The topology of hair streams and whorls in man, with an observation on their relationship to epidermal ridge patterns.

Hair slope, whorl, cross and field formation is expressible in a topological form. The mathematical description required suggests an origin for the patterns in a growth process occurring in the upper dermis which determines the patterns of the hair slope. The formulae proposed by Euler, Poincaré and Ludwig are adopted as a descriptive method for the analysis of hair patterning resulting from hair slope. A unitary theory for hair streams and fingerprint patterns is suggested by the discovery, on one remarkable human foetus, of sites where epidermal ridges and convergent hair whorls were combined. Placement of the parietal scalp whorl in man is linked to hominid brain and skull development, and its associated hair field is noted to be bipartite, as revealed through patterns of differential hair loss.