I recently re-read Gwern's Drug Heuristics, and this jumped out at me:
....In other words, from the starting point of those wormlike common ancestors in the environment of Earth, the resources of evolution independently produced complex learning, memory, and tool use both within and without the line of human ancestry....
...The obvious answer is that diminishing returns have kicked in for intelligence in primates and humans in particular5354. (Indeed, it’s apparently been argued that not only are humans not much smarter than primates55, but there is little overall intelligence differences in vertebrates56. Humans lose embarrassingly on even pure tests of statistical reasoning; we are outperformed on the Monty Hall problem by pigeons and to a lesser extent monkeys!) The last few millennia aside, humans have not done well and has apparently verged on extinction before...
...The human brain seems to be special only in being a scaled-up primate brain41, with close to the metabolic limit in its number of neurons...
If I had more time, I'd try to look more into the intelligence tests that are given to animals. Assuming animals are smarter (in some sense of the word), then why are humans dominant? I think the answer to this might be something like "Humans evolutionarily stumbled upon language, then encoded this in our genes, and language allows us to reason about the world, which is something raw animal intelligence/pattern-matching cannot do."
I think it's an interesting hypothesis, but I don't know where I'd start trying to evaluate it, or how likely I think it's true.
Huh! Yeah, that's super interesting, but it seems like it might be hard to actually tackle. The finding of info on animal intelligence as well as the supporting of specific reasons for human dominance anyway both seem a little messy. I'll put it on the list of options though :)
As part of a philosophy course I'm currently taking called Intelligence in Machines, Humans, and Other Animals, I have to write a <3000w essay on a topic related to intelligence. The description is here, but I've copied the important details below. I figured I might as well solicit suggestions for things to research. Realistically, I am likely to optimize the essay more for passing the course than for rigour though, so if you're expecting a very thorough review of something then you may be disappointed. But I suspect that it will still be at least an interesting jumping-off point.
Edited to add: Note that these are pretty squirrellable. E.g. Last time I took "Learning" and used it to talk about (recursive) self-improvement in machines and humans (planning to post this at some point). So feel free to propose something even if you only have a vague notion of how it would fit into one of the categories
One constraint: I need to be able to ask some sort of question and then produce evidence towards either side of it, i.e. it can't just be a review of the topic. But this too can be pretty vague; in my last essay I did "are humans or machines better suited for self-improvement?", concluding "humans for now, ultimately machines".