Humans didn’t evolve to eat meat
- Published: 14 August 2010
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Humans didn’t evolve to eat meat any more than we evolved to build skyscrapers – and it’s time we stopped attributing our consumption of animals to ‘evolution’, writes Tim Gier.
There is a recurring argument which vegans (and vegetarians, too) constantly hear about how evolution has shaped humankind in terms of what we should eat. Although the specific argument may take different forms, all of them basically come down to this:
Humans have evolved to eat meat, it is unnatural for us not to eat meat, and therefore we should eat meat; it is right for us to do so.
Did humans evolve to eat meat?
Before trying to understand what a study of the fossil record can tell us about evolution, it will be helpful to understand what we mean by evolution in the first place.
Humans have not evolved to do anything. That is, the theory of evolution describes what we can observe as having already happened; it predicts what will most likely happen next and it explains how both those things come to be.
But the theory of evolution does not suggest that there is some goal to the process or that any living thing is evolving to be or to do anything at all. In other words, evolution describes how things are, not why they are.
For instance, sharks have been sharks for a long, long time. Sharks have all the brain size, eyesight, sense of smell, ability to move and all the other qualities of being that they need to live quite well as sharks.
Evolution is not thinking about making them move up the food chain, or pushing them toward some progressive goal. Sharks are highly suited to their environment. They are efficient exploiters of the resources available to them. They have evolved over time, but the ancient sharks in the fossil record are very similar in the most important ways to modern sharks.
What is evolution doing then?
Evolution isn’t doing anything, because evolution isn’t some “thing” that acts upon the world, it is a description of the processes in the world.
Sharks have adapted to the various pressures in their environments which have threatened their survival. Individual sharks have not done so though, “sharks,” as a population of beings, have done so.
Imagine that it is 200 million years ago and that “sharks” live mostly in fresh water and not in the salty oceans. Something happens that threatens the habitat – maybe an ice age freezes huge amounts of water and fresh water lakes and ponds shrink dramatically in size. The population of sharks in endangered. We can imagine that even though the salt water oceans also shrink in size, they are not affected nearly as much as the lakes would be.
Now suppose that some individual sharks have a strange mutation (we might call it a birth defect) that allows them to survive in salt water.
Normally, those sharks would not survive particularly well, but these are not normal times and what was once a hindrance is now a benefit. So, because they are better suited to living in the salt water which is now more abundant than the fresh water, they reproduce successfully while the strictly fresh water sharks become more and more scarce.
The fresh water sharks are stuck in an environment that is shrinking and they are competing for fewer and fewer resources. The salt water mutants have all the water and resources they could possible want.
The mutated sharks survive, and they are the most fit to survive in the new and altered environment they find themselves in. But evolution had no purpose, and the sharks didn’t evolve to live in the salt water, it all happened by chance.
So, did humans evolve to eat meat?
No, because humans haven’t evolved to do anything. We didn’t evolve to build skyscrapers, or read books, or fight wars. We can do all those things but we are not purposely designed to do those things; it is just how we are, and those are among the many, many things we are able to do.
Did humans evolve by eating meat?
That’s a better question, and lots of people want to believe that the answer is yes, but I’d like for you to consider this:
A recent study by Pappenbeimer (1998) on the significance of absorptive mechanisms in relation to scaling of the dimensions of small intestines goes one step farther towards the interpretation of the above allometric relationships.
Transcellular absorption is lower in large species than in small species, whereas paracellular fluid absorption is greater. Paracellular fluid absorption may dominate in large faunivores with a small mucosal area (scaled to L^ in fig. i), whereas in large folivorous species the relatively diluted intestinal fluid and the low rate of transcellular absorption may be compensated for by an increase in the mucosal area (tending towards I’ rather than L^), the frugivores being intermediate.
What? That’s from the paper On Diet and Gut Size in Non-human Primates and Humans: Is There a Relationship to Brain Size? in the journal Current Anthropology and it shows, I think, that trying to understand the relationship between diet and the evolution of our brain power, or anything else that makes us human for that matter, may be more like rocket science than many of us think. This is some highly technical stuff and it would be a mistake to think that there are easy and simple answers to very complicated questions.
It is intuitive to think that eating “high quality” proteins from animals led to our own “high quality” intelligence, but scientists don’t rely on intuition, and even they don’t agree on what the evidence shows.
For every study that purports to show that meat-eating caused us to be who we are today, there’s another (from the same paper, by the way) that reaches a conclusion such as this:
In conclusion, H. sapiens does not seem to be an exception among the primates in terms of diet and gut size. There is no doubt that our species needs a rich diet to cover large energy expenses, but it requires relatively no richer a diet than many Cehidae and Cercopithecidae feeding on sweet fruits, complemented by the protein and fat of a large proportion of insects. The areas of mucosa that have been actually measured in humans do not show any trend towards a reduced intestine that would have allowed a supplement of energy for a large brain.
Whatever archaeology and anthropology can tell us, how far back in time would we like to look?
If we take the conclusion of the article cited above as instructive, then we should all be eating cockroaches for breakfast (and indeed in some cultures we do).
A review of the trajectory of evolution can’t tell us anything definitive about what we ate when and how it affected who we have evolved to be today. In that sense, our appraisals of the history of diet may be more like a Rorschach test revealing not what is true, but only what we already want to believe.
Humans did not evolve to eat meat, because we haven’t evolved to do anything, and although eating meat may have contributed to our success as a species, we cannot use evolution as justification for moral behavior.
After all, we have also survived throughout time with the capacities for greed, violence and hatred. No-one suggests that we should celebrate or encourage those things, even though it may be true that they have contributed to our better chances for survival.
It is no more unnatural to abstain from exploiting all the other animals of the world than it is unnatural to abstain from assaulting others on the street to steal the things they have which we desire.
Just because our ancestors would have done so 250,000 years ago as they fought tooth and nail to survive in a cold cruel world does not mean that we should or that it would be right for us to do so now.
If we have evolved to “do” anything, then we have certainly evolved to think beyond our basest impulses and to act as something more than creatures driven by unthinking instincts.
We have survived on this planet because we have the capacity for rational thought, the imagination to see a better future and the ability to recreate our own environments.
Some people may want to view evolution as an excuse to remain trapped in the violent nature of ancient history. I choose to see it as our best hope to break free of those chains to live in a peaceful tomorrow.
Tim Gier is a vegan abolitionist writer whose former career in automobile sales management spanned 25 years. He writes about business, politics, human behavior and sometimes pop culture at his blog.