Welsh Journals

their analysis and classification finally, their interpretation. In the unceasing struggle for existence favoured variations would tend to be preserved and unfavoured ones to be destroyed- this, thought Darwin, was the key to all the wonderful diversity and beauty of the world in which we live. If any small variation appeared in an individual of a species, in the direction of greater strength which made that individual more powerful than his neighbours, or in the direction of greater beauty which made him more attrac- tive as a mate in the sight of his neighbours, or in the direction of greater cunning which enabled him in some way to take advantage of the innocence of his neighbours, that small variation would give him a better chance than others to survive and to perpetuate his kind. Hence, if like begets like, that variation would also be passed on, and, assuming the environment continued favourable, in the course of countless generations so great a change would have taken place that a new species would have come into existence, far excelling the original in strength or beauty or cunning or whatever faculty it was which gave the first individual of the species an advantage over his neighbours in the struggle for existence. I would emphasise one point here: good qualities no less than bad may, according to this theory, be of advantage to their possessor, but, as society becomes more moral-and I believe it is progress- ing in that direction, though progress seems often painfully slow-we shall set a higher price on the nobler qualities and competition will be raised on to a loftier plane. Now that ideal seems remote at present and if we are to wait while small variations are slowly evolved and accumulated on the Darwinian plan we must feel at times impatient if not hopeless. I will therefore turn to consider other aspects of the subject which have been developed by the statistical method to see if any more encourage- ment is to be found. Just as many people imagine mathematics to be no more than a kind of glorified arithmetic, so there are some who associate the idea of statistics simply with masses of figures collected into tables and bound up in blue books. And indeed, as a science with refined methods, we only need go back to the time when Darwin and Wallace were engaged upon their researches to find its beginning, which we owe to a Belgian, Adolphe Quetelet. One idea which Quetelet introduced was that all men can be graded in respect of any quality they possess in common. For instance, pick 1,000 men at random and they can be arranged in order of ability, judged in whatever way we please. At one end of the scale we shall find a few geniuses, then a group who can be classed as very bright, then a larger group who can be classed as bright, then a still larger group of average intellect beyond them come the dull, the very dull, and finally, right at the opposite end of the scale to the geniuses, the feeble- minded and idiots. We might, in fact, picture the whole of society, so far as the distribution of intelligence is concerned, by a bell-shaped curve like the different grades being arranged at equal intervals along a straight line and the height of the curve at different points above this line being proportional to the numbers in the corresponding groups defined below. The representative man, or the man most typical of the whole population so represented, is the man of average intellect the measure of whose ability is given by the position of the point on the base line which lies immediately below the summit of the curve. This curve is known as a normal curve, and it is found that many physical characters, e.g., stature, weight, length of forearm, size of head, conform in their distribution to such a shape. No doubt many mental and even moral qualities could be pictured in precisely the same way, giving us a photograph of society at any par- ticular time in regard to any particular quality and showing how that quality is distributed throughout the population. Francis Galton, a cousin of Charles Darwin, did much to extend Quetelet's methods, and he applied them in particular to the study of heredity. A photograph of society as it exists at any moment is not enough if we want to understand it properly we must have a film of it-we must see it changing its form as one generation succeeds another. So Galton set out to try and discover what measure of relationship exists between parents and their children in the possession of any particular quality. Take, for instance, stature. If we pick out a number of fathers who are taller than the average and measure the heights of their grown-up sons, it is found that the sons, too, are taller than the