chimpanzees.
- fossils date back between 6-7 million years Genetic analysis shows that
humans diverged from chimpanzees between 5-6 million years ago
WHERE DID IT ALL START?
Two debated theories: 1. Multiregional
Hypothesis Locally adapted
populations interbreeding
2. “Out of Africa” Hypothesis
Single population leaves and replaces existing populations over time.
Darwin predicted this when he wrote “The Descent of Man”
MITOCHONDRIAL EVE
• All mitochondria in human population are descended from the mitochondria of a single woman called “Mitochondrial Eve” about 200,000 years ago
• Mitochondrial DNA (mtDNA) only transferred via eggs (maternal)
EARLY HOMININS
Sahelanthropus Dates 6-7 mya Western Africa Small brain and most
primitive hominin fossil Was bipedal
EARLY HOMININS
Kenyanthropus platyops 3.5 mya Represented by skull
fragments, jaws, teeth, and leg and arm bones
EARLY HOMININS
Australopithecus afarensis 3.5 mya Fossil remains are most
extensive found (named “Lucy”)
Bipedal (fossilize footprints) Primitive features: low face,
long canines, long arms, small brain (400 cc), and curved fingers (tree climbing)
Lucy Video - Biointeractive
EARLY HOMININS
Paranthropus “robust” australopithecines Three named species Large molars and premolars
for chewing plant material May have made stone tools
(2.6 mya) Went extinct and didn’t
contribute to human lineage
EARLY HOMININS
Homo halibis Missing link between
Australopithecus and Homo (1.9 - 1.5 mya)
Greater cranial capacity (610-800 cc)
Flatter face and shorter tooth row
Stone tools (Olduwan technology)
ARCHAIC HOMO SAPIENS Homo erectus
1.6 mya – 200,000 years ago Modern human skull features Larger cranial capacity (avg.
1000 cc) Spread out from Africa to Asia Associated with stone tools
(Acheulian culture), more diverse than the Olduwan tools of H. halibus
First to use fire (500,000 years ago)
ARCHAIC HOMO SAPIENS
Homo neanderthalensis Europe and SW Asia Dense bones and projecting
brow Larger brains than us (1500
cc) Mousterian culture (stone
tools, burial rituals, brain surgeries?)
NOT a direct ancestor, but we may have interbreed with them
ARCHAIC HOMO SAPIENS Modern Homo sapiens
170 – 160 Kya Modern cranial capacity (avg.
1400 cc) Indistinguishable from us Started in Africa and
overlapped range with Neanderthals
Abrupt change 40,000 years ago allowed for “replacement” of Neanderthals
Crossed land bridge 12,000 years ago to Americas
EVOLUTIONARY DRIVING FORCES
Selective pressures put a premium on two traits throughout our evolution:
1. Bipedalism- A. afarensis fossil footprints (3.6 mya in
Tanzania)- great toe not splayed out
2. Cranial Capacity and Intelligence (high
selection!)- learning and
communication