Last Spring, I received an email from one of my readers offering to pen some anonymous essays for the PaNu blog. Now, what made this of interest is that the offer came from a Tutor in Zoology at an “institution of prominence” in the UK with 20 years of research and teaching behind him. We exchanged a few emails, and my reader told me of his desire to write essays anonymously on human evolution and diet.
I have eaten ”PaNu” style for around 8 years; after years of “healthy eating” resulted in the consumption of a small pharmacy’s worth of medicine just to maintain “health”. I ditched the drugs and hit the medical library (PubMed too, still in its infancy); discovered the dogma and after a year or so of tweaking had arrived at +/- ‘PaNu’ and have not seen a doctor since (nor yet dropped down dead).
I’m not a regular commentator anywhere really and have only been reading the “paleo blogs” for a little over a year. I think I’m fairly conversant with what’s out there though and your site is probably the only one that I can’t find much fault with! Congratulations on this – I’m sure many people are finding it very resourceful.
I could enhance the appeal to authority by listing his credentials, but that would threaten his anonymity. Suffice to say that he is well qualified to comment on human evolution and animal behavior.
We’ve agreed to assign our guest the nom de plume Professor Gumby.
I have decided it was appropriate to post this in advance of some of my own as my plans for the future of the blog are to try and steer it more towards evolutionary biology and science in general, and somewhat away from the “paleo as a lifestyle or fashion statement” thing.
Sidebar: In future, foolish-looking shoes, body building superstitions and weight loss tweaks will be even more de-emphasized here in favor of my original interest in diseases of civilization and their relationship to the hypothesized neolithic agents of disease. I feel well-grounded in medicine and human metabolism, but many writers on paleonutrition (me included) seem to have a skimpy grounding in actual evolutionary science. Some luminaries even substitute pure fantasy and metaphors borrowed from other disciplines for actual reading of evolutionary biology, genetics and paleoanthropology. In order to avoid this, I feel it is not enough to simply mock “paleo reenactment”, rather we should strive to actually know something about the science of human evolution. Accordingly, I have been focusing on reading academic and scholarly popular texts on human evolution and paleoanthropology for the past few months. This partly explains the blog’s going dark for 6 months, as serious reading of scholarly sources and trying to learn something takes a lot of time. Professor Gumby’s essay dovetails nicely with my current reading…..
So, with apologies to the Professor for sitting on his work for so long, here are his thoughts in italic, with occasional comments from me interspersed in roman.
I have a problem with the unending anthropological studies that are continually quoted as examples of good/healthy diets that should be emulated. The irrelevance of agricultural (and to a degree pastoral) ‘traditional cultures’ is easy to argue (so I wont!) but there does seems to be ‘love affair’ with living Hunter-Gatherers [H-Gs], the assumption being that they are good analogues of Palaeolithic H-Gs. But is this really the case?
My comments here relate mainly to the San (aka ‘Bushmen’, Basarwa, !Kung, Khoisan, Khwe, etc.) as I have a passing interest in them (see later), and have at least read some on the literature on them, but can probably be applied at all.
So, what are my objections?
Firstly, the vast majority of H-G studies have been ‘ethnographic’ in nature – descriptive and qualitative. Studies have usually been conducted with preconceived paradigms and as such are heavily influenced by the researchers’ own assumptions and objectives (the anthropological literature is one of the most vocal and vociferous I’ve come across in this respect!). Most studies have been concerned with the sociocultural and economic systems; nutritional aspects being recorded as a descriptive adjunct. Actual nutritional studies are very rare, have invariably used poor and inconsistent methodologies and have usually been limited in extent, addressed under the umbrella of ‘evolutionary ecology’.
Secondly, just how analogous to palaeo H-Gs are they? The San have probably not ‘practised’ a pre-contact h-g existence for many centuries. [By pre-contact I mean interaction with local agriculturalist/pastoral peoples.] In fact there is some archaeological evidence that this may go back some 1,500 years. The degree and intensity of interaction with other peoples is debatable but the effects, although seemingly subtle, can have profound knock-on effects on diet. Even with the earliest San studies, contact with local agriculturalists had been in existence for long enough that the procurement of exchange/trade goods (skins, meat and other ‘wild’ products [also labour] > metalwork [knives, spearheads, pots, etc.], milk, tobacco, cloth, etc.) had undoubtedly resulted in a shift in h-g patterns/priorities to provide such items. Even in relatively ‘traditional’ H-G communities the h-g lifestyle has switched from a functional one to an adaptationist one [i.e. they are no longer living an ‘isolated’ traditional lifestyle but one that has ‘adjusted’ to outside influences.] The situation with the San today is even more complex with a reclamation of a quasi-H-G lifestyle on cultural/ideological grounds under the constraints of political interference (in particular there have long been limits on what and how much they can hunt as well as territorial restriction).
There are also some practical problems that should be taken into account with the interpretation of these studies…
Observer bias… The ethnobotanical knowledge of the San is immense. They have intimate knowledge of hundreds/thousands of plant species both as sources of food and for medicinal/’spiritual’ purposes. The collection, preparation and application is often very complex and tailored to the individual plant species. Researchers have gone to great pains in documenting these specifics. By contrast, hunting techniques are limited and (at least with vertebrates) ‘meat is meat’ - there are only so many ways of preparing/cooking and eating it – whether it’s a rat or a giraffe. Although the variety of available food sources is wide, undue emphasis may therefore be given to certain foods. This is mainly a problem with earlier studies – improved methodologies for gathering data in more recent years have largely removed this confounder but this has been to the detriment of the sort of information that anyone reading this piece would want to know; favoured data-gathering techniques have switched back to more qualitative measures that provide better comparability and consistency across different studies.
Observer influence… Tied in with observer bias is observer influence. Plant utilisation is often complex and therefore ‘interesting’ to the observer requiring considerable questioning to elucidate accurate and comprehensive data. Consciously or subconsciously this may be picked-up by the observed and influence the prominence given to these ‘interesting’ aspects of diet.
I suppose a salad can be more entertaining than a slab of meat, both for the cook and the guest… I’ve often thought it obvious that HGs might eat or forage differently depending on the influence of observing scientists. Of course this effect might as easily be biased in favor of hunting as well -KGH
Variety may increase and every opportunity to include the more unusual items may be taken. I have seen this acknowledged as a problem in a few papers but as it is difficult (impossible?) to eliminate it is largely dismissed. In theory long-term studies should minimise this, as behaviour reverts to ‘normal’, but unfortunately long-term studies are few and far between; most usually lasting a few months at most. In primate field studies, data obtained during the ‘habituation’ period is normally treated as purely anecdotal to avoid this However, given that with anthropological studies interaction between the observer and observed is so involved it is quite possible that long-term studies will not in fact eliminate this factor; perceived preconceptions becoming even more ingrained in the observed.
‘Evolutionary ecology’ of H-Gs has received increasing attention over the years and Optimality Modeling and in particular Optimal Foraging Theory has been employed to analyse and predict foraging strategies and diets. I had already written a concise account of this but it has become apparent that in order to communicate it effectively I’ll have to go into far greater detai,l soqqq I will leave that for another day, if it is of any interest. Suffice to say that while I have only minor niggles with the usage, application and interpretation within the anthropological literature it is often severely mangled whenever mentioned in the ‘palaeosphere’ – what it will NOT do is tell you what is best to eat!
The point being that modeling what one should theoretically eat based on a mathematical equation that factors in the caloric value, abundance and effort expended to obtain food does not and cannot tell you which food is or should be preferable or more healthy. Optimal foraging strategy would tell busy western humans to eat two supersized meals at McDonalds before shopping for grass-fed beef. -KGH
So, how good an analogy are the remnant H-Gs of today to our ancestral H-Gs? Probably not very good… While modern H-G populations inhabit areas that traditionally they always have, these are all ‘marginal’ habitats. They’ve been displaced from the more optimal habitats by encroaching agriculturalist/pastoralists. Dietary choices have been further altered by interaction with these encroachers. Studying animals in marginal as well as optimal habitats is a good tool for elucidating the ecological requirements of the species concerned – the dietary and strategy shifts seen can be very enlightening. With H-Gs this is just not possible as there are no longer any populations in optimal habitats left. The ‘modern’ H-Gs’ diet is likely to be atypical compared to what was normal in the past – more akin to a ‘fall-back’ or ‘subsistence’ diet rather than a ‘nutritionally optimal’ one. (my emphasis – KGH) Modern H-G diets may be the closest examples that we’ve got but they’re probably not very representative. They ARE fascinating studies, that show the variety and range of foods that can be eaten, they may give you an indication of what is eaten but what they don’t tell you is what you should eat.
Nothing I have written above is new, but it is still just ‘armchair theorising’ on a subject on which I don’t have complete breadth or depth of knowledge. However, it is strongly influenced by personal experience…
In the mid ‘90s I spent the best part of 2 years living and working out of a San ‘village/community’ whilst studying Chacma Baboons in the Kalahari. The village was relatively traditional with few ‘modern influences’ (pots, knives, sugar, coffee, cigarettes and clothes were the main ones that I remember). The village relocated twice a year to ‘static’ settlement sites and they did not keep any livestock, which was quite common. I employed two ‘guides’ throughout this time and they accompanied me everywhere – in the region of 75% of nights were spent ‘in the bush’ the remainder in the village. I brought coffee and rice (and some canned foods as treats) to supplement what food was provided, but that was the extent of it. Now, bear in mind that I was not at all interested in [human] nutrition at the time so I paid little attention to what was being eaten. So, the following are offered purely as ‘anecdote’ -- merely representing observations that stuck out - either at the time or subsequently…
i) Upon arrival and for the ensuing first few weeks the food provided was very varied. As the weeks/months went by, food became quite monotonous with the same handful of foods/dishes again and again.
This speaks to Prof Gumby’s previous point about observation or the presence of “guests” influencing the food variety - KGH
ii) There are many accounts of ‘Mongongo’ nuts being a staple of the San. But, they were rarely eaten – I only recall eating them on a few occasions (I’d concede that they may have been added to other dishes unbeknown to me). They may be a high-energy food but they are also a high-cost food – they need to be gathered, roasted in the fire, cracked to extract the seeds (not an easy process – the seed coats are very tough and the seeds are small) then roasted again. Although they may be eaten intact they are usually processed further entailing many hours of pounding. This assumes that ‘cleaned’ nuts are collected in the first place – if intact fruits are collected there is further pre-processing involving boiling to remove the flesh (which although I’ve subsequently read can be eaten, was discarded here). Descriptions often include the phrase “much sought after” but the fact is they are to be found commonly everywhere. Nothing else eats them! Well, plenty of animals do, they just pass-out the other end untouched – this is a widespread source of ‘cleaned’ nuts, they are at low density everywhere. For some bands of San who live in the harshest of habitats they may well be a staple but in more productive environments they are probably rarely bothered with.
My emphasis – but speaks to the point that food eaten in a marginal habitat shows the versatility of humans but may not be very representative of the longer historical dietary pattern – or, to use my phrase, the evolutionary metabolic milieu (EM2).
On Stephan’s blog, there was discussion recently of Mogongo nuts, whether they really were a staple, and if they were, might they even be problematic in that it seems they are more a source of linoleic acid than edible starch? If they were historically less important than some claim we may have an answer to whether !Kung-San had excess LA intake
Then again, shelled-roasted nuts are one of the San’s most valuable trade goods so they may never entirely lose their significance…
iii) Except in the context of “This is good to eat, try it!” I do not recall ever seeing my guides eat fruit. This was bizarre to me at the time as some were quite delicious and I would partake of them whenever encountered.
It seems common to say we are “hard-wired” to favor sweets, but I wonder how much is conditioning since an early age? If that is what happens, how much more intractable must a sweet tooth be for those who are 20 years younger than the professor and I – the generation weaned on fruit juice boxes and lowfat chocolate milk, later progressing to 64 oz big gulps and Grand Theft Auto? -KGH
Whilst my guides would be constantly chewing on various leaves/barks/gums (no doubt some may interpret this as supplementing with vital phytochemicals, but in reality this was probably no more significant than chewing-gum) their ‘browsing’ seemed restricted to caterpillars and grubs that were eaten on the spot, birds eggs that were retained and taken back to the village and, when encountered, honey which was part eaten, part retained. I would point out that they were not actively ‘foraging’ as they were busy doing things for me so this was not at all representative of their typical day.
iv) If hunting was good and meat plentiful it was eaten to the exclusion of other foods.
It was normal practise for the women to go foraging every morning for roots/tubers and other plant source items.
If however meat was in plentiful supply, this foraging was suspended and the only accompaniment to the meat was what could best be described as ‘herbs and spices’. It was common to go for weeks eating nothing much but meat and was equally common to go for weeks, when hunting was poor, eating solely plant sources. The idea of a ‘balanced’ diet on a day-to-day basis was not born-out in reality.
[Unsuprisingly perhaps, nutritional studies on the San have put the % of calories from animal sources in their diet at anywhere from 20-80% (from memory so, don’t quote me!) – do these figures reflect geographical, seasonal, or preference variation? Whatever, you can pick the study that best matches what YOU consider to be the best diet.]
v) As reinforcement of the last point, once every six months or so the Wildlife Department would drop off the carcass of an elephant (culled due to overpopulation - the San were not allowed to hunt them) – NOTHING but elephant was eaten for about the next month!
“Spam, Spam, Spam, Spam, …”
This is the key point to me. It should be instructive to ask apparently healthy HGs what they prefer to eat in addition to what they have to eat. In a population that is healthy and not conditioned to a lifetime of non-foods as in the diet of a westerner with metabolic syndrome, it may have meaning to know what they prefer to eat. Not accounting for costs, how would they apportion their caloric intake from their extant food sources? I see no reason that relative food preferences could not be genetically or epigenetically influenced in addition to culturally influenced. Absent the interference of modern medicine, could a preference for the foods that make one live a healthier, more robust life be selected for and rapidly move through a population in a few generations? Do the Kitavans actually prefer yams/sweet potatoes/cassava over coconut and fish in the same ratio as the proportions they eat them in? Would Inuit happily prefer half their calories as sweet potatoes if they grew in the arctic? Or does each dietary pattern just reflect the preference to avoid starvation? These seem to me to be legitimate questions. We simply can’t assume that the current dietary adaptation in any population is either optimal now or representative of the past.
And as far as meat and animal consumption, there seem to be some biases in studying present day HGs that may underemphasize the importance of meat in the original EM2.
If we really believe that late Paleolithic HGs were capable of hunting large mammals to extinction, how apt are the foodways of the relict HGs we see today now that these large mammals are extinct or diminished? How can one presume that hunting was usually ineffective (women gather and men only brag about hunting) yet also blame Paleolithic man for being an agent of extinction at the same time?
In The Third Chimpanzee, Jared Diamond displays the currently typical reactionary attitude to the “man the hunter” archetype of the 20th century. In describing New Guinea HGs he lived with, he talks about how..
“conversations at campfires go on for hours over each species of game animal.. ..and how to hunt it…. to listen to them, you would think they eat fresh kangaroo for dinner every night and do little each day except hunt. In fact, when pressed for details, most New Guinea hunters admit that they have bagged only a few kangaroos in their whole lives.”
So to Diamond, the fact that the cultural importance of hunting in New Guinea is disproportionate to the dietary intake of meat means that hunting for meat is just primitive cultural machismo worthy of ridicule.
I think he has it entirely backwards. It think the fact that HGs do not talk about plants around the campfire reflects that a desire for killing animals and eating them has been selected for during human evolution and the selection pressure is precisely that it is healthier for us to emphasize eating animals even if we also have a multi-fuel metabolism that can live on starchy tubers.
Thanks again to professor Gumby for these very interesting observations. If he can forgive me for putting his post in suspended animation, I might be able to persuade him to post some more essays. Stay tuned.