I´m writing an essay about the ToM in animals. My Problem is that there are a few hints of ToM in animals but there are also some interferences. I tried to set up a conclusion which uses Morgan's Law about cognition  and the language experiments with apes and sign language which show no language reproduction (Gardner & Gardner (1975)).
So my question is how are these two areas connected and what are the criteria of ToM? I can´t find a paper that mentions this.
: In no case is an animal activity to be interpreted in terms of higher psychological processes if it can be fairly interpreted in terms of processes which stand lower in the scale of psychological evolution and development.