D.— ZOOLOGY 95 



reproduction, there is no hope of making the human species much more 

 innately altruistic than it is at present. 



Another example concerns the reproduction of the higher plants. In 

 them the pollen-grains may be affected in various ways, including the 

 rapidity of their growth down the style, by the genes they bear. As a 

 result of this, certation, or a ' struggle for fertilisation ' between genetically 

 different types of pollen-grain, often occurs. Nothing of the sort, 

 however, appears to take place in the sperm of higher animals, where 

 the genes exist in a condensed and apparently inactivated form. Thus 

 genes for rapid pollen-growth will be at a premium in plants, and their 

 effects may spill over into other phases of the life-history ; whereas in 

 animals no such effects can occur. 



It is a common fallacy that natural selection must always be for the good 

 of the species or of life in general. In actual fact we find that intra- 

 specific selection frequently leads to results which are mainly or wholly 

 useless to the species as a whole. The protection afforded by a cryptic 

 or a mimetic resemblance of moderate accuracy might approach the limit 

 so far as its value to the species is concerned, if there were any way in 

 which selection could be restricted to effects on the species as a species. 

 Actually intra-specific competition between individuals will often lead 

 to the process of adaptation being continued until almost incredibly 

 detailed resemblances are reached — for instance, in some of the leaf- 

 butterflies. Such ' hypertely ' is sometimes held up as a disproof of 

 natural selection. In point of fact, it is to be expected from natural 

 selection when intra-specific. 



In other cases intra-specific selection may even lead to deleterious 

 results. This is especially true with intra-sexual competition, between 

 members of the same sex of the same species. When polygamy or 

 promiscuity prevails, the selective advantage conferred by characters 

 promoting success in mating will be very high indeed ; and accordingly 

 in such forms (for instance, peacock and Argus pheasant) we meet with 

 male epigamic characters of the most bizarre sort which, while advantaging 

 their possessor in the struggle for reproduction, must be a real handicap 

 in the struggle for individual existence. In such cases, of course, a balance 

 will eventually be struck at which the favourable effects slightly outweigh 

 the unfavourable ; but here again extinction may be the fate of such 

 precariously balanced organisms if the conditions change too rapidly. 



We may, however, go further and proclaim with Haldane that intra- 

 specific selection is on the whole a biological evil. The effects of com- 

 petition between adults of the same species probably, in his words, ' render 

 the species as a whole less successful in coping with its environment. No 

 doubt weaklings are weeded out, but so they would be in competition with 

 the environment. And the special adaptations favoured by intra-specific 

 competitions divert a certain amount of energy from other functions.' 



Intra-specific competition among pollen-grains has led to a real over- 

 production of pollen by anemophilous plants ; intra-sexual competition 

 among male mammals has led to unwieldy size or to over-developed 

 weapons and threat organs ; intra-specific competition among parasites 

 has led to their often monstrous exaggerations of fertility and complications 

 of reproductive cycle. 



