Environmental extremes: origins, consequences and amelioration in humans.

Professor Sir George Lindor Brown (1903-1971) is known for his pioneering research into cholinergic neuromuscular transmission. However, during World War II he worked in hyperbaric physiology, and his research into underwater physiology greatly improved the safety of divers. It is perhaps fitting, therefore, that this review, which accompanies the Physiological Society's G. L. Brown Prize Lecture for 2015, explores the impact and mitigation of the environmental stresses which, to varying extents, have shaped our past, threaten our present and inform our future. From a whole-body, integrative perspective, this review examines our current understanding of microgravity, hypo- and hyperbaria, heat, cold air and cold water as both individual and combined stresses. Consideration is given to ways of mitigating the threat posed by environmental extremes, including the differing extents to which humans can demonstrate adaptation to them. Finally, recommendations for further study are suggested that might result in both direct and indirect insights.