The Malthusian Oscillation

Both Charles Darwin and A.R. Wallace, the co-founders of the theory of evolution, explicitly cited T.R. Malthus' Essay on Population as the source of their inspiration. Textbooks of evolution usually give Malthus a passing mention.

Malthus' First Essay (as it is usually called) appeared anonymously in 1798, some 60 years before Darwin's Origin of Species. The book was one long and lively attack on what Malthus saw as the unrealistic, utopian speculations about the perfectability of man in the writings of William Godwin, Condorcet, and others.

As Malthus saw it, human populations would grow geometrically until they had overtaken the ability of their food resources to sustain them, at which point there would be general distress, increased mortality among the young and old, falling wages, increasing labour hours, with the cheapness of labour encouraging cultivators to bring new land under cultivation, so that the means of subsistence would be brought back to a level that could support the population, and life would again become tolerably comfortable. The result was a resource-constrained oscillating system, not the steady ascent to perfection envisaged by Godwin.

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. (Malthus. 1st Essay. ch. 2)

The logic is spelt out:

The constant effort towards population, which is found to act even in the most vicious societies, increases the number of people before the means of subsistence are increased. The food therefore which supported seven millions must now be divided among seven millions and a half or eight millions. The poor consequently live much worse, and many of them be reduced to severe distress. The number of labourers being above the proportion of the work in the market, the price of labour must tend towards a decrease, while the price of provisions would at the same time tend to rise. The labourer therefore must work harder to earn the same as he did before. During this season of distress, the discouragements to marriage, and the difficulty of rearing a family are so great that population is at a stand. In the mean time the cheapness of labour, the plenty of labourers, and the necessity of an increased industry amongst them, encourage cultivators to employ more labour upon their land, to turn up fresh soil, and to manure and improve more completely what is already in tillage, till ultimately the means of subsistence become in the same proportion to the population as at the period from which we set out. The situation of the labourer being then again tolerably comfortable, the restraints to population are in some degree loosened, and the same retrograde and progressive movements with respect to happiness are repeated.
This sort of oscillation will not be remarked by superficial observers, and it may be difficult even for the most penetrating mind to calculate its periods. Yet that in all old states some such vibration does exist... no reflecting man who considers the subject deeply can well doubt. (Malthus. 1st Essay. ch.2 -emphases added-)

If the First Essay had simply been restricted to human life, then Darwin's genius would have been to transpose its argument from the human world to the natural world of plants and animals. But no genius was required: Malthus himself performs the transposition.

The First Essay touches not only upon the natural world, but also the high multiplication rates of plants and animals, their degree of perfectability, and much else. Indeed, the First Essay contains virtually every single component of the subsequent Darwinian scheme:

1	Geometric population growth combined with arithmetic food resource growth (chapter 1 & 2), already quoted. This was Malthus' singular and central argument, with the logic of which he rigorously pursued his utopian opponents.
2	Malthus applies the argument to the natural world: Through the animal and vegetable kingdoms, nature has scattered the seeds of life abroad with the most profuse and liberal hand. She has been comparatively sparing in the room, and the nourishment necessary to rear them. The germs of existence contained in this spot of earth, with ample food, and ample room to expand in, would fill millions of worlds in the course of a few thousand years. Necessity, that imperious all pervading law of nature, restrains them within prescribed bounds. (ch. 1) Among plants and animals the view of the subject is simple. They are all impelled by a powerful instinct to the increase of their species; and this instinct is interrupted by no reasoning, or doubts about providing for their offspring. Wherever therefore there is liberty, the power of increase is exerted; and the superabundant effects are repressed afterwards by want of room and nourishment, which is common to animals and plants; and among animals, by becoming the prey of others. (ch. 2)
3	Malthus also discusses the perfectability of domestic cattle, sheep, and flowers: The capacity of improvement in plants and animals, to a certain degree, no person can possibly doubt. (ch. 9)
4	Malthus argues that the inability of a "savage nation" to sustain a growing population may cause the inhabitants to invade other lands, and a "struggle for existence" to ensue: The peaceful inhabitants of the countries on which they (i.e. the invaders) 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 desperate courage, inspired by the reflection, that death was the punishment of defeat, and life the prize of victory. In these savage contests many tribes must have been utterly exterminated. (ch. 3 -emphasis added- )
5	In Malthus' view, pressure of population obliges men to exert themselves, and to grow in intellect. He offers a form of 'natural selection': Nothing can appear more consonant to our reason, than that those beings which come out of the creative process of the world in lovely and beautiful forms, should be crowned with immortality; while those which come out misshapen, those whose minds are not suited to a purer and happier state of existence, should perish, and be condemned to mix again with their original clay. (ch. 19)
6	The Deity does not create perfection, but a progressive succession of beings: With the crude and puerile conceptions which we sometimes form of the attribute of the Deity, we might imagine that God could call into being myriads and myriads of existences, all free from pain and imperfection, all eminent in goodness and wisdom, all capable of the highest enjoyments, and unnumbered as the points throughout infinite space. But when from these vain and extravagant dreams of fancy, we turn our eyes to the book of nature, where alone we can read God as he is, we see a constant succession of sentient beings, rising apparently from so many specks of matter, going through a long and sometimes painful process in this world, but many of them attaining, ere the termination of it, such high qualities and powers as seem to indicate their fitness for some superior state. (ch. 18)
7	The entire grand process is one of awakening matter into Mind: I should be inclined, therefore, to consider the world, and this life, as the mighty process of God, not for the trial, but for the creation and formation of mind; a process necessary to awaken inert, chaotic matter, into spirit; to sublimate the dust of earth into soul; to elicit an aethereal spark from the clod of clay. (ch. 18)

Malthus' views on the matter did not change. In 1830, four years before his death, he wrote:

The great check to the increase of plants and animals, we know from experience, is the want of room and nourishment; and this experience would direct us to look for the greatest actual increase of them in those situations where room and nourishment were the most abundant. (A Summary View. 1830 )

Thus, scattered through the First Essay, and re-organised here, may be found nearly all the components of the subsequent Darwinian system. Not only geometric population growth, but the explicit recognition of the same processes in the plant and animal worlds; the explicit possibility of variation and improvement of plant and animal species; an exact word-for-word "struggle for existence" (among men, note, not animals) in which the losers are exterminated - the "fitness" of the survivors ensuring continued existence -; the rejection of a simple Creationism; natural selection (a term which Darwin had to invent) in which the most "lovely and beautiful" survive while the "misshapen" perish; and finally a reverential awe at the entire cosmic process - which evokes the closing paragraph of Origin.

Darwin, therefore, simply took this naturalistic sub-theme of the otherwise political Essay, and worked it up into an entire book - The Origin of Species -, adding a plethora of data and observations.

But, crucially, Darwin changed Malthus' argument. Malthus, note, saw want of room and nourishment suppressing the multiplying plants and animals. It was among men that there was a "struggle for existence". But in Darwin, this human struggle for existence is extended into a War of Nature.

Worse, for Darwin, the geometric increase in natural populations simply resulted in a ceaseless fight for survival, as the population rose until an area was "fully stocked" - or had, in modern parlance, reached its carrying capacity. The oscillation between periods of ease and distress that Malthus foresaw entirely vanished.

If Darwin had followed Malthus, he would have seen that during the season of distress the creatures would have had to work harder to stay alive - and that those handicapped by age, or ill health, or some other infirmity, would not have survived this season. Thus during this season, some fraction of the population would die, and the remainder would live on through a subsequent season of relative idleness - until their numbers increased again to bring on another period of distress.

In Darwin's static and overcrowded world, the creatures jostle and fight for food and for mates: competition is constant and inescapable. But in a Malthusian world, periods of distress occur intermittently. And during these periods of distress, the creatures simply work harder to find food. Hard work is not competition: it's simply hard work.

The Malthusian scheme offers a simple evolutionary cycle. During the season of relative comfort, the creatures multiply and vary. And in the subsequent season of distress, these variants are tested. Those that survive the test into the subsequent season of ease again multiply and vary. And so on, in a repeat cycle of design and test, design and test.

Darwin didn't fully understand Malthus. And the reason that he did not understand was because Malthus was a mathematician, and he was not - a fact that Darwin deeply regretted.

I attempted mathematics, and even went during the summer of 1828 with a private tutor to Barmouth, but I got on very slowly. The work was repugnant to me, chiefly from my not being able to see any meaning in the early steps of algebra. This impatience was very foolish, and in after years I have deeply regretted that I did not proceed far enough at least to understand something of the great leading principles of mathematics, for men thus endowed seem to have an extra sense. (Darwin. Autobiography. Watts, London 1929)

Malthus was also above all a theoretician who constructed a population model, and was driven, in his Second Essay, to find facts to support his speculative hypothesis. By contrast, Darwin was an empirical observer of the natural world, with plenty of facts, but looking for a theory to hold them together. In the introduction to the Penguin edition of the First Essay, Antony Flew noted that the Malthusian conceptual scheme resembled classical mechanics.

We know that Malthus was soundly grounded in Newtonian physics at Cambridge. In the First Essay he goes out of his way to express admiration for ... Newton; and he argues strongly that the 'causes of population and depopulation have probably been as constant as any of the laws of nature with which we are acquainted.' (First Essay Ch. 7) In seeing classical mechanics as the model for human studies Malthus put himself in a long and distinguished tradition extending back as far as Hume of the Treatise...

Darwin was derisive of theory. After giving an estimate (wrong, it seems) of the population of elephants after reproducing unchecked for centuries, he continues:

But we have better evidence on this subject than mere theoretical calculations, namely, the numerous recorded cases of the astonishingly rapid increase of various animals in a state of nature... (Darwin Origin 1st ed. ch.3)

Darwin made a drama out the Malthusian crisis, replacing the Malthusian oscillation between ease and toil with a "war of nature", a struggle for existence between the creatures. If Malthus had developed the theory of evolution implicit in his Essay, it would almost certainly not have been such Darwin's drama. But, given some of his attitudes, Malthus may not have developed the theory in the direction of Idle Theory.