Wednesday, March 10, 2010

The "aquatic ape" and the fate of eccentric hypotheses in science

Holly Dunsworth is a fine and responsible scholar and a highly knowledgeable paleoanthropologist. That's why we are delighted to have her occasional participation as a guest blogger on The Mermaid's Tale. In a recent post, she took issue with the 'aquatic ape' hypothesis, and staunch defenders of that hypothesis took issue back. The many blog hits that generated was nice, and strong debate, kept reasonable, is an essential part of science.

When someone suggests an hypothesis that is eccentric--off-center--to the mainline views of a science at any given time, it is received as a heresy, in just the way a new religious ideology is. Science has to defend its current beliefs if it is to be a coherent way to address questions in nature. In fact, from the point of view of responsible science, the vast majority of fringe hypotheses deservedly stay in the junkyard of wrong ideas. That's why they should be greeted skeptically.

The credibility, whackiness, or seriousness of new hypotheses has to be worked out over time. History is little guide. Wrong ideas, fervidly or even universally held, have had long shelf-lives in science: the four humors, trephanation, miasma. Some have come from the fringe to become mainline at least for a while, only to wither from lack of cogency: alchemy, phrenology, Freudian psychiatry. Others have started on the fringe and deservedly stayed there: astrology, hormesis, homeopathy, even while retaining at least some followers.

Hypotheses can eventually show that they have at least some truth. Acupuncture is an example. And of course a few have been resisted until expressed properly, or until enough really strong evidence develops, at which time they transform a field: evolution and plate tectonics (continental drift) are great examples of this.

Now, while one can never tell which idea will have legitimate staying power, one characteristic of those that come from left field and make it to home plate is that they are eventually supported by sufficiently strong, serious evidence that even skeptical peer reviewers have to begin recognizing. Typically, predictions based on the new theory are born out (as in evolution and plate tectonics).

The aquatic ape hypothesis must currently be viewed as a wild-guess Just-So story that got some attention in the popular press. It was apparently first promulgated in 1940, then pushed hard by Elaine Morgan for decades. The question of whether she is a qualified person to be taken seriously for such views may be part of the skeptical lack of credence given to her ideas by the mainline science club. As with other fringe ideas, the blogosphere is alive with advocates and critics, but in these media-saturated days the amount of attention given to such ideas is not a reflection of their credibility (to wit: creationism, Intelligent Design).

Scientists may be clubby, but we're (mostly) not idiots. Indeed, we all hunger to seize on a captivating idea. After this much time, if an idea deserves to be accepted as science rather than popularized speculation, it legitimately can be expected to have developed strong, consensus-building evidence to support it. Put another way, scientists cannot be faulted for their resistance in the absence of such evidence.

If that evidence ever is produced, it will have to be compellingly consistent with the wealth of evidence on hominid evolution that has accumulated since the hypothesis was first aired, which evidence should clearly and preferentially have supported the hypothesis's predictions. If such evidence does some day arrive, a lot of us will have to eat crow. It won't be the first or last time this has happened to the often self-satisfied mainline science.

On the other hand, when an assertive hypothesis is long maintained in the absence of clear-cut evidence, it can fairly be judged to be show business until it does better. If Morgan and her followers argued too strongly, and hence can't bring themselves to back down, too bad. They will have deserved to stay in the corner they zealously painted themselves into. That's what happened to much more qualified and distinguished scientists such as Linus Pauling (vitamin C miracles), Francis Crick (life here was seeded from outer space) and Peter Duesberg (HIV doesn't cause AIDS).

The burden of proof remains on them in the meanwhile.

The three of us who write this blog want it not to be a rant, but to be thought-provoking. That's why, despite having our own opinions, we generally try to stay out of the fervid creationism or scientific atheism blogogalaxies. We want to be open to new ideas and we certainly think the status quo or stupid antiscientific ideas should be challenged when they stray from what the best evidence shows. But we try to do that responsibly, and to stay within the evidence. In this case, you may or may not accept Holly's take on the aquatic ape hypothesis, but that's what she was doing, too, and she is an expert in her field.

Ken and Anne

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