One of the things that half-decent site analytical software does is to capture the parameters of Google searches as an integral part of its 'referring page' analysis. This is obviously a necessary feature if you want to maximise the traffic through your website; it enable you to look at what end users, those people at the blunt end of a browser, are searching for and thus tailor your site more closely to the search terms. I have no such requirement and, by and large, have no real desire to expand my audience; I do not even bother with filling in the 'key words' on each blog. For me, having such analyses is a by-product of using a counter, I am seldom if ever going to make use of it. Except........
The post about huias earlier in the month got 'hit' by someone from an Australian Academic Network (probably something akin to an Oz 'JANET'*) and in amongst the 'referring page' details were the search parameters 'Why do male and female huias have different bills'. This type of question is very common in biological circles which is perfectly understandable given the weight Darwin's Theory of Natural Selection carries in the community; if there is 'selection' then 'something' must be selected for and, by extension, against. While it is actually the genes that are selected, it is the phenotype, the bodily manifestation of those genes, that influences which genes are selected. As a result, the question of an organism's success, or otherwise, is generally couched in such 'why' orientated terms. Why do cheetahs' claws not retract like all other cats? Why do beavers dam rivers? Why does the osprey have 'spicules' on the undersides of its toes? These all have answers which relate, in some way, to the animals 'fitness' profile in their environment,**
However, I do sometimes wonder whether these types of question are in fact valid. Is there in fact a reason, or multiple reasons, for an animal's success or otherwise. Do the 'why' questions actually provide answers or are they simply a more logical and (pseudo)scientific 'just so story'? A good example might be: 'Why do giraffes have long necks?'
Well, why do they? The 'party line' would suggest that there is some advantage to the animal in having such a ludicrously long neck and make no mistake, it is ludicrously long. As a child, I was taught that such a long neck allowed the animal to graze on tree tops which no other terrestrial could reach; as a species they had no competition for their food source and this was to their advantage. Unfortunately, this is just not true or, at least, is hotly disputed. While it is true that the neck coupled with the long legs do enable the giraffe to browse at far greater heights than do their competitors, kudu, steenbok and impala, they do not do so exclusively and they are often to be seen grazing at a much lower height, well within the reach of their competitors.
The other main 'contender' in the 'why' stakes is 'sexual selection'. As bizarre as it may sound, males engage in extremely violent fights with other males in competition for mates using their necks and heads as weapons. Effectively, the male 'winds up' his extremely flexible neck, the vertebrae have 'ball and socket' type joints to them, and 'punches' his rival with his head in the other male's neck and head; such fights can, and on occasion do, lead to death. (A clip of males fighting is here) However, this poses a number of problems. In animals where this form of sexual competition occurs, only the males tend to have the defining characteristics; stags and antlers, the size dimorphism of primates, the development of the kype in salmon. In addition, a giraffe's neck needs to be long to engage in this kind of fighting; therefore how did the process, elongation of the neck, actually get started? There is also some evidence to suggest that, in fact, giraffes with the longest necks have the highest mortality in periods of drought, presumably because the longer the neck, the larger the animal and, therefore, the more food required to sustain it.***
So, we have two competing answers to the 'why the long neck' question and both have some merit but also some problems. I would therefore like to throw a third option into the ring, namely that there is no answer to the 'why' question because it is the wrong question to be asking. As mammals go on the African plains, giraffes are relatively successful. Their size mostly precludes predation, except among very young calves, and they do not need to be particularly fecund to ensure their collective survival. Acacia trees, on which they almost exclusively feed, are relatively abundant and so ensure a steady food supply. As a result, one could imagine that a giraffe with a much shorter neck, all other things being equal, would still be as successful; the okapi, a near relative with a 'normal' neck, is.
We like to pose 'why' questions because a basic human trait is to want to understand the world, find reasons for the way that it is how it is. From quantum mechanics to the existence of God, we seek such answers to the 'why' question because for us, as a species, there must always be a reason for everything; it is how we live our daily lives. What if the reason for the giraffe's neck, the peacock's tail, was just a genetic blip which conferred no advantage but, conversely, no debilitating disadvantage? What if they just were?
However we do not like to think that things can just be, do we?
PS Of course, it might be that the genetics that 'switched on' the elongation of a giraffe's forelimbs also 'switched on' the elongation of the neck and there was selection pressure for animals that were better able, because of long necks, to drink; not to have to sit down to get at water which would make them much more vulnerable to predation. Although the giraffe's solution is not ideal by any stretch of the imagination, its splay-legged posture it is still better for a quick 'getaway' than sitting down would be.
PPS A curious fact. The spell-checker that comes with the blogspot blogging software does not recognise 'blog' (or 'google')
* JANET - the Joint Academic NETwork; one of the biggest networks in the UK, currently in its SuperJanet5 incarnation (a mere 100Gbs).
** The cheetah's claws help it to run faster and be more manoeuvrable, much like an athlete's 'running spikes'; beavers build dams to create a 'larder' outside their lodge; the osprey has rough undersides to their toes to ensure a good grip on a slippery fish.
*** Mitchell, G.; van Sittert, S.; Skinner, J. D. (2010). "The demography of giraffe deaths in a drought". Transactions of the Royal Society of South Africa 65 (3): 165–68. Download as a pdf here.
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