The World's Common Danger
AT best, our hungry descendants will be fighting for food within 260 years. At worst, our own children will, in eighty- five years, see the filling up of the world and the desperate struggle for bare existence which will ensue. The latter is more likely than the former.
These estimates of Sir George Knibbs seem to have created a sensation, though—as he himself would be the first to acknow- ledge—there is nothing substantially new in them. Indeed, only recently E. M. East, in his Mankind at the Crossroads, pursued much the same line of thought and reached practically identical conclusions. The value of the present book lies rather in the massing of weighty scientific support and in the terseness and clarity of the writing. Anyone can read it. Sir George sets out to estimate from his own and other men's work (1) how much, at a pinch, of the earth's land area could be brought under cultivation ; (2) how much food could be grown on it with all possible improvements in agriculture ; (3) in how many years the population of the world, at various rates of increase, would reach' the utmost limit set 'by the food supply. To-day we number 1,950 millions, and if we grew at 'the world-rate during the past century 'of 0.864 per cent., our descendants in 2169 A.n. would number 15,600 millions, a figure quite beyond the earth's resources. If we grew at the recent rate of the Western world, 1.16 per cent. per annum—by no means the highest rate of increase known—the limit would be reached between 85 and 150 years hence. Sir George establishes his case
beyond reasonable doubt, and greatly strengthens it by studied underStatement. He tells us 'the best, not the worst.
ko one, of course, Would expect mankind to grow to the limit, and then to stand still and starve. Long before then
death rates would start to rise and standards of living to fall, acute migration problems would flare "Up 'into Wars, and starvation, plague; and sudden death would thin the baitilions of humanity in 'the goad ald-fashiotied way: It is rather curious, incidentally, that Sir George, in discussing the extremely _ low rate of increase of mankind up to the industrial revolution, should incline to attribute it to cata-
clysms and devastating unknown plagues. It is sufficiently explained by the very high death rate" which is known to be normal among animals and primitive men. The lowering of that death rate and a consequently high rate of increase are, as he says, the unusual phenonienon ; though we, creatures of a day, tend to look upon it as normal and undisturbing.
Echoing bath Sir George and Mr. J. Maynard keynes, one can safely say that papulation "is not merely an economists' problem," but will in the " very near future be" the greatest of all political questions," national and international. Sir George therefore pleads for the setting aside of national egoisms, and foi 'United international action to tackle it before it comes acute: His tentative remedy is " constructive birth "'Control," which includes, but does not mean, contra- ception. It certainly involves, in his opinion, the checking of the fertility of the ' relatively " less fit " and very fecund. One Warideri; indeed, whether this,' the qualitative aspect, is not also the key to the whole problem. It should not be over difficult for populations of well bred and well educated citizens to control themselves, though it would be quite imposeible to check the reproduction of a seething mass of people little higher than the beasts.
Sir George makes some particularly useful criticisms of the too-rigid " logistic curve " which Professor Pearl believes to describe population growth, though he is wrong in assuming (as he appears to do) that the food supply was the limiting factor in the latter's experiments. At the same time, he tends to support the main implication of Pearl's work, that its own density is the factor, which governs the increase of a population. This is significant, for Sir George is one of the most cautious and experienced of the world's statisticians.
This theory has a very practical bearing on immediate migration problems, since to relieve density by large-scale migration will only speed up natural increase in the emigrating country, while perhaps damping it down in the country of immigration. Therefore, as Sir George points out, it can only be a temporary relief for local population problems. He does not add what is very possibly true, that migration may thus even bring nearer the day of World saturation. It Populates the few remaining vacant spaces, while removing a check on the increase of overpopulated countries. He emphasizes that even the temporary relief afforded by migration is lately offset by economic difficulties and by the barriers of language, race, and social custom.
Quite a little book, but it may be described as Jimmy Wilde once was (by a dazed opponent), as " a ghost with a 'anuner in his fist." It has " punch " and goes straight to the point.
EL DON MOORE.
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