ScienceDaily reported a few days ago on an interesting story (actually, a journal article in the April PLOS Biology) about how bats track insects they want to catch in a way that is very different from that of humans and some other animals. Essentially, humans, fish, dogs, and others use a strategy the article calls "constant bearing" to follow things -- basically, they just head straight for their target. Bats, on the other hand, actually take into account the target's velocity and direction and flies partially parallel to the target. In other words, bats work out in advance where they think their targets will be, and head there, rather than directly towards the target, which saves time.
This is pretty interesting. Even further, the article points out that this is a strategy similar to that developed by engineers for guided missiles.
But here's the part I find the most interesting:
This study also demonstrates, for the first time, that bats work out ahead of time how they will catch an insect. Evolutionary pressure to catch flying insects as fast as possible, the researchers speculate, may have pushed the bat to adopt this technique to catch a meal on the go as quickly as possible. Their paper appears in the May issue of PLoS Biology.
There is no mention of evolution in the journal article, so I assume ScienceDaily must have talked to the researchers. But the article also points this out:
The pursuit strategy is different from that reported in earlier studies of target pursuit in humans and other animals.
Now, my gripe is this:
Evolution is invoked as an explanation of why bats fly this way -- they need to catch their prey as quickly as possible. Does that mean that humans and other animals don't need to catch their prey as quickly as possible? It really seems like a useless remark to me. As far as I can tell, it is completely impossible to predict based on the theory of evolution whether a particular kind of animal will follow use one search strategy or another. It's purely a subjective opinion of the researcher -- these researchers think it fits with evolution (indeed, it must fit with evolution if bats evolved!), but I suppose another researcher could disagree. In other words, evolution really has no explanatory power in this case. Essentially, it just amounts to saying, "Well, bats which track their prey that way survive better, so of course they fly that way!"