I noted here that long before Darwin, there was fairly decent evidence for some sort of theory of evolution, even evidence available from the general human experience of plant and animal life, without deep scientific study.
As said in the earlier post, Aristotle notes that Empedocles hypothesized something along the lines of natural selection:
Wherever then all the parts came about just what they would have been if they had come to be for an end, such things survived, being organized spontaneously in a fitting way; whereas those which grew otherwise perished and continue to perish, as Empedocles says his ‘man-faced ox-progeny’ did.
Since Aristotle is arguing against Empedocles, we should be cautious in assuming that the characterization of his position is entirely accurate. But as presented by Aristotle, the position is an argument against the existence of final causes: since things can be “organized spontaneously” in the way “they would have been if they had come to be for an end,” there is no reason to think they in fact came to be for an end.
This particular conclusion, namely that in such a process nothing comes to be for an end, is a mistake, based on the assumption that different kinds of causes are mutually exclusive, rather than recognizing that different kinds of causes are different ways of explaining one and the same thing. But the general idea regarding what happened historically is correct: good conditions are more capable of persisting, bad conditions less so, and thus over time good conditions tend to predominate.
It should be known that we — may God guide you and us — notice that this world with all the created things in it has a certain order and solid construction. It shows nexuses between causes and things caused, combinations of some parts of creation with others, and transformations of some existent things into others, in a pattern that is both remarkable and endless. Beginning with the world of the body and sensual perception, and therein first with the world of the visible elements, (one notices) how these elements are arranged gradually and continually in an ascending order, from earth to water, (from water) to air, and (from air) to fire. Each one of the elements is prepared to be transformed into the next higher or lower one, and sometimes is transformed. The higher one is always finer than the one preceding it. Eventually, the world of the spheres is reached. They are finer than anything else. They are in layers which are interconnected, in a shape which the senses are able to perceive only through the existence of motions. These motions provide some people with knowledge of the measurements and positions of the spheres, and also with knowledge of the existence of the essences beyond, the influence of which is noticeable in the spheres through the fact (that they have motion).
One should then look at the world of creation. It started out from the minerals and progressed, in an ingenious, gradual manner, to plants and animals. The last stage of minerals is connected with the first stage of plants, such as herbs and seedless plants. The last stage of plants, such as palms and vines, is connected with the first stage of animals, such as snails and shellfish which have only the power of touch. The word “connection” with regard to these created things means that the last stage of each group is fully prepared to become the first stage of the next group.
The animal world then widens, its species become numerous, and, in a gradual process of creation, it finally leads to man, who is able to think and to reflect. The higher stage of man is reached from the world of the monkeys, in which both sagacity and perception are found, but which has not reached the stage of actual reflection and thinking. At this point we come to the first stage of man after (the world of monkeys). This is as far as our (physical) observation extends.
It is possible that he makes his position clearer elsewhere (I have not read the entire work.) The passage here does not explicitly assert that humans arose from lower animals, but does suggest it, correctly associating human beings with monkeys in particular, even if some of his other connections are somewhat strange. In other words, both here and elsewhere, he speaks of one stage of things being “prepared to become” another stage, and says that this transition sometimes happens: “Each one of the elements is prepared to be transformed into the next higher or lower one, and sometimes is transformed.”
While Ibn Khaldun is at least suggesting that we notice a biological order that corresponds to some degree to an actual historical order, we do not see in this text any indication of what the mechanism is supposed to be. In contrast, Empedocles gives us a mechanism but no clarity regarding historical order. Admittedly, this may be an artifact of the fact that I have not read more of Ibn Khaldun and the fact that we have only fragments from Empedocles.
One of the strongest anticipations of all, although put in very general terms, can be found in David Hume’s Dialogues Concerning Natural Religion, in the following passage:
Besides, why may not motion have been propagated by impulse through all eternity, and the same stock of it, or nearly the same, be still upheld in the universe? As much is lost by the composition of motion, as much is gained by its resolution. And whatever the causes are, the fact is certain, that matter is, and always has been, in continual agitation, as far as human experience or tradition reaches. There is not probably, at present, in the whole universe, one particle of matter at absolute rest.
And this very consideration too, continued PHILO, which we have stumbled on in the course of the argument, suggests a new hypothesis of cosmogony, that is not absolutely absurd and improbable. Is there a system, an order, an economy of things, by which matter can preserve that perpetual agitation which seems essential to it, and yet maintain a constancy in the forms which it produces? There certainly is such an economy; for this is actually the case with the present world. The continual motion of matter, therefore, in less than infinite transpositions, must produce this economy or order; and by its very nature, that order, when once established, supports itself, for many ages, if not to eternity. But wherever matter is so poised, arranged, and adjusted, as to continue in perpetual motion, and yet preserve a constancy in the forms, its situation must, of necessity, have all the same appearance of art and contrivance which we observe at present. All the parts of each form must have a relation to each other, and to the whole; and the whole itself must have a relation to the other parts of the universe; to the element in which the form subsists; to the materials with which it repairs its waste and decay; and to every other form which is hostile or friendly. A defect in any of these particulars destroys the form; and the matter of which it is composed is again set loose, and is thrown into irregular motions and fermentations, till it unite itself to some other regular form. If no such form be prepared to receive it, and if there be a great quantity of this corrupted matter in the universe, the universe itself is entirely disordered; whether it be the feeble embryo of a world in its first beginnings that is thus destroyed, or the rotten carcass of one languishing in old age and infirmity. In either case, a chaos ensues; till finite, though innumerable revolutions produce at last some forms, whose parts and organs are so adjusted as to support the forms amidst a continued succession of matter.
Suppose (for we shall endeavour to vary the expression), that matter were thrown into any position, by a blind, unguided force; it is evident that this first position must, in all probability, be the most confused and most disorderly imaginable, without any resemblance to those works of human contrivance, which, along with a symmetry of parts, discover an adjustment of means to ends, and a tendency to self-preservation. If the actuating force cease after this operation, matter must remain for ever in disorder, and continue an immense chaos, without any proportion or activity. But suppose that the actuating force, whatever it be, still continues in matter, this first position will immediately give place to a second, which will likewise in all probability be as disorderly as the first, and so on through many successions of changes and revolutions. No particular order or position ever continues a moment unaltered. The original force, still remaining in activity, gives a perpetual restlessness to matter. Every possible situation is produced, and instantly destroyed. If a glimpse or dawn of order appears for a moment, it is instantly hurried away, and confounded, by that never-ceasing force which actuates every part of matter.
Thus the universe goes on for many ages in a continued succession of chaos and disorder. But is it not possible that it may settle at last, so as not to lose its motion and active force (for that we have supposed inherent in it), yet so as to preserve an uniformity of appearance, amidst the continual motion and fluctuation of its parts? This we find to be the case with the universe at present. Every individual is perpetually changing, and every part of every individual; and yet the whole remains, in appearance, the same. May we not hope for such a position, or rather be assured of it, from the eternal revolutions of unguided matter; and may not this account for all the appearing wisdom and contrivance which is in the universe? Let us contemplate the subject a little, and we shall find, that this adjustment, if attained by matter of a seeming stability in the forms, with a real and perpetual revolution or motion of parts, affords a plausible, if not a true solution of the difficulty.
It is in vain, therefore, to insist upon the uses of the parts in animals or vegetables, and their curious adjustment to each other. I would fain know, how an animal could subsist, unless its parts were so adjusted? Do we not find, that it immediately perishes whenever this adjustment ceases, and that its matter corrupting tries some new form? It happens indeed, that the parts of the world are so well adjusted, that some regular form immediately lays claim to this corrupted matter: and if it were not so, could the world subsist? Must it not dissolve as well as the animal, and pass through new positions and situations, till in great, but finite succession, it falls at last into the present or some such order?
Although extremely general, Hume is suggesting both a history and a mechanism. Hume posits conservation of motion or other similar laws of nature, presumably mathematical, and describes what will happen when you apply such laws to a world. Most situations are unstable, and precisely because they are unstable, they will not last, and other situations will come to be. But some situations are stable, and when such situations occur, they will last.
The need for conservation of motion or similar natural laws is not accidental here. This is why I included the first paragraph above, rather than beginning the quotation where Hume begins to describe his “new hypothesis of cosmogony.” Without motion, the situation could not change, so a new situation could not come to be, and the very ideas of stable and unstable situations would not make sense. Likewise, if motion existed but did not follow any law, all situations should be unstable, so no amount of change could lead to a stable situation. Thus since things always fall downwards instead of in random directions, things stabilize near a center, while merely random motion could not be expected to have this effect. Thus a critic might argue that Hume seems to be positing randomness as the origin of things, but is cheating, so to speak, by positing original stabilities like natural laws, which are not random at all. Whatever might be said of this, it is an important point, and I will be returning to it later.
Since his description is more general than a description of living things in particular, Hume does not mention anything like the theory of the common descent of living things. But there is no huge gulf here: this would simply be a particular application. In fact, some people have suggested that Hume may have had textual influence on Darwin.
While there are other anticipations (there is one in Immanuel Kant that I am not currently inclined to seek out), I will skip to Philip Gosse, who published two years before Darwin. As described in the linked post, while Gosse denies the historicity of evolution in a temporal sense, he posits that the geological evidence was deliberately constructed (by God) to be evidence of common descent.
What was Darwin’s own role, then, if all the elements of his theory were known to various people years, centuries, or even millennia in advance? If we look at this in terms of Thomas Kuhn’s account of scientific progress, it is not so much that Darwin invented new ideas, as that he brought the evidence and arguments together in such a way as to produce — extremely quickly after the publication of his work — a newly formed consensus on those ideas.