Mind begins as skin. Namely, with melanocytes of the neural crest. Take a look at these pictures of melanocytes. Notice the dendritic extensions that foreshadow neuronal dendritic processes.
Our dendritic depth began on the surface of our skin.
“Melanin, from which human skin derives most of its pigmentation, is a remarkable molecule that has had literally thousands of uses in the evolution of life. […] Melanin is distinguished by a range of extraordinary optical and chemical properties. In the body, it is able to absorb, scatter, and reflect light of different wavelengths. […] Melanocytes originate in a part of the embryo called the neural crest, which flanks the neural tube. They start out as actively as actively dividing cells known as melanoblasts, which migrate to the epidermis during the eighteenth week of embryonic development, finding their way to into the skin, ears, eyes, and brain covering. Melanocytes produce melanin pigment in small membrane-bound packets called melanosomes, which are then pushed out of the melanocytes and into the keratinocytes of the epidermis via spidery extensions known as dendrites.” (Nina Jablonski, Skin: a Natural History)