Hair for brain trade-off, a metabolic bypass for encephalization

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Table 5 Estimation of total body hair synthesis and amino acid wearing away by the pre-human hominid by two approaches

A. Hair synthesis of a single follicle
Body area (70 kg body weight; 170 cm height), cm²^a	18000
Follicles density per cm²^b	316
Total follicles	5.7 × 10⁶
Daily hair synthesis, μg per follicle^c	5 – 10
Hypothetical whole body hair synthesis, g/d	28 – 56
B. Total scalp hair production
Scalp hair follicles^d	80 – 150 × 10³
Scalp hair production, g/d^e	0.3
Total body follicles^f	5.7 × 10⁶
Hypothetical whole body hair synthesis, g/d	21 – 40
Overall estimation, g/d	21 – 56

^aCalculated for a 70 kg body weight and 170 cm height as follows, Body area (m²). = 0.00718 × kg^0.425× height^0.725 DuBois and DuBois (1915).
^bPaus and Cotsarelis (1999); Sinclair et al. (2005); Krause and Foitzik (2006).
^cRogers (2004).
^dKrause and Foitzik (2006).
^eGalloway et al. (1971).
^fSinclair et al. (2005).