This post is part of an ongoing series called Most Common Justifications for Eating Animals where we seek to provide answers and resources to better address these justifications.
One could claim that our brains have also evolved to become addicted to smoking, gambling, video games, alcohol, drugs, sex, violence, and harmful fast food. Our brains have evolved to create complex societies where Hitlers and Stalins exist along with great visionaries like Ghandi and Leonardo da Vinci. Fortunately, our brains appear to also be well equipped at making rational and moral judgments about what is good and bad, what is right and wrong — for ourselves and for others directly affected by our decisions.
And we recognize that just because we are endowed with the capacity for something doesn’t necessarily mean we should use it. We’ve evolved into an age where our weapons of mass destruction could annihilate all life on this planet, but it would be insane to try to justify using them based on the fact that we had the mental capacities to develop them!
Often referred to as the expensive tissue hypothesis, the widely-accepted claim that our brain size and complexity are connected to eating animals has been rigorously tested and refuted in a key report published in Nature (Navarrete, 2011). This comprehensive report evaluates the research into more than 100 mammalian species, including 23 primate species, analyzing brain size and organ mass data. Lead researcher Navarrete concludes that “human encephalization (brain development) was made possible by a combination of stabilization of energy inputs and a redirection of energy from locomotion, growth and reproduction.” Then in 2015 In a study published in The Quarterly Review of Biology, led by Dr. Karen Hardy, compiles archaeological, anthropological, genetic, physiological and anatomical evidence to argue that carbohydrate consumption, particularly in the form of starch, was critical for the accelerated expansion of the human brain over the last million years.
But even if the expensive tissue hypothesis were true, would it really matter? Just as the fact that our country was built by slaves does not justify the continued enslavement of other human beings, neither would the fact that our brain size evolved from eating animals be a justification for continuing to exploit animals for food when we have no need to do so.
Lastly, it’s important to recognize that the study of neuroscience and brain function is in its infancy. World-renowned neuroscientist Lesley Rogers just discovered in the mid-1990s the lateralization of the avian brain of chicks. Prior to Rogers’ discovery, it was widely accepted that only humans and primates had lateralized brains, which endow us with “multi-tasking” and advanced cognitive states. We still have much to learn about the brains of other animals as well as our own.