Wednesday, August 10, 2011

Portuguese Teeth and Skeletal Pathologies – the Agricultural Revolution and the Metaphysics of Decline

Studies of contemporary hunter-gatherers as they transition from traditional to modern lifestyles reveal a marked reduction in their health and in the nutritional adequacy of their newly acquired diets.  In addition to studies on extant populations, in the last few decades there is an increasingly sophisticated understanding of how environmental stressors and limited resources translates into pathologies detectable in ancient bones.  This has led to an especially interesting range of investigations by archeologists on populations before and after the Agricultural Revolution starting over 10,000 years ago.  Studies on the recently settled and on old bones may answer the perplexing question of why after the seeming ecological stability of the ancient human lifestyles (lasting, after all, from 200,000 to a mere 10,000 years ago) did the transition from hunter-gatherer modes of existence to an agricultural lifestyle occur at all?
Trugernanner (1812–1876)

The diet of Australian Aborigines has been reasonably well studied.  The modern self-selected diet of Australian aborigines reflects that of the cattle stations where many lived after the colonization of Australia by White pastoralists.[i]  Accompanying these dietary changes were disimprovements in Aborigine’s health – increased prevalence of hypertension, diabetes, and heart disease in adults was noted, as were low child birth weights, and increased childhood morbidity.  

The traditional diet for aboriginal Ngatatjara people, for instance, in the Western Desert was primarily vegetarian supplemented with small game; hunting was largely unsuccessful despite the effort.  Station diets consisted of flour, meat, sugar (usually consumed in tea) and powdered milk.  There was very little fresh fruit and vegetables, milk, cheese, and butter, though individuals supplemented their diets with “bush tucker” and with purchases from neighboring towns.  Ironically, the food at the stations may have reflected the food priorities of hunter-gathers with the ready availability of meat.  However, in the absence of other food items and the increasingly sedentary nature of their lifestyles and the “emotional stresses associated with dispossession” resulted in declining health.[ii] 

Aborigines were given citizenship in 1967, after which many left the cattle stations and were moved to town camps and later to more remote communities, health in the Aborigine community further declined.  Although diets remained similar to the diet consumed at the cattle stations, the quality of supplementary foodstuffs decreased; now these were often “exotic and delicious items” bought from the store.  After an acknowledgement of the health crisis amongst aborigines in the early 1970s improvements in diet and health have been noted in recent years.

This observation of declining health among Australian Aboriginal populations in their transition to a modern lifestyle is not atypical.  The Turkana people of northwestern Kenya who are traditionally nomadic pastoralists also suffer health problems associated with the increasingly sedentary nature of the new behavioral regimes.[iii]  Nomads consume primarily animal foods, especially meat, milk and blood.  Their settled counterparts consume cereals and legumes.  Settled Turkana reported higher frequency of eye infections, chest infections, backache and colds.  Settlers were also shorter than their nomadic counterparts and had a correspondingly higher Body Mass Index (BMI). Calorie intake of settled folk was twice that of nomads (1,830 versus 772 kcals/day).  Similarly, the !Kung San of the Kalahari bore a heavier pathogen load, increased risk of anemia, and overall poorer self-reported health as they became semi-sedentary.  In the latter case the causes of poor health were not reported to be related to diet, but rather to a decrease in mobility.[iv]

Although it is not always easy to make a direct statistical connection between poor nutrition and the sorts of illnesses reported by relatively recently settled peoples, the overall assessment that the suite of complaints reported by these populations are associated with the relinquishing of a traditional lifestyle (either hunter-gatherer or pastoralist) seems secure.  It may be, to paraphrase one author, that settled people have more time and a greater tendency to complain, and of course, recently settled people collectively tend to be extremely impoverished with little access to healthy diets.  Nevertheless, studies such as these give some substance to a commonplace allegation that a transition from traditional lifestyles, to a modern one results in sharp declines in human health.  They do not by themselves, however, provide us with a direct window into the health ramifications of the transition to agriculture all those thousands of years ago.  This is why there has also been a substantial interest in the study of ancient bones.  What do the investigations of the remains of populations that have gone through the transition reveal?


As part of a comprehensive study on Alepotrypa Cave, a Greek Neolithic site occupied from 5000-3200 BC  Anastasia Papathanasiou studied the remains of 161 individuals from the site for signs of pathology.  The most frequent pathological conditions observed in this population were anemic conditions, osteoarthritis, musculoskeletal stress and healed cranial fractures.  She interprets the anemic as derived from poor diet, the osteoarthritis as derived from increased physical activity and heavy workloads associated with early agricultural enterprises, and the smashed skulls as evidence of violent, nonlethal confrontations.  Their teeth, however were in pretty good shape also, exhibiting a low prevalence of dental caries. The pathological conditions reported from this study are consistent with observations of Neolithic populations elsewhere in Greece and the Mediterranean.[v]  This study, one of many, confirms what many have been arguing – the switch to the farming lifestyle was not picnic.

Contrast this study with one on populations from the Mesolithic- Neolithic transition in Portugal.  About nine thousand years ago the wear and tear on Portuguese teeth changed abruptly.  Archeologist David Lubbell from the University of Waterloo and his colleagues examined Mesolithic-aged skeletal remains from central western Portugal using an analysis of stable isotopes and found changes in the rate and type of dental attrition and pathology that confirmed a modification in diet dating to about nine thousand years ago.  Before nine thousand years ago the people at their study sites subsisted on catches from the estuaries and streams close by their settlement sites.  The diet was a varied molluscan one; shellfish supplemented by some seasonal hunting for terrestrial sources of food (deer and boar) was their mainstay.  With the transition to the Neolithic farming, the diet became more terrestrial and more homogenous.  Domesticated pig, sheep and goat becomes more prevalent in middens (deposits of waste materials at a settlement site). 

The switch to domesticated and terrestrial resources resulted in dramatic shifts in dental wear for the Portuguese.  With the transition to farming, and increasing dependence on crops and domesticated animals, attrition of molars decreased substantially.  The molar grinding patterns were quite different on the opposite sides of the Neolithic transition.  Farmer’s teeth show a grinding consistent with consumption of grain, whereas our clam-eaters flattened their teeth by the ingestion of coarse sand along with their marine food resources.  Patterns in tooth decay (dental caries) with the transition to agriculture are even more complex.  There is a high incidence of tooth pathology in some of the populations of pre-agricultural folks in this study.  The difference in the dental decay rates of early farmers is not necessarily greater that their Mesolithic counterparts.

Now, the observations on these Portuguese populations at the time of transition to agriculture are made on a relatively small number of skeletons and the claims made by the authors are appropriately modest.  The pattern they report of a switch to terrestrial dietary sources is widely accepted but that this was not accompanied by a marked decline in dental health is, however, mildly controversial.   It is controversial because it challenges a contemporary orthodoxy that a decline in the health of individuals inevitably accompanied the Agricultural Revolution. 

The transition to the farming lifestyle is fundamentally problematic and calls for explanation.  To recall, the question is this: why did human ecology transition to agriculture if the diet had undesirable implications for human health?  Reassessments of Pleistocene hunter-gatherer lifestyle which indicate that life was not a nasty, brutish and short as was formerly believed complicate matters further.  However, as the few cases studies I have discussed caution us (caution me, at the very least) to hesitate before accepting that things were the same everywhere – clearly they were not.
In rethinking the transition to agriculture as a regressive trend are environmental writers simply replacing the Victorian metaphysics of progress with the new environmental orthodoxy of a decline? 

[i] Smith, Pamela A. and Smith Richard M.  (1999) Diets in Transition: Hunter-Gatherer to Station Diet and Station Diet to the Self-Select Store Diet: Human Ecology, Vol. 27, No. 1  pp. 115-133
[ii] Smith and Smith, p132.
[iii] Barkey, Nanette L. Campbell, Benjamin C. Leslie, Paul W. A (2001) Comparison of Health Complaints of Settled and Nomadic Turkana Men Medical Anthropology Quarterly, New Series, Vol. 15, No. 3 (Sep., 2001), pp. 391-408
[iv] Kent, Susan 1991 The Shift to Sedentism as Viewed from a Recently Sedentary Kalahari Village. Nyame Akuma 35:2-11; cited in Barkley et al (2001)
[v] Papathanasiou A 2005 Health status of the Neolithic population of Alepotrypa Cave, Greece. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY  Volume: 126   Issue: 4   Pages: 377-390

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