Rant: ‘Lower Organisms’

This rant is dedicated to Diana, who knows better, but who still takes pleasure in provoking me.
Also note that I cannot take credit for any of the photos in this post.

As an insect lover, jellyfish groupie, and worm advocate, the term ‘lower organism’ sends a shiver down my spine. What a condescending, unkind, prejudicial label! Thankfully my invertebrate friends are spared the offense, as they have no appreciation for terminology, nor indeed any spines that shivers might be sent down. As such, they also cannot defend themselves, so I will try my best on their behalf.

There is no zoological basis for classifying invertebrates as ‘lower’. What does such a term even mean? If you think it indicates lower biological complexity, I point to the cephalopods (octopi and squid) who independently evolved sophisticated nervous systems including eyes that are more practically arranged than our own. As another counter-example, there is more anatomical variety among the animals we collectively refer to as ‘worms’ than in all vertebrates taken together.

If you think ‘lower’ refers to social complexity, I refer you to E. O. Wilson’s ‘The Ants‘, which documents the castes, hierarchies, and rich community life of this insect group. There is no feature, whether anatomical, or social, that has not first been explored by invertebrate animals long before the vertebrates even existed.

If ‘lower’ referred to evolutionary success, I’m afraid we would find ourselves with the lowest of the low. In geological time we are relative newcomers, and we seem poised to drive ourselves to extinction after a lightening-quick appearance of just a few million years. Contrast that to the insects, who have been on our planet almost 300 million years and have dominated every ecological niche available through vast swathes of natural history.

I suspect that most readers believe invertebrates to be ‘lower’ because “they do not have a brain.” In technical terms, the collection of nervous tissue towards one end of the body is called cephalization, and it is a hallmark in the development of vertebrates. But that’s an entirely arbitrary criterion on which to base a hierarchy of life!

In ‘The Ancestor’s Tale‘, Richard Dawkins points out that we use cephalization as a benchmark for evolutionary “progress” mostly because it puts our own species on top. He amusingly speculates that if elephants were to generate a similar hierarchy, perhaps they would base it on proboscity (length of nose), thus raising elephant seals and elephant shrews to newfound glory.

Our ego-boosting bullying of invertebrates because of their brainless-ness is just as ridiculous. So let’s put away our anthropocentric bias, and stop referring to the vastly more diverse, more numerous, and more successful animals of our planet with derogatory terms.