The psyche doesn’t remain visible in fossils, but it do appear indirectly in stone tools. However, in human evolution, the making of stone tools is not a feature of species, it’s a trait of only a few genetically divergent and unfit individuals. This explains the unchangeability of the tools. Therefore, species cannot be defined by tool findings. For modern humans, all individuals are exceptionally divergent.
The first stone tools were made at least about 2,5 million years ago. In fact, as the tools modify the environment, they signify the first appearance of humanity, even though modern humans did not even exist then. How is it possible? Well, it is because humanity, in the broad sense, has not been a feature of modern humans only. Actually, humanity used to be a rare disorder of all homo species. Naturally there are no traces of this in the fossils, but indirect signs can still be seen in the stone tools. The path of the evolution of homo species is embellished with the small stones of humanity, so to speak. All these stones tell the same story, but the story is not the one of the entire population, but only of the few. It is the story of the random unfit individuals who took the destiny in their own hands and, in the dark, began a silent rebellion which unexpectedly broke out into a revolution only much later.