Increasingly we have the scientific ability to correct what are perceived as design flaws in human evolution – but every advance brings with it an ethical dilemma, writes PAUL O'DONOGHUE
A 1991 REVIEW by Randolph M Nesse and George C Williams, titled The Dawn of Darwinian Medicine, first drew attention to an interesting area of inquiry. They followed up in 1995 with a book called Evolution and Healing, arguing that evolutionary science would positively inform our understanding of a variety of conditions and some apparent anomalies in our make-up.
While the human body is an impressive biological achievement, it is far from perfect in its construction. For example, we would be far better off without our appendix, which no longer contributes to digestive functions and can become inflamed and life-threatening.
The mammalian eye, which is often lauded as an example of immaculate design, also has its weaknesses. Unlike the eye of the squid, for example, ours is constructed in such a way as to produce a blind spot where nerves and blood vessels penetrate the retina in a bundle; this also leaves us prone to retinal detachment.
We can choke while swallowing because of the close proximity of our trachea and oesophagus, and the female pelvis could be a little better designed to allow the easier passage of babies.
Woody Allen has quipped: “If it turns out that there is a God, I don’t think that he’s evil. But the worse you can say is that basically he’s an underachiever.” And in a world preoccupied with environmental issues one might wonder who in his right mind would construct two waste-disposal units right next to a recreational area?
Aside from these anatomical issues, Nesse and Williams provide examples of physiological responses that may be sensibly interpreted from an evolutionary perspective. A rise in temperature in response to infection, for example, slows down the reproduction of pathogens, which aids the immune system in mounting a stronger response. Likewise, they argue that symptoms such as pain, coughing, vomiting, diarrhoea and anxiety are not disease or design defects but constitute evolved defence mechanisms. This raises the question as to whether it’s better to control high fever or vomiting, for example, or to allow them to perform their evolutionary function (provided, of course, that they are not so severe as to be life-threatening).
Morning sickness, which causes discomfort for many women in the first trimester of pregnancy, may be understood as a protective function for the foetus at its most vulnerable stage of development. A woman who is nauseous and repulsed by strong-tasting foods is less likely to ingest dangerous toxins.
Sometimes an evolved defensive function results in significant costs, as in the case of sickle-cell anaemia. Those who carry a single copy of this gene are protected from malaria but those with two copies suffer the ravages of sickle-cell disease. From an evolutionary viewpoint there is the benefit that more people will survive in areas where malaria is a significant problem. The situation is reversed, however, in areas where malaria has been effectively controlled.
Paul Ewald has drawn attention to the relationship between the virulence of pathogens and the modes of transmission of disease. Lowered virulence will occur where the transmission of disease requires direct host-to-host contact, as killing the host is of no advantage to the pathogen. But where a vector is active, as in malaria transmission, it doesn’t matter whether the host is incapacitated, and virulence remains high.
The understanding gleaned from an evolutionary perspective on disease can helpfully inform medical practice. For example, understanding the evolution of antibiotic resistance in bacteria has implications for prescribing.
The limitations of our bodies may suggest that we should try to do something to remedy our defects, which leads me into a controversial and stimulating area of analytic philosophy. Human Enhancementis a new book, edited by Julian Savulescu and Nick Bostrom, which examines this issue in detail. Developments in medicine, the biological sciences and biotechnology will enable us to significantly modify many aspects of our structure and function over the remainder of this century.
Of course, many forms of enhancement exist and are utilised already, from contact lenses and reproductive technologies to cosmetic surgery and doping in sport. But, as is often the case in science, rapid developments precipitate ethical dilemmas. The suggestion is made in the course of Human Enhancementthat all such processes and technologies are best considered individually and in depth. The editors argue that in order to deal effectively with the potential risks and benefits of enhancement, we will require wisdom, dialogue, good scientific research, good public policy and academic debate. They offer this challenging book as a first step in the process.
I will leave the last words to Woody Allen: “More than any other time in history, mankind is at a crossroads. One path leads to despair and utter hopelessness. The other, to total extinction. Let us pray we have the wisdom to choose correctly.”
Paul O’Donoghue is a clinical psychologist and founder member of the Irish Skeptics Society; contact@irishskeptics.org
