When Do We Become Truly Conscious?
The new science of consciousness should change how we think about thorny ethical dilemmas.
Having prided myself on my objectivity throughout my adult life, I’ve embarrassingly found that my daughter is the main exception to this aim: I’ve not only been taken aback by how fiercely I love her but also by how proud I am of her and how quickly I distort the truth to make her seem exceptional in every way. But when I can step back from these views, I ask myself: At what point did she become conscious? Obviously she is conscious now, as she can tell me her inner thoughts via language. But when did she start experiencing her environment? On a personal, intuitive level, I had little doubt that her first intense bursts of laughter at my silly antics, when she was a few months old, reflected a substantive consciousness. But was she conscious well before this? Was she aware when she was still in the womb, kicking away? Or could she only experience things when she first opened her eyes to the outside world on the day of her birth?
Finding answers to these questions isn’t merely a matter of curiosity. In the United States, people have been murdered for carrying out abortions. In many other countries, abortion is illegal even if the woman has been raped, and some prominent U.S. politicians, including Republican vice-presidential nominee Paul Ryan, support similarly harsh laws. Although such positions are usually determined by religion, a related mindset is that fetuses are already conscious and even capable of feeling pain. Indeed, this has recently been the basis states have used to further restrict a woman’s rights on this issue, with Arizona the latest state to join this group by disallowing abortions after 20 weeks.
But what does science have to say on this matter? The evidence is clear that a fetus can respond to sights, sounds, and smells, and it can even react to these by producing facial expressions. The evidence is equally clear, however, that these responses are generated by the most primitive parts of the brain, which are unconnected to consciousness, and therefore these actions don’t in any way imply that the fetus is aware. Furthermore, the fetus is deliberately sedated by a series of chemicals produced by the placenta, so even if it had the capacity for consciousness, there is almost no chance that it could ever be conscious in the womb. Consequently, it can’t consciously feel pain.
But what if the fetus is removed from the womb and its sleep-inducing chemicals? Will the fetus suddenly be conscious in the outside world? In adult humans, for normal consciousness to occur, it is now generally agreed that two sets of regions need to be intact, functional, and able to communicate effectively with one another: the thalamus, a kind of relay station in the middle of the brain that connects many regions with many others; and the prefrontal parietal network, our most high-level, general purpose section of cortex. If either the thalamus or prefrontal parietal network is substantially damaged, the patient is likely to enter into a vegetative state, with virtually no sign of consciousness.
When do these brain regions form in the growing fetus? Only after about 29 weeks are the connections between these areas properly laid out, and it takes another month or so before the thalamus and the rest of the cortex are effectively communicating, as revealed by brain waves. So it’s highly unlikely that consciousness, at least in any form that we’d recognize as human awareness, arises before about 33 weeks into pregnancy. There are therefore no scientific reasons for restricting abortion on the grounds that the fetus will experience pain, at least until very late in pregnancy. This evidence has heavily influenced my views here, and consequently I am very much pro-choice.
Another ethical issue that hinges on questions of consciousness is that of animal rights. Every person on the planet, on average, consumes twice his or her weight in animal-derived food each year. Food production, as well as animal experimentation, could be causing the suffering of many millions of animals yearly.
If no animals except humans have consciousness, there’s no problem, as suffering requires consciousness. But if even those animals classically assumed to have very limited mental faculties, such as poultry and fish, have a substantive awareness and significant capacity for suffering, then are we justified in inflicting all this pain and discomfort on them?
If science could come up with some means of testing for the presence of consciousness in other animals and perhaps also a way of gauging the extent of consciousness when it’s found, this would have a huge impact on all ethical spheres of the animal rights debate.
On the surface, because animals can’t use language to tell us they are conscious, this seems an intractable problem. But a surprising amount of evidence has emerged that addresses the question of animal consciousness. For a start, we can ask which other species have brain regions similar to those we know are critical for human consciousness, namely the thalamus and prefrontal parietal network. Most mammals share these structures with us in some form, suggesting strongly that they too have some significant levels of consciousness. But this is a problematic approach, ignoring the possibility that very distant species independently evolved the capacity for consciousness. For instance, crows can use a series of tools to hook a juicy grub, and octopuses can open a screw-on lid to a jar to retrieve a tasty crab. Although these animals have no cortex, they appear to demonstrate a mental life that many would classify as conscious.
Daniel Bor is a cognitive neuroscientist at the Sackler Centre for Consciousness Science at the University of Sussex, United Kingdom. He is the author of The Ravenous Brain: How the New Science of Consciousness Explains Our Insatiable Search for Meaning (Basic Books). Learn more at www.danielbor.com or on Twitter @DanielBor.