My end goal is to extrapolate observed intelligences in the animal kingdom to determine whether or not it is statistically likely that a simulation argument is probable (though this could easily be used for the Fermi Paradox as well). Defining terms: "intelligence." Obviously all animals would fail an IQ test, but I have heard there are ways of determining intelligence. One being brain size. I am also aware of self-recognition in mirrors of primates, somewhat sophisticated languages amongst dolphins, and dogs' ability to shape the world around them, i.e. shake their head if a blanket is put over their head. What is/are common ways of comparing inter-species intelligence? Then, using this definition, are there any studies or results on the distributions? Specifically, what kind of shape (Bell, Poisson, skewed towards intelligence, etc.) do the distributions obey? Lastly, would intelligence be the highest deciding factor in the evolutionary cycle? Or is the need of a vertebrae or endoskeleton more influential in the overall evolutionary path? I understand this is probably the most speculative of the questions but I am unsure. Papers of the likes of https://arxiv.org/abs/0711.1751 would be most appreciated. I am also curious what and how others think about this. Thanks!