I don't have any good sources.Can you cite a reference for this without too much bother? This has bothered me for decades. "How come gorillas and chimpanzees don't seem to suffer from pernicious anemia?" If the correct answer is "The other great apes don't rinse their veg in clean water like zealous puritans," then I will sleep better. I truly have not made time to look this up in the last 30 years.
Here are two articles, both speculative about prehistoric diet:
Vitamin B12: What Everyone Should Know
Vitamin B12 is often cited as a key nutrient that vegans may be deficient in. However, there's a lot of mystery and misinformation surrounding it.
thepeskyvegan.com
The Evolutionary Quirk That Made Vitamin B12 Part of Our Diet
If animal products are our only source of B12, and it's vital to survival, how do herbivores survive?
www.discovermagazine.com
The first includes the speculation that our ancestors got B-12 from dirt and dirty water. The second goes into greater detail and claims that colonic bacteria in both humans and our ape cousins/ancestors synthesize plenty of B-12. But a quirk in humans is that we can only absorb B-12 from our small intestine, so we excrete all the B-12 synthesized in the colon! It claims the apes (and other herbivores) retain the ability to absorb B-12 from the colon. This article takes this as evidence of regular meat eating among our ancestors, but it seems to me that it could be evidence of regular dirt ingestion, dirty water ingestion, or herbivore dung ingestion/handling/picking.
It is also clear that many traditional fermented foods (sauerkraut, miso, kimchi) can be decent sources of B-12. Depending on the cobalt content of the source plants, these might have been important for these cultures when meat was limited or unavailable.
It seems that much of this is going to be speculative. Field work suggests that B-12 ingestion and synthesis depends strongly on cobalt content in soils, which is low in many areas, and why cattle are commonly given synthetic B-12. As pointed out by the first article.
I am also left wondering if the soil in East Africa is much higher than elsewhere in the world? Perhaps our B-12 'quirk' says we evolved in or around the Congo...
I found this abstract: https://www.sciencedirect.com/science/article/abs/pii/S0166248108701703
Cobalt is found in all the rocks of the earth's crust, the contents varying with the nature of the rock. The average content of cobalt in the lithosphere is about 30 ppm. There are only few data concerning the parent rocks corresponding to the different types of soils studied. The total cobalt contents of soils vary widely: 0.05 ppm. (podzols of the U.S.S.R.) to 300 ppm (vertisols of the Central African Republic). In soils, these contents vary in relation to those of the rocks from which the soils originate and in relation to the types of soils whose characteristics are more or less directly related to the climate, which has dominated their evolution, and to the major geographical zones. Total cobalt contents for the soils of these regions range from values of 0.05 to 200 ppm. They depend closely on the parent rocks, even though they tend to vary from one horizon to another in relation to certain pedologic processes. The soils of arid and semiarid regions have higher average cobalt contents than those of temperate and boreal regions. Cobalt is an important element for animals. Its compounds play a role in the formation of hemoglobin; and in several regions of the globe, sheep and cows may become anemic because of eating vegetation grown in cobalt-deficient soils.
But I could not retrieve the article nor the author's names from the Journal, even with my Uni tools (frickin Elsevier).
But this suggests that tropics+semi-arid+Africa means lots of cobalt and B-12 everywhere, versus wetter, temperate or boreal and non-Africa... much harder to find.
The chimps and gorillas are gonna be ok.
ETA: Found a paper from 1970: https://journals.sagepub.com/doi/pdf/10.1258/002367770781036526
It indicates that Old World Monkeys kept in captivity and fed an unsupplemented entirely plant-based diet suffer from B-12 deficiency that resembles that in humans on the same diet. So perhaps the 'quirk' in human absorption did not occur recently, but is universal to African primates.
And so we are back to speculations about trace eating of meat/eggs/insects/feces/dirt.
Also, there is plenty of evidence of humans eating insects: https://en.wikipedia.org/wiki/Entomophagy_in_humans
It could be argued that in many non-Western cultures, eating insects is more common than eating dairy.
And just for @Ashful, there are in fact Cave paintings and paleolithic carvings that show edible insect collection and honey sources.
Entomophagy in humans - Wikipedia
en.wikipedia.org
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