Title: Hominid
1Hominid EvolutionOn The Origin of Humans
2What is a Hominid?
- The term hominid is also used in the more
restricted sense as hominins - Humans and relatives of humans closer than
chimpanzees - Bipedal
- Modern man is the only member of this group alive
today
3Hominid Sites
- Earliest fossil hominid sites are in Africa
- They now span the latest Miocene to the early
Pleistocene from about 6-7 mya to about 1.6 mya - The major groups of sites are
- Ethiopia Middle Awash valley Hadar
(Australopithecus afarensis) - Kenya Lake Turkana
- Tanzania Olduvai Gorge
- South Africa various sites in limestone caverns
centered around Sterkfontein
4What Makes A Hominid? - Bipedalism
- Primary feature distinguishing hominids from
other hominoids is walking erect on two legs
erect bipedalism - Adaptations for bipedalism in the partial
skeleton of Lucy, an australopithecine ( 3.2
mya) clearly seen in the hip, spine and leg bones
5Why did bipedalism become the primary adaptation
of hominids?
- Climate Change resulting in forest habitat being
replaced - by grasslands.
6Advantages of Bipedalism
- 1. Carrying behavior
- 2. Reduction of overall heat stress -
facilitates heat loss through convection by
exposing body to air currents, only humans have
sweat glands that produce moisture to cool body - 3. Most energy efficient way to travel long
distances - 4. Allows for better vision in open
environments defensive action against predators
by freeing hands to throw objects
7Evidence for Early Bipedalism
- The record of bipedalism is most graphically
preserved in the fossilized footprints at
Laetoli, Tanzania, 3.6 mya - Tracks of 2 individuals were uncovered in
volcanic ash by Mary Leakey (1978-79) - Footprints were left by 2 australopithecines in
damp volcanic ash of Laetoli - Notice how close the tracks are!
8Laetoli Footprints
- Laetoli footprints clearly show that the
creatures who made them were fully bipedal - Big toe hardly diverges from the rest of the
foot, unlike in apes - Gait heel-strike followed by toe-off the
way modern humans walk
9Laetoli Reconstruction
- 2 early hominids walk bipedally across an open
ash field produced by an erupting volcano. - Rain wet the volcanic ash footprints filled up
with more ash, and were thus preserved. - Footprints reveal that our ancestors walked
upright with a gait very similar to our own.
10First Adaptive Radiation
- 7-6 mya in the late Miocene, potential last
common ancestors between humans and apes - 1. Sahelanthropus tchadensis
- 7-6 mya in Chad (North Central Africa)
- 2. Orrorin tungenensis
- 6 mya in Kenya (East Africa)
- Note These organisms were forest adapted.
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111. Sahelanthropus tchadensis
- Discovered in Chad (7-6 mya)
- Most complete cranium from this time period
- Mosaic of ape human-like features, but at the
ape grade of evolution - Cranial capacity (320-380 cc)
- U-shaped upper jaw
- Very wide distance between the orbits
- Large, thick continuous brow ridge
- Human-like flat face
- Human-like dentition
122. Orrorin tungenensis
- Fossils from Tugen Hills in Kenya have been
dated to about 6 mya - Earliest Evidence for
- Walking on Two Legs?
13Orrorin tungenensis (cont.)
- Fossils Include upper portion of a femur, lower
portion of the humerus, some lower jaw fragments,
teeth - Arm bone virtually identical to that of a
chimpanzee - Femur more human-like, most important for
showing adaptations for walking on 2 legs - Was Orrorin a direct human ancestor, or a
common ancestor of chimps and humans?
14Second Adaptive Radiation
- 5-4 mya in early Pliocene, first true hominids
- 1. Ardipithecus ramidus
- 5.5-4.5 mya in Ethiopia (East Africa)
- 2. Australopithecus anamensis
- 4.2-3.9 mya in Kenya (East Africa)
- Note These organisms were forest adapted and
fully bipedal.
151. Ardipithecus ramidus
Earliest True Hominid or Last Common
Ancestor? LAST COMMON ANCESTOR OF CHIMPS HUMANS
MOST LIKELY HAD A MIX OF FEATURES SOME RETAINED
IN CHIMPS, OTHERS RETAINED IN HUMANS!
16Ardipithecus ramidus (cont.)
- Between 4.5 and 5.5 mya from the Middle Awash
valley site in Ethiopia - Fossil Remains very fragmentary limb bones, toe
bones, jaws teeth - Straight toe bones suggest it may have been
bipedal - A mosaic of features seen in later hominids
modern chimpanzees
172. Australopithecus anamensis
- Lake Turkana Region of Kenya
- 4.2-3.9 mya
- Probably walked upright
- Teeth enamel thicker than Ardipithecus ramidus,
so diet included hard foods
18Australopithecus anamensis (cont.)
- Fossil Remains very fragmentary
- Those shown here include
- Jawbone
- part of the front of the face
- parts of an arm bone (radius)
- fragments of a lower leg bone (tibia)
19(No Transcript)
20Third Adaptive Radiation
- 4-3 mya in middle Pliocene, many hominids
- 1. Australopithecus afarensis (Lucy)
- 4-3 mya in East Africa
- 2. Australopithecus africanus
- 4-2.5 mya in South Africa
- 3. Kenyanthropus platyops
- 3.5-3.2 mya in Kenya
- Note These organisms lived in open woodlands
along wooded streams in the savannas, ate fruits
and soft foods, maybe had a tool-culture like
modern chimps
211. Australopithecus afarensis
- 4-3 mya in East Africa
- Pelvis leg bones resemble modern humans
- Sexual dimorphism (males larger with sagittal
crest) - Tree climbers (curved fingers toes)
- Ape-like Features
- Small brain case (430 cc.)
- Prognathic (jutting out) face
- U-shaped palate (v. parabolic shape)
22Australopithecus afarensis
23A. afarensis Skeleton - Lucy
242. Australopithecus africanus
- 4-2.5 mya in Transvaal region of South Africa
- 1924 1st Australopithicine to be described by
Raymond Dart! - Globular cranium, slightly higher ratio of brain
to body size than A. afarensis - Face less prognathic than A. afarensis
- Proportions of arm to leg lengths may be more
ape-like than A. afarensis
25Australopithecus africanus
Australopithecus africanus
best known A. africanus cranium (front lateral
views)
Most complete A. africanus skull
Taung Child
26A. afarensis
A. afarensis verses A. africanus
Australopithecus afarensis
Australopithecus africanus
273. Kenyanthropus platyops
- 3.5-3.2 mya found in 2001 west of Lake Turkana
in Kenya - Ape-like features small ear canal, small brain
case - Human-like features flat face, small molars
- Importance flat face appeared early in
evolution, alongside the range of other facial
forms. Evidence that evolution is not linear or
progressive.
28Kenyanthropus platyops
29Fourth Adaptive Radiation
- 3-1 mya in late Pliocene, more robust hominids
- 1. Paranthropus boisei
- 2.2-1.2 mya in East Africa
-
- 2. Paranthropus robustus
- 2-1 mya in South Africa
- 3. Australopithecus garhi
- 3-2 mya in East Africa
- Note Lived in open dry woodlands savannas.
The robust species are famous for eating hard-to-
chew food, like seeds, nuts, and roots. May have
used tools to dig for roots in dry seasons. -
301. Paranthropus boisei
- 2.2-1.2 mya in East Africa Ethiopia, Kenya,
Tanzania - Largest teeth found in any hominid!
- Referred to as hyper-robust due to massive
molars and premolars - Skull broad, short face with flaring cheek
bones, relatively small brain, pronounced
sagittal crest in males - Skull and dental features are adaptations for
heavy chewing!
31Paranthropus boisei (KNM-ER 406)
32Paranthropus boisei (KNM-ER 406)
332. Paranthropus robustus
- 2-1 mya in South Africa
- Short, broad face with deep zygomatic arches
(cheek bones). Larger individuals have sagittal
crests. - Large molars covered with thick enamel
- Wear patterns on teeth herbivorous diet of hard
resistant foods such as seeds, nuts, roots - Lived in grasslands near rivers and wetlands
34Paranthropus robustus
353. Australopithecus garhi
- 3-2 mya in East Africa spotty fossil record,
cranial dental remains found in 1999 in Bouri,
Ethiopia - Bones of antelopes, horses, and other animals
with cut marks made by stone tools butchering
animals smashing bones for marrow. First meat
eaters? - Molars too large to be early Homo genus
- Ape-like long lower arm, human-like upper arm
leg - Mixed traits classified as a new species, maybe
ancestor of early Homo genus
36Australopithecus garhi
37Australopithecus garhi
One surprise in the A. garhi skull was enormous
back teeth, instead of smaller ones seen in later
Homo species
38Australopithecus garhi
- EARLIEST BUTCHERS
- Signs that hominids scraped smashed animal
bones, like this antelope tibia, 2.5 mya - Earliest documented percussion marks made by
hominids, presumably extracting fatty marrow from
these bones
39Rise of the Genus Homo
- Homo habilis Handy Man
- Homo erectus or Homo ergaster in Africa
- Homo heidelbergensis Archaic Homo sapiens
- Homo sapiens neanderthalensis - Neanderthal
- Homo sapiens sapiens Modern Man
40Homo habilis
2.4 1.4 MYA
- Slightly larger braincase and smaller face and
teeth than Australopithecus - Still retains ape-like features of long arms and
moderately prognathic face - Average height 34 to 45
- Average weight 70 lbs.
41Homo habilis
- Thick tooth enamel suggests they had an
omnivorous diet, but were capable of eating
fairly tough foods like leaves and woody plants
By this time, the feet of early humans had a
modern-type arch
42Homo erectus
1.89 MYA 143,000 years ago
- Modern human-like body proportions indicate
adaptations for living exclusively on the ground - Expanded braincase relative to the size of the
face - Left Africa and spread into Asia
- Longest lived early human relative (9 times
longer than we have been around so far) - Used fire (warmth, cooking)
- Evidence they cared for the sick and old (see
skull to left) - Average height 49 to 61
- Average weight 88-150 lbs.
43Homo erectus
Turkana boy fossil
Hand axe first major innovation in stone tool
technology
44Homo heidelbergensis
- Very large brow ridge
- Larger braincase and flatter face than earlier
human ancestors - Short, wide bodies adapted to living in colder
climates - Most likely candidate to have been common
ancestor between Neanderthals and modern humans - Average height males 59, females 52
- Average weight males 136 lbs., females 112 lbs.
700,00 200,00 years ago
45Homo heidelbergensis
- Used wooden spears to routinely hunt large
animals - Built shelters out of wood and rock
46Homo sapiens neanderthalensis
- Short, stocky bodies and huge noses were
adaptations for living in cold environment - Larger braincase than modern man
- Sophisticated tools, used shelters, wore clothing
- First human ancestor to bury their dead and mark
the graves - Modern humans led to their extinction but unclear
as to exactly how - Average height males 55, females 51
- Average weight males 143 lbs., females 119 lbs.
200,000 28,000 years ago
47Homo sapiens neanderthalensis
Ornamental jewlery
La Ferrassie 1 Most complete Neanderthal skull
ever found
48Homo sapiens sapiens
- Originated in Africa 200,000 years ago
- Highly vaulted, thin-walled skull led to more
developed frontal lobe of brain - Flat forehead and face
- Less heavily developed jaws and small teeth
49Homo sapiens sapiens
50Homo sapiens sapiens
Many advancements in art, culture and tool making
technology
51Map of Hominid Evolution