I would point out that the old theory of giraffes having long necks has largely been debunked (although you seem to have hinted at this with the third note), and more can be seen in this webpage. But basically, there are multiple reasons for a giraffe having a long neck, including the fact that males need long necks for their courtship ritual. (They club each other with their heads and horns to gain dominance - a long neck gives massive leverage when swinging their heads. The longer-necked giraffes are capable of winning courtship duels and getting mates to pass on their genes with, giving an evolutionary advantage to long-necked males.) That isn't to say that long necks don't help with other evolutionary advantages, either (like having an elevated perch from which to watch for predators), but that it's not a single reason.
As thorough as I attempted to be (sorry, WallOfText-time, again) I did indeed not clarify things as I might have done.
Just as there is no
purpose/plan for any given evolutionary development, neither does it really follow that there be a single beneficiary effect from any given phenotype-shift, nor that a single phenotype-shift be alone linked to any end result. Instead it'd be a complex interaction between any and all...
For the latter, I mentioned the circulatory system needing changes to support the neck which
may have been made to allow drinking... In a way that was not strictly causal, but obviously a less capable vascular system would hinder the neck-enhanced, and the neck-'normal' ones with long(er) legs would also have had a problem, as the ancient form of the animal evolved by drunkards-walk steps into the form as we see it now.
For the former, I agree that a good strong neck is good for the male-on-male battles for dominance (which can be brutal). Although I somewhat think that if (for example) the proto-giraffes were, say,
head butters, in their equivalent of this ritual, then as the necks got longer this may have been impractical and (possibly with a structural change in the hind-brain wiring that accompanies this semi-instinctual aspect of behaviour) the combat became more and more like it is today. Which obviously brought the strong-necked males to the top of the breeding-pile (possibly even killed off those that were less fortunate).
But I'm more thinking that you don't want to confuse matters by implying that the necks evolved in order to support the mating hierarchy. Even taking into account that the rather loosely worded "...evolved in order to..." bit is not implying a sought target state (which I would hope we could agree on, that being sometimes an irresistible/convenient short-cut phrase), I think we're better arguing that the otherwise undirected behavioural developments co-evolved with (at least partially reinforced, but also was reinforced
by) the otherwise undirected physical ones.
(And that's ignoring, or at least taking for granted, pressures from environment, predation, etc, etc.)
I
think we're basically in agreement, but just taking the opportunity to go into more detail about points that I may have skimmed over/left unsaid. Naturally there are still holes in the wording. I might have been able to write a more concise and accurate response, but it would have taken far more editing than I've already made.
W.R.T. Dwarf Fortress and the subject of this topic... erm... this particular issue is (currently) not actually relevant, I now realise. But it's
interesting. (Or at least an interesting heresy, for those that disagree!) I shall now go back and see what (if anything) I can add that is actually
on topic!
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Topic: Alternative (RAW-defined) Reproduction (Read 15029 times)