Aristotle
384-322 B.C.E. - Wrote in Greek
On Longevity and Shortness of Life
Written 350 B.C.E
Translated by G. R. T. Ross
On Longevity and Shortness of Life
By Aristotle
Part 1
The reasons for some animals being long-lived and others short-lived, and,
in a word, causes of the length and brevity of life call for
investigation.
The necessary beginning to our inquiry is a statement of the difficulties
about these points. For it is not clear whether in animals and plants universally
it is a single or diverse cause that makes some to be long-lived, others
short-lived. Plants too have in some cases a long life, while in others
it lasts but for a year.
Further, in a natural structure are longevity and a sound constitution
coincident, or is shortness of life independent of unhealthiness? Perhaps
in the case of certain maladies a diseased state of the body and shortness
of life are interchangeable, while in the case of others ill-health is
perfectly compatible with long life.
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. We find this distinction affecting not only entire genera
opposed as wholes to one another, but applying also to contrasted sets
of individuals within the same species. As an instance of the difference
applying to the genus I give man and horse (for mankind has a longer life
than the horse), while within the species there is the difference between
man and man; for of men also some are long-lived, others short-lived, differing
from each other in respect of the different regions in which they dwell.
Races inhabiting warm countries have longer life, those living in a cold
climate live a shorter time. Likewise there are similar differences among
individuals occupying the same locality.
Part 2
In order to find premisses for our argument, we must answer the
question, What is that which, in natural objects, makes them easily destroyed,
or the reverse? Since fire and water, and whatsoever is akin thereto, do
not possess identical powers they are reciprocal causes of generation and
decay. Hence it is natural to infer that everything else arising from them
and composed of them should share in the same nature, in all cases where
things are not, like a house, a composite unity formed by the synthesis
of many things.
In other matters a different account must be given; for in many
things their mode of dissolution is something peculiar to themselves, e.g.
in knowledge and health and disease. These pass away even though the medium
in which they are found is not destroyed but continues to exist; for example,
take the termination of ignorance, which is recollection or learning, while
knowledge passes away into forgetfulness, or error. But accidentally the
disintegration of a natural object is accompanied by the destruction of
the non-physical reality; for, when the animal dies, the health or knowledge
resident in it passes away too. Hence from these considerations we may
draw a conclusion about the soul too; for, if the inherence of soul in
body is not a matter of nature but like that of knowledge in the soul,
there would be another mode of dissolution pertaining to it besides that
which occurs when the body is destroyed. But since evidently it does not
admit of this dual dissolution, the soul must stand in a different case
in respect of its union with the body.
Part 3
Perhaps one might reasonably raise the question whether there is
any place where what is corruptible becomes incorruptible, as fire does
in the upper regions where it meets with no opposite. Opposites destroy
each other, and hence accidentally, by their destruction, whatsoever is
attributed to them is destroyed. But no opposite in a real substance is
accidentally destroyed, because real substance is not predicated of any
subject. Hence a thing which has no opposite, or which is situated where
it has no opposite, cannot be destroyed. For what will that be which can
destroy it, if destruction comes only through contraries, but no contrary
to it exists either absolutely or in the particular place where it is?
But perhaps this is in one sense true, in another sense not true, for it
is impossible that anything containing matter should not have in any sense
an opposite. Heat and straightness can be present in every part of a thing,
but it is impossible that the thing should be nothing but hot or white
or straight; for, if that were so, attributes would have an independent
existence. Hence if, in all cases, whenever the active and the passive
exist together, the one acts and the other is acted on, it is impossible
that no change should occur. Further, this is so if a waste product is
an opposite, and waste must always be produced; for opposition is always
the source of change, and refuse is what remains of the previous opposite.
But, after expelling everything of a nature actually opposed, would an
object in this case also be imperishable? No, it would be destroyed by
the environment.
If then that is so, what we have said sufficiently accounts for
the change; but, if not, we must assume that something of actually opposite
character is in the changing object, and refuse is produced.
Hence accidentally a lesser flame is consumed by a greater one,
for the nutriment, to wit the smoke, which the former takes a long period
to expend, is used up by the big flame quickly.
Hence [too] all things are at all times in a state of transition
and are coming into being and passing away. The environment acts on them
either favourably or antagonistically, and, owing to this, things that
change their situation become more or less enduring than their nature warrants,
but never are they eternal when they contain contrary qualities; for their
matter is an immediate source of contrariety, so that if it involves locality
they show change of situation, if quantity, increase and diminution, while
if it involves qualitative affection we find alteration of
character.
Part 4
We find that a superior immunity from decay attaches neither to
the largest animals (the horse has shorter life than man) nor to those
that are small (for most insects live but for a year). Nor are plants as
a whole less liable to perish than animals (many plants are annuals), nor
have sanguineous animals the pre-eminence (for the bee is longer-lived
than certain sanguineous animals). Neither is it the bloodless animals
that live longest (for molluscs live only a year, though bloodless), nor
terrestrial organisms (there are both plants and terrestrial animals of
which a single year is the period), nor the occupants of the sea (for there
we find the crustaceans and the molluscs, which are
short-lived).
Speaking generally, the longest-lived things occur among the plants,
e.g. the date-palm. Next in order we find them among the sanguineous animals
rather than among the bloodless, and among those with feet rather than
among the denizens of the water. Hence, taking these two characters together,
the longest-lived animals fall among sanguineous animals which have feet,
e.g. man and elephant. As a matter of fact also it is a general rule that
the larger live longer than the smaller, for the other long-lived animals
too happen to be of a large size, as are also those I have
mentioned.
Part 5
The following considerations may enable us to understand the reasons
for all these facts. We must remember that an animal is by nature humid
and warm, and to live is to be of such a constitution, while old age is
dry and cold, and so is a corpse. This is plain to observation. But the
material constituting the bodies of all things consists of the following-the
hot and the cold, the dry and the moist. Hence when they age they must
become dry, and therefore the fluid in them requires to be not easily dried
up. Thus we explain why fat things are not liable to decay. The reason
is that they contain air; now air relatively to the other elements is fire,
and fire never becomes corrupted.
Again the humid element in animals must not be small in quantity,
for a small quantity is easily dried up. This is why both plants and animals
that are large are, as a general rule, longer-lived than the rest, as was
said before; it is to be expected that the larger should contain more moisture.
But it is not merely this that makes them longer lived; for the cause is
twofold, to wit, the quality as well as the quantity of the fluid. Hence
the moisture must be not only great in amount but also warm, in order to
be neither easily congealed nor easily dried up.
It is for this reason also that man lives longer than some animals
which are larger; for animals live longer though there is a deficiency
in the amount of their moisture, if the ratio of its qualitative superiority
exceeds that of its quantitative deficiency.
In some creatures the warm element is their fatty substance, which
prevents at once desiccation and congelation; but in others it assumes
a different flavour. Further, that which is designed to be not easily destroyed
should not yield waste products. Anything of such a nature causes death
either by disease or naturally, for the potency of the waste product works
adversely and destroys now the entire constitution, now a particular
member.
This is why salacious animals and those abounding in seed age quickly;
the seed is a residue, and further, by being lost, it produces dryness.
Hence the mule lives longer than either the horse or the ass from which
it sprang, and females live longer than males if the males are salacious.
Accordingly cock-sparrows have a shorter life than the females. Again males
subject to great toil are short-lived and age more quickly owing to the
labour; toil produces dryness and old age is dry. But by natural constitution
and as a general rule males live longer than females, and the reason is
that the male is an animal with more warmth than the
female.
The same kind of animals are longer-lived in warm than in cold
climates for the same reason, on account of which they are of larger size.
The size of animals of cold constitution illustrates this particularly
well, and hence snakes and lizards and scaly reptiles are of great size
in warm localities, as also are testacea in the Red Sea: the warm humidity
there is the cause equally of their augmented size and of their life. But
in cold countries the humidity in animals is more of a watery nature, and
hence is readily congealed. Consequently it happens that animals with little
or no blood are in northerly regions either entirely absent (both the land
animals with feet and the water creatures whose home is the sea) or, when
they do occur, they are smaller and have shorter life; for the frost prevents
growth.
Both plants and animals perish if not fed, for in that case they
consume themselves; just as a large flame consumes and burns up a small
one by using up its nutriment, so the natural warmth which is the primary
cause of digestion consumes the material in which it is
located.
Water animals have a shorter life than terrestrial creatures, not
strictly because they are humid, but because they are watery, and watery
moisture is easily destroyed, since it is cold and readily congealed. For
the same reason bloodless animals perish readily unless protected by great
size, for there is neither fatness nor sweetness about them. In animals
fat is sweet, and hence bees are longer-lived than other animals of larger
size.
Part 6
It is amongst the plants that we find the longest life-more than
among the animals, for, in the first place, they are less watery and hence
less easily frozen. Further they have an oiliness and a viscosity which
makes them retain their moisture in a form not easily dried up, even though
they are dry and earthy.
But we must discover the reason why trees are of an enduring constitution,
for it is peculiar to them and is not found in any animals except the
insects.
Plants continually renew themselves and hence last for a long time.
New shoots continually come and the others grow old, and with the roots
the same thing happens. But both processes do not occur together. Rather
it happens that at one time the trunk and the branches alone die and new
ones grow up beside them, and it is only when this has taken place that
the fresh roots spring from the surviving part. Thus it continues, one
part dying and the other growing, and hence also it lives a long
time.
There is a similarity, as has been already said, between plants
and insects, for they live, though divided, and two or more may be derived
from a single one. Insects, however, though managing to live, are not able
to do so long, for they do not possess organs; nor can the principle resident
in each of the separated parts create organs. In the case of a plant, however,
it can do so; every part of a plant contains potentially both root and
stem. Hence it is from this source that issues that continued growth when
one part is renewed and the other grows old; it is practically a case of
longevity. The taking of slips furnishes a similar instance, for we might
say that, in a way, when we take a slip the same thing happens; the shoot
cut off is part of the plant. Thus in taking slips this perpetuation of
life occurs though their connexion with the plant is severed, but in the
former case it is the continuity that is operative. The reason is that
the life principle potentially belonging to them is present in every
part.
Identical phenomena are found both in plants and in animals. For
in animals the males are, in general, the longer-lived. They have their
upper parts larger than the lower (the male is more of the dwarf type of
build than the female), and it is in the upper part that warmth resides,
in the lower cold. In plants also those with great heads are longer-lived,
and such are those that are not annual but of the tree-type, for the roots
are the head and upper part of a plant, and among the annuals growth occurs
in the direction of their lower parts and the fruit.
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.
THE END
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