The ethics of food-3: Evolutionary implications

By Mano Singham

The theory of evolution has, of course, implications for the question of whether we should eat meat. One popular view of evolution lends support to the perceived superiority of humans over other species. This view sees evolution as a ladder-like hierarchy, rising ever upwards to higher and higher forms: as a sequence: amoebas→ sponges→ jellyfish→ flatworms→ trout→ frogs→ lizards→ dinosaurs→ anteaters→ monkeys→ chimpanzees→ Homo sapiens. (Steven Pinker, The Language Instinct, 1994, p. 352)

In this model, since humans are the most evolved and higher than other forms, it gives us the right to kill and eat other species. In the Christian equivalent of this hierarchical model, that last step up in the ladder was the addition of the soul. But even if we do not take the idea of the soul seriously, the idea that humans are at the apex of evolution can be used to support the exploitation of 'lower' species.

But that linear, ladder-like model of evolution is simply wrong. Evolution is a branching theory, more like a spreading bush. Starting from some primitive form, it diverged into other forms, and these in turn branched out into yet more forms and so on, until we had a vast number of branches at the periphery. All the species listed above are like the tips of the twigs of the bush, except that some (like the dinosaurs) are now extinct.

According to this model, although all existing species have evolved from some earlier and more primitive forms, none of the existing species is more evolved than any other. All existing species have the same evolutionary status. They are merely different. We are not higher or lower than them. They are our cousins.

The actual theory of evolution says that while some species may be considered to be more 'primitive' than others, that word is used in the evolutionary context in a purely technical sense, and not as a measure of any intrinsic worth that might justify killing them. It is not meant to signify that they are inferior in some way but just that their present forms are similar to their ancestral forms. So present-day bacteria and sponges are 'primitive' because they are not very different from the forms that their ancestors had billions of years ago. On the other hand, the ancestors of humans start looking very different just a few tens of millions of years ago, so we are considered to be less primitive.

If humans are just the tip of one particular branch in the tree of life, is there any reason to think of us as special or superior? Religious people who accept this correct view of evolution could still argue that god gave only humans a soul and so the justification for dominating other species and eating meat still exists. This requires the soul (or mind or consciousness) to appear just after the human lineage separated from its nearest evolutionary cousins in the Great Ape family, and seems too much like an ad hoc self-serving rationalization for comfort. In the erroneous ladder model of evolution, the emergence of the soul at the final step was still an arbitrary assumption, but had a little better justification since a ladder-like hierarchy could be used to argue for qualitative differences between the rungs.

If we dispense with the idea that humans are uniquely possessed of a soul or some such entity, the basic question is whether humans possess a moral right to kill and eat nonhuman animals. Philosopher Peter Singer argues that the principle of equality that we apply to all humans should be extended to animals as well. In particular, the interests of animals should receive the same consideration as the interests of humans.

But how would this extension of equality work out in practice? Do we have an obligation to send animals to schools like we do with children? Singer explains:

The extension of the basic principle of equality from one group to another does not imply that we must treat both groups in exactly the same way or grant exactly the same rights to both groups. Whether we do so will depend on the nature of the members of the two groups. The basic principle of equality does not require equal or identical treatment; it requires equal consideration. Equal consideration for different beings may lead to different treatment and different rights. (From his book Animal Liberation (1975), excerpted in Writings on an Ethical Life by Peter Singer (2000), p. 29.)

Some philosophers have argued against Singer's view by saying that rights and obligations are inseparable. Humans have rights because they also have obligations. Animals cannot enter into social contracts and thus don't have obligations, so they do not have rights. Wikipedia has a good article that summarizes the various positions on this issue.

Those who disagree with Singer's point that animals deserve equal consideration tend to look for specific markers that distinguish humans from nonhuman animals and thus can be used to grant humans privileged status.

In the next post, I will look at whether we can find such markers.

(For previous posts in this series, see here.)