Walker, A. (1839). Breeding in-and-in. In A. Walker, Intermarriage: or, The mode in which, and the causes why, beauty, health and intellect, result from certain unions, and deformity, disease and insanity result from others: Demonstrated by delineations of the structure and forms, and descriptions of the functions and capacities, which each parent, in every pair, bestows on children,--in conformity with certain natural laws, and by an account of corresponding effects in the breeding of animals (pp. 312-313). New York, NY, US: J & H G Langley.
http://dx.doi.org/10.1037/11926-022
Of in-and-in breeding among mankind, Dr. Hancock (15, August) says, "To the want of renovation, I conceive, we may chiefly attribute the barbarism which, for unnumbered ages, has reigned in Africa, and probably in the South Sea Islands, and amongst the aboriginal tribes of America;" and a jealousy of strangers, perhaps, has kept the Chinese stationary for many thousands of years. "The Arowacks and other American tribes roam at perfect liberty through their native forests and savannahs, but, as it were by one universal magic spell or enchantment, they are all kept most strictly to their respective tribes; and by such isolation, through a long succession of ages, they have dwindled into pigmies compared with those whose races are renovated and refreshed by inosculation, or engrafting of other varieties." (PsycINFO Database Record (c) 2016 APA, all rights reserved)