AGING VERSUS GROWTH R. J. GOSS* For over a century it has been generally recognized that aging begins when growth ceases, that those animals which grow as long as they live may live as long as they grow. The possibility that aging does not take place in animals with indeterminate growth is intriguing, especially since we have no way of knowing whether growth inhibits aging or vice versa. In either case, the implications are as important for our understanding of growth mechanisms as they are for aging. The fact that some animals exhibit unlimited body growth points up the need to know why others, like ourselves, stop growing (and start aging?) at a predetermined stage of the life cycle. Indeterminate Growth Although aging is considered by some to be a universal attribute of life, early biologists suspected that certain creatures might be exempt from the tyranny of senescence. In 1870, Lankester [1, pp. 26-27] noted that "in some organisms we cannot clearly say from observation that there is ... an inherent limit (to potential longevity); in fact, their absolute potential longevity appears to be very nearly practically unlimited. . . . Such organisms are fish, molluscs, large crustácea, annelids, many trees and seaweeds." With regard to fish, he wrote: "They are notknown to get feeble as they grow old, and many are known not to get feebler." In 1925, Bidder [2] recognized the problem of reconciling the apparent longevity of certain fishes with the consequences of unlimited growth. According to Huxley's [3, p. 227] allometric equation, y = bxa, an organ, y, which grows faster than the body as a whole, x, with a relative size, b, will have a growth coefficient, a, that is greater than one. The North Sea plaice, a regular entree on British menus, is one of those fishes for which a species-specific body size cannot be indicated. Although the males evidently die after spawning, the females continue to enlarge, some of them reaching weights of 6 kg. Bidder [4] determined *Division of Biological and Medical Sciences, Brown University, Providence, Rhode Island. Supported by USPHS grants GM 18805 and HE 13659. Perspectives in Biology and Medicine · Summer 1974 | 485 that the growth coefficient of the plaice ovaries was 1.6, which means that the larger the fish grows, the greater the percentage of body weight represented by the ovaries. It was predicted that the ovaries would represent one-half the body weight when the fish grew to 6 kg. Unless the value for the growth coefficient decreased, any female plaice growing beyond this limit would run the risk of acquiring disproportionately large ovaries to the point where the residual body might be depleted to little more than a shell enveloping the reproductive organs. Such are the drawbacks of potential immortality. If body size is to be indeterminate, the relative growth of its parts must be adjusted so as to preserve physiological balance. Not all fishes are ageless. Annual fishes, for example, are adapted to parts of the world where there is a seasonal drought. As the ponds dry up, one generation of fishes dies but the succeeding one survives as eggs resistant to desiccation. Add water, and the eggs hatch out as fish which will reach sexual maturity in a few months, stop growing, and, even if kept in the water, succumb within the year [5]. But such a programmed death is not typical of all species. According to Günther [6, p. 79]: "Fishes which rapidly grow to a definite size are short-lived, whilst those which steadily and slowly increase in size attain to a great age." It is this apparently indeterminate size and age which coaxes anglers to rise to the challenge of hooking record-breaking big game fishes. Other aquatic animals are likewise famous for the large sizes to which they can grow. Notable among these are such crustaceans as the lobster and the giant Japanese spider crab, representing arthropods which apparently never lose the ability to molt. Equally spectacular are certain molluscs such as the giant clam (Tridacna gigas), the largest specimen of which weighed almost 600 lb, was 43 inches wide, and was estimated to be 100 years old. The giant...