The only problem I see here is that if intelligence has a large evolutionary advantage over non-intelligence (or lesser intelligence), then intelligence should

The only problem I see here is that if intelligence has a large evolutionary advantage over non-intelligence (or lesser intelligence), then intelligence should always emerge given a large enough population over a large enough time-scale. Given the galaxy, and given billions of years, the Great Filters that seem most likely are the ones that occur on the edges of the timeline: before multi-cellular life begins, or after a hyper-dominant intelligent species arises. Having said that, I think you’re absolutely right about mammals and societies. If the Great Filter does occur in between life and intelligence, it seems like it would happen where the first signs of intelligence begin. And for earth, that means mammals and the arms race of mind-modeling that their social lives initiated. No other type of animal on earth has parental-care so fully built into its biology: milk glands and placentas force mammals to be social from the start. A great book that doesn’t deal with intelligence and mammals directly, but provides a key connection, is “Consciousness and the Social Brain.” The book makes a strong argument that consciousness sprung from evolutionary pressures that were essentially social — that being able to model (and predict) the mind of another is essential for communication and cooperation. But one can only model the mind of another if you first model your own mind, and thus, consciousness (which I would argue is just another name for general intelligence).