Already the question—What constitutes advance in the evolution of conduct, as we trace it up from the lowest types of living creatures to the highest? has been answered by implication. A few examples will now bring the answer into conspicuous relief. (§4 ¶1)

We saw that conduct is distinguished from the totality of actions by excluding purposeless actions; but during evolution this distinction arises by degrees. In the very lowest creatures most of the movements from moment to moment made, have not more recognizable aims than have the struggles of an epileptic. An infusorium swims randomly about, determined in its course not by a perceived object to be pursued or escaped, but, apparently, by varying stimuli in its medium; and its acts, unadjusted in any appreciable way to ends, lead it now into contact with some nutritive substance which it absorbs, and now into the neighbourhood of some creature by which it is swallowed and digested. Lacking those developed senses and motor powers which higher animals possess, ninety-nine in the hundred of these minute animals, severally living for but a few hours, disappear either by innutrition or by destruction. The conduct is constituted of actions so little adjusted to ends, that life continues only as long as the accidents of the environment are favourable. But when, among aquatic creatures, we observe one which, though still low in type, is much higher than the infusorium—say a rotifer—we see how, along with larger size, more developed structures, and greater power of combining functions, there goes an advance in conduct. We see how by its whirling cilia it sucks in as food these small animals moving around; how by its prehensile tail it fixes itself to some fit object; how by withdrawing its outer organs and contracting its body, it preserves itself from this or that injury from time to time threatened; and how thus, by better adjusting its own actions, it becomes less dependent on the actions going on around, and so preserves itself for a longer period. (§4 ¶2)

A superior sub-kingdom, as the Mollusca, still better exemplifies this contrast. When we compare a low mollusc, such as a floating ascidian, with a high mollusc, such as a cephalopod, we are again shown that greater organic evolution is accompanied by more evolved conduct. At the mercy of every marine creature large enough to swallow it, and drifted about by currents which may chance to keep it at sea or may chance to leave it fatally stranded, the ascidian displays but little adjustment of acts to ends in comparison with the cephalopod; which, now crawling over the beach, now exploring the rocky crevices, now swimming through the open water, now darting after a fish, now hiding itself from some larger animal in a cloud of ink, and using its suckered arms at one time for anchoring itself and at another for holding fast its prey; selects, and combines, and proportions, its movements from minute to minute, so as to evade dangers which threaten, while utilizing chances of food which offer: so showing us varied activities which, in achieving special ends, achieve the general end of securing continuance of the activities. (§4 ¶3)

Among vertebrate animals we similarly trace up, along with advance in structures and functions, this advance in conduct. A fish roaming about at hazard in search of something to eat, able to detect it by smell or sight only within short distances, and now and again rushing away in alarm on the approach of a bigger fish, makes adjustments of acts to ends that are relatively few and simple in their kinds; and shows us, as a consequence, how small is the average duration of life. So few survive to maturity that, to make up for destruction of unhatched young and small fry and half-grown individuals, a million ova have to be spawned by a cod-fish that two may reach the spawning age. Conversely, by a highly-evolved mammal, such as an elephant, those general actions performed in commoa with the fish are far better adjusted to their ends. By sight as well, probably, as by odour, it detects food at relatively great distances; and when, at intervals, there arises a need for escape, relatively-great speed is attained. But the chief difference arises from the addition of new sets of adjustments. We have combined actions which facilitate nutrition—the breaking off of succulent and fruit-bearing branches, the selecting of edible growths throughout a comparatively wide reach; and, in case of danger, safety can be achieved not by flight only, but, if necessary, by defence or attack: bringing into combined use tusks, trunk, and ponderous feet. Further, we see various subsidiary acts adjusted to subsidiary ends—now the going into a river for coolness, and using the trunk as a means of projecting water over the body; now the employment of a bough for sweeping away flies from the back; now the making of signal sounds to alarm the herd, and adapting the actions to such sounds when made by others. Evidently, the effect of this more highly-evolved conduct is to secure the balance of the organic actions throughout far longer periods. (§4 ¶4)

And now, on studying the doings of the highest of mammals, mankind, we not only find that the adjustments of acts to ends are both more numerous and better than among lower mammals; but we find the same thing on comparing the doings of higher races of men with those of lower races. If we take any one of the major ends achieved, we see greater completeness of achievement by civilized than by savage; and we also see an achievement of relatively numerous minor ends subserving major ends. Is it in nutrition? The food is obtained more regularly in response to appetite; it is far higher in quality; it is free from dirt; it is greater in variety; it is better prepared. Is it in warmth? The characters of the fabrics and forms of the articles used for clothing, and the adaptations of them to requirements from day to day and hour to hour, are much superior. Is it in dwellings? Between the shelter of boughs and grass which the lowest savage builds, and the mansion of the civilized man, the contrast in aspect is not more extreme than is the contrast in number and efficiency of the adjustments of acts to ends betrayed in their respective constructions. And when with the ordinary activities of the savage we compare the ordinary civilized activities—as the business of the trader, which involves multiplied and complex transactions extending over long periods, or as professional avocations, prepared for by elaborate studies and daily carried on in endlessly-varied forms, or as political discussions and agitations, directed now to the carrying of this measure and now to the defeating of that,—we see sets of adjustments of acts to ends, not only immensely exceeding those seen among lower races of men in variety and intricacy, but sets to which lower races of men present nothing analogous. And along with this greater elaboration of life produced by the pursuit of more numerous ends, there goes that increased duration of life which constitutes the supreme end. (§4 ¶5)

And here is suggested the need for supplementing this conception of evolving conduct. For besides being an improving adjustment of acts to ends, such as furthers prolongation of life, it is such as furthers increased amount of life. Reconsideration of the examples above given, will show that length of life is not by itself a measure of evolution of conduct; but that quantity of life must be taken into account. An oyster, adapted by its structure to the diffused food contained in the water it draws in, and shielded by its shell from nearly all dangers, may live longer than a cuttlefish, which has such superior powers of dealing with numerous contingencies; but then, the sum of vital activities during any given interval is far less in the oyster than in the cuttle-fish. So a worm, ordinarily sheltered from most enemies by the earth it burrows through, which also supplies a sufficiency of its poor food, may have greater longevity than many of its annulose relatives, the insects; but one of these during its existence as larva and imago, may experience a greater quantity of the changes which constitute life. Nor is it otherwise when we compare the more evolved with the less evolved among mankind. The difference between the average lengths of the lives of savage and civilized, is no true measure of the difference between the totalities of their two lives, considered as aggregates of thought, feeling, and action. Hence, estimating life by multiplying its length into its breadth, we must say that the augmentation of it which accompanies evolution of conduct, results from increase of both factors. The more multiplied and varied adjustments of acts to ends, by which the more developed creature from hour to hour fulfils more numerous requirements, severally add to the activities that are carried on abreast, and severally help to make greater the period through which such simultaneous activities endure. Each further evolution of conduct widens the aggregate of actions while conducing to elongation of it. (§4 ¶6)