Life span

“ There is no question that under such conditions life could be prolonged far beyond what is now usually considered its span. One hundred years or more might easily, we imagine, become the average of life, instead of the great exception. ”

“ We can't allow nature to forget the proper chronology of the species, can we?"
"It will be slow work, but—"
"But not impossible. Their life span averages less than thirty years; ours exceeds a century. ”

“ We can imagine what one hundred years are like—a span of time seemingly short to the hale and hearty octogenarian, enormous to the child, totally inapplicable to certain [Pg 136] animals whose whole life is crowded into one single day. ”

“ The ravages of nature and time take many of us early and take a large toll of us over the age of sixty-five. Our span of life after sixty-five is very short. We die very rapidly; therefore, our cost and responsibility to you are not large or long lasting. ”

“ By the 1840s, a well known expression}
We hear daily that life is short; and, surely, Time flies with fearful rapidity if we measure his course by years: three-score-and-ten, the allotted span of man, are soon numbered. ”

“ Now it takes the human animal twenty years at least to grow to maturity; therefore the human animal really should live five times twenty years, which makes a round hundred or a CENTURY; and I firmly believe it is intended for him to live that long, if he only acted in accordance with the laws of life and health. And, dear uncle, you seem always to have acted so, and therefore I think you may safely calculate upon living out your century and then dying the gentle death of mere old age. ”

“ It divides itself very naturally into four periods—of about equal length—twenty to twenty-four years: the period of youth, the period of the prime of life, the period of middle age, and the period of old age. ”

“ To be tending towards death from five-and-forty seems to them ridiculous. So it would be as a matter of sentiment, among people who think about death in such an exaggerated way as we, of this age, do. But I am here speaking of the natural facts which bear upon the condition of old age; and that is my concern with forty-five. In a rough way, the physiological distribution of our life is set down as including five-and-twenty years of growth, five-and-twenty of decline, and twenty of maturity between them. ”

“ An early bloom is too apt to presage an early decay; and though our mortuary statistics, thanks to the advance of medical and sanitary science, do undoubtedly show that [Pg 79] the average duration of life is becoming more and more extended, and that the Golden Age, in this respect, is before us rather than in the past ”

“ As the years go on they bring many changes—changes that come as naturally as the seasons—that tend as naturally to anticipated growth and decay—that scarcely startle the subjects of them, till a lengthened-out period of time discloses their vitality and extent. Between the ages of twenty and thirty, ten years do not seem very destructive to life. ”

“ Why should seventy or eighty years remain as the usual limit of human life? Why should its natural duration under perfectly healthy surrounding conditions not be at least 100 years, with an occasional extension of some ten or fifteen years more? ”

“ These matters however will be specially investigated in the work On Plants. But this is our account of the reasons for the duration of life and for short life in animals. It remains for us to discuss youth and age, and life and death. To come to a definite understanding about these matters would complete our course of study on animals. ”

“ These more marked nodes in the unity of man’s individual existence are: (1) childhood, (2) adolescence from puberty to full nubility, (3) middle life or the prime, when we are at the apex of our aggregate of powers, ranging from twenty-five or thirty to forty or forty-five and comprising thus the fifteen or twenty years now commonly called our best, (4) senescence, which begins in the early forties, or before in woman, and (5) senectitude, the post-climacteric or old age proper. ”

“ The days and months and years of a life race with accelerating pace and youth goes and age comes as the days race, but one is not older for the white days. The clock stops, the blood runs faster, furrows in gray matter smooth out, time forgets to put in tiny crow's-feet and the extra gray hair a week, or to withdraw by the hundredth of an ounce the oxygen from the veins; one grows no older for the days spent out of doors. ”

“ But that which interested me most in reckoning up their divisions of time was the ascertainment of the average duration of life amongst them. I found on minute inquiry that this very considerably exceeded the term allotted to us on the upper earth. What seventy years are to us, one hundred years are to them. Nor is this the only advantage they have over us in longevity, for as few among us attain to the age of seventy, so, on the contrary, few among them die before the age of one hundred; and they enjoy a general degree of health and vigour which makes life itself a blessing even to the last. ”

“ But see here, my lad! our bodies are built to last three score and ten years. Some linger to an hundred; but so few beyond, that every month of continued [24] being renders them more and more a sort of prodigies. As the end of a long life approaches—say a life of ninety years—there is such decay, such dry-rot, that the whole frame is but one remove from ashes. ”

“ We are told by good authority that a study of the human body, its structure, and the length of time it takes it to come to maturity, in comparison with the time it takes the bodies of various animals and their corresponding longevity, reveals the fact that its natural age should be nearer a hundred and twenty years than what we commonly find it today. But think of the multitudes all about us whose bodies are aging, weakening, breaking, so that they have to abandon them long before they reach what ought to be a long period of strong, vigorous middle life. ”

“ So, too, we speak of middle age and think vaguely of it as half way between birth and death or between adolescence and senescence. If we think of life as a binomial curve rising from a base line at birth and sinking into it at death, midway is the highest point with the longest ordinate; and as the crest of a wave has its spindrift, so life at this point often foams, or at least shows emulsive tendencies. We come in sight of the descent while the ascent behind is still visible. ”

“ It is very presumptuous to attempt to add to it, yet I have been struck with the fact that life admits of a natural analysis into no less than fifteen distinct periods. Taking the five primary divisions, infancy, childhood, youth, manhood, old age, each of these has its own three periods of immaturity, complete development, and decline. I recognize on old baby at once, - with its “pipe and mug,” (a stick of candy and a porringer,) - so does everybody; and an old child shedding its milk-teeth is only a little prototype of the old man shedding his permanent ones. ”

“ It is therefore obvious that the duration of life is extremely variable, and not only depends upon physiological considerations, but also upon the external conditions of life. With every change in the structure of a species, and with the acquisition of new habits, the length of its life may, and in most cases must, be altered. ”

“ Our life, bounded by birth and death, has five chief stages, each of which, while it may be divided into substages, also passes into the next so gradually that we cannot date, save roughly and approximately, the transition from one period to that which succeeds it. ”

“ My own life work, such as it is, as a genetic psychologist was devoted for years to the study of infancy and childhood, then to the phenomena of youth, later to adulthood and the stage of sex maturity. To complete a long-cherished program I have now finally tried, aided by the first-hand knowledge that advancing years have brought, to understand better the two last and closing stages of human life. ”

“ Before we advert to the nature of our adaptations for this period of life, we must draw a distinction between age and "premature old age." The former is the decline of nature, which must always take place, whilst the latter is the result of disease or improper habits. ”

“ Altogether the interval is small [between birth and death] ; and consider with how much trouble, and in company with what sort of people, and in what a feeble body, this interval is laboriously passed. Do not then consider life a thing of any value. + For look to the immensity of time behind thee, and to the time which is before thee, another boundless space. In this infinity then what is the difference between him who lives three days and him who lives three generations? ”

“ It must of course be understood that, here as in all other instances, these are not the only factors which determine the duration of life, but many other factors, at present unknown, may be in combination with them and assist in producing the result. ”

“ There is no real birth nor death, as we understand the terms--simply a gradual emergence from, and a return to, a subtler state of being. This process takes some time, probably years in certain varieties, and their life on the denser level, corresponding to our adult period, may be as long as the average human. ”

“ During the days following the Fourth, this impression of death which had entered my mind began to assume more definite limits, and grew pertinent to my own status. I had heard that the average age of man was thirty-three years, and granting that I should reach that age, I could expect to live a little over twenty years more. ”

“ The years from about eight to twelve constitute a unique period of human life. ”

“ Now, if life can be suspended for six weeks and then restored to an organism which, from all physiological standpoints, must be regarded as inanimate, why not for six years or six hundred years, for the matter of that? ”

“ And the greater correspondence thus established, must, other things equal, show itself both in greater complexity of life, and greater length of life: a truth which will be fully perceived on remembering the enormous mortality which prevails among lowly-organized creatures, and the gradual increase of longevity and diminution of fertility which we meet with on ascending to creatures of higher and higher developments. ”

“ This makes up the three-score years and ten which the Psalmist speaks of as the natural duration of human life. He adds that if by reason of strength, we reach four-score years, yet is that strength but labour and sorrow, and soon cut off. ”

“ The period of a generation, or the term of its life, is determined by the laws of mortality, which, varying a little only in different climates, offer a general average, to be found by observation. I turn, for instance, to Buffon’s tables, of twenty-three thousand nine hundred and ninety-four deaths, and the ages at which they happened, and I find that of the numbers of all ages living at one moment, half will be dead in twenty-four years and eight months. ”

“ As a matter of fact, this word 'duration' possessed a divine significance for the ancients, for the fulfilment which includes the period of life of any creature, outside of which no natural development can fall, has been called its duration. ”

“ Two things are very obvious,—the uncertainty as to the hour of death in individuals, but the regularity and constancy of the circumstances which influence the duration of human life in the aggregate. It is a matter of certainty that the average life of all persons born in this country extends to about forty-five years. ”

“ In a table he shows that seven of the ninety causes of death are responsible for over one-half of the shortening of life. He gives us a diagram that shows where the saving of life has been and might be greatest. ”

“ The latter is thus almost, although perhaps not quite, as primordial as the phase of growth itself, and among the most ancient and persistent of all the heritages that higher forms of life received251 from the lower is this power to grow young. Thus the systole and diastole of the heart of the Zoölogos began. The monad becomes a duad; the individual, a dividual, almost as inevitably as the former grows; and the processional through this tiny life cycle contains in it the promise and potency of countless other processes that developed from it later. ”

“ Again, we have made great progress along another line, namely, in distinguishing physiological and especially psychological from chronological age, but here we have little consensus of either method or result beyond the early teens. Yet no observer of life can fail to doubt that there is the same and perhaps even, on the whole, greater average diversity among individuals in mental age as they advance along the scale of years. ”

“ Variations from different causes are essentially distinct from a regular and unretrograde increase. The average duration of human life will, to a certain degree, vary from healthy or unhealthy climates, from wholesome or unwholesome food, from virtuous or vicious manners, and other causes; but it may be fairly doubted whether there is really the smallest perceptible advance in the natural duration of human life, since first we had any authentic history of man. ”

“ Of sleep and waking we have already treated; about life and death we shall speak later on, and likewise about health and disease, in so far as it belongs to the science of nature to do so. But at present we have to investigate the causes of some creatures being long-lived, and others short-lived. ”

“ When the improvements have been in existence for a longer period, so that the lives of all who are living must have been affected from birth by the changed conditions, we may infer that even a greater gain in the mean duration of life will be shown. ”

“ The views which I have brought forward in this paper are based on a comparatively small number of facts, at least as far as the duration of life in various species is concerned. The larger the number of accurate data which are supplied, and the more exactly the duration of life and its conditions are ascertained, the more securely will it be possible to establish our views upon the causes which determine the duration of life. ”