What do we really know about ancestral diet?

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(Windmill Tilter) #182

I don’t think wikipedia is useless. I found a brilliant article entitled “Pleistocene Human Diet”. It covers our early human ancestors like neanderthals, heidelbergs, as well as homo sapiens. Fascinatingly, in the section on homo sapiens, the article highlights the fact that increased brain size and decreased gut size is correlated with the advent of fire because this was a critical innovation that allowed for the digestion of starches otherwise inedible. Incredibly, they go on to note that key distinction between our closest extinct relatives the neanderthals and homosapiens is the ability to digest cooked starches. Even more incredibly they note that tubers were critical to the diet of the prehistoric peoples! If that’s not bad enough, it says that the key role of tubers was food stability throughout the year. I was just speculating when I was saying that stuff above because it made logical sense to me, but apparently I wasn’t too far off. It looks increasingly likely to me that our ancestors were tuber rooting omnivores…

Here is the section on Homo Sapiens:

Homo sapiens [edit]

The evidence of early Homo sapiens diet stems from multiple lines of evidence, and there is a relative abundance of information due to both a larger relative population footprint and more recent evidence. A key contribution to early human diet likely was the introduction of fire to hominins toolkit. Some studies indicate a correlation with the introduction of fire and the reduction of tooth and gut size, going so far as to indicate their reduction as clear evolutionary indicators of the widespread introduction of fire.[22]

A key difference between the diets of Homo sapiens and our closest extinct relatives H. neanderthalensis is the ability to effectively digest cooked starches, with some evidence found linking cooked starch and a further increase in H. sapiens brain size.[23] Roots and tubers were introduced into the broader human diet, and can likely be assumed to be associated with fire as cooking would likely be necessary for many tubers to be digested.[1] The use of root and tuber species in some Hunter Gatherer cultures makes up a critical component of diet. This is not only for the nutritional value of the species, but the relative annual stability of the species. This buffer effect would be important for many groups that relied on tubers.[24] The ability to process starch is linked genetically to modern humans, with the genes necessary to its consumption not found in H. neanderthalensis . The timing of this mutation on modern humans is important as it means the ability to digest heavily starchy foods has only developed in the last 200ky years.[12]

(Edith) #183

Dr. Bill Schindler has an interesting perspective on human anatomy. He believes we are terrible physical specimens in the animal kingdom. We are terrible carnivores because we don’t have sharp claws or teeth, we are terrible herbivores because we can’t digest plants very well, we can‘t run fast, we can’t jump high, we can’t climb trees very well. But, we are innovative and we can build tools to hunt, we can ferment plants to predigest them so we can extract their nutrients more easily, we can build ladders to climb trees. He goes into a whole litany of what we’ve invented as a species to get more nutrients into us. It was a very interesting podcast.

(Michael - When reality fails to meet expectations, the problem is not reality.) #184

Thank you, Don, for the links. I shall read both.

I don’t know if you’ve read the linked article provided by Elizabeth. The author attempts to reconstruct the Paleolithic diet based on 10 examples of physiologic evidence. His first evidence:

Life history, the age at which animal reach certain stages in life like gestation, weaning, mating, and death, is strongly defined in a species. Psouni et al. [19] found that adult brain mass, limb biometrics, and dietary profile can explain 89.2% of the total variance in time to weaning. Comparing 67 species, they found humans to be in the carnivores’ group while chimpanzees and other primates with the non- carnivore’s group. They conclude: “Our findings highlight the emergence of carnivory as a process fundamentally determining human evolution.”

I think this and the remaining lines of evidence discussed are much more compelling than trying to figure out exactly what and how much plant materials humans ingested and what amount of nutrition derived therefrom when that line of evidence is very circumstantial and very spotty.

As the author states:

So, if ethnography and archaeology are poor sources for DPA (caloric Plant:Animal ratio) estimates, are there other fields of knowledge we can explore? As it turns out, physiology can be a trove of information for evolutionary DPA, as adaptations to one DPA or another are stored in our body in the forms of genetics, morphology, metabolism, and sensitivity to pathogens.

(mole person) #185

But the invasiveness of cattails is recent. It’s tied to modern agriculture, fertilizers, and water management. So I’m talking about the quantities that would have been available to recent hunter gatherers on our continent. Even a few hundred years ago the quantities of cattails that you’re describing would not have existed, never mind a hundred thousand years ago.

Never take me to be saying we didn’t eat plants at all or use them for all sorts of things. My thesis is that we don’t have a nutritional dependence on them, that for many human populations they were only rarely an easy source of nutrition, and our evolutionary history is one of tending towards a highly meat based diet.

How do you figure they are irrelevant when they are the genetic parents of those 2000? Sure there may have been some adaptations that favoured those 2000 but we’re talking about the same species here. Not any major differences in physiology. Obviously, at some point we turned more to plants (I’m not arguing against this although I think it happened far later), but that wouldn’t change us being essentially carnivores. An adaptation to digest plants or dairy doesn’t make that food source necessary or even as good. It would just mean that we can now get more nutritional value from those things then previously, and that is only a hypothetical adaptation.

A shortened gut hurts the digestion of any plant source because it interferes with the digestion of cellulose and the effective break down of fibre. It’s an adaptation only seen in mostly meat eating species. Similarly check out our stomach acidity. Acidity increases in animals as you go from herbivorous species to carnivores. We have one of the most acidic stomachs of any animal on the planet. Then there is the line of evidence about the nitrogen isotope contents of our ancestors collagen. This too points in the direction of a high-level carnivores.

Finally, the suggestion that our increased brain size and decreased gut size evolved in conjunction with the discovery of fire is strange. Homo-Erectus is thought to have discovered fire and Homo Erectus already had a very short gut and a very increased brain size.

(Michael - When reality fails to meet expectations, the problem is not reality.) #186

About that human genone ‘bottleneck’. Whomever of our ancestors survived, they carried within them all the previous human/homonid/homo genes. They carried with them the human physiology of all the previous ancestors that made them who they were. Yes, we lost some diversity. We did not lose our genetic and physiological heritage. We descendants still carry Neanderthal and Denisovan genes sufficient to be measured. We still mostly retain the physiology that has characterized the human family for 2.5 million years. You, I and every single human on the planet in 2019 could trace our direct line of descent to the very first individual of the line that would become homo sapiens millions of years later. The continuity of life on earth is simply astounding.

(Justin Jordan) #187

If there was a bottleneck of a few thousand individuals, then those individuals would carry the genes of the ancestors that lead to them. That doesn’t mean a lot of adaptations weren’t lost from the lines that were wiped out entirely.

(Windmill Tilter) #188

We already know that people were using tools to process cattails and other tubers like them tens of thousands of years ago. There is no evidence that the presence or success of cattails is predicated on modern agriculture, fertilizer or modern water management. If this were so, how did they get there hands on them 20,000 years ago, as evidenced by specialized tools for processing tubers, and tuber starches on said tools found throughout the world during a wide span of epochs? As for fertility, let’s imagine that yields of cattails triple in the presence of nitrogen rich runoff, such that prehistoric yields were 1/3rd of what we see today. Under these conditions cattails would still be yielding 2200lbs of flour per acre. Using potato starch as a reasonable proxy, lets assign a caloric value of 1600kcal/lb to this starch. This would still mean 3,520,000kcals per acre. Let’s imagine our paleolithic tuber rooters were smaller in stature than present day humans and happily lived on 2000kcal/day, and therefore 730,000kcal/year. That would mean a single acre of cattails could single-handedly support the total annual caloric requirements of 5 people. Lets assume that these folks were eating a diet consisting of 33% carbohydrates. That’s gets us to a single acre providing 1/3rd of the annual calories for 15 people. Now lets imagine a modest 10 acre marsh; this would provide 1/3rd of the calories for 150 people! Is this what happened? I dunno, but the potential calories aren’t irrelevant by any stretch.

As to whether or not they are an invasive species, I don’t follow the line of reasoning. All species that out-compete incumbents are invasive by definition because they expand geographically. That cattails accomplished this without cultivation across several continents seems like a strange criticism of the probability that a wide swath of humanity had access to it as a resource. Again, I’m not suggesting all paleolithic people had access to tubers, just that those who did had competitive advantage to survive and procreate.

As I mentioned above, shortened guts and increased brain size indicates increased calorie density. Whether the increase in calorie density is owing to increased roasted tuber starch consumption, fattier prey, or a combination of the two is impossible to say. The wikipedia article on Pleistocene human diet seems to unfairly attribute this to the cooking and eating of starches, but it seems implausible to me that increased meat consumption didn’t play a pivotal if not principal role.

I don’t think we’re that far apart on this one. I think the majority of calories for hunter gatherers came from meat. If I had to make an estimate, I would imagine that there was wide variation in the contribution of carbohydrates to human nutrition ranging from 10% like the innuit to perhaps 50% for geographically advantaged people. I don’t think it’s crazy to imagine that the majority of paleolithic peoples derived 33% of their annual calories from carbohydrates.

(Windmill Tilter) #189

The same as what @Justin_Jordan mentioned. The existence of pure carnivores 100,000 years ago is less relevant if they were a genetic dead end 99,999 years ago and all subsequent generations were the progeny of starch eaters. They are absolutely still relevant for all the reasons you mentioned, but they are less relevant than those branches of the tree from which we are more directly descended. Another valid criticism of my argument is that it’s impossible to know which groups survived such bottlenecks, or what their dietary composition was. I was simply trying to point out that it’s entirely plausible that access to stationary, calorie dense food that could be dried, transported, and was available 3 seasons of the year might have provided an advantage to starch eaters during particularly lean years.

No argument here. I think prehistoric peoples probably got the majority of their calories from animal sources. That said, this still describes an omnivore not a carnivore.

(Elizabeth ) #190

Just gonna leave this here https://facultativecarnivore.com/

(Michael - When reality fails to meet expectations, the problem is not reality.) #191

Thank you again, Elizabeth. By the way, the author is Amber O’hearn (yes, our Amber). I hope she adds a bibliography and more citations.

PS: I’ve bookmarked this to continue reading as Amber continues writing. This looks to be a very interesting project to stay in touch.

(Justin Jordan) #192

Aside from the lots of other things about that -and there’s a lot of other things - not all apex predators eat ONLY meat. Even polar bears do actually eat plants, although it’s (normally) a fairly trivial part of their diet.

Apex predator just means an animal that preys on something (hence, predator) and isn’t normally prey itself. They’re at the very least always omnivores, but they’re not necessarily hypercarnivores.

(Justin Jordan) #193

Although if you’re going by stomach acid, we should probably be eating rotting meat.

(my point here isn’t that we should be eating rotten meat - although that is apparently a thing among some carnivore folks, but that context is important in conclusions)

(Michael - When reality fails to meet expectations, the problem is not reality.) #194

Source

(Michael - When reality fails to meet expectations, the problem is not reality.) #195

New Chapter:


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(Elizabeth ) #196

Bookmark this www.justmeat.co. It’s a compendium and wiki of decades of carnivory