MAN'S SPAN OF LIFE.

New Zealand Herald, Volume LXIII, Issue 19221, 9 January 1926, Page 13

MAN'S SPAN OF LIFE.

NATURE'S INTENDED LIMIT. AN AVERAGE OF 45 YEARS. OUR PRESENT MODE OF LIVING " When we have replaced our ignorance by real knowledge, we shall then be in a position not to adapt oar bodily structure to our mode of living, but our mode of living to our bodily structure. This seems the best wily out of the great experiment on which civilisation has launched man." Such was the conclusion reached by Sir Arthur Keith in a lecture delivered before the Royal Society of Medicine. The rate of man's evolution, Sir Arthur Keith argued, was far more rapid than had hitherto been supposed, and it wsi§ certain that agriculture had not been practised more than 5000 years ago in Western Europe. «City life was a new experiment for Europeans, and most of those living in London, if they could go back 20 generations, would find an ancestry which was living on the soil and Of the soil. The poorest, however, to-day could add to his dietary products brought from the ends of the earth. The alimentary tract had now to accommodate itself to a modern dietary, and undoubtedly civilisation was exposing the body to A vast and critical experiment. It said much for the body of the primeval hunter that it had been, able to adapt itself to stand the new stresses as well as it did. The hunting people Would never have shown statistics like. those of the recruits examined, when out of 10,000 no less than 363 were found to have hernia and 113 flat feet. In one re*pect modern civilisation had reduced tho d«mands made on the body. Heat conditions were much better regulated than before, and man lived now much in the conditions of a hothouse plant. " Useless " Appendix. Referring to the appendix, the lecturer said that, despite Ba,rwin, it was not a useless organ. He had dissected half-a-dozen Gibbon monkeys, and in two of them had found an appendix holding a row of fruit stones showing that the appendix shared in the digestive work of tho caecum. There was no evidence to show that the . anthropoid suffered from appendicitis in its natural habitat, but they became subject to the disease when kept in confinement. Of 61 chimpanzees dying in Captivity, 10 suffered from appendicitis. The appendix could be compared with the tonsils and Certain other organs which were merely unable to withstand the con* ditions to which they were exposed. Archdeacon Paley had been right whenhe said that our list of useless structures decreased as our knowledge increased. Discussing tho defects of thai eye in modern man, Sir Arthur Keith refused to believe that under hunting conditions every man was like civilised man in suffering from short sight. By the age of 45, he said, most people needed spectacles. Metchnikoff had placed the natural ago of man at 100 years, but he believed, that Nature had worked on the basis that the mean life tenure of 45 years should be the limit, and had decided to fun the human army on the short service system. It was a moot point whether it would be an advantage to civilisation that all should live to be centenarians. Ho Turning Back. \ Metchnikoff was right, concluded Sir Arthur, when he declared that civilisation had launched man on a great experiment. From that experiment there was no turning back. We could not return to conditions that prevailed 6000 years ago. There were more people in one of tho meaner back streets of London than could find an existence in the whole length and i breadth of the Thames Valley if they returned to the manner of living of our distant ancestors. " Seeing low differently we are circumstanced," to added, " in every situation of life, the wonder is not that structural imperfections and functional disharmonies should develop in a proportion of our numbers, but that so many of us should escape harm altogether and enjoy good health. It says much for the adaptational reaction inherent in the human body that it withstands the artificial conditions of modern civilisation as well as it does."