The Use of Optimal Foraging Theory to Estimate Late Glacial Site Catchment Areas From a Central Place: The Case of Eastern Cantabria, Spain

In a previous post, the hunting strategies of Neanderthals 125,000 years by were discussed, and in this post we’ll be taking a look at a paper published in the Journal of Anthropological Archaeology, by Dr. Ana Belén Marín Arroyo, partly because she too cites an interestlaredo in discerning why Neanderthals became extinct, and partly because the paper is fully accessible, thus enabling a greater breadth of discussion than just the abstract alone would permit:

Abstract:

By defining the area of economic influence associated with a given archaeological site, valuable information can be obtained about human occupation patterns, whilst differentiation of the surrounding biotopes facilitates research into the adaptive relationship between subsistence strategy and resource availability. Despite the inherent potential of this type of analysis, its development comes up against important conceptual and methodological limitations.

The present article analyses the possibility of using optimal foraging theory, as representative of the hunting behaviour of hunter–gatherer groups, in the accurate objective estimation of the catchment areas of a site. The obtained results are applied to the study of the reasons behind the geographical site specialisations observed in eastern Cantabria, Spain during the Magdalenian.

The focus of this paper is on the post-Last Glacial Maximum era known as the Magdalenian, defined in this paper as 14–10 kya BP, many thousands of years after the last traces of European Neanderthals appear in the fossil or artefactual record, but in common with Professor Bent Sørensen’s paper, account is taken of the energy expended by hunters in pursuit of specific animals in distinct ecological niches, balanced against the amount of calorific energy that could be physically transported back to a centralised camp, where the non-hunting contingent of the forager communities would be waiting. As far as I can tell, however, this paper takes no account of other resources from hunted animals that would have been of calorific benefit to these Magdalenian people, such as hides and fur, sinew and other body parts, which amongst other considerations, would have been essential to keep them clothed in the day, and warm at night.

But as a study based purely on how Magdalenian people might have serviced various carnivorous elements of their diet, in this case red deer and ibex whose butchered remains appear in the archaeological record, this paper is very well worth reading, especially as rather than merely impose imagined hunting tactics on extinct people living in the mountainous regions of Palaeolithic Eastern Cantabria, northern Iberia, ethnographic studies involving the modern-day Hadza people of Tanzania have also been employed. Obviously, the two scenarios cannot be direct parallels of one another, particularly when the different climatic conditions are factored in, but we are at least afforded potential insights into hunting strategies, butchery and transport of meat. Key to this study is the Central Place Foraging Prey Choice Model, which is discussed here:

Based on the principles established in the Central Place Foraging Patch Choice Model ((Orians and Pearson, 1979) and (Cannon, 2003) formulated his Central Place Foraging Prey Choice Model, which aimed to solve the problem of which species should be hunted and in what order, and which anatomical parts should be transported to base camps to maximise the output: input ratios of energy, usually measured usually in Kcal. Thus, in addition to a logical preference for species providing a higher caloric yield in relation to calories expended in their acquisition, which usually results in larger catchment areas for large prey, the model can also predict aspects of the butchery process at kill sites, taking into account the type of prey obtained and the distance from the base camp. The greater the distance to the kill site, the more intense the butchery will be, in order to maximise the energetic contribution of the load being transported.

In order to assess how profitable it is to invest time in butchering an animal, Cannon (2003) defines a theoretical processing function that relates the additional time used to butcher the carcass once the prey is in an appropriate condition for its transport (i.e., after handling time) with the energy that can be transported to the base camp. In all cases, it is assumed that a physical limit for transport exists where the animal cannot be carried away whole, and therefore the more useful parts must be chosen.

This function begins with an initial value, equal to the maximum energy that can be transported without any butchering, decreasing monotonically afterwards, because the butchery process will commence with the most productive parts, those that offer the greatest amount of meat for the least processing time ([Bunn et al., 1988], [Monahan, 1998], [O’Connell et al., 1988], [O’Connell et al., 1989] and [O’Connell et al., 1990]), and will finish with the high cost/low yield extraction of bone marrow. In the case of small prey, however, the processing function is reduced to a single point, equivalent to the total caloric yield of the animal, which can be carried whole to the camp. In summary, this is basically an up-date for ungulate-hunting of the model developed by Metcalfe and Barlow (1992) for nut-gathering.Bunn et al., 1988 H.T. Bunn, L.E. Bartram and E.M. Kroll, Variability in bone assemblage formation from Hadza hunting, scavenging, and carcass processing, Journal of Anthropological Archaeology 7 (4) (1988), pp. 412–457. Abstract | Article | PDF (6019 K) | View Record in Scopus | Cited By in Scopus (74)

As I mentioned earlier, I think this study would have benefited by at least referring to other energy benefits derived from prey animals such as maintenance of optimal body heat to further conserve energy in humans, but what I liked about this paper was the exploration of the bio-geographical context in which the Magdalenian hunters would have mounted their expeditions, with particular reference made to steepness of slopes, vegetation and tree cover, and calculations that would have determined over what distances it would have been more profitable to hunt ibex instead of red deer. Interesting too to note that there was probably a seasonal divide between coastal and mountain areas as the foragers of eastern Cantabria were at the mercy of the elements and the effect they took on the floral and faunal resources available to them at different times of the year.

Mention too is made of territoriality, and there must have been occasions when hunting groups from different areas came into contact, and even conflict with one another, a point that is crucial for understanding the pressures brought to bear on the existing Neanderthal population of Europe, when they for the first time began to experience direct and increasing competition for their resources at the time of the Middle to Upper Palaeolithic transition around 40 kya BP , a topic which will be the subject of a forthcoming post regarding competitive exclusion.

On a final note, I’d like to point readers towards the references at the end of this paper, some of which are also free to access – I imagine for example, that The Molecular Dissection of mtDNA Haplogroup H Confirms That the Franco-Cantabrian Glacial Refuge Was a Major Source for the European Gene Pool (PDF) byAchilli et al 2004,  would be a case in point.

Reference: The Use of Optimal Foraging Theory to Estimate Late Glacial Site Catchment Areas from a Central Place: The Case of eastern Cantabria, Spain by Ana Belén Marín Arroyo, Leverhulme Centre for Human Evolutionary Studies, University of Cambridge, The Henry Wellcome Building, Fitzwilliam Street, CB2 1QH Cambridge, United Kingdom.

Journal of Anthropological Archaeology
Volume 28, Issue 1, March 2009, Pages 27-36,

doi:10.1016/j.jaa.2008.11.001

11 thoughts on “The Use of Optimal Foraging Theory to Estimate Late Glacial Site Catchment Areas From a Central Place: The Case of Eastern Cantabria, Spain

  1. So basically this paper comes to conclude that the ancestors’ basic groups (clans or whatever) lived in single valley areas are seldom went outside them, at least not for hunting. It seems to be saying that at least here, in the Cantabrian strip, semi-sedentarism and not nomadism was the rule already in Magdalenian times. I had already read such ideas before but it’s interesting to see them confirmed in such detail.

  2. I also wonder to what extent the role of nomadism has been over-stated for the earlier UP and even eras within the Middle Palaeolithic, because I think it would have dawned on humans way back that simply wandering the countryside in a random fashion wasn’t a very reliable way of finding food and shelter on a predictable basis.

    1. No hunter-gatherers today have ever been found to wander the countryside in a random fashion. They know every tree and hill of their home range and in the home ranges of all their relatives. I should hope that nobody has ever suggested that hunter-gathering human groups in the UP EVER just “wandered around”!

  3. Guess this may vary from place to place, and even in time. I just checked the Wiki article on hunter-gatherers to refresh my mind and seems that while many hunter-gatherers are more or less nomadic, this is not always the case, specially where game abounds.

    In the Cantabrian strip case, geography also seems to favor semi-sedentarism because it’s rugged and offers a variety of ecological niches (from coast to mountain) in what they could walk in a single day. I think this last aspect is emphasized in the paper.

    Also we rely heavily on settlements in caves, what implies certain conditions and limitations. We know that some caves were used only seasonally, while others seem to have been more permanent homes. I also guess that outside of the karstic areas, and even in them when convenient, people would use camps and not rocky shelters. In fact some of them have been found in the Cantabrian strip too, one not far from Bilbao: in Getxo (the map of Magdalenian sites in the paper is quite incomplete, it seems to me).

    I imagine anyhow that people in the more open areas of Central and Eastern Europe would anyhow be more mobile, with whichever exceptions.

  4. If, by nomadic, one means a pattern of high mobility within an annual range large enough to supply their subsistence needs, then I suppose hunter-gatherers could be considered nomadic. However, in most mobile groups, there is also access to the ranges of neighboring groups, which is reciprocal and which permits survival even when local resources fail due to drought or other factors.

    Under such circumstances, it would be foolish for groups to aggress against neighboring groups or to mount any kind of defense of their territory.

    Sedentism is also a term that should be used with caution. If by sedentism one means that the population had a fixed village location that remains occupied for generations, then the people can certainty be considered sedentary. But if you merely have a situation where the population is moving around within a limited area in an annual round designed to best exploit the resources within the area, then they cannot be considered sedentary. Under those circumstances they would be like all other mobile hunter-gatherers.

  5. About territoriality – why must it always be assumed that having a home range – a territory where you were born and had a right to live, – always means that people would be bound to have conflicts erupt if groups meet at their territorial boundary? What if people have rights of reciprocal access? What if there is a rule of exogamy (as exists in all known human cultures) that means your mate will come from another territory? This automatically gives you and your family the right to visit in the territory of your in-laws. If the resources can’t support all the visitors, then they are the first to notice that everyone is having to go farther and farther for food, and they might even suggest the whole camp move back to their own territory if they know of resources that might be ripening there.

    1. Yes to Helga- Its likely that things almost never reached ‘warfare’. We should view intergroup interactions on a more subtly graded scale, relative to a sense of familial or other affective attachments They were much like us; we would feel more comfortable giving our dog or coat away to our first cousin than our third cousin. It is also in our interest to find something in common with strangers– fighting really consumes a lot of energy vs. what it might yield, so there;s good reason to avoid it.

  6. Luis said:
    “seems that while many hunter-gatherers are more or less nomadic, this is not always the case, specially where game abounds.”

    Just remember that today when we speak of Hunter-Gatherer, we are talking mostly about isolated groups in harsh environments. In the pre-Neolithic, its probable that most Hunter-Gatherers were mostly sedentary for much of the year. And as you say where game abounds – like the Salmon runs of the Pacific NorthWest in the US, people subsisted on fresh fish for much of the year and dried fish for the rest – so they were completely sedentary, and never adopted agriculture, even when exposed to it.

    1. I think we might be careful about accepting this statement in the above comment; “we are talking mostly about isolated groups in harsh environments.” I doubt that most of the people who practice a hunter-gatherer mode of production and distribution today have been doing so in isolation from other human economic systems.

      This “isolation” idea came out of people’s efforts to explain why hunting and gathering might have persisted in the face of what many people used to believe were more productive options like farming and pastoralism. The idea that the hunting and gathering economy might be able to compete as an economic option did not seem feasible to many earlier scholars. I also take exception to the “harsh environments” idea, actually.

      I think our ideas on this are at a cross-roads. If we assume that human beings are always going to settle whenever a dense resource like Salmon runs or wild wheat presents itself, or, more recently to grow food when presented with suitable climate and soils, or to prefer pastoralism to foraging where it is possible to keep domesticated livestock, we follow a model that assumes that hunting and gathering is less attractive in areas of rich soils and moderate climates than are other economic options.

      We also assume that up until just recently, that is, until about 10,000 years ago, most human being were not bright enough to figure this out. After all, apparently modern Homo sapiens sapiens, in most of Africa, even in the middle East, Europe and Southeast Asia, spent a fair amount of time farting around as foragers (upwards of 100,000 years, by all received theory). The suggestion that a more settled way of life might actually be preferred even in the absence of agriculture needs to be carefully distinguished from assumptions that sedentism in any way affected the mode of production and distribution. In other words, if somewhat long term (say, several years) settlements exist and are supported by the proceeds from “windfall” hunting or foraging (whether animal or vegetable), does this automatically make the culture different from that of more mobile foragers?

      I can think of several open questions here: the first of course, is the idea that a “permanent settlement” means that nobody is mobile. I suggest that even permanent settlements such as today’s urban cities can have a fairly mobile population. A pattern of reciprocal resource use between communities occupying different ranges, mediated by the often social mechanisms of mobility undertaken to avoid conflict, visit relatives, share in a healing ceremony, and attend dances and other courtship related events, continue to operate even in sedentary situations. I do not even have to gather much supporting evidence of this from sedentary hunter-gatherers, since such resource use strategies and social mechanisms have survived sedentism in virtually every human economy. Granted, in some cases where there is a high level of population density, opportunities to move freely (to share in resources, especially) sometimes become constrained.

      What I am suggesting is that the existence of evidence of permanent occupation of some locales does not automatically imply that people were not mobile. In fact, it may not correlate with low mobility at all. It may simply show that when people were living in a particular part of a range, they generally stayed in certain permanent structures (caves or walled shelters) because it was more efficient to do so than to build each time anew.

      We have to be very careful in thinking that permanent settlement automatically means ownership of structures or resources. The idea that certain assets become inherited within a corporate group, (lineage or clan) implies a hierarchy of rights to these resources will exist, and a certain core population will tend to occupy the permanent settlement. However, it is a big stretch to assume that the change in a system of kinship and the hierarchy of access was something that happened very quickly. The settlements along the NorthWest coast of North America were permanent for a long time before Boas went to study them, and yet, despite his best efforts to categorize their kinship and access to resources according to known systems of lineal descent, he failed, and it was left to later scholars to find that they still had a fundamentally bilateral system – at least in terms of distribution of food and goods.

      The idea that Upper Paleolithic people were essentially sedentary because of the richness of their resource base also assumes that they did not need to move their dwellings to exploit a full seasonal round of subsistence activities. Granted, this might have precluded mobility. But why? Only if the advantages of keeping dwellings going over time outweighed the benefits of relocation. Can anyone imagine what might be some benefits of mobility? I can. Fewer fleas, ticks and other parasites, for one thing. A new area designated as the latrine, for another. Avoidance of the ghosts of the dead, who tended to be buried within the settlement or even in the earth inside of their dwelling is another. A shifting pattern of settlement location, even within a fairly constrained home range, also creates a different set of trails and trap lines from the previous year, and allow the area immediate to previous locals to recover ecologically.

      Then there are all the benefits of maintaining mobility within a whole populations. Some settlements might be permanent because they are fully occupied at some times of the year by many otherwise mobile smaller groups of people who come together to undertake the joint hunting of some migratory animal. There is plenty of evidence of alternation between small mobile groups and a larger assemblage among hunter-gatherers, and indeed a seasonal disbursal to smaller agricultural areas is widespread among horticultural and pastoral folk as well.

      Patterns of visiting and reciprocal resource sharing might not always be needed economically, but still be vital to the social life of the larger community. Desire for trade in nonessentials like jewelry, news, gossip, story telling, healing and other ceremonials play important roles in motivating mobility among all known human groups, let alone hunter-gatherers.

      There is also the simple possibility that hunting and gathering, whether mobile or sedentary, is the most highly efficient and sustainable system as long as the human population was low enough to be supported by the gifts of nature. This might explain why the people of the Pacific North West “never adopted agriculture, even when exposed to it”, in addition to why the San informant told Richard Lee “why should we plant, when there are so many mongongos in the world?”

      That this system ran on a logic of reciprocal access to resources among neighboring territories, high values placed on sharing, bilateral kinship, fluid group membership, and absence of frequent mutual intra-group hostilities, is not entirely testable with the archaeological data, but some of it is.

      The evidence for hostility certainly can be tested for. Evidence of parasite load might be more difficult, but morbidity and mortality data can be used from the skeletal remains. Evidence from dentition might be crucial here. ( See for instance

      Click to access Antiquity.pdf


      Click to access Jackes_violence.pdf

      There is also the interesting effect of sedentism on human fertility (via high calorie weaning foods) and population growth to be considered. This would suggest that sedentism around a stored high calorie dietary staple might lead to a period of population growth, which would be followed by increased conflict, malnutrition due to limitations to the diet as local flora and fauna were depleted, and increases in infant and child mortality. From what I have read, it seem this was more characteristic of the late Mesolithic than the Upper Paleolithic, at least in parts of Europe.

      I am open to discussion here. I am just not in favor of the whole scale resurrection of the “nasty, brutish, and short” model of mobile hunter-gatherer modes of production and existence.

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