Department of History
University of California, Irvine
Instructor:    Dr. Barbara J. Becker


Week 9.  Natural Selection

adapted excerpts from
An Essay on the Principle of Population,
as it Affects the Future Improvement of Society
... (1798)

by Thomas Robert Malthus (1766-1834)


It is an obvious truth, which has been taken notice of by many writers, that population must always be kept down to the level of the means of subsistence; but no writer that the Author recollects has inquired particularly into the means by which this level is effected:  and it is a view of these means which forms, to his mind, the strongest obstacle in the way to any very great future improvement of society.  He hopes it will appear that, in the discussion of this interesting subject, he is actuated solely by a love of truth, and not by any prejudices against any particular set of men, or of opinions.  He professes to have read some of the speculations on the future improvement of society in a temper very different from a wish to find them visionary, but he has not acquired that command over his understanding which would enable him to believe what he wishes, without evidence, or to refuse his assent to what might be unpleasing, when accompanied with evidence....

Chapter 2

[P]opulation, when unchecked, increase[s] in a geometrical ratio, and subsistence for man in an arithmetical ratio....

Taking the population of the world at any number, a thousand millions, for instance, the human species would increase in the ratio of--1, 2, 4, 8, 16, 32, 64, 128, 256, 512, etc. and subsistence as--1, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc.  In two centuries and a quarter, the population would be to the means of subsistence as 512 to 10:  in three centuries as 4096 to 13, and in two thousand years the difference would be almost incalculable, though the produce in that time would have increased to an immense extent.

No limits whatever are placed to the productions of the earth; they may increase forever and be greater than any assignable quantity.  Yet still the power of population being a power of a superior order, the increase of the human species can only be kept commensurate to the increase of the means of subsistence by the constant operation of the strong law of necessity acting as a check upon the greater power....

Chapter 3

In the rudest state of mankind, in which hunting is the principal occupation, and the only mode of acquiring food, ... the comparative population must necessarily be thin ... from the scarcity of food.... [I]t would immediately increase if food was in greater plenty....  [M]isery is the check that represses the superior power of population and keeps its effects equal to the means of subsistence....

Of the manners and habits that prevail among nations of shepherds, ... we are even more ignorant than of the savage state.  But ... these nations [can] not escape the general lot of misery arising from the want of subsistence, Europe....

It is well known that a country in pasture cannot support so many inhabitants as a country in tillage, but what renders nations of shepherds so formidable is the power which they possess of moving all together and the necessity they frequently feel of exerting this power in search of fresh pasture for their herds....  Restless from present distress, flushed with the hope of fairer prospects, and animated with the spirit of hardy enterprise, these daring adventurers were likely to become formidable adversaries to all who opposed them.  The peaceful inhabitants of the countries on which they rushed could not long withstand the energy of men acting under such powerful motives of exertion.  And when they fell in with any tribes like their own, the contest was a struggle for existence, and they fought with a desperate courage, inspired by the rejection that death was the punishment of defeat and life the prize of victory.

In these savage contests many tribes must have been utterly exterminated.  Some, probably, perished by hardship and famine.  Others, whose leading star had given them a happier direction, became great and powerful tribes, and, in their turns, sent off fresh adventurers in search of still more fertile seats.  The prodigious waste of human life occasioned by this perpetual struggle for room and food was more than supplied by the mighty power of population....  An Alaric, an Attila, or a Zingis [Genghis] Khan, and the chiefs around them, might fight for glory, for the fame of extensive conquests, but the true cause that set in motion the great tide of northern emigration, and that continued to propel it till it rolled at different periods against China, Persia, Italy, and even Egypt, was a scarcity of food, a population extended beyond the means of supporting it.

The absolute population at any one period, in proportion to the extent of territory, could never be great, on account of the unproductive nature of some of the regions occupied; but there appears to have been a most rapid succession of human beings, and as fast as some were mowed down by the scythe of war or of famine, others rose in increased numbers to supply their place....

Where there is any inequality of conditions, and among nations of shepherds this soon takes place, the distress arising from a scarcity of provisions must fall hardest upon the least fortunate members of the society....

Chapter 4

[F]oresight of the difficulties attending the rearing of a family acts as a preventive check, and the actual distresses of some of the lower classes, by which they are disabled from giving the proper food and attention to their children, act as a positive check to the natural increase of population....

Chapter 5

An increase of population without a proportional increase of food will evidently have the same effect in lowering the value of each man's patent.  The food must necessarily be distributed in smaller quantities, and consequently a day's labour will purchase a smaller quantity of provisions....

Chapter 7

Other circumstances being the same, it may be affirmed that countries are populous according to the quantity of human food which they produce, and happy according to the liberality with which that food is divided, or the quantity which a day's labour will purchase....

The happiness of a country does not depend, absolutely, upon its poverty or its riches, upon its youth or its age, upon its being thinly or fully inhabited, but ... upon the degree in which the yearly increase of food approaches to the yearly increase of an unrestricted population....

Were a country never to be overrun by a people more advanced in arts, but left to its own natural progress in civilization; from the time that its produce might be considered as an unit, to the time that it might be considered as a million, during the lapse of many hundred years, there would not be a single period when the mass of the people could be said to be free from distress, either directly or indirectly, for want of food....

Famine seems to be the last, the most dreadful resource of nature.  The power of population is so superior to the power in the earth to produce subsistence for man, that premature death must in some shape or other visit the human race.  The vices of mankind are active and able ministers of depopulation....  But should they fail in this war of extermination, sickly seasons, epidemics, pestilence, and plague, advance in terrific array, and sweep off their thousands and ten thousands.  Should success be still incomplete, gigantic inevitable famine stalks in the rear, and with one mighty blow levels the population with the food of the world.

Must it not then be acknowledged by an attentive examiner of the histories of mankind, that in every age and in every state in which man has existed, or does now exist:

Chapter 9

I am told that it is a maxim among the improvers of cattle that you may breed to any degree of nicety you please, and they found this maxim upon another, which is that some of the offspring will possess the desirable qualities of the parents in a greater degree.  In the famous Leicestershire breed of sheep, the object is to procure them with small heads and small legs....  Though I may not be able in the present instance to mark the limit at which further improvement will stop, I can very easily mention a point at which it will not arrive.  I should not scruple to assert that were the breeding to continue for ever, the head and legs of these sheep would never be so small as the head and legs of a rat.

It cannot be true, therefore, that among animals, some of the offspring will possess the desirable qualities of the parents in a greater degree, or that animals are indefinitely perfectible.

The progress of a wild plant to a beautiful garden flower is perhaps more marked and striking than anything that takes place among animals, yet even here it would be the height of absurdity to assert that the progress was unlimited or indefinite.

One of the most obvious features of the improvement is the increase of size.  The flower has grown gradually larger by cultivation.  If the progress were really unlimited it might be increased ad infinitum, but this is so gross an absurdity that we may be quite sure that among plants as well as among animals there is a limit to improvement, though we do not exactly know where it is....

The capacity of improvement in plants and animals, to a certain degree, no person can possibly doubt.  A clear and decided progress has already been made, and yet, I think, it appears that it would be highly absurd to say that this progress has no limits.  In human life, though there are great variations from different causes, it may be doubted whether, since the world began, any organic improvement whatever in the human frame can be clearly ascertained.  The foundations, therefore, on which the arguments for the organic perfectibility of man rest, are unusually weak, and can only be considered as mere conjectures.  It does not, however, by any means seem impossible that by an attention to breed, a certain degree of improvement, similar to that among animals, might take place among men.  Whether intellect could be communicated may be a matter of doubt:  but size, strength, beauty, complexion, and perhaps even longevity are in a degree transmissible.  The error does not seem to lie in supposing a small degree of improvement possible, but in not discriminating between a small improvement, the limit of which is undefined, and an improvement really unlimited.  As the human race, however, could not be improved in this way, without condemning all the bad specimens to celibacy, it is not probable that an attention to breed should ever become general....

Chapter 18

Locke, if I recollect, says that the endeavour to avoid pain rather than the pursuit of pleasure is the great stimulus to action in life:  and that in looking to any particular pleasure, we shall not be roused into action in order to obtain it, till the contemplation of it has continued so long as to amount to a sensation of pain or uneasiness under the absence of it.  To avoid evil and to pursue good seem to be the great duty and business of man, and this world appears to be peculiarly calculated to afford opportunity of the most unremitted exertion of this kind, and it is by this exertion, by these stimulants, that mind is formed.  If Locke's idea be just, and there is great reason to think that it is, evil seems to be necessary to create exertion, and exertion seems evidently necessary to create mind.

The necessity of food for the support of life gives rise, probably, to a greater quantity of exertion than any other want, bodily or mental....  The processes of ploughing and clearing the ground, of collecting and sowing seeds, are ... made previously necessary to the enjoyment of the blessings of life, in order to rouse man into action, and form his mind to reason.

To furnish the most unremitted excitements of this kind, ... it has been ordained that population should increase much faster than food....  Strong excitements seem necessary to create exertion, and to direct this exertion, and form the reasoning faculty....  The constancy of the laws of nature, or the certainty with which we may expect the same effects from the same causes, is the foundation of the faculty of reason....  The constancy of the laws of nature is the foundation of the industry and foresight of the husbandman, the indefatigable ingenuity of the artificer, the skilful researches of the physician and anatomist, and the watchful observation and patient investigation of the natural philosopher.  To this constancy we owe all the greatest and noblest efforts of intellect....

[I]f we return to the principle of population and consider man as he really is, inert, sluggish, and averse from labour, unless compelled by necessity (and it is surely the height of folly to talk of man, according to our crude fancies of what he might be), we may pronounce with certainty that the world would not have been peopled, but for the superiority of the power of population to the means of subsistence.  Strong and constantly operative as this stimulus is on man to urge him to the cultivation of the earth, if we still see that cultivation proceeds very slowly, we may fairly conclude that a less stimulus would have been insufficient.  Even under the operation of this constant excitement, savages will inhabit countries of the greatest natural fertility for a long period before they betake themselves to pasturage or agriculture.  Had population and food increased in the same ratio, it is probable that man might never have emerged from the savage state.  But supposing the earth once well peopled, an Alexander, a Julius Caesar, a Tamberlane, or a bloody revolution might irrecoverably thin the human race, and defeat the great designs of the Creator.  The ravages of a contagious disorder would be felt for ages; and an earthquake might unpeople a region for ever.

The principle, according to which population increases, prevents the vices of mankind, or the accidents of nature, the partial evils arising from general laws, from obstructing the high purpose of the creation.  It keeps the inhabitants of the earth always fully up to the level of the means of subsistence; and is constantly acting upon man as a powerful stimulus, urging him to the further cultivation of the earth, and to enable it, consequently, to support a more extended population.  But it is impossible that this law can operate ... without occasioning partial evil.  Unless the principle of population were to be altered according to the circumstances of each separate country (which would not only be contrary to our universal experience, with regard to the laws of nature, but would contradict even our own reason, which sees the absolute necessity of general laws for the formation of intellect), it is evident that the same principle which, seconded by industry, will people a fertile region in a few years must produce distress in countries that have been long inhabited.

[T]he acknowledged difficulties occasioned by the law of population ... excite universal exertion and contribute to that infinite variety of situations, and consequently of impressions, which seems upon the whole favourable to the growth of mind.  It is probable, that too great or too little excitement, extreme poverty, or too great riches may be alike unfavourable in this respect.  The middle regions of society seem to be best suited to intellectual improvement, but it is contrary to the analogy of all nature to expect that the whole of society can be a middle region.  The temperate zones of the earth seem to be the most favourable to the mental and corporal energies of man, but all cannot be temperate zones.  A world, warmed and enlightened but by one sun, must from the laws of matter have some parts chilled by perpetual frosts and others scorched by perpetual heats.  Every piece of matter lying on a surface must have an upper and an under side, all the particles cannot be in the middle.  The most valuable parts of an oak, to a timber merchant, are not either the roots or the branches, but these are absolutely necessary to the existence of the middle part, or stem, which is the object in request.  The timber merchant could not possibly expect to make an oak grow without roots or branches, but if he could find out a mode of cultivation which would cause more of the substance to go to stem, and less to root and branch, he would be right to exert himself in bringing such a system into general use.

In the same manner, though we cannot possibly expect to exclude riches and poverty from society, yet if we could find out a mode of government by which the numbers in the extreme regions would be lessened and the numbers in the middle regions increased, it would be undoubtedly our duty to adopt it.  It is not, however, improbable that as in the oak, the roots and branches could not be diminished very greatly without weakening the vigorous circulation of the sap in the stem, so in society the extreme parts could not be diminished beyond a certain degree without lessening that animated exertion throughout the middle parts, which is the very cause that they are the most favourable to the growth of intellect.  If no man could hope to rise or fear to fall, in society, if industry did not bring with it its reward and idleness its punishment, the middle parts would not certainly be what they now are....

That the difficulties of life contribute to generate talents, every day's experience must convince us.  The exertions that men find it necessary to make, in order to support themselves or families, frequently awaken faculties that might otherwise have lain for ever dormant, and it has been commonly remarked that new and extraordinary situations generally create minds adequate to grapple with the difficulties in which they are involved....

Chapter 19

When the mind has been awakened into activity by the passions, and the wants of the body, intellectual wants arise; and the desire of knowledge, and the impatience under ignorance, form a new and important class of excitements.  Every part of nature seems peculiarly calculated to furnish stimulants to mental exertion of this kind, and to offer inexhaustible food for the most unremitted inquiry.  Our mortal Bard says of Cleopatra:

Custom cannot stale
Her infinite variety.
The expression, when applied to any one object, may be considered as a poetical amplification, but it is accurately true when applied to nature.  Infinite variety seems, indeed, eminently her characteristic feature.  The shades that are here and there blended in the picture give spirit, life, and prominence to her exuberant beauties, and those roughnesses and inequalities, those inferior parts that support the superior, though they sometimes offend the fastidious microscopic eye of short-sighted man, contribute to the symmetry, grace, and fair proportion of the whole.

The infinite variety of the forms and operations of nature, besides tending immediately to awaken and improve the mind by the variety of impressions that it creates, opens other fertile sources of improvement by offering so wide and extensive a field for investigation and research.  Uniform, undiversified perfection could not possess the same awakening powers....  Both reason and experience seem to indicate to us that the infinite variety of nature (and variety cannot exist without inferior parts, or apparent blemishes) is admirably adapted to further the high purpose of the creation and to produce the greatest possible quantity of good.

The obscurity that involves all metaphysical subjects appears to me, in the same manner, peculiarly calculated to add to that class of excitements which arise from the thirst of knowledge.  It is probable that man, while on earth, will never be able to attain complete satisfaction on these subjects; but this is by no means a reason that he should not engage in them.  The darkness that surrounds these interesting topics of human curiosity may be intended to furnish endless motives to intellectual activity and exertion.  The constant effort to dispel this darkness, even if it fail of success, invigorates and improves the thinking faculty.  If the subjects of human inquiry were once exhausted, mind would probably stagnate; but the infinitely diversified forms and operations of nature, together with the endless food for speculation which metaphysical subjects offer, prevent the possibility that such a period should ever arrive.

The finest minds seem to be formed ... by efforts at original thinking, by endeavours to form new combinations, and to discover new truths, than by passively receiving the impressions of other men's ideas.  Could we suppose the period arrived, when there was not further hope of future discoveries, and the only employment of mind was to acquire pre-existing knowledge, without any efforts to form new and original combinations, though the mass of human knowledge were a thousand times greater than it is at present, yet it is evident that one of the noblest stimulants to mental exertion would have ceased; the finest feature of intellect would be lost; everything allied to genius would be at an end....
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