It does seem strange to me to use other animals as a measure of the gut vs. brain hypothesis. Without opposable thumbs and bipedalism, other species might lack a rewarding avenue to take advantage of trading gut for brain. I wonder what the plot looks like for primates?After all, no other species uses fire to prepare their food and we’re the only primate to eat a large quantity of meat.
The main reason they were examining other animals is that a lot of the raw data Aiello and Wheeler based their original hypothesis on came from non-human species. Thus animal data has always played a big role in the expensive tissue hypothesis. Of course, whether animal data can be used to examine humans is a big fat question mark given how different we are. At the same time I'm also weary of special pleading. The "refuting" paper noted that for the expensive tissue hypothesis to remain viable we must propose unique mechanisms operating in humans, which Occam's Razor doesn't like.
Thanks. I can see that. However, I wonder if the study included fish and arachnids? :) At some point a line was drawn based on taxonomical definitions. It seems to me, the question is not whether or not animals sacrifice gut for brain, but whether 'gut for brain' was a niche that humans filled, or if the inverse change of the two was coincidence. It doesn't seem to be possible to answer that question by analogy unless all species included in the data set could explore the niche to begin with. Glad that I'm not an evolutionary biologist. :)At the same time I'm also weary of special pleading. The "refuting" paper noted that for the expensive tissue hypothesis to remain viable we must propose unique mechanisms operating in humans, which Occam's Razor doesn't like.
No, the study only included mammals. However they - and others - note that the expensive tissue hypothesis does seem to be in play in fish (such as the artificial selection study I mentioned in the post; where fish who were "evolved" to have big brains also developed a smaller gut) and a few other groups. Of course, if we're debating over whether or not data from other mammals is applicable to humans then data from fish surely suffers from the same flaws and then some! Last time I checked they didn't have fire either!