Homo erectus

Genus Homo
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Soon after 1.8 million B.P. in Africa and nearly as long ago in
Asia and Europe, an acceleration of human evolution took
place.
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Many paleoanthropologists believe that all of the hominids that follow
Homo habilis and predate Homo sapiens—from after 1.8 million B.P
until about 300,000 B.P. or even later—belong to a single species:
Homo erectus.
Recent discoveries have convinced others that this period of human
evolution presents us with a number of related, but more or less
geographically separate, species.
Homo rudolfensis & ergaster in Africa
Homo erectus in central and east Asia
Homo antecessor in Europe.
Homo Erectus
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Soon after 1.8 million B.P., a new form of
hominid appeared in the fossil record of
eastern Africa.
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The cranium of Homo erectus was quite different
from that of its evolutionary antecedent, Homo
habilis.
The back, or occipital, portion of the erectus skull is rounder that that of
habilis, with a much larger area for muscle attachment.
Cranial endocasts of a number of Homo erectus specimens shows intriguing
similarities to the modern human brain.
A massive ridge of bone called a supraorbital torus, which is present in the
skulls of all ape species and is generally absent in the modern human form.
They walked upright, in a manner similar, if not identical, to that of modern
human beings.
Homo ergaster:Nariokotome boy
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1.6 mya
Tall (over 6 ‘)
Narrow pelvis
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Robust, Long legs
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Increased infant
dependency?
Increased
territory
Hunting
Fire?
Acheulian tools
Language?
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Brocca’s area
1.8 mya
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Sangira skull Java: 1.7 mya ?
China: 1.9 mya?
Ngandong, Java: 27,00053,000 BP?
Issues and Debates
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Human children are utterly dependent on adults to satisfy all
their needs for a very long time.
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The term altricial is used to characterize baby birds who are completely
dependent on their parents for fulfilling their needs.
Human babies are said to be secondarily altricial.
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An additional hypothesis holds that one of the key changes that characterized
ancient hominids from Homo habilis on is neoteny, or the “holding on” to features
that are typical of newborn apes (Gould, 1977).
A long period of learning is emblematic of the human species.
What Do We Know About the Early Hominid Brain?
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Under rare circumstances a cast of the brain, showing features of its
exterior surface, can survive.
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Endocasts, natural models of ancient brains, can show us what the exterior
surface of an ancient brain looked like.
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Endocasts of Australopithecus africanus show that the exterior surfaces are
indistinguishable from the brains of modern apes.
Artificial endocasts of a Homo habilis specimen shows a far more humanlike,
asymmetrical morphology. Brocca’s area.
Homo erectus migrations (2mya-0.8mya)
Dmanisi (1.7 mya)
Ubediya (1.5 mya)
Sangiran (1.8 mya)
Longgupo (1.9mya)
Atapuerca 780,000
Issues and Debates
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Did the climatic change cause the Evolution of Homo
Erectus?
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Though the first appearance of erectus and the accepted beginning of
the Pleistocene epoch are roughly contemporaneous, significant global
cooling and the growth of continental ice sheets predate the appearance
of erectus as well as its expansion into Asia and Europe.
What Enabled the Geographic Expansion of Homo
Erectus?
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Intelligence
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Homo erectus seems to have been the first human ancestor to rely
on the invented, learned, and passed-down adaptations of culture for
survival.
Control of Fire
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The best available evidence indicates that Homo erectus was our first
ancestor able to control fire.
Expansion into Europe is later
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Israel has the earliest firmly dated Acheulian
assemblage outside Africa at 1.4-1mya
Earliest European evidence from Gran Dolina, a cave at
Atapuerca, Spain dated to 800,000 ka. Is attributed to
Homo antecessor. This may be an offshoot of H.
ergaster that disappeared after failed attempt to colonize
southern Europe. No Acheulian at this age
Then there is a gap until after 500,000-400,000 when
several finds from Africa and Europe are grouped as
Homo heildelburgensis. This is when Acheulian artifacts
probably introduced to Europe. In Europe this may be
the last common ancestor to both Neanderthals and
modern humans.
Oldowan
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Choppers
Flakes
Cores
Homo habilis
Australopithecus Garhi
Early
Acheulian
Handaxe
Cleavers
Cores
Late
Acheulian
Flakes
Choppers
Hard
& soft hammers
Homo erectus
Later Acheulian
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Soft hammer
Decrease in size
Increase in symmetry
Evidence for structures
Seasonal transhumance
“Ends” about 250,000 BP
with new levallois technique
added
Regional variants of evolved
Homo erectus
Issues and Debates
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The “Art” of Making Tools
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A high level of consistency in
handaxe form can be found
within sites, as if the makers
were adhering to a particular
standard.
That such extra care was taken in
their production implies that their
makers were interested in more
than simple utility.
 Some have argued that evidence
of bilateral symmetry in later handaxes is related to cognitive
development. Cf. Piaget’s
Late Acheulian hand axe
developmental stages in children. (Kalambo Falls)
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African Acheulian complex
Early Acheulian
Later Acheulian: Levallois, Sangoan, Fauresmith
Sangoan
Fauresmith
Homo erectus subsistence
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Hunting, scavenging and gathering wild plants
together provided subsistence for Homo habilis.
The Homo erectus diet consisted of much more
than meat.
At the 800,000-year-old Gesher Benot Ya’aqov
(GBY) in Israel (Goren-Inbar et al. 2002),
researchers recovered chunks of stone, 54
exhibited pitting that experimental replication
suggests were produced by using them as
hammers to break open nuts.
Hominids Conquer the World
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China
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Stone artifacts (crude core tools and flakes) associated with
Homo erectus were found in the Nihewan Basin of northern
China show that they are approximately 1.36 million years old
(Zhu et al. 2001).
Europe
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The oldest unequivocal hominid remains found in western
Europe were recovered at the site called Gran Dolina in the
Atapuerca Mountains in Spain (Carbonell et al. 1995).
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Environmental stress, cannibalism, local extinction?
It is reasonable to say that African hominids first entered Europe
by at least 800,000 years ago.
Atapuerca, Spain
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Gran Dolina
 Homo antecessor ca. 800 ka
 Gran Dolina has yielded the remains
of at least 6 individuals dated from
before 780,000 years ago.
 There is debate whether these
represent a new species, or fall within
the range of variation of other H.
erectus specimens.
 Evidence for cannibalism is evident
on 25% of bones with cut marks. This
could be a sign of nutritional stress.
Perhaps this unsuccessful adaptation
represents a migration into Europe
that failed?
Issues and Debates
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The Mystery of the Missing Hand Axes
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Beginning about 1.4 million years ago, hand axes
become ubiquitous at Homo erectus sites in Africa.
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Hand axes are extremely rare or more commonly entirely
absent from Homo erectus sites in Asia east of the Indian
subcontinent.
It seems that Homo erectus
populations in Africa expanded
into Asia before they had
developed Acheulean
technology with its emblematic
hand axe.
Later Acheulian
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Soft hammer
Decrease in size
Increase in symmetry
Evidence for structures
Seasonal transhumance
“Ends” about 250,000 BP
with new levallois technique
added
Regional variants of evolved
Homo erectus
The Age of Ice
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The earth became a significantly colder place, particularly after about
900,000 years ago, with northern latitudes and higher elevations becoming
covered by expanding ice fields called glaciers (Shackelton and Opdyke
1973, 1976).
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The older period of time is called the Pleistocene epoch.
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The Pleistocene was an epoch of fluctuating climate, with periods called glacials much
colder than the present.
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Within the glacials were colder and warmer periods, with attendant glacial advances
(stadials) and retreats (interstadials).
Between the glacials were relatively long interglacial periods, during which the temperature
often approached, sometimes equaled, and rarely may even have exceeded the modern
level.
The worldwide sequence of glacial advances and retreats can be studied
indirectly, via the ratio of two isotopes of oxygen (16O:18O).
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The Shackleton and Opdyke curve (1973, 1976) covers the last 780,000
years.
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It exhibits 10 periods of drops in 16O and, therefore, significantly colder
temperatures and greater ice cover on the earth’s surface.
Adaptive flexibility seems to have been a hallmark of the Homo erectus species.
Issues and Debates
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The “Art” of Making Tools
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A high level of consistency in
handaxe form can be found
within sites, as if the makers
were adhering to a particular
standard.
That such extra care was taken in
their production implies that their
makers were interested in more
than simple utility.
 Some have argued that evidence
of bilateral symmetry in later handaxes is related to cognitive
development. Cf. Piaget’s
Late Acheulian hand axe
developmental stages in children. (Kalambo Falls)
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When Did Homo Erectus Become Extinct?
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Only the Homo erectus
population in Africa
(ergaster) is directly
ancestral to us.
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That line evolved into
another hominid that
looked and behaved
more like modern
humans.
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Ngandong, Java: fossils
identified as erectus
have been dated as late
as 27,000-53,000 BP???
Stability or Change?
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Homo erectus is one of
the longest-lived of the
hominid species.
About
400,000 years ago a
steep increase in brain size over
a short interval is seen. Those
changes produced and defined
the first Homo sapiens.
The Multiregional Model
Proposed by Milford Wolpoff (Univ. of Michigan)
The basic tenets of the theory are as follows:
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erectus evolves in Africa and is the first hominid to migrate out of Africa
The species spreads through the Middle East and into Asia
Once dispersed H. erectus evolves independently into H. sapiens neanderthalensis
The chief implications of Multiregional model are:
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There is only 1 migration out of Africa
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All modern races of humans have evolved in situ and are directly or indirectly decended
from H. erectus
What evidence supports the Multiregional model?
It is possible to detect the regional racial traits of modern humans in archaic hominids living in the
same region
Key problems with the Multiregional Model
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Not all researchers agree with the racial trait observations
The problem of 'Parallel Evolution'
There is not enough genetic variation in modern populations
Out of Africa I
Chief proponent: Chris Stringer (Natural History Museum)
The basic tenets of the theory are as follows:
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H. erectus evolves in Africa and is the first hominid to leave Africa
The species spreads through the Middle East and into Asia
Once dispersed H. erectus evolves independantly into H. (sapiens) neanderthalensis
Modern humans evolve in Africa from 'stay-at-home' erectus' (H. ergaster) c. 120 kyr
Modern humans leave Africa c. 100 kya and spread into Asia (c. 90 kyr) and central
Europe (c. 40 kyr)
What are the implications of this model?
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There are 2 migrations out of Africa
Neanderthal populations are an evolutionary dead-end
Modern humans may have come into contact with neanderthals
What is the evidence for Out of Africa I?
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Anatomical and social differences between neanderthals and modern humans too great
Problems with Out of Africa I
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Too simplistic - 'The garden of Eden' epithet
Anatomical evidence suggests general continuity (Tabun and Skhul)
Out of Africa II (A variation on Out of Africa I)
The basic tenets of the theory are as follows:
* Same as the Multiregional and Out of Africa I models up to the spread of H. erectus across Asia
and Europe
* Archaic sapiens evolve in Africa from stay-at-home H.ergaster and move into Eurasia, replacing
existing H.erectus populations
* Archaic sapiens evolves into H.neanderthalensis in Europe
* Modern humans (H. sapiens sapiens) evolve in Africa out of stay-at-home archaic sapiens and
move into Eurasia, replacing H.neanderthalensis
Implications of the Out of Africa II model
* There are at least 3 migrations out of Africa
* H.erectus is an evoultionary dead-end
* H. neanderthalensis is an evolutionary dead-end
What is the evidence for Out of Africa II?
* Mitochondrial DNA (mtDNA) analyses indicate that our oldest common ancestor probably lived c.
200 kyr in Africa - ie. rules out H.erectus and archaic sapiens in Europe
Problems with Out of Africa II
* Rate of mtDNA mutation (3% per 1myr) queried?
* How was replacement of populations achieved?
Multi-regional hypothesis
Out of Africa hypothesis
Africa and the origins of modern humans
Homo ergaster & H. antecessor
Archaic Homo sapiens (Homo heidelburgensis)
Kabwe and Florisbad skulls
Neanderthals
Prepared cores and levallois flakes (MSA)
Homo sapiens idaltu
Homo sapiens sapiens
Early Archaic Homo
sapiens:
Kabwe mine, Zambia
400,000 BP?
Later Archaic Homo
sapiens:
Florisbad, South Africa
: 259,000 BP
*Note: some now refer to A. Homo sapiens as H. Heideburgensis
Archaic Homo sapiens: 400-200,000 BP
(Homo heidelburgensis). Early hunting?.
Olorgesaile, Kenya: 400,000 BP
Kabwe
(Broken
Hill),
Zambia
400,000
BP?
Kalambo Falls, Acheulian ±300=400 ka
Wooden throwing club
Seeds and nuts
Grass bedding