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What’s for lunch?
Chris
Brown explores how archaeologists discover what our ancestors ate.
I like my food. My
dad liked his food. My granddad liked
his food too. I am sure that somewhere back in the mists of time one of my
early hominid ancestors was chided by his family for being overly fond of
eating too many leaves or ants or whatever they ate back then. Since I am such a food lover (or greedy pig
if you prefer) the question of what our ancestors ate does intrigue me.
Thankfully it also intrigues many archaeologists who have
shown that we can find out about ancient diets through a number of means.
These include examining the environment, analysing artefacts and investigating
the remains of plants, animals and humans.
With
regard to the environment, it is tempting to simply look and see what could
have been eaten and then take it as read that this is what actually was being
eaten. Common sense says that if a particular resource was exploitable then
it seems fair to assume that my porky ancestors were there, exploiting it.
we might think that people living by the coast would be eating lots of seafood. The discovery of mounds of limpet shells in Mesolithic community
sites on the Colonsay in the Hebredes of would indicate that in this case
at least, the assumption is valid,[1]
But just because food is there,
doesn’t mean it was being eaten. For instance, isotopic analysis of jaw and
skull fragments of Neanderthal skeletons from Croatia carried out by Michael
Richards of Oxford University revealed that the Neanderthal’s diet was almost
totally carnivorous[2] There certainly was a supply of tasty plant
material, but for reasons as yet unknown, the Neanderthals seem to have stuck
to meat.
If the Neanderthals were our direct
ancestors, then I am a rather poor example of their offspring because I haven’t
eaten meat in over a decade. There again, they didn’t have BSE, Foot and
Mouth or Chernobyl fallout to worry about.
But we don’t have sabre-tooth tigers so it all evens out in the end.
So what were homo sapiens eating
before agriculture got going? Certain Native Americans are known to have eaten
plants as diverse as ferns, marsh marigold and even the bark of elm, lime,
ash and pine trees.[3] In his excellent
book on plant archaeology, Geoffrey Dimbleby notes that; “The standards by
which the overfed members of Western civilization judge the acceptability
of food are probably very different from those of people to whom the collecting
of an adequate food supply is the first necessity of life.”[4]
On to the fun topic of digging holes in the ground. Certain
artefacts that we find in the soil give clear indications regarding the eating
habits of our forbears. Discovering
a plough or similar tool such as the Iron Age ard discovered at Pict's Knowe,
near Dumfries[5] is clear evidence of an agricultural as opposed
to hunter-gatherer society.
A microscopic investigation of artefacts can, in some circumstances,
provide more evidence by showing us whether a cutting edge of a tool has been
used for butchery or for plant cutting. The study of microwear by pioneers like Sergey Semenov in the 1950’s
or Ruth Tringham and later Lawrence Keeley allow us to look at the polish
and minute chips in the edges of stone tools and know whether a particular
tool has been used on wood, bone, hide, meat, antler or non-woody plant material.[6]
As scientific analysis techniques improve, future archaeologists
will probably be able to discover more from artefacts about subsistence practices.
For the present, we find more information comes directly from the remains
of what was actually being eaten. An
investigation of the remains of plants can tell us much about the diets of
past societies.
Dimbleby's
book explains; “There is no firm guide as to the parts of plants which archaeologists
may come across.” Further, that; “Plant materials vary a great deal in their
resistance to decay; and different environments can promote different types
of decomposition.” [7]
Occasionally the local conditions favour a slowing down of the usual processes
of communition (physical break-up of materials) digestion (by animals and
bacteria) and leeching (washing away) such that organic remains can be recognised
and recovered from a site. [8] These conditions are often environmental extremes
of heat or cold, aridity or wetness, which inhibit one or more of the decomposition
processes.
The remains of seeds might indicate whether a particular
crop is being gathered from the wild or farmed. Wheat, a staple European crop
has been altered by selective breeding, such that modern wheats are easy to
distinguish from either einkorn or emmer, their primary ancestors.[9]
Although there is practically no chance for the preservation
of presumed staples such as tuber roots of Manioc or Yams,[10]
stashes of grains or carbonised seeds and fruits might be found on occasion.
The remains of these and other plant materials will be identified either by
viewing the cell structure using a microscope, or by chemical analysis. However,
since preservation of plant remains is so relatively poor, according to Macintosh,
our main insights in relation to subsistence of past societies have come from
the skeletal remains of animals.[11]
The limpet shells of Colonsay mentioned earlier, are by no
means an uncommon occurrence on coastal sites. Kevin Greene explains that;
“Many coasts bear evidence of extensive sea shell exploitation in the form
of large mounds of discarded shells; for some societies it was the central
activity of their lifestyle, for others it was a seasonal occurrence.”[12]
Beyond the simple fact that shell fish were harvested, we can learn considerably
more that sheds light on the subsistence practices of the harvesters.
For instance, since limpet shells are generally smaller when living
close to the shoreline, a disproportionate number of larger shells in the
midden heap might indicate planned exploitation rather than random collection,
itself an indication of a greater reliance on shellfish over other possible
food sources.[13] Measuring Oxygen isotope levels in shells can
give us an understanding of whether the shellfish were being exploited all
year round or just seasonally, since the isotope levels fluctuate according
to changes in temperature. [14] This helps paint a picture which extends beyond
just the issue of ‘what they ate’ to provide evidence for whether a community
might have lived a fixed, nomadic or semi-nomadic existence.
Again, we have to exercise caution, knowing that the uses
for shellfish were not purely for sustenance. Greene lists spoons, containers,
tools, dyes, charms, jewellery and even ceremonial trumpets as possible uses
for shells recorded by both archaeologists and ethnologists.[15]
Further, when confronted with a large shell midden it is easy to assume that
shellfish comprised a large proportion of a society’s regular diet. Jane McIntosh
notes that in the case of the Ertebolle site in Northern Jutland, Denmark;
although a midden contained almost nothing but shells, the bulk of the diet
of the people who left it behind comprised red deer and pigs. “The large number of shells is explained by
the fact that the edible part of shellfish is fairly small compared with the
shells which are discarded.”[16]
Bones are often well preserved in many soil conditions, except
where the earth is strongly acidic. They can provide a wealth of information
about subsistence. At the most basic
level, identification of animal bones will tell us which species coexisted
with past peoples and butchery marks on the bones will show which species
were being eaten. Beyond this, the
size of the bones can indicate the ages and sometimes the gender of individual
animals. This is invaluable because
it can show what strategies were being employed in relation to other species.
For instance, disproportionate numbers of adult female as opposed to
adult male cattle bones is a good indication of stock management.
This is because it is uneconomical to keep lots of ‘unproductive’ bulls
when the same feed and effort could keep a greater number of cows that provide
both meat and milk to the community. This is a global farming practice and
it seems safe to assume that it has a long history. Another ingenious interpretation
of a quantity of Oxen bones from Garnsey, New Mexico provides clues to how
much relative value was placed on particular parts of male and female Oxen
by Native American hunters of the 15th Century AD.[17]
Bone and teeth assemblages can also sometimes tell us if
hunters were using certain killing techniques.
When a herd of animals all succumb to a natural disaster such as a
flash flood the proportion of bones of specifically aged animals should relate
to that of an average living herd. If
an assemblage relates to human hunting we would expect to see disproportionately
large numbers of animals in their prime, while if we find a disproportion
of the weaker animals (old and young) this indicates the assemblage is the
result of natural predation. [18] Richard Klein has recorded these mortality
profiles in Mesolithic assemblages in the Cape Province, South Africa.
A
radical change in cattle size also occurred as a result of domestication,
and so by looking at the average size of bones we can know something about
whether a society were stock breeders and indeed how productive their herds
might have been in relation to modern domesticated livestock. Indeed, the
whole field of investigating animal bones is becoming ever more refined and
archaeozoology is now seen as a discipline in its own right.[19]
Having looked at animal remains, we turn our attention to human remains to see how they can inform us about subsistence practices of past societies. Renfrew and Bahn tell us that there is only one form of incontrovertible proof that a particular substance, be it animal or vegetable, was actually being used by a particular society for food. The only incontestable evidence is to find remains of that substance within human coprolites.[20]
These semi-fossilised pieces of human excrement are the direct remains of
previously eaten meals. Therefore anything found in a coprolite in
any quantity can be said to be part of a human’s diet. This can sometimes lead to shocking conclusions,
such as Professor Richard Marlar of the University of Colorado’s announcement
that human myoglobin had been found in a human coprolite from a 12th
Century Pueblo in Colorado. He stated
that since myoglobin never appears naturally in the intestinal tract, this
is clear evidence of cannibalism.[21]More mundane, although
no less interesting information which might come from coprolites include the
specific makeup of meals and even insights into their preparation. For instance, the inclusion of silica particles
within a coprolite from Tiahuanaco, southern Peru containing the remains of
corn, beans, and meat, probably indicates that some elements of the food were
prepared by being ground in a soft stone mortar.[22]
The wide variety of identifiable
remains, which can come from human excrement, is of great value in understanding
the diversity of diets of past cultures. Analysis of the 15th Century drains
of Paisley Abbey, Scotland revealed the remains
of opium poppies,
horseradishes, leeks or onions black oats, apples, damsons, walnuts, figs,
cress, mace, rowan, raspberry, hazelnut, bilberry, beef, pork, lamb, fish
and shellfish.[23] The wide variety of food available is at odds
with our understanding of the remoteness of the location and the perceived
austerity of a monastic lifestyle of that period.
While stomach contents can show us the constituents of a particular
meal, bone analysis can give us information about diet covering a far longer
timescale. By using a mass spectrometer
we can analyse the ratios of two Carbon isotopes (12C and 13C) in bone collagen
and conclude that a diet was predominately seafood, meat or vegetative in
nature.[24] This analysis actually splits plant matter into
two distinct categories and has been used by Anna Roosevelt to highlight the
shift from eating manioc to eating maize during the first Millennium AD on
the Orinoco floodplain in Venezuela.[25] Renfrew and Bahn inform us that similar work
is also being conducted in relation to both Nitrogen and Strontium Isotope
analysis of bones, hair and teeth.
The most common diseases to be
seen in the human skeleton are tooth decay and periodontal disease,[26]
Since dental caries is statistically linked to sugar intake, evidence in bones
can give a good indication of a high sugar diet. Dimbleby states that up until the Neolithic, advanced dental disease
was a rare incidence.[27] Wearing of the enamel can also indicate something
about diet, such as in certain Neolithic North American teeth, which have
excessive, wear caused by lots of sand in their food (which Dimbleby attributes
to the use of sand as a leeching agent to remove bitter tannins from their
staple diet of acorns).[28] At a microscopic
level, striations on tooth enamel show a largely vertical pattern in relation
to eating meat and a horizontal pattern from eating a vegetable diet.[29]
As we have seen, by investigating
the environment, human artefacts, plant animal and human remains; much can
be learned about the subsistence practices of peoples of the past . With each technique, varying degrees of caution
must be exercised, and care must be taken at all stages, from retrieval, through
identification, preservation, analysis and interpretation. Having said that,
we are fortunate to have ever more precise techniques to analyse remains and
gain an ever-greater understanding of what past societies ate.
Copyright Chris Brown 2002-02-16
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