Green vs red

Should we eat animals? Many voices say food from plants is enough. So who is right?

FEW PEOPLE DOUBT we eat more animal protein than we should. Those in the paleo fringe advocate more, not less, but they are voices in the wilderness. Animal food has harmful constituents, particularly when intensively raised, over-cooked or chemically processed ( bacon), and no one should eat it every day, even the healthiest versions. The issue is whether we should eat any at all.

There are broader questions, of course, such as animal welfare. It is problematic to eat something sensate, particularly if it lived under fluorescent lights standing in its own droppings. Egg and milk ethics are no different as the animals involved still get mass slaughtered in the end.

There are also environmental issues, but they are less clear. Factory farms pollute the world but animals on grassland much less so. Grazing animals can be good for topsoil, which captures carbon. Grass-eaters also use terrain that won’t yield food any other way. Oats and apple trees don’t grow up hillsides. So, there is more to it than just human health. But if human health is the issue, what is the optimal dietary setting?

Consulting experts doesn’t get us far. There is no consensus, and most points of view have vociferous advocates. In my view, most of the evangelists for some definition of the ideal diet, including the ones with PhDs, are expressing their philosophy, not hard science. Best rely on common sense deductions.

The frame you stand in is the product of a very long period of road testing. Multiple generations of your lineage were buffeted by harsh environments that have fine-tuned numerous details of the modern human you are. So, what do forensics tell us?

Our bowels are long like those of grazing animals, not short like those of carnivores, and our teeth are grinders, not cutters. But this just means we are intended to eat plants mainly, not exclusively. Long bowels and flat teeth do not make meat unpalatable.

Brain-wise, our hard-wired preferences gravitate towards meat, which implies that our ancestors were better off for seeking it out when it was rare and hard to get. Salt and sugar are the same. We now consume too much in a world that delivers abundance, but that obscures the underlying insight. Things we are programmed deep in our instinctive brain to seek out are likely to be things we need.

This brings us to vitamin B12. B12 irritates vegans because it is a niggle for which they don’t have a good answer. B12 is needed for red blood cells and nerves, but the human body doesn’t make its own, and only animal food delivers it. Vegans would be seriously ill if they didn’t get B12 in pills or fortified food. Vegan websites advocate them. The modern world delivers such things, so vegans are okay, but the argument before us is nature’s preferred design. We did not evolve from the African savanna, shopping at Health 2000. If a diet doesn’t deliver something essential — even just one item — it can’t be what we evolved to eat.

Soil bacteria also make B12, so maybe vegans in ages past — strict Hindus, for instance — got theirs from the dirt on veg. If that is true, it doesn’t advance the issue as dirt also brings disease, and unwashed food is not an argument for what suits us best.

Much the same arises with vitamin D, a vitamin of ongoing interest linked to weak immunity, cancer, heart disease, and much else when deficient. Sunlight on your skin makes most of what you need, but not all, and even the most sun-exposed people need to eat some. Edible requirements are particularly high for people with dark skin as well as those who live in the planet’s sunshine-limited zones — which is most of us. Above and below the 33rd parallel lines of latitude, northern and southern, sunlight in winter is not strong enough to make vitamin D. The northern 33 parallel latitude line goes through the top of Africa, and the southern one goes through lower Australia so you can see the problem. Most of humanity is affected.