Table 1: The skin surface lipid (SSL) composition (%) of Homosapiens adults and non-human primates (according to [65, 66]).

Lipid FractionHomo sapiens (n=30)Gorilla gorilla (n=3)Pongo pygmaeus (n=3)Pan troglodytes (n=4)Hylobates sp. (n=1)Macaca sp. (n=5)

Squalene (SQ)11.8 ± 0.6n.d.n.d.n.d.n.d.n.d.
Cholesterol esters (CE)1.4 ± 0.23.54.69.832.640.6
Cholesterol (CH)1.4 ± 0.11.71.81.81.93.0
Triglycerides (TG)34.1 ± 6.52.30.95.12.04.9
Diglycerides (DG)1.3 ± 0.20.80.41.00.20.1
Monoglycerides (MG)0.4 ± 0.10.1trtr0.20.2
Wax mono-esters (WE)24.5 ± 2.137.425.031.32.015.2
Wax di-esters (WDE)n.d.tr2.0tr1.52.3
Free fatty acids (FFA)24.6 ± 6.13.42.57.45.08.3
Others (paraffins, etc.)0.550.862.843.654.626.4

SSLs were sampled from the forehead and upper chest, with diethyl ether cup extraction method [30]. Results for human skin (30 subjects) are expressed as mean ± S.D.; for primates they are the results of the varying number of samples. Macaca sp. sample is a pooled extract of 5 samples, consisting in 1 single individual from each of the following species: Macaca sp., M. mulatta, M. nemestrina, M. assemensis, and M. fascicularis. tr: traces.