[Aztlan] Pre-Clovis sites in the Americas

[David Hixson]

Estimados Listeros,

Regarding claims for pre-Clovis archaeological
materials in the Americas, I figured some
non-archaeologists on Aztlan might desire a bit of
background on how these claims are evaluated.  If
other archaeologists see any errors or would like to
add to these comments, please feel free to post a
response...

Archaeologists must use a variety of methods, combined
with a great amount of luck, in order to find,
excavate and prove the validity of a pre-Clovis site. 
While this discussion on Aztlan has focused upon the
need for time, and outside confirmation, these aren’t
the main criteria used to evaluate a proposed site.

One of the early proponents of pre-Clovis occupation
of the Americas (I can’t find the original reference
at the moment, but I will keep looking) proposed a set
of criteria that still carries a lot of weight today.

1)  Solid geological context

Among the many ramifications of this criterion, this
includes having to differentiate between what
archaeologists term “primary” vs. “secondary”
deposition, and “c-transforms” from “n-transforms”. 
For example, a jumble of Pleistocene fauna in
association with stone tools may or may not be a
cultural site (such as a “kill site” or “butchering
site”).  One must examine the geological context of
this data, to evaluate whether such an accumulation of
remains may have been the result of other forces, such
as water action, (e.g., a river that mixed this debris
together from different time periods).  As many sites
are indirectly dated by examining what materials lie
above and below the proposed cultural material, this
also means the archaeologists must have a very clear
understanding of the stratigraphy, without any
possibility of an “inverted” or “mixed” depositional
history.

2) Recovery of an adequate sample of unambiguously
cultural material.

With regards to an “adequate sample”:  A single
artifact at any site may have migrated to its current
position through any number of post-depositional
processes (rodents, roots, etc.).  The term
“unambiguously cultural” is also important, in that
some cave “sites” have been proposed with an abundance
of “artifacts” that have since been proven to be
naturally fractured lithic debris.  Other “sites” have
been proposed based upon only bone tools, which may or
may not have naturally broken to create tool-like
splinters, or burnt animal bones with no tools, which
may have been burned through natural processes.

3) Well dated unambiguous cultural contexts.

Here I would put the emphasis upon “well-dated”. 
Provided points 1 and 2 are met, what techniques were
used to date the materials?  For example, if the
technique was radiocarbon dating: were the radiocarbon
dates acquired from a single *unambiguously cultural*
feature (e.g., a hearth with stone tools around it),
or by collecting small bits of charcoal from
throughout the matrix (mixing carbon samples in this
fashion is what led to the mis-identification of the
Early Formative complex at Cuello – showing these
criteria are important for more than just pre-Clovis
assertions).    Or was there only a single radiocarbon
date run for the site (usually a number of radiometric
dates are required, due to the many possible errors
that could occur).  The relatively recent advent of
AMS radiocarbon dating has led to improvements in this
area, as smaller samples are needed and therefore
materials can be directly dated more easily and more
samples can be run.  Or, were other techniques used
that provide too large of a margin of error
(especially those techniques that are at the limits of
their usefulness due to their particular atomic decay
rate).  And, once again, stratigraphy plays a large
role in this.  Surface sites cannot be considered to
have unambiguously dated cultural contexts, as
significantly later or earlier c-transforms and
n-transforms could easily affect surface remains.

Another way to list the criteria would be:
1) Artifacts of indisputable human manufacture
2) Primary depositional context within clearly defined
stratigraphy
3) Multiple, consistent and reliable radiometric dates

So, one way to look at the pre-Clovis debate is
through a legal analogy:  do we require proof “beyond
a shadow of a doubt” (all of the above criteria must
be met unequivocally); or might we consider the
“preponderance of the evidence” (many sites across the
Americas point towards the likelihood of a certain
hypothesis, but without any “smoking guns”).

As Mike has stated, only a couple of sites can
unequivocally push the peopling of the Americas back,
but these only push the date back a millennium or so. 
Those proposing dates as far back as 30,000 B.P. are
growing in number, so we may lean towards accepting
these based upon the “preponderance of the evidence”
but as yet we have no sites that pass all of the
criteria for “beyond a shadow of a doubt”.

Sorry for the lengthy email.  I know many members of
Aztlan are interested in this topic but do not have
archaeological training.  I hope this helps those
folks understand why the question of the “first
Americans” is so difficult to settle.

For further reading, I suggest:

Dillehay, T., and D. Meltzer (eds.)
1991  The First Americans:  Search and Research.  CRC
Press, Boca Raton, FL.

Saludos,

-Dave



 
____________________________________________________________________________________
Food fight? Enjoy some healthy debate 
in the Yahoo! Answers Food & Drink Q&A.
http://answers.yahoo.com/dir/?link=list&sid=396545367