I just finished a challenging but deeply edifying book called Consciousness: Confessions of a Romantic Reductionist, by Cal Tech biologist Kristof Koch. The book is the finest example of making hard science accessible without dumbing it down that I've encountered in some of the modest reading I'm doing on the physical basis of consciousness. My underlying goal is to get a sense of what the most knowledgeable experts on the brain have to say about the connection between neurological sophistication and consciousness.
Koch, for one, certainly posits a correlation. He writes, "Consider simpler animals-simplicity measured by the number of neurons and their interconnections-such as mice, herrings, or flies. Their behavior is less differentiated and more stereotyped than that of dogs. It is thus not unreasonable to assume that conscious states of these animals are less rich, filled with far fewer associations and meanings, than canine consciousness."
I know this line of thought makes some animal rights advocates, many of whom prefer to view all animal life as deserving the same moral consideration, nervous. But I like the proposition in part because neurological complexity is the same physical basis that biologists use to distinguish a category of life that we do not grant equal moral consideration: plants. This distinction is one that animal rights advocates very much need to preserve at all costs. Consider this excellent overview of the plant/animal distinction on the basis of evolutionary cellular development by Oliver Sacks:
The calcium ion channels that plants rely on do not support rapid or repetitive signaling between cells; once a plant action potential is generated, it cannot be repeated at a fast enough rate to allow, for example, the speed with which a worm ‘dashes ... into its burrow.' Speed requires ions and ion channels that can open and close in a matter of milliseconds, allowing hundreds of action potentials to be generated in a second. The magic ions, here, are sodium and potassium ions, which enabled the development of rapidly reacting muscle cells, nerve cells, and neuromodulation at synapses. These made possible organisms [i.e., animals] that could learn, profit by experience, judge, act, and finally think.
The proposition of a continuum of consciousness based on neurological complexity does not necessarily mean that humans will use that continuum as a justification to abuse animals with nervous systems that are nominally less complex. Curious about Koch's stance on this issue, I poked around the Web. In an interview with Scientific American, he was asked if his research influenced his own behavior. I put a fist in the air when he explained, "I have stopped eating the flesh of mammals and birds, as they too share the wonders of experience with us."
In this respect, I think the pursuit of a physical understanding of consciousness-even if we never uncover it-can be a benefit for animals. That is, as humans begin to understand that the nature of existence originates and is sustained exclusively by measurable physical forces, the less we will seek answers to our existence and its meaning in traditional spiritual frameworks that impose unfounded hierarchies that arbitrarily favor human exceptionalism over "brute creatures."
That catch, of course, is that to pursue the quest for consciousness, scientists seem to think that the only way to do so is to experiment on the animals their findings suggest have qualities that demand our respect and moral consideration. Therein lies a conundrum I hope to address soon.