Could human decision making have evolved from food finding?
C. elegans is the simplest model organism whose nervous system has been studied extensively. C. elegans certainly makes decisions; I would feel pretty confident in saying that decision making is an ubiquitous feature in the nervous system of freely moving animals.

It is also non-controversial to consider more complex behaviors as having evolved from more simple ones (finding food/evading predation/mating). You can even reduce a lot of complex behaviors directly to those simple ones, and certainly neural mechanisms for grouping and distinguishing between different patterns (an essential component of language but also many other behaviors) are conserved across domains.

However, it is not correct to refer to all decision making as a tree search: a tree search is a particular family of algorithms and not what you describe. Even tree-like problems need not be solved with a tree search. Specifically, tree search is a computational algorithm that works well in the serial processing environment of computer science. Analogies between brains and computers often break down at the level of algorithms, because brains are massively parallel. That doesn't mean tree search-like algorithms are absent from the brain, but you should not take such a narrow view a priori.



Christiansen, M. H., &amp; Kirby, S. (2003). Language evolution: Consensus and controversies. Trends in cognitive sciences, 7(7), 300-307.

Faumont, S., Lindsay, T. H., &amp; Lockery, S. R. (2012). Neuronal microcircuits for decision making in C. elegans. Current opinion in neurobiology, 22(4), 580-591.

Fitch, W. T. (2005). The evolution of language: a comparative review. Biology and philosophy, 20(2-3), 193-203.