When, as in the higher mammals, the power of learning by experience is rapid, the individual organism is better able to adjust itself to the dangers of life, and once more there is less sacrifice of individuals in the struggle. The same organism persists: but of two possible types of behaviour, the unmodified innate type is eliminated, the type modified by experience survives. If we like to put it in a way which is perhaps not wholly justifiable, there comes into being, besides the struggle for existence between individuals, a struggle for existence between different possible modes of reaction of one and the same organism.
With the advent of man upon the scene, still new possibilities arise. First of all, he is capable of ideas, which, biologically speaking, are to be regarded as potentialities of behaviour. There is no evidence at present that even the highest animals possess ideas or even images.[25] Secondly, these ideas are transmissible by speech and writing, and accordingly tradition has come into being, so that modification of behaviour by experience can be operative not only within the individual life, not only from one generation to the next immediately succeeding, as in many mammals, but for an indefinite period. The experience of Moses, Archimedes, or Charlemagne, of Jesus, Newton, or James Watt is modifying our behaviour to-day.
The result, both for individuals and communities, is that a selection of ideas instead of a selection of organic units can to an ever greater extent take place; and thus the actual extinction of living matter be increasingly avoided. For instance, we find the substitution of judicial procedure, in which the ideas of two disputants about the matter in dispute are weighed and a selection made in favour of one, for various forms of violence and combat in which one or other of the actual disputants was often eliminated. Or again, in struggles between communities, even though warfare is still resorted to, yet it does not operate in the same way as in earlier stages of human evolution. A salient example of this is afforded by the result of the recent war to Germany; although an equally good instance can be seen, for example, in the Boer War. In primitive wars, the defeated tribe was wherever possible exterminated or enslaved: it ceased to exist as an independent unit, and the great majority of its male members were killed. This is impossible under present conditions: and all those who preserve, or have ever possessed, any political sanity aim, for instance, neither at the physical nor the economic destruction or subordination of Germany, but—to use one of those attractive catchwords that sounded so well in war-time—at her “change of heart”—in other words, the extermination, not of a nation, but of a national tradition.
To what extent this substitution of mental for physical will continue it is hard to say; already, to take another field, the multiplication of cheap books has led to an ever increasing number of men and women finding most of their adventure and romance in books instead of in the life that we are accustomed to call real. But that would lead us away from our main point—enough to have indicated another great difference between processes above and below the human level.
There are numerous important questions concerning our right to apply biological ideas of heredity directly to human beings which I would have liked to touch upon. But for one thing I have not the time, and for another, Mr. Carr-Saunders in his recent book on the Population Problem has dealt so fully with the relation between biological inheritance and what may be called tradition-inheritance, that I omit them with a good conscience.
In this brief treatment I have had to ask you to take conclusions on trust, without presenting the evidence on which they are based; this, however, is inevitable when transferring ideas from one science to another. I have attempted to show, first, that biology can profit by incorporating certain conclusions of sociology and so rounding off and completing certain of its own principles: on the other hand, I have put before you my belief that there are certain basic biological principles which must be taken into account by the sociologist—principles which hold good in sociology because man too is an organism.
By now, however, we can see more clearly the way in which the various sciences with which we are concerned, of whose relations we had something to say at the beginning of this essay, properly interlock.
They interlock thus. The physico-chemical sciences are basic to biology. Organisms are made of the same substances as are non-living compounds; their processes are therefore conformable to certain physico-chemical laws, such as the indestructibility of matter, the conservation of energy, and so forth; and in so far as we analyse the material aspect of life, physico-chemical concepts are adequate. On the other hand, physico-chemical concepts—or at least our present ones—are not all-sufficient. In the first place, the very complicated arrangement of matter which is found in living substance has not been yet sufficiently analysed by physics and chemistry: accordingly we find many processes occurring in biology—such as the directional changes in evolution of which we have spoken—which could not have been foretold on our present physico-chemical knowledge, but must be investigated separately as adding to our store of facts and principles, in the confident hope that a synthesis will one day be possible. Secondly, a whole new category of phenomena, the psychological, is first met with in biology, and to this we cannot as yet apply physical or chemical ideas at all.
For a combination of these two reasons, biology deals with certain concepts which are not implicit in current physico-chemical ideas. Physics and chemistry are basic for biology, but they are not exhaustive.
In a very similar way, biology is basic for sociology, but again not exhaustive. Certain limits are set to human life through man’s organic nature. Certain of his activities can be completely analysed in terms of biology. But other of his activities, especially those concerned with his new type of mental organization, find no counterpart in the rest of the biological kingdoms, and must be studied in and for themselves.