The age old question of whether animals are capable of thought has yet to be answered convincingly. This is due to the unresolved issue of what exactly counts as »thought« and how humans came to be capable of it.
The oldest answers involved a god or divine language creator that endowed humans with the gift of speech. These answers were countered with a naturalistic theory for genesis of thought and speech asserting that they developed from song. That was the thesis maintained by Rousseau and Darwin. Melodies supposedly assumed grammatical structures, but how can this be examined more precisely? It becomes an arbitrary matter. If the origins of human thought and speech are not understood, the question we posed in the title cannot be answered. Those who admire animals' cognitive performance will say: Of course animals are capable of thought. Those looking at the vast difference between our consciousness and the situation-based intelligence of animals would contradict that supposition: Animals are incapable of thought.