Of life and death

As humans, we seem to love putting things into boxes, sorting them into categories—black and white, horses and zebras, living and dead. But biology isn’t like that. It’s a continuum.

One of the simplest images of life is that of a cell dividing. One minute, there is a living cell; the next, it has split into two. But where is the original cell. Is it dead? Or is it still alive in its offspring? In fact, what are the points of the beginning and end of life? Life is a cyclical process. All of us had ancestors. Some of us have or will have children. So when did our lives begin? And when will they end? Do we, in some way, live on in our offspring?

As far as Archimedes knows, there is no good scientific answer to these questions. He knows of no foolproof scientific definition, for instance, of what constitutes living and non-living. Quite the reverse. Science, in the form of technology, seems these days to be muddying the water.

It all used to be so simple. A person was dead if they stopped breathing or their heartbeat ceased. Then came life support systems which could take over the job of pumping the blood and the lungs. Was a person dependent on life support living or dead? If you switched off a respirator, were you killing someone, committing murder? Respirators are integral to the process of organ donation, as kidneys and lungs and livers need to be kept alive with oxygenated blood while awaiting transplantation from donor to recipient. And so the legal concept of brain death came into being—the idea that a person was legally dead if they were on life support, but their brain was medically determined by doctors to be incapable ever of controlling independent existence.

Science is about to complicate things further. There are now researchers trying to assemble simple forms of life by combining (dead) off-the-shelf chemicals. These life forms would be separate from the environment in which they existed, and able to support some form of chemical reaction to maintain and reproduce themselves. If we could produce such entities, would we have made life?

A growing body of researchers into the process of ageing now look at death as an engineering problem—a barrier that they will eventually overcome. As they find out more about the causes of ageing and death, they are becoming more and more confident that it might be possible for an individual to live forever.

All of which brings us to where we started. When does life begin and end? These are significant questions which stir the very depths of our humanity. The point at which a new human life begins, for instance, is central to any discussion of the ethics of abortion and stem cell research. Those who believe humanity begins at conception have a completely different view from those who think that humanity implies the existence of some sort of organised nervous system.

The sad, sorry and protracted battle over the fate of Florida woman Terri Schiavo, revolved around the point at which human life ends. The resolution of this question so stirred some segments of American society that their representatives in Congress tried to assert control over the courts, whose independence from such action is supposedly guaranteed in their Constitution.

What has become clear to Archimedes is that science offers little assistance in the determination of the points at which life begins and ends, so important to our concept of our own humanity. These are legal, social, ethical and, yes, religious decisions. Life itself flows on. 

Tim Thwaites is a freelance science writer.



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