For exam, lecture 3 Flashcards
when did the Pleistocene Epoch last
from between 1.8 mya- 12 kya
what are the divisions of the Pleistocene Epoch
lower
middle
upper
how long did the lower Pleistocene last
1.8 mya - 780 kya
what is the lower Pleistocene characterized by
steadily decreasing global temperatures
when the did middle Pleistocene happen
780 cya - 126 kya
what is the middle Pleistocene characterized by
generally low, yet wildly fluctuating temperatures
when did the upper Pleistocene happen
126 cya - 12 kya
what is the upper Pleistocene characterized by
corresponding to the end of the last major ice age
Earth’s glacial and interglacial periods within the Late Pleistocene have been caused primarily by what
cyclical changes in the Earth’s circumnavigation of the Sun
what do the cyclical changes affect
These changes affect the seasonality and location of solar energy around the Earth, thus impacting contrasts between the seasons
what are the 3 changes of the cyclical changes
eccentricity
obliquity/ Axial Tilt
precission
what are the cyclical cycles called
milankovich cycles
what is Eccentricity
changes to the shape of the Earth’s orbit around the Sun. Orbital shape ranges between more and less elliptical on a cycle of about 100,000 years. Greater variation in Sun’s energy reaching Earth when orbital shape is more elliptical
what are we currently in (which cycle)
in between the stages of eccentricity AND axil tilt
what is Axial Tilt
is the inclination of the Earth’s axis in relation to its plane of orbit around the Sun. Oscillations in the degree of Earth’s axial tilt occur on a periodicity of 41,000 years from 21.5 to 24.5 degrees. Affects the severity of the Earth’s seasons
what is Precession
is the Earth’s slow wobble as it spins on axis. This wobble has a periodicity of 23,000 years. Contributes to differences in seasons felt by the Northern and Southern hemispheres
are H. erectus and H. ergaster the same or different
Until fairly recently, all specimens today classified as H. erectus or H. ergaster were considered a single species: H. erectus (“upright man”); those from outside of Africa still are
what led many paleoanthropologists to classify these as members of a separate species(dragster and erectus)
However, some marked morphological differences in the specimens from East and southern Africa have led many paleoanthropologists to classify these as members of a separate species
what does H. ergaster mean
working man
intros course do we consider eraser and erects the same or different
different
In this course, we will consider these two variants to be separate species; however, the groups are morphologically, behaviorally and (likely) culturally very similar to one another, and share a clear ancestral relationship
what is the main difference between erectus and ergaster
Although both H. erectus and H. ergaster appear at around the same time in both Africa and Asia (ca. 1.8 mya), the scholarly assumption is that the origin is Africa, as it’s the only place with a likely bipedal ancestor— H. habilis. However, the closeness of dates poses a problem…
What are the Homo ergaster Early Dates (E. and S. Africa)
The earliest confirmed dates for H. ergaster coalesce around 1.8 mya.
Fossil specimens come from several sites in Kenya, Ethiopia, Tanzania and Swartkrans, South Africa
The finds in Kenya indicate H. ergaster and H. habilis may have overlapped by around how many years
500,000 years
The early H. ergaster fossils are occasionally associated with what
Oldowan tools
what are the Homo erectus Early Dates (Europe / Asia)
H. erectus georgicus appears at the crossroads of Europe and Asia (Dmanisi, modern–day Republic of Georgia) 1.78 mya
what is the cc of the Dmanisi fossils compare to the other H. erectus / ergaster
brains that were unusually small (~600 cc) compared to all other H. erectus / ergaster individuals (between ~850 –1100 cc).
what is the problem of Homo erectus / ergaster Origins
The problem is one of distance and time. The Dmanisi and Javan H. erectus specimens don’t differ significantly either morphologically (as we’ll see) or temporally from the earliest H. ergaster specimens in Africa. Thus, the presumed emigration of H. ergaster out of Africa could only have occurred if…
1. A few or all of the acquired dates are wrong;
2. The expansion out of Africa was a very rapid one;
3. The expansion out of Africa occurred earlier than 1.8 mya and involved H. habilis (!)
None of these scenarios is particularly convincing, and at this point, we simply don’t know the answer.
what is the Cranial Morphology of Homo erectus / ergaster
High vault elevation above orbits.
Relatively low post-orbital constriction.
Increasingly robust supraorbital toris
Longitudinal elongation of the skull
Decreased facial prognathism.
Reduction in molar/premolar size and thickness.
cranial capacity between 850 and 1100 cc
what is the Post-Cranial Morphology of Homo erectus / ergaster
Postcranial bones of all known H. erectus and H. ergaster individuals show modern H. sapiens body proportions.
Body size was significantly greater than that of H. habilis / H. rudolfensis and generally similar to modern humans (avg. height of between 4’ 9” to 6’ 1”; avg. weight of between 88 and 150 lbs)
the 1.5-million-year-old footprints discovered in 2009 at Ileret, Kenya (nearby to Koobi Fora) are likely attributable to what
H. ergaster
The prints show distinctly modern human-like foot anatomy – markedly different from that of the Laetoli footprint-makers.The stride was also similar to that of modern humans
is there sexual dimorphism among H. erectus/ergaster
there is still a strong degree of sexual dimorphism among H. erectus/ergaster; males are approximately 25% larger than females.
However, the degree of dimorphism in erectus/ergaster was still ~30% less than that of earlier hominins, such as paranthropines
what are the Homo erectus / ergaster Morphological Differences
Variation between only two key physical traits separate the two species:
Slightly more robust supraorbital tori in H. erectus.
Cranial bones are thinner in H. ergaster
Lack of a prominent occipital bun in H. ergaster
The size-related (e.g., H. erectus georgicus) and other morphological differences (e.g., H. ergaster) we have discussed are defined largely by geography, and are evidence that there was—at some point— genetic isolation among H. erectus / ergaster groups. This raises an interesting question: just how much gene flow, if any, was there among these groups?
what may the differences between Homo erectus / ergaster be attributable to
These differences may be attributable to environmental / social variation, making H. ergaster simply an earlier / geographically distinct variant (or subspecies) of H. erectus. This would lead us to categorise H. erectus as a polytypic species (containing more than one taxonomic rank below)
‘Lumpers,’ advocating that the various H. erectus/ergaster groups represent a single polytypic species (H. erectus), argue what
that genetic drift, natural selection and some gene flow among the various H. erectus groups on earth resulted in the morphological differences we see in the fossil record
what do splitters argue about H. erectus / ergaster
Splitters’ argue that these difference can be explained through the various groups’ genetic/reproductive isolation (e.g., a founder’s effect), which resulted in distinct subgroups with little-to-no significant gene flow among them
We know that anatomically modern humans evolved from H. erectus / ergaster.
If the ‘splitter’ position is true, it means what
that speciation events in one area would not be reflected in another; importantly, it also means our modern human ancestors could only have developed in one of three known areas (Europe/Asia, E. Africa or E./SE Asia)
Between 1.8 and 1.6 mya, H. ergaster was utilizing what technology
Oldowan technology
what was the diet of . ergaster
They were likely foraging and scavenging, much like H. habilis.
when did Acheulean Tradition happen
Around 1.6 mya, a new tool tradition begins in Africa. Known as the Acheulean Tradition
what is Acheulean Tradition characterized by
it’s characterized by pear- or teardrop-shaped handaxes. This becomes the dominant form of technology until around 600 kya—making it the longest-lasting tool technique ever utilized
when does Acheulean technology reach europe
In SE and E. Asia, the Oldowan-style Chopper Chopping-Tool industry thrives, while Acheulean technology doesn’t reach Europe until between 500 and 800 kya
The first uncontested examples of hearths (fire‐pits) for any hominin are found where
at Gesher Benot Ya’aqov, Israel
When do the fire pits date to
dating to between 690 and 790 kya, where numerous hearths were found.
where is there contested evidence of use of fire
There is, however, contested evidence of use of fire (possibly naturally-produced) by between 1.4 and 1.6 mya (Lower Pleistocene) at two sites in E. Africa
what proof of fire was found At Chesowanja, Kenya
51 very small, concentrated flecks of reddish-‐brown clay, fired at 400° C.
what species is argued to have used fire first and what evidence is there
At Chesowanja, Kenya, 51 very small, concentrated flecks of reddish-‐brown clay, fired at 400° C. The fragments were were found approximately 15 m from several P. boisei cranial vault fragments and fragmented non-hominin animal bones. Despite this, the researchers argue that H. ergaster was responsible for the fire and animal bone deposits
what could be another explanation for the fire
Skeptics argue the concentration of these clay fragments appear to be consistent with a tree stump, burned out by a naturally-occurring brush fire
what evidence of fire was found At Koobi Fora
discolored soil patches with Oldowan tools were once exposed to temperatures of between 200 and 400° C. It is unclear whether or not this was the result of natural fires. These patches were dated to between 1.5 and 1.6 mya
where was H. erectus pekinensis found
Fossil remains of at least 15 individuals, later designated H. erectus pekinensis (“Peking Man”) were recovered from the site of Zhoukoudian, northern China, in 1921 by Canadian paleoanthropologist Davidson Black
when does . erectus pekinensis date back to
The specimens date to between 650 and 780 kya (the end of the Lower Pleistocene).
when might have H. erectus pekinensis used fire
770 kya?
what evidence and doubt is there of H. erectus pekinensis using fire
Apparent ash layers within the Zhoukoudian cave site may indicate in-situ control of fire. Further, very small, charred animal bone fragments were found within these deposits, indicating cave occupants were cooking.
At this time, northern China would have been very cold, so heating would also have been important, however, much of the material from early excavations was lost during WWII, and evidence remains in doubt
what evidence is there of H. Ergaster and fire and cooking
At the very large Wonderwerk Cave site in Northern Cape Province, South Africa, burned bits of animal bone and vegetation (as ash) have been recovered from sediments dating (not very securely) to around 1 mya. These deposits were approximately 30 m from the mouth of the cave, meaning they were likely not carried in by the elements
why cook
Cooking meat kills bacteria and parasites, and it detoxifies some vegetables, essentially rendering them edible.
It takes far less energy to digest cooked food than raw food. This likely freed up more energy for the ever-developing brains of our H. erectus ancestors
Cooking food correlates with biological changes what
H. erectus / ergaster
how does Cooking food correlates with biological changes H. erectus / ergaster
Faster calorie absorption from cooked food results in species-wide growth spurt (increased body size)
Cooked food requires less digestion, so a narrowing in the ribcage and reduction of the intestinal tract
Reduced need for musculature related to chewing, so decreased importance and size of temporal muscles
