OUCC Proceedings 9 (1979)

by Simon Fowler

Caving is successful in the sense that the number of cavers, or attempted cavers is increasing (whether we like it or not). In biological terms a successful strategy must increase fitness. The latter is a unit of evolutionary success, probably not connected to physical fitness; the number of caving beer guts testifies to this. Biological fitness simply involves an increased ability to survive reproduce successfully. It is notable that caving is mainly restricted to males and that males are biologically notable for their desire to mate with as many females as possible: in this way they, unlike females, can increase their biological fitness enormously.

There is a dilemma here, caving would not seem to increase either survival or reproductive success. First there is clearly a survival risk inherent in caving, at least for active cavers. Novices are obviously a high risk category, which is reasonable since most cavers do not spend long under this label. However, all the super-heroes of the caving world including pushers of huge sumps, enormous boulder chokes, minuscule passages and dangerous foreign caves are also in an ongoing high risk situation.

Secondly, caving seems superficially unlikely to increase reproductive success. Not only is the likelihood of sexual encounter reduced but the sheer difficulty of mating underground would seem to be an insurmountable (!) problem. Just think what it would be like in those unstable boulder chokes. However, some old graffiti in Swildon's' barn refers to some success in sump 4, it must have been bloody tight (!)

With these great biological disadvantages, caving must have some enormous counter-advantages. Invoking Zahavi's controversial handicap theory presents a way around this problem (Zahavi 1975, 1977a). Females who actively select males that are fitter (biologically speaking) will be successful, by producing fitter offspring. Female choice is therefore a potent force in evolution, but how can they make the choice reliably, avoiding cheating males who merely pretend to be fitter? Zahavi suggests a simple answer to this: a male that has managed to survive with a major handicap (use some imagination here, it's quite amusing) must be fitter on average than males without such handicaps. The offspring of such a sensible female will then consist of handicapped males and non-handicapped females (assuming that the handicap is sex-linked). The latter will have some of the father's superfit genes, not counter-balanced by the handicap, hence a race of superfit females?

The somewhat ludicrous desire to cave is thus a handicap which females select, since, on average, it must be counteracted by fitter genes.

So can caving be regarded as an evolutionary stable strategy (ESS) i.e. no other strategy is better? If so, then the spread of caving to fixation (entire population of cavers) is inevitable! However even the handicap principle is open to cheating. A non-caver who pretends to be a caver is not exposed to the risks but reaps all the benefits. In a society of 100% cavers such an individual would do very well! So cheats will prosper, but a society of nearly 100% cheats is unstable since it would be

advantageous for females to select against them. Consequently a mixed strategy is the only stable possibility with either a small percentage of cheats or with each caver cheating a small percentage of the time!

How stable is your club?

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