The seven million years old Sahelanthropus tchadensis (i.e. Sahel man from Chad), nicknamed Toumaï, already had a hominin structure in its small brain:
… though Toumaï’s brain was apelike in its small size, it was apparently
homininlike in other ways. In a presentation given on April 2 at the
annual meeting of the Paleoanthropology Society, Bienvenu reported that
the endocast shows strongly posteriorly projecting occipital lobes, a
tilted brainstem, and a laterally expanded prefrontal cortex, among
other hominin brain characteristics.