The Economist explains

Do rats have souls?

By G.C.

AUGUST is the silly season for news. With politicians on holiday, and acres of newsprint, screen-space and airtime to fill, desperate editors will reach for anything that might keep the reader’s, viewer’s or listener’s attention. Occasionally, though, such stories touch on deep questions. That may be the case for a widely reported study by researchers at the University of Michigan which shows that dying rats could be undergoing something similar to the strange near-death experiences of some people whose hearts have stopped beating, but whom medical intervention has then revived.

Such experiences come in two sorts. One is a sensation of floating disembodied above your own physical selflooking down from the ceiling, as it were. The other is of a beckoning light at the end of a tunnel. Not surprisingly, these are sometimes interpreted as religious phenomena: evidence for the existence of immortal souls. Sceptics, conversely, think they are but a manifestation of the electrical death throes of the brainthough some suspect such experiences in past, more religious ages, may have contributed to the idea of a soul and an afterlife. Actual evidence of what is going on in the brain at such moments of crisis, though, is understandably lacking.

Jimo Borjigin’s experiment, intended to fill this gap in knowledge, was small (it used only nine rats) but intriguing. She and her colleagues implanted six electrodes into the brain of each of rat and then killed it by injecting potassium chloride into its heart. In every case, for up to 30 seconds after the animal’s heart stopped beating, there were spikes of electrical activity in its brain. What spiked in particular was a phenomenon called coherent gamma waves. These are believed to reflect neurological processes that bind together the activities of various parts of the brain and are thought by some researchers to be involved in generating the mysterious phenomenon known as consciousness. Whether rats are conscious in the way that human beings are is moot. A handful of other animals, notably great apes, elephants and certain cetaceans share the human ability to recognise oneself in a mirror. They are, in other words, self-aware, and many investigators believe self-awareness is a crucial aspect of consciousness. Rats do not pass this mirror test. But they are clever, which is why psychologists like them for experiments.

What Dr Borjigin’s rats were thinking in their final seconds is impossible to know. Indeed, as they were anaesthetised at the time they would not have known themselves. It may have been the murine equivalent of another widely reported type of near-death phenomenon, namely seeing one’s life flash in front of one’s eyes. This sometimes happens to those faced with a palpable external threat, such as drowning or being in a car about to be hit by an oncoming lorry. One speculation is that a mass-scanning of the memory occurs in these circumstances as part of a desperate neurological search for a way to escape a looming fate. However, if what Dr Borjigin has found is not that, but rather truly is the equivalent of an out-of-body experience or the light at the end of the tunnel, then those who see such experiences as visions of heaven’s gate have some serious thinking to do. Either they are wrong, or rats, too, have souls.

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