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- [Voiceover] We are the paradoxical ape.
Bipedal, naked, large brained.
Long the master of fire, tools and language,
but still trying to understand ourselves.
Aware that death is inevitable, yet filled with optimism.
We grow up slowly.
We hand down knowledge.
We empathize and deceive.
We shape the future from
our shared understanding of the past.
Carta brings together experts from diverse disciplines
to exchange insights on who we are and how we got here.
An exploration made possible by the generosity
of humans like you.
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- Thank you, welcome.
And I'd like to start by thanking the organizers
of this symposium and Carta for inviting us
and hosting us for this session.
Our goal today is to look back at our origins
and ask how, where and when?
One species of African hominin gained the ability
to spread across Africa into Eurasia,
replacing all of its hominin relatives.
I investigate this through archeology,
the material remains of ancient human behavior.
To investigate today's topic, generally archeologists
have looked for evidence of complex cognition,
including the use of language, symbols
and cumulative culture.
Ornaments, beads, representational works,
abstract designs and complex technologies
are thought to be indicative.
When tracking the development of
these complex behaviors, we can look
for evidence of continuity or punctuation,
the tempo of evolution.
Broadly speaking, the African archaeological record
for the period of interest has been divided
into three phases, primarily based
on characteristics of stone tool technologies.
The earlier Stone Age or Acheulean, the Middle Stone Age
and the later Stone Age.
The timing of the transition from one
to the next are active areas of investigation
and may not be synchronous across all regions of Africa.
Much of the discussion about modern human origins
has focused on the Middle to later Stone Age transition,
so we can begin here.
The typical MSA is characterized
by largest flakes struct from prepared cores.
The resulting flakes, flake blades and points
were subject to varying forms and degree
of retouch or reshaping.
Although often less than what is seen
in Mousterian assemblages created by Neanderthals.
Occasionally for discrete periods of time,
there are more specific shaped pieces,
such as this backed segment or crescent.
The later Stone Age is often characterized
by hafted microlithic tools,
and numerous implements made out of bone
such as these bone points.
Importantly, in the LSA people
are ubiquitously making pendants and beads
out of shell, bone, and ostrich egg shell.
And many argue that these non-lithic artifacts
are really the basis of the striking contrast
with the Middle Stone Age.
MSA people had many advanced behaviors,
such as sophisticated stone flaking, active hunting,
pigment collection, and the control of fire.
However, some have argued that they were not fully modern.
These colleagues have argued
that items indicating complex symbolic behaviors,
such as these ostrich egg shell beads
don't appear until late in the record.
Appearing abruptly about 50,000 years ago
and marking the onset of the later Stone Age.
Some colleagues have argued
that biological evolution stimulated
these abrupt changes, while others think
that technological socio-cultural
and demographic changes provide sufficient explanations.
Even while some colleagues were arguing
for the punctuated appearance of modern behaviors
with the start of the later Stone Age,
others found evidence for more complex behaviors
within the MSA.
These researchers focused on the complexity
of stone tool technologies, and
the abundant hearts found in MSA sites.
Which stimulated speculation on plant use
and the use of fire to manage local environments.
In particular, there is focus on the
Howiesons Poort, which is characterized
by segments or crescents that we saw
in the earlier slide.
These were made on fined (mumbles) materials.
This industry was originally seen
as Upper Paleolithic-like, and transitional
to the LSA.
But there was a problem, the
Howiesons Poort disappears from the record
and is followed by a more typical
Middle Stone Age assemblages.
However, this idea of modernity in
the Middle Stone Age stuck.
Human fossils had pointed to Africa
for the origins of modern humans,
and genetic studies were confirming
that all living humans can trace
their ancestry back to Africa.
The idea that the Middle Stone Age showed evidence
of advanced, even modern behavior has gained support
in the 1990s, especially with the announcement
of these two bone assemblages associated
with Middle Stone Age artifacts.
At Blombos, the points were associated
with a distinctive Still Bay variant
of the Middle Stone Age, characterized
by these bifacial points, which
(mumbles) also just showed us.
Despite the fact that the associations
and therefore the age of both these sets of points
were questioned by other researchers,
these fines stimulated further consideration
of precocious artifacts in the Middle Stone Age.
And cemented the idea that we should find evidence
of modern behavior within the Middle Stone Age.
The gradual accumulation model
for behavioral innovations during
the Middle Stone Age was proposed.
The proposal did acknowledge that something
still changes 50,000 years ago,
and that this intensification was the result
of population growth combined
with environmental deterioration.
This led to increased population density
which affected the economy, technology
and social lifes of the groups involved.
The increase in population size would
have been due to new technologies
and new risk management strategies,
such as long distance exchange.
This model was further supported by additional fines
from Blombos of engraved ochre and perforated shells
that may have been beads.
Other sites preserved engraved ostrich eggshell.
These generally have been accepted as support
for symbolic behavior and abstract thinking
in our Middle Stone Age ancestors.
A big question remains however, how far back
in time to these behaviors go within
the Middle Stone Age?
Is evolution gradual within the Middle Stone Age
or is there a punctuated appearance with
the start of the Middle Stone Age?
Within the Middle Stone Age of South Africa,
the location of most of our examples so far
we find a complex ochre processing kit
at 100,000 years ago.
An interest in ochre and non-subsistence shells
going back as far as 110,000 years ago.
In the last 10 years, we have recognized
that MSA people often heat treats silcrete
by roasting silcrete cobbles in the fire
to improve their flaking properties.
This has now been generally accepted
as good evidence of complex technologies
within the Middle Stone Age.
Heat treatment is now well documented
in the Late Middle stone age and
has been identified in numerous assemblages.
And the technology probably extends back
to 164,000 years ago.
Beyond these examples however, early evidence
for symbolic or complex behaviors is sparse.
Beyond the oldest deposits of pinnacle point B,
there are still 150,000, earlier years of Middle Stone Age.
So far, the archaeological record of South Africa
has dominated the conversation.
However, as I regularly remind my undergraduates
Africa is big and it is not one place.
North Africa, particularly Morocco
is also interesting because it has provided
the largest sample of early modern humans
as we heard about earlier from (mumbles).
With some morphological characters that link
them with the earliest fully modern humans expanding
out of Africa and into Europe.
The later Middle Stone Age of North Africa
is often expressed as the Aterian variant,
characterized by stemmed points and scrapers,
bifacial foliates and end scrapers.
Turning focus to North Africa at
Taforalt Cave in late Aterian context,
excavators found perforated shells
that were likely used as beads, based
on polish from use wear and ochre residue.
These are similar informed to those
from Blombos, although the procurement
and potential manufacturing differ.
In Morocco, the antiquity of interest
and non subsistence shells can be pushed back
to 115,000 years ago, into the Maghrebian Mousterian.
At Contrebandiers, small shells like those
from Taforalt exhibit use wear and ochre traces,
and may have been used as beads.
These are found alongside larger shells
also collected already dead on the beach
like those from pinnacle point 13 B.
Again, we can ask how much further back in time
in the MSA can we find similar behaviors?
As we go back further in time of course,
appropriately age deposits become rare,
especially those that have benefited
from modern excavation practices.
And we get to see these stone artifacts
for the third time today (laughs).
So, one exception, which we've heard about earlier
is Jebel Irhoud.
These deposits provide a lower boundary
for the Middle Stone Age of the region
and preserve evidence of
Levallois based stone tool tradition and fire use.
However, we have not yet found ochre
or evidence of engravings or ornaments.
From my current reading of the record,
there is continuity from the late, earlier stone age
to the Early Middle Stone Age.
For example, late ESA people were already interested
in using ochre, something that
we find well established within the MSA,
even the early MSA at Olorgesailie.
However, other signs
of complex behaviors such as ornaments engravings
or even heat treatment are extremely limited
and not always well contextualized.
However, to make this comparison robust
there's dire need for more assemblages
from both the late ESA and early MSA
from good contexts.
Especially those that preserve materials
in addition to stone.
As I have presented here, within the
Middle Stone Age there is strong evidence
of increasing behavioral complexity,
such that the later MSA is quite different
from the earlier MSA.
Moving from the Middle Stone Age to
the later Stone Age, much of what has been said
about the LSA is characteristic of assemblages
that have accumulated within the last 20,000 years.
There are unfortunately few examples of well preserved,
well excavated, well dated early,
later Stone Age assemblages, especially those
with non-stone components.
One exception is Border Cave, where
the early LSA component preserves perforated marine shells,
ostrich egg shell beads and bone tools,
dated to about 44 to 42,000 years ago.
One challenge in further investigating
these developments within the Middle Stone Age
and into the later Stone Age, is that many
of these issues samples that I have mentioned
are isolated.
Generally instances are few and far between,
and interpretation is confounded by
the archaeological challenges
of building robust chronologies and preservation.
A second challenge is that the evidence
is especially sparse in the regions
where expanding human populations would have left Africa.
Further, we lack direct archaeological evidence
of a demographic expansion 60 to 50,000 years ago.
Something did change 60 to 50,000 years ago
to encourage a population to expand out of Africa.
But what and where?
Was the population expansion found
throughout Africa, or just within the one region
of the source population?
In order to move forward, we need
to develop better defined and more specific models
that allow for the generation of testable hypotheses.
We need to further refine the timing
of these expectations and incorporate
them into a regional approach.
Variation between regions seems clear
and that's one of the things I think today's symposium
has really highlighted is the variation
that we see within Africa.
And regions such as West and
Central Africa remain virtually unknown.
Again, especially with regard to
the non-stone components of their assemblages.
And of course, any behavior based model needs
to be well integrated with the data
from human palaeontology and genetics.
And so I think symposiums like what
has been organized today is a fantastic way
to keep people working on different lines
of evidence integrated, talking to each other
and updated on the types of data
that are being produced.
Thank you
(audience claps)
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