Taphonomy - Research Methods in Human Skeletal Biology - page 238

which results of natural processes are observed; and (4) experimental research design, in
which a causal event is replicated in order to reproduce an observed effect. The ethnographic
approach is beyond the scope of this chapter, but the other three approaches will be discussed
in more depth below.

ACTUALI STIC METHODOLOGY: NATURAL AND EXPER IMENTAL

Natural Experiments
Perhaps the most effective research approach to determine the diagnostic characteristics of
taphonomic bone modification is through comparison with marks on bone of known origin.
Often this is accomplished through what is termed a “ natural experiment ,” involving obser-
vation of bone changes produced by real events. One source for comparative collections from
“natural experiments” is from archaeological contexts, wherein the etiology of marks is
inferred from the depositional context and morphological features of the marks themselves.
The drawback to this method is that the causative agent was not directly observed, and the
interpretation is therefore limited to the judgment of the researcher, which may not actually
be correct. A classic example of this method is the “taphonomic signature of cannibalism” in
the pre-Columbian Southwest, in which the authors attribute a set of marks on bone to
human cannibalism in early Puebloan communities ( Turner and Turner, 1999 :478), a conclu-
sion that has recently been challenged on taphonomic grounds ( Marden, 2011a ).
Forensic cases can also offer comparative data for marks on bone, similarly functioning as
“natural experiments.” However, as in archaeological assemblages, these marks cannot
always be reliably attributed to a specific actor and/or effector. Even in cases in which
a confession describes the events surrounding the death event, it is not always possible to
directly attribute a mark to a specific cause. For example, if a suspect admits to having
stabbed the victim in the chest, it still cannot be assumed that linear marks observed on
the thoracic skeleton are directly attributable to the acts related to the manner of death, to
the exclusion of other explanations. Root etching, excavation trowels, autopsy scalpels,
and other agents must also be considered.
Therefore, despite their tremendous value from having resulted from actual events, the
precise etiology of marks on bone resulting from natural experiments is usually unknown,
having been inferred or assumed rather than directly observed. Therefore, any errors in inter-
pretation of the control collection will unwittingly be transferred to the analysis of the data in
question. “Control collections can only be considered adequate if the actor and effector were
actually observed to be the agent inflicting the surface modification

. For example, modern
hyaena dens cannot be considered control collections” ( Blumenschine, 1988 :505).
There is a demonstrated need for caution when inferring evidence of human action on
skeletal remains that have been affected by multiple agents, some of which may not even
enter the imagination of the researcher ( Andrews and Cook, 1985 :688). For example, recent
research in the Northeastern region of the United States has indicated the involvement of
multiple faunal species, some never previously considered as an important part of the taph-
onomic sequence, such as bobcats and pine martens ( Sorg, 2011; Sorg et al., 2012 ). The poten-
tial confusion of the signatures of numerous and varied processes necessitates a rigorous
methodological approach to bone modification.

.