Whereas adaptation is most advanced in humans, the basal components of adaptation mechanisms are similar throughout the animal kingdom. Reversely, maladaptation disturbs homeostasis and causes severe physiological and, especially in primates, mental disorders (Boeke, 2004 Keller, 2004 Bijlsma and Loeschcke, 2005 Bridle and Vines, 2007 Weinert et al., 2008 Merila, 2009 Ravigne et al., 2009). Successful adaptation to either external (e.g., geographical, physical, or social) or internal (e.g., blood oxygen and glucose levels, energy reserve, state of mind) changed conditions, restores internal homeostasis of the organism, thus maintaining physiological and, in “higher” organisms, mental well-being. While awaiting new technological developments to study the living human brain at the cellular and molecular levels, continuing progress in the insight in the functioning of human adaptation mechanisms may be expected from neuroendocrine research using invertebrate and vertebrate animal models.Īdaptation may be considered as the most fundamental and universal process in living organisms to enable survival, reproduction, and evolution in a continuously changing environment. Special attention is being paid to the actions of neurochemical messengers, such as neuropeptide Y, urocortin 1, and brain-derived neurotrophic factor.
(1) the egg-laying behavior of a snail, Lymnaea stagnalis: how one neuron type controls behavior, (2) adaptation to the ambient light condition by a toad, Xenopus laevis: how a neuroendocrine cell integrates complex external and neural inputs, and (3) stress, feeding, and depression in rodents: how a neuronal network co-ordinates different but related complex behaviors. This will be illustrated by reviewing research on three of such animal models, viz. Neural adaptation mechanisms have many similarities throughout the animal kingdom, enabling to study fundamentals of human adaptation in selected animal models with experimental approaches that are impossible to apply in man.