Recently I told my readers my hair had had a scary month or two of falling out on my vegan diet. It also became straight and more limp and depressingly thin than it always has been.
It might have been a B12 deficiency, so we have been on B12 slow release vitamins.
I asked vegans how our ancestor humans evolved if we never ate food containing B12, for B12 is essential. We don’t get any from a plant based diet because no plants actually contain it.
I found this very interesting article about the very same question. There is an enormous amount of information here, if you are interested. In modern times, it seams, we no longer get enough B12, even if we eat animal products.
But about our evolution as plant eaters – once, we got enough from other sources.
Please read this article if you want – it’s a mine of information for meat eaters and vegans!
In summary, it appears that non-pathogenic soil microbes, human small intestinal bacteria, lactobacilli from fermented foods, some sea algae, common mushrooms, and plants grown on soil fertilized with animal manure can all can provide biologically active B12. Any of these could have served as ongoing sources of B12 for prehistoric human ancestors, but modern circumstances may make these non-animal sources of B12 unreliable for modern humans.
I think it safe to assume that our prehistoric ancestors had more contact with soil than we do, sitting on it, sleeping on it, digging in it, and drawing water from sources in contact with the soil. Humans like other primates are apt to touch their own lips from time to time, providing a vector by which soil microbes could enter the human gut.