This theory is also strengthened by some few other facts in regard to instincts; as by that common case of closely allied, but distinct, species, when inhabiting distant parts of the world and living under considerably different conditions of life, yet often retaining nearly the same instincts.
Teoria hau instintuei buruzko beste zenbait egitatek ere indartzen dute, adibidez, espezie oso hurbil baina diferenteen kasu arruntak, espezieok munduko alde urrunetan eta bizi-baldintza nahiko ezberdinetan bizi arren, instintu bertsuekin diraute eta.