Martin Rundkvist at Aardvarchaeology wrote an interesting blog entry looking at the cultural phenomenon of CAM (complementary and alternative medicine) from the point of view of Darwinian selective pressures. He argues that CAM modalities are under two types of negative selective pressures – to minimize harm and to avoid being co-opted by mainstream medicine, and that these two selective pressures produce CAM modalities that are optimized for zero-effect.

The notion of CAM as a cultural meme that evolves is very apt – an evolutionary analogy I have used myself. Culture and ideas certainly evolve, and it is a very useful exercise to think about the selective pressures that drive this evolution. The marketplace is also a system that evolves, and CAM very much exists within the market system.

I think Rundkvist has hit upon two real pressures, but we can take this evolutionary analysis much further. Orac has also blogged about Rundkvist’s original entry, arguing that these two negative selective pressures are not very important because CAM modalities never go extinct – they persist even if they are harmful or versions of them become scientific.

Orac has a point, but I think he is looking at the evolutionary analogy too narrowly. Even though few CAM modalities go extinct, their popularity waxes and wanes. Some modalities become more widespread while others become increasingly marginalized. Also, cultural evolution does not require extinction – a CAM species can itself change over time. Also, even though modalities rarely vanish, new ones do appear – usually variations on old ideas, but better adapted to the CAM market.

What are the dominant market pressures affecting CAM? I think Rundkvist and Orac are both correct in implying that CAM modalities are NOT under pressure to actually work. Rather they are selected to be user friendly, they are optimized for customer service in those aspects that customers can readily perceive. Therefore CAM practitioners spend time with their clients, they use treatments that are not intimidating or frightening, that do not involve discomfort, that may even be pleasant. They also tell their clients what they want to hear: your problem is simple and I can fix it without risk.

CAM modalities have evolved toward these features because they are not constrained by reality. They don’t have to work, they don’t have to be based upon science or evidence, and they don’t have to be honest.

CAM also reveals the weakness of evolutionary pressures in the market place of medicine. The problem is that customers (patients) are mostly not able to perceive the quality of the medicine that is actually being delivered. This is because of two things mainly. The first is that the practice of medicine is highly complex and specialized, so unless you have a significant amount of medical training it is very difficult to judge the clinical decision making and knowledge base of your provider. You can use proxies – like certification and reputation – but this is imperfect. The evidence shows that patient perception of the quality of the medical care delivered to them correlates with bedside manner – and not quality.

But even more important than this is that biological systems and disease processes are too complex and chaotic to assess the outcome of interventions anecdotally. The placebo effect, confirmation bias, assumption of cause and effect, and a host of other psychological factors confound any attempt to decide from personal experience if any intervention was effective or not. The best medical intervention available can still result in a bad outcome, and ineffective treatments will not prevent a self-limiting illness from getting better on its own.

Admittedly, this is overstating the case. If you have acute appendicitis and you get treated by an acupuncturist or homeopath, you will likely die. If you go to a mainstream doctor you will get a simple surgical procedure and be fine. Some illnesses and outcomes are obvious enough to perceive and drive behavior. We have to think of CAM and evolutionary pressures also in the context of niche. CAM has filled those niches (an evolutionary phenomenon called habitat tracking) where it is most difficult to perceive outcomes: with chronic and common complaints that tend to wax and wane over time but are largely benign, or with self-limiting illnesses that will get better on their own. The notion of complementary medicine itself is an attempt to expand the niche of CAM by piggybacking onto scientific medicine. You will get an appendectomy so you won’t die from a ruptured appendix, and then get completely worthless therapeutic touch in recovery.

In the niches CAM has filled, CAM modalities are largely unhinged from scientific reality and the constraints of professionalism. So they evolve under the selective pressures of the marketplace, which drive service, feel-good interventions, wishful thinking, and profit for its practitioners – but not effectiveness. Selective pressures for effectiveness, in environmental niches where it can be reasonably perceived, strongly favor scientific medicine, and so scientific medicine has dominated there.

Also, the evolutionary environment of CAM is the marketplace, but this marketplace is not completely free. It is constrained by regulation that is designed to establish a standard of care and protect the public from fraud, deception, harmful treatments, or just worthless treatments. CAM does not like regulation, because regulation constrains its evolutionary choices. This is precisely why CAM proponents are pushing for “healthcare freedom.” What they really want is a free marketplace for medicine, or at least CAM (they have no problem with a double standard).

A completely free CAM marketplace, free from any constraints of regulation, allows CAM to evolve toward optimality for service and profit. So while CAM is evolving under the above pressures, CAM practitioners are trying to actually alter the environment in which CAM lives. This is like a species changing its environment rather than adapting to it. Man is the quintessential example of this, but there are others – like beavers building dams.

All of this is exactly why scientific ethical medicine requires regulation. Selective pressures of scientific plausibility and evidence for safety and effectiveness need to be imposed upon medicine. History has clearly shown that consumers do not impose these pressures by the choices they make. That is why CAM continues to survive.