Today historians and social scientists disagree with the "civtree" model and ideas of progress and social evolution stressing contingency and particulars. How do they explain generalised trends like the decline of foragers and rise of agriculture, growth of capitalism across the world?

I'm an anthropologist and happy to talk about general trends related to subsistence. But I don't really know what you mean by civtree. I have never heard the term in any academic way and only as kind of silly memes. Could you give a brief overview of what you're talking about so I can think about how to respond in a way that would be useful? Do you mean Morgan and Tylor's stages of civilization from the 1800s, which has been critiqued as simplistic, incorrect and frankly racist? Or is there some new version?