Biology Reference
In-Depth Information
inductive approach. Based on observations made of specialized adaptations in different
animals, he developed a hypothesis that adaptations leading to the survival of an organism
so that it could reproduce would be beneficial and therefore would be selected for (
Darwin,
1859
).
Deductive approaches work in an opposite manner, from theory to hypothesis to observa-
tions (
Snieder and Larner, 2009
). Scientific theory sometimes is based on inferences that may
not have yet been directly observed. For example, the discovery of the structure of
DNA
to be
a double helix in the 1950s took a deductive approach. Based on other evidence and infer-
ences, scientific theory stated that a molecule of life existed. Several researchers therefore
devised hypotheses as to what that molecule would look like and set out to make observa-
tions that ultimately revealed the double helix structure (
Watson and Crick, 1953
).
Each study in skeletal biology can fit into one of several broad categories of inquiry: (1)
testing a hypothesis; (2) measuring a relationship or relationships; (3) constructing a model
or models; or (4) generating a descriptive analysis or analyses. The first category is explained
in detail in the upcoming section on hypotheses. Examples of studies that measure relation-
ships are stature and craniometric studies. For instance, the study of craniometrics looks for
relationships between measurements of the skull and certain aspects about either the indi-
vidual or their population, such as ancestry or
biological distance
(see DiGangi and Hefner
[Chapter 5]; and McKeown and Schmidt [Chapter 12], this volume). If a relationship exists,
the study results will be used to construct a model (in the form of stature formulae, discrim-
inant functions, biological distance, etc.). Model constructing can include experimental
research, as seen in studies in taphonomy or trauma for example (refer to Marden et al.
[Chapter 9]; and Kroman and Symes [Chapter 8], this volume) or when theory building, as
seen in the
osteological paradox
for instance (
Wood et al., 1992
) (see DiGangi and Moore
[Chapter 1]; Smith [Chapter 7], this volume). Descriptive analysis has been used most often
in
paleopathology
, although there is a movement towards model building and hypothesis
testing in this area (see Smith [Chapter 7], this volume).
Step 1: Observation and Inference
The first step of the scientificmethod is
observation
. Observations can be qualitative or quan-
titative. In general, qualitative observations focus on description, while quantitative observa-
tions focus on numbered amounts. We can further break down qualitative observations into
the categories of nominal and ordinal-categorical variables. A variable is some characteristic
that can be observed or measured in some way (
Walsh and Ollenburger, 2001
). Nominal vari-
ables have no logical ordering, at least not in the sense that numbered amounts do (L. Konigs-
berg, personal communication 2012). Presence/absence traits fall into this category, such as
presence/absence of the metopic suture or presence/absence of parietal foramen. Ordinal-
categorical variables have a relative ranking scale not associated with quantitative differences
(
Zar, 2010
). An example would be the scoring system for sexually dimorphic cranial features
from Standards for Data Collection from Human Skeletal Remains (
Buikstra and Ubelaker, 1994
):
features such as the nuchal crest and mental eminence are scored on a scale from 1 to 5,
with “1” being minimal expression and “5” being maximum expression.
Another way to think of quantitative variables is as metric variables (L. Konigsberg,
personal communication 2012). Examples could be that the measurement of maximum
