The science of Biological Anthropology
Biological Anthropology is a science the same
way that Biology, Chemistry and Astronomy are.
A science is a methodological search
of information regarding a particular subject,
in our case – biological anthropology. We
follow the scientific method while researching
the genetics, anatomy, and behavior of humans
and human relatives. As a science, we base
our understanding on three main principles
or assumptions: Natural Causality, Uniform
Space and Time, and Common Perception. Natural
causality means that all phenomena must be
attributed to a natural cause – something
within our natural environment. For example,
Tides are caused by the gravitational force
of the moon and earthquakes are caused by
continental plates shifting on the earth’s
surface. In other words, phenomena are NOT
due to a supernatural cause, such as a spirit,
ghost, or deity. Keep in mind that humans
are part of the natural world, so anything
we make or cause is still attributed to natural
cause. Uniformity in space and time means
that all phenomena will work the same way
no matter where in the world the event is
occurring or when in time it is doing so.
In other words, natural laws do not change
whether you are in San Francisco, New York,
or Timbuktu, in 2015, 1850, or 20,000 years
ago. Gravity in Sacramento is the same as
gravity in London, or Zimbabwe, or Singapore.
This means that in order for something to
be tested via scientific study, it must be
repeatable. It has to be able to be done over
and over again. Common perception refers to
the fact that all humans have the same senses
for interacting with the world, and thus for
something to be tested via science, it must
be observable by anyone using the same senses
and the same technology. Anyone can view the
moon, with the naked eye or with a telescope,
and as technology improves and becomes affordable,
some day we may all be able to view the moon
by taking a trip to it. What is commonly perceivable
also is the only one of the three assumptions
that changes, because as technology improves,
we can observe things we could not observe
previously. For example, in the 1500s microscopes
did not exist, so cells were outside the realm
of science because they were not perceivable.
In the late 1600’s, when the microscope
was invented many new things, including cells
became observable and thus a part of science.
It wasn’t until 1950 when Maurice Wilkins
used X-ray photography that we were able to
observe DNA for the first time. Now, anyone
can do so with the help of a scanning electron
microscope. These three assumptions define
the realm of science, but it is important
to remember that as technology changes so
too does the realm of science, allowing new
things into it that previously were unobservable.
To recap – in order for something to be
tested by scientific study, it must be within
the realm of nature, be repeatable and be
observable at the time of study. Science differs
from religion and faith because it requires
proof. Religion is belief without the need
for proof or fitting within the realm of science
created by the assumptions of natural cause,
uniform space time, and common perception.
This allows religion to explain things outside
of science’s realm, such as: What is the
meaning of life? What happens to our soul
when we die? Why do bad things happen? Etc.
This leads us to how we study the science
of biological anthropology. We use the same
scientific method as all other sciences, following
the same 5 steps: Observation, Hypothesis,
Experiment, Results, and Conclusion. The first
step in the scientific method is observing
something, anything. It can be as simple as
your keys falling to the ground when you let
them go, or snow falling, or lightning flashing
and thunder crashing. In the observation,
the researcher is using their senses to observe
some phenomena, going back to our common perception
assumption. For the purpose of this lecture,
we will pretend we are doctors who work in
the neonatal ICU at a hospital. We notice
that a lot of the babies in the NICU that
are underdeveloped are born to mothers who
smoke cigarettes. This is our observation.
From the observation we ask ourselves a question
about the observation. While this is not an
actual step in the scientific method, it leads
us from our observation to our hypothesis.
For example, we may want to know why smoking
causes underdeveloped infants, or we may ask
what chemical in the cigarettes causes lack
of development in fetuses. Regardless of our
question, the hypothesis, which is our next
step, is the answer proposed by the researcher.
Because it is an answer, a hypothesis is always
a statement, never a question. We got our
question from the observation. So our hypothesis
may be “the nicotine in cigarettes causes
underdevelopment due to lower oxygen levels
in the blood stream of the mother” or “cigarettes
decrease the appetite thus reducing the calorie
intake of pregnant smokers resulting in poor
development of fetuses”. Both of these are
perfectly valid hypotheses, however they will
result in different experiments since they
are focusing on different potential causes
for the same phenomena. This leads to the
experiment step, or the test of the hypothesis.
There are two main types of experiments, natural
and controlled, though in certain circumstances
an experiment can be partially controlled
and partially natural. A controlled experiment
is one in which the researcher controls all
aspects of the test. For example, I am interested
in the yield of tomato plants. My hypothesis
is that Early Girl will produce the most tomatoes.
For my experiment, I plant 10 different tomato
varieties, I provide them a specific amount
of water, fertilizer, soil pH, sunlight, etc.
Then when they produce fruit, I keep count
of how many each type produces. In this study,
I am controlling all parts, from what type
of tomatoes to plant, to when and where they
are planted, and their care during growth.
All these things that I am controlling are
called controlled variables. One of these
controlled variables is the specific one that
I am testing – the different types of tomatoes.
This variable is called the independent variable.
There is only one thing I am not able to control,
the yield of the plants. Since this is the
topic under study, this variable is called
the dependent variable, because it depends
specifically upon the independent variable.
A way to think about the independent and dependent
variable is to remember that the independent
variable is the cause while the dependent
variable is the effect. So the tomato type
(independent) causes the amount of yield (dependent).
There are times when the researcher either
cannot control all or part of the situation,
or when they should not control it. For example,
researchers studying tornados cannot cause
a tornado to happen just so they can study
it. However, we know that tornados occur regularly
in certain areas, so the researchers simply
wait until one happens naturally and conduct
their experiments then. They may set up the
experiment far ahead of time so that when
the tornado occurs, their experiment runs
without them needing to be present and do
anything. Natural experiments still have dependent
and independent variables, just no controlled
variables. Based on the tornado research above,
let’s say our hypothesis is “tornados
at low speed cause more damage than high speed
tornados”. What is the independent variable?
How about the dependent one? If you said the
speed is the independent variable and the
damage is the dependent, you are correct!
Once the experiment is concluded the researcher
collects the results of the experiment and
draws a conclusion. Below you will see a table
of the results for our tomato experiment.
Based on these results, what is your conclusion?
Tomato Type Average yield after 2 months of
producing
Early Girl 32
Brandywine 28
Better Boy 41
Roma 36
Black Krim Heirloom 12
Big Beef 15
My conclusion is that my hypothesis (Early
Girl will produce the most) is incorrect,
Better Boy is actually the highest yield tomato
plant. This conclusion has a validity that
the hypothesis did not. My hypothesis was
a guess based upon my knowledge that Early
Girl tomatoes begin producing tomatoes more
quickly than other types of tomatoes. My conclusion
that Better Boy tomatoes produce the highest
yield in two months, is supported by the experiment,
and thus a provable fact. In my experiment
Better Boy produced the highest yield – this
is not subject to personal opinion or interpretation
the way a hypothesis is.
Once you have completed the 5 steps, as a
researcher your job is not over. If your conclusion
was that you were incorrect, you have to go
back to your hypothesis and revise it or make
a new one, based on the results from your
experiment. Then you go through the steps
again. This may take many experiments before
you are able to conclude that your hypothesis
is correct, however once it is correct, (even
if it is correct the first time) you still
need to conduct the experiment again, just
to be sure that the results are repeatable.
Once you have tested and retested and always
get the same results, then the researcher
will publish the experiment so that others
can conduct the same experiment in other places.
This is another part of the repeatability
necessity of science – remember uniform
space/time and common perception. By having
others conduct the same experiment, it is
proving that the phenomena occurs the same
way in multiple places and different times,
and that different researchers will perceive
the phenomena the same way. Eventually, once
the hypothesis has been supported by many
different researchers at different times in
different places, the hypothesis will become
a scientific theory. To be a scientific theory,
it does not have to be accepted by the general
population, it just has to be supported via
experiment enough times that its validity
is not seriously doubted by the scientific
community. A few examples of current theories
are: Gravity (yes it’s “just” a theory),
Heliocentric solar system (the earth revolving
around the sun is “just” a theory), Plate
tectonics (crustal plates moving on the earth’s
mantle is “just” a theory), and Evolution
(genetic change over time is “just” a
theory). Of these examples, very few people
doubt gravity or the earth revolving around
the sun, and while there may be some hold
outs on plate tectonics, the majority of the
general population accepts these with no difficulty.
In terms of scientific acceptance, Evolution
is at the same level of acceptance and has
equal amount of “proof” as the rest of
these theories, however there are many parts
of the population that do not accept it. That
lack of acceptance in no way reduces its status
as a scientific theory. Now, you may be saying
to yourself – “wait, I thought gravity
was a law!” Yes, it is a law. A law generalizes
a body of observations, that, at the time
it is made, no exceptions have been found
to a law. So, every time you let go of something,
it falls to the ground – that is the law
of gravity. It does not explain WHY the apple
falls to the ground, it just makes the generalization
that it will always happen that way, not matter
what. The theory of gravity, however, explains
why things fall – the larger mass of the
earth attracts the smaller mass of your keys,
pen, phone, etc.
This method, and the reliance on the three
assumptions defining the realm of science,
is the strength of scientific study. It allows
us to continue refining our understanding
of the world because we continue to test and
retest everything, even things that have attained
the status of theory and are no longer doubted,
because maybe we can refine that too, especially
as technology improves.
