Originally Posted by Aaron W.
It also makes me wonder in the broader sense, how such a claim is justified for a strictly biological/physiological explanation of something. Is there a way to further justify these types of reasoning beyond the level of "it kind of makes sense that..."?
i think the biggest problem is that these things are presented as actual fact (if the presenter even recognizes it really isn't a fact) rather than say that it's the best explaination available (then again my limited experience suggests that the average joe doesn't think that our best explanation is important) . there is evidence that some of these X evolved because of Y are likely, largely it's determine when the trait came about, correlate that to environmental changes that came about the same time, then go, "it kind of makes sense that...".
in it's defense most of science (at least biology) does the "this makes sense" thing, we just wait for other things that also make sense to come up and then come up with ways to eliminate other hypotheses. some things we can do experimentally, but with others, we just have to look at the existing evidence and say, "this
kind of makes sense, but that
makes more sense, so until some more evidence or a new explanation comes up, we'll go with that
". multiple rounds of the process does give some confidence though.
my problem with the blood idea is that i don't believe all organisms that can see red have red blood (not sure if their red vision came from the same ancestor or originated independently though, i'm sure someone knows, just don't care enough to look it up) or if they actually know that blood is bad. without more info, i'd put my money on mating or food before