A honeybee scientist, Andrew Barron, and a philosopher, Colin Klein, have collaborated on a study that suggests insects may have consciousness and emotions:Insects Are Conscious
Does insects' inner life comprise more than simple reflexes? Conventionally, the neocortex is thought to be the site of consciousness. Suppose, rather, the "much more primitive midbrain" synthesizes experience into "a unified, egocentric point of view"? Barron and Klein maintain that insects have midbrain-like neural structures that enable them to "model themselves as they move through space." (The quotations come from an article about this study in SMITHSONIAN magazine.) Insects may feel, at the very least, hunger and pain.
Since I've always shared the prevailing belief that invertebrates don't have enough neural processing capacity to feel anything, this hypothesis strikes me as rather unsettling. Insects do appear to "plan," in a sense, in that they pursue definite goals. They can learn from experience (even flatworms, a much "lower" life form, can do that), so do they have "memory"? They make choices between alternatives, so are they "deciding"?
Whether insects have consciousness and the ability to think depends, of course, on how we define "conscious" and "think." C. S. Lewis in THE PROBLEM OF PAIN points out that an unconscious human body may reflexively react to hurtful stimuli although obviously without being aware of pain. If by "self-awareness" we mean the ability to meditate on our own existence, possibly only human beings have that quality. Self-awareness on the level of recognizing one's own reflection in a mirror is confined to us, some primates, and a select few other animals. If "thinking" means only abstract thought that can be formulated in words, by definition we classify ourselves as the only thinking organisms on the planet. If any kind of problem-solving equals thinking, the field becomes much wider.
I once read a story (can't remember the title or author) in which one character tries to convince another that thought isn't confined to human beings and higher animals. He says, "With what does a plant think, in the absence of a brain?"—classifying a plant's phototropism as a form of thinking.
Barron and Klein hope investigating the mental lives of insects may throw light on the origins of subjectivity in "higher" species, including ourselves.
Margaret L. CarterCarter's Crypt