Paleoanthropology = The study of human origins
and evolution.
Primates have been
present for 65 million years (end of Mesozoic era) and are defined by
characteristics shaped by natural selection for living in trees. Later, this
selection pressure will change. A diagram of probable primate evolution. Fig. 27.2
- Limber shoulder joints which make
it possible to brachiate. Movie of
brachiation!
- Dexterous hands for hanging on
branches and manipulating food.
- Sensitive fingers with nails, not
claws.
- Opposable thumb and 4 fingers.
- Eyes are close together on the
front of the face, giving overlapping fields of vision for enhanced depth
perception (binocular vision). Fig 34.40
- Excellent eye-hand coordination.
- Parental care with usually single
births and long nurturing of offspring.
- Poor sense of smell
Prosimians Fig 27.1
(non-anthropoid primates) For images
of lemurs, lorises, etc.
The anthropoids include all other primates.
- Fossils of monkey-like primates
indicate anthropoids were established in Africa and Asia by 45 million years
ago (S. Amer. and Africa were separated)
- Primates became diurnal about 36 million years ago
- Refinement of opposable thumb
-
The New World monkeys, (images)
some with prehensile tails (Fig 27.3)
-
The Old World monkeys (images)
Hominoids: hominids plus apes (Fig 34.37)
Hominids: humans and their direct
ancestors
Homo sapiens is the only living hominid.
Evolutionary Origins
of Humans. 5-8
mya
Trends in hominid
evolution
- the location of the foramen
magnum (where the spinal cord enters the skull).
- shape of the pelvis
- curvature of the spine
- first toe opposable or not
- Laetoli footprints in Tanzania (Fig. 27.8
and Image)
(about 3.5 MY old) support the conclusion of early bipedalism. Fig. 27.7.
Hominids walked upright
for two million years without a substantial increase in brain size. It is a
common misconception that all traits evolved at the same time.
This link will take
you to a page
that has a paragraph or 2 about each of these species.
Fig 27.9
gives approximate time lines for some of these species. Talk Origins timeline.
Map
of Africa.
Sahelanthropus
tchadensis
discovered in
2001 in Chad - between 6 and 7 myo. Not certain if it is a hominid or more kin
to apes. Face much flatter but not certain at this point if it was fully
bipedal. Significant also because found much further west in Africa than any
other hominid fossil. See an article and links here and here. See a website on
this species here. And an article.
Orrorin tugenensis (about 6 mya)
Ardipithecus ramidus
(Australopithecus ramidus) (4.4 - 4.2 mya). Fossil.
Australopithecines: (southern ape) Figs 27.6a
and 27.6b.
The First Humans: 4.4 - 1.1 mya. Map of eastern Africa
and sites of fossil finds. Map
with skulls.
Australopithecus
anamensis. (4.2
- 3.9 myo). Jaw.
Australopithecus
afarensis. (3.7 - 2.8 myo) "Lucy" about 3.2
myo. Skull.
Found in Ethiopia in Afar region in 1974. Skeleton (Image)
Kenyanthropus
platyops (3.5
myo). It lived about the same time as A. afarensis, but has a flatter face and
smaller teeth, appearing more similar to modern humans than did A. afarensis. The skull was found on the
shores of Lake Turkana in Kenya. More information here and here.
Australopithecus
africanus (3 -
2 myo). Skull.
First hominid fossil found.
Australopithecus
afarensis and africanus are known as gracile australopithecines
Australopithecus
garhi (2.5 myo) - possibly first tool
user. Found in Ethiopia with shaped tools. Skull.
Australopithecus
boisei (2.3 -
1.4 myo). Skull.
Australopithecus
robustus (1.9 -
1.5 myo). Skull.
Australopithecus
robustus and boisei are known as robust australopithecines.
Gracile
vs robust skulls. And here.
Homo spp. 2.4 myo to present.
Significantly larger brain size than australopithecines. Figs. 27.12a
and 27.12b
Homo habilis "handy man" (2.5 - 1.6 myo). Skull.
Once thought to be the first tool user. Broca's area developed.
Homo rudolfensis (2.4-1.8 myo). Skull.
May be larger habilis.
Homo ergaster Fig. 27.10.
similar to Homo habilis but larger.
Homo erectus (1.8 myo to perhaps 250,000
years ago). First with evidence that they used fire. Replica of skull.
Another skull.
Homo floresiensis
(95,000 and
13,000 years ago) National Geographic article
and the Nature article.
Homo heidelbergensis (800,000 - 100,000 years ago) -
may have led to sapiens or neandertalensis.
Homo
neanderthalensis
(some consider
as Homo sapiens neanderthalensis) (230,000 - 30,000 years ago) Neanderthals. Skull.
Neanderthals
versus sapiens.
Homo sapiens (modern) (100,000 years ago to
present). Skull.
Cro-Magnon
- More info here
The Multiregional
Hypothesis
The Out-of-Africa or
Replacement Hypothesis (Fig 27.13)
This image
compares these
two models.
Cultural evolution -
See some prehistoric art here.
And here.
Agriculture began about
8,000 BC in the fertile valley of Mesopotamia.
Links: