“Know Thyself ”
Carolus Linnaeus
Human Origins:
A Confluence of Research





Paleontology
Anthropology
Archaeology
Genetics
Paleoclimatology
Conflict, Racism and Uncertainty




Human origins – commonly at center of the Evolution
vs. Creation “debate”
Evolution and human origins are investigated
scientifically – hypotheses are proposed and tested
Creationism/Creation Science/Intelligent Design, etc.
are faith, not science
Topic is full of uncertainty


A) Very young discipline
B) Relatively sparse fossil record
A Family Dynasty – the Leakeys:
Louis, Richard, Mary and Richard Jr.

Mary Leakey - A lifetime
of contributions
including:


Many “first discoveries”
of skulls, etc.
First hominid footprints
A Patchy Fossil Record





Upland habitat – erosion vs. deposition
Fossils are not abundant
Most important sites are in Tanzania, Kenya,
Ethiopia (East African Rift System) and Egypt
Teeth predominate
Jaw and skull fragments




Taphonomic changes make taxonomy difficult
Rare post-cranial skeleton
Few complete or nearly complete skeletons
Footprints
The Cradle of Humanity





The East African Rift
System
Earthquakes and formation
of rift as Africa splits
Sinking of rift floor
promoted accumulation of
sediments
Early hominids preserved
in these sediments
Recent erosion cuts
through sediments to
reveal fossils
Famous locations
of hominid fossils

Olduvai Gorge

Hadar

Laetoli
Arboreal Ancestors?






Characteristics of tree dwellers
Flexibility and agility
Parallax vision – eyes in front of head
Vision predominates over sense of smell
Enlarged brain to handle visual data
Secondary adaptations to bipedality (from tree
swingers)
Of Apes and Man






Divergence in Early Cenozoic – Oligocene?
Apes and Hominids
More gap than record
Too early to establish evolutionary relationships
among species
Discovery of each new species changes picture
So, what is a hominid?
Characteristics of Hominids
(a.k.a. hominins)







Arched palate
U – shaped jaw
Uniform dentition (no diastema)
Enlarged skull and brain case
Opposable thumb
Bipedal
Paralax vision
Australopithecus afarensis – “Lucy”







Circa 3.8 Ma Pliocene to
Pleistocene (?)
Female
Four feet tall
Less than 100 lbs.
Tool user, but not maker
Coexisted with A. robustus
Upright posture and
bipedality arise before
enlargement of braincase
Australopithecus afarensis
Footprints at Laetoli, Tanzania
(3.6 Ma) – probable A. afarensis
Australopithecus afarensis and
Homo habilus
One Version of the Time Line
General Picture of
Hominid Evolution




Probable common ancestor of humans and
chimps circa 5.5 Ma
Pliocene saw several hominid species coexising
Several lineages became extinct
Which one was our ancestor?
Kenyanthropus platyops –
an early ancestor to rival A. afarensis?





Mid-Pliocene (circa 3.5 Ma)
Some similarities to Homo
(Kenyanthropus) rudolfensis
Coeval with A. afarensis
More “modern”
appearances millions of
years earlier than previously
thought
Possibly incorrect –
taphonomic distortion?
General Picture of
Hominid Evolution




Genus Homo arises circa
2.0 Ma (H. habilus) Pleistocene
H. habilus – a tool maker
and user, fire, built
shelters, social structure
H. sapiens arises circa
500,000 to 300,000 ybp
(Late Pleistocene)
Modern Humans arise
about 100,000 ybp
The Hominid Time Line




Accurate dating of fossils is critical
Direct evolutionary relationships are still unclear
New fossil discoveries prompt revisions all the
time
The burning questions: Who are we? What is
our heritage? Where do we fit in the grand
scheme of things?