A feature of some southern African rock art is that the human figures have a hook where their head should be. This is because the figure was drawn in red ochre, a mineral which over time becomes part of the rock. The hollow within the hook is likely to have been drawn in a pale colour using a material less long lasting.
In the absence of a brain, I have used artist-pathologist Santiago Ramon y Cajal’s drawings, the first showing neurons in brain tissue, which won him a Nobel Prize in 1906.
Not that the hookheads were brainless. They co-existed happily with this planet for millenia. Their successors, fossilheads, have imperilled it within just 200 years.
The Marginalian. Beautiful brain: the stunning drawings of neuroscience founding father Santiago Ramon y Cajal. February, 2017.
Figure re-drawn from Rock-paintings of the South-West Cape, 1959. Townley Johnson, Hyme Rabinowitz and Percy Sieff.