evolution - Did human hairs actually evolve from scales?

As to the early evolution of mammalian hair, Rowe et al. (2011) hypothesized that the primitive function for hair was not thermoregulatory, but rather for tactile sensation (contra the hypotheses of Spearman and Maderson). Rowe et al. say:

Body hair develops as migrating neural crest cells induce patterns of
tiny placodes that mature into hair follicles equipped with
mechanoreceptors. These include lanceolate endings (velocity detectors
excited by hair deflection), Ruffini receptors (tension receptors
activated as hair is bent), and Merkel cells (slowly adapting
sensors). In ontogeny, hair is first sensory, and only later does it
insulate, as underfur thickens and thermoregulation matures.

So the developmental argument is in favor of tactile sensation.