The Ancient Origins of Ageing

It is well established that populations of bacteria or yeast can go on growing forever, as long as nutrients are provided. Many plants reproduce vegetatively (or asexually), by forming tubers, bulbs or corms, or they can be propogated by cuttings. Thus, the continuous growth of complex living organisms such as plants is perfectly possible. Why then do so few animals have this ability The interrelationship between sexual reproduction and the existence of ageing have been...

The Evolution of Human Longevity

From a simple biological standpoint, it is remarkable that Homo sapiens is the longest lived terrestrial mammalian species. The largest, such as the elephant, hippopotomas and rhinoceros, have long lifespans, but not as long as human beings. There are herbivores which are much larger than man, and also carnivores, but their lifespans are well under half the human one. Scientists studying ageing have correlated brain size, or the ratio of brain weight to body weight, with lifespan. There is in...

The Modulation of Longevity

Chapter 9 discussed the mythical claims, ancient and modern, that humans can have very long lifespans. This one is devoted to the various ways in which ageing and longevity can be modulated, including either an increase or a decrease. We know that there are at least three major components that determine the expectation of life at birth. One is the species itself, because in mammals maximum lifespan varies by at least 30-fold, and if we accept the reports of extreme longevity in some whales,...

Maintenance of the Body

The fertilised egg develops to a foetus, a baby, a child and finally an adult. It is obvious that this sequence of development is extremely complex. However, there is not only the unfolding of the genetic programme for development, but there is also a set of mechanisms that can recognise and repair any mistakes or defects that arise. These mechansims also maintain the adult in an active normal state for several decades, so that reproduction and the raising of offspring can proceed. Ageing is...

Mice and

Fibroblast Cells From Mammal

Although mammals have successfully adapted themselves to a wide variety of habitats and life styles, their basic physiological design is very uniform. Also, their mode of reproduction does not vary significantly. After a given period of gestation, offspring feed from their mothers milk, the mammary glands being the primary taxonomic feature which provides the name for the whole group. The variable features of mammals are, most obviously, their size and external morphology. This is the result of...

Myths of Life Extension

Ever since humans became fully aware that they will get old and die, individuals must have wondered about the possibility of extending longevity, or achieving immortality on earth. This has resulted in innumerable myths relating to supposed examples of life-extension, one of the most notable being the 969 year lifespan of Methuselah, as recorded in the Bible. Christian fundamentalists are liable to say that in those days people lived much longer than they do today These are many other claims,...