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4 The Selective Cause

In the struggle for existence there must have been some strong advantage attendant upon individual causal memory to render possible its survival and triumphant evolution. At the very outset of this investigation one is, therefore, met by the questions: How did this type of mind come to be selected? What were the advantages which it conferred upon a species?

All transformations in organic matter, all modifications of organ function brought about by natural selection, are specialisations. That is to say, every modification is selected to react favourably under certain definite sets of natural conditions, and the organism in which such modification has been selected is limited, as far as that modification is concerned, to the special set of natural conditions which selected it. It is under these conditions only that it confers a real benefit upon the possessor.

Some specialisations may appear to be more extensive adaptations to natural conditions than others, but in any case it is only in a relative sense that a modification can be described as general. However widespread these conditions may be, the modification which embraces them is nonetheless a specialisation, and

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the limitation of the organism to the specific environment in which these selecting conditions exist is an inevitable condition.

No specialisations in nature are without an attendant number of disadvantages. Whether the specialisation continues and the attendant disadvantages are eliminated by selection of course depends upon their relative values in the struggle for existence. But even the elimination of a disadvantage can only be effected by fresh specialisation. There is no such thing in nature as an organism in perfect accord with its environment. Even the highest adaptations are never ideal. In ultimate analysis, this practical truth rests upon the certainty that all the laws of the inanimate universe are inherently hostile to organic life. The struggle of life is not, as it often appears in popular conception, merely the struggle of the organism against competing fellows. From its inception, an organism struggles against opposing laws of matter which make for dissolution and the hindrance of growth. Organic evolution is at best but the line of least resistance. Selection is not so much the preservation of the fit as it is the destruction of the unfit. For the fit it is not so much a conquering invasion as a lucky escape.¹⁰

But it is, after all, the restriction to a definite environment which constitutes the main disadvantage which every adaptation drags after it. The more highly an organism is adapted to struggle against a certain set of natural conditions, the more effectively is it confined to the environment in which those conditions exist. That is the universal law. The higher the adaptation to one environment, the more complete is the discord under a suddenly changed one. And since the natural conditions which select modifications are very often local - especially so with the higher mammalia - the effect of such organic reactive adaptations is to impose often a local as well as an environmental limitation upon the possessors. It is, in fact, difficult to escape the conclusion that one great tendency of natural selection is to localise as well as to specialise.

It is a general law of nature that a suddenly changed environment means destruction, and it has been practically illustrated in numberless instances in this continent of rapidly changing natural conditions. Reference has already been made to the inability of drought-affected otters to exist outside their natural environment even in the presence of abundant food for which they have not been specialised. But the destruction of species is due on a far greater scale to the changed conditions attending man's advent. We have watched the dwindling and extermination of one great species after another, species that perished because they could not change their environment. The vast herds of bontebok (Damaliscus pygargus), blesbok (Damaliscus albifrons), springbok (Antidorcas marsupialis marsupialis) and black gnu (Connochaetes gnou) which at one time covered the great inland plains of Africa from horizon to horizon are on the verge of extinction or have vanished because they were unable to exist in the

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Bushveld which lay as a harbour of refuge before them. There is the same food, the same water, the same climate, and numbers of other great species could and did take advantage of this means of escape and still live. But these unfortunates were so highly specialised for the open plains that existence in the bush was impossible for them. One little factor - the treelessness of a locality - decided their fate.

In Waterberg it is possible at present to study this singular type of development closely. Large herds of springbok have always existed on the Springbok Flats. These flats are a small island of level, open country about sixty miles long by sixty wide, in a sea of bushveld. The open country and the bushveld merge almost imperceptibly into each other. Of late years the flats have become settled by farmers and the springbok are rapidly approaching extinction. A single step divides them from safety and they cannot take it.

There is also the instance of a herd of giraffe driven by hunters into a treeless portion of the Highveld from which escape was difficult. Great herds of other big game, with which the giraffe commonly associates in the bush country, lived there. The pasturage was good (and the giraffe can feed on grass), water was plentiful and yet within a few years the entire herd had perished.

It is sometimes a very slight and apparently insignificant morphological modification which decides the fate of an animal under a changed environment. Very often it is not even apparent, and such is certainly so with respect to the springbok mentioned.

Organic modification, however, is never as powerful in limiting an animal to a certain environment as psychic specialisation. An instinct is in this respect tyrannous. Where it is a dominant factor in behaviour, an animal will overcome the fear of death itself - that strong determinant of action - rather than violate the inborn direction. In nearly all the examples of non-primate behaviour I have described, this compelling power of hereditary memory will be apparent. Nature abounds with instances. I might add to these a classic illustration, that of the Galapagos lizard (Amblyrhynchus cristatus) described by Darwin in his Journal of Researches. It is an amphibious animal and spends most of its time in the sea. It swims and dives with just the same ease and perfection that it moves on land. It feeds chiefly on seaweed and goes long distances out to sea to procure it. It can remain under water for at least an hour. Now, it happens that all its natural enemies live in the sea. On land it is quite safe from predatory foes, or rather was until man arrived on the scene. So a hereditary memory was therefore selected and when danger threatened the lizard had to reach the shore in order to be safe. If the animal is frightened on land, it will not enter the water but persist in trying to get inland. Even when cornered on the beach, it will allow itself to be caught and handled rather than enter the sea, and if, when caught, it is flung into the water, instead of swim-

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ming out to sea, it at once hurries back to land and climbs out on to the rocks.

But it is not necessary to multiply instances in order to make clear the power of hereditary memory. It is a thing that can be proved experimentally by very simple means in the case of every animal whose behaviour is dominated by this type of mind.

It will be seen that from the given facts a very general rule is deducible:

Below the order of primates an animal can seldom acquire an individual causal memory of sufficient force to inhibit the action of an hereditary one. Where an instinct is replaced or modified in nature, it is done not by the acquisition of an individual causal memory but by the evolution of a fresh hereditary memory through natural selection. It is only when we reach the order of primates that we find as a general process non-hereditary causal memories immediately replacing and modifying the action of hereditary memories.

Among the mammalia the disadvantages attendant upon all specialisations are therefore far more irremediable in the case of instinct than one can conceive it to be where mere morphological modification is concerned. Even in cases where instinct is strictly correlated to organic structure it seems evident that the bodily specialisation never so surely confines an animal to a limited environment as the attendant instinct. The one is, in the nature of things, rarely an insurmountable obstacle; the other cannot be overcome.

If now we picture the great continent of Africa with its extreme diversity of natural conditions - its high, cold, treeless plateaux; its impenetrable tropical forests; its great river systems; its inland seas; its deserts; its rains and droughts; its sudden climatic changes capable of altering the natural aspect of great tracts of country in a few years - all forming an apparently systemless chaos, and then picture its teeming masses of competing organic life, comprising more species, more numbers and of greater size than can be found on any other continent on earth, is it not at once evident how great would be the advantage if under such conditions a species could be liberated from the limiting force of hereditary memories? Would it not be conducive to preservation if under such circumstances a species could either suddenly change its habitat or meet any new natural conditions thrust upon it by means of immediate adaptation? Is it not self-evident that in a species far-wandering, whether on account of sudden natural changes, competitive pressure, or through inborn ‘wanderlust’, those individuals which could best and most quickly adapt themselves to the most varied conditions would be the ones most likely to survive and perpetuate the race, and that among species, one equipped for distant migrations would always have a better chance than a confined one? Are not all the elements present to bring about the natural selection of an attribute by means of which a species could thus meet and neutralise one of the most prolific causes of destruction?

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This is not advanced as a demonstrable theory. It is no more than an attempt to show that it is hardly possible to imagine conditions existing anywhere in nature at any time which would not in some degree tend towards the evolution of such an attribute. If these present conditions are self-evidently likely to select it, how much more likely, for instance, would not its birth and growth have been during the earlier history of the planet, during the Pleistocene period, when cataclysmic movements of its crust and great and repeated climatic changes still belonged to the usual and customary category of natural events.

What then would be the nature of the attribute which would have to be selected in order to realise this advantage? I think that I have made it clear that no mere somatic change, except in one respect, could attain it. No generalising perfection of hand or foot, nor the attainment of the upright position, nor the transformation of any function in any single organ could render a species immune from the danger inherent in suddenly changing natural conditions. It is not conceivable that it could have been attained in any other way than through a modification of the brain and its functions. In other words, the attributes selected had necessarily to be psychic.

The first step was the selection and perfecting of a mentality capable of individual causal memory. And the probable course of its evolution can be read in the stages of this mentality discernible in different existing species. From its first glimmerings in the lowliest vertebrate, through the high stage attained in the mammals, to its perfection in the primates, is reproduced the course it ran through the ancestors of the highest primates. The accumulated causal memories themselves were not hereditary. If they had been selected, it would at once have re-subjected a species to the disadvantage of limitation. The causal memories inherited by offspring would have reacted favourably only under the conditions which created them. To me this seems the only reason why accumulated causal memories were not selectively rendered hereditary just as instinctive ones were.

The next step was the obliteration of the mentality which inherits environmental memories. It will be seen later that where there is dual control - as in the lower monkeys - the analysis of behaviour invariably creates the impression of an apparent conflict, and it seems an inevitable conclusion that those individuals least burdened with phyletic memories are the ones most likely to survive. The least reflection will show that this must be so in the case of all animals in which the new mentality has taken shape as a determinant of action.

However, instead of heredity in the new environmental memory, another benefit was conferred. If the animal had had to acquire its own memories by direct individual experience only, it would have been subjected to many new disadvantages. It would individually have had to meet every environmental danger, it would have had to discover for itself every possible food supply and

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the best means for utilising it, before its memory could have been of any assistance. An average mammalian life-time would hardly have sufficed to adapt such an animal effectively to its environment. If such a species possessed no hereditary environmental memories, each individual would have had to adapt itself to existence in this laborious fashion, no matter whether the environment into which it was born was an ancient or recent one. Under such circumstances an animal with the most highly developed causal memory would hardly have had the same chance as the animal that enters upon life furnished with all the most essential environmental memories. But inherent in the new mentality is the element of tradition. It is in reality only a consequence of the normal activity of the causal memory, but it has the result of enabling an animal to reap the benefit of the accumulated memories of its ancestors without the need of direct experience. In the highest primate, articulate speech has enormously increased the scope and extended the benefit of tradition. The general effect of tradition therefore is equivalent to the general effect of hereditary memory. It is hereditary memory without the sting of limitation.

There was, of course, no sudden leap in the inception of the new mind. It was a thing of infinite gradations and stretches away through vast periods of time. The mills of God grind slowly and very uniformly. This de-specialising tendency is, in fact, as widespread as organic life itself. It is only when we reach the order of primates, however, that the new mind emerges for the first time to take a great or even a controlling share in generally determining the animal's reaction to its environment. And it is here that we encounter for the first time behaviour clearly under dual control. It is the same duality of control that we see in the human child when individual memory first becomes active. In the lower African arboreal monkeys this psychic doubling can be clearly studied in many different stages.

There are species where the individual grows up equipped with many important hereditary environmental memories while the causal memory is also active. For instance, a considerable number of vervet monkeys (Ceropithecus aethiops pygerythrus), reared in captivity, grew up with fairly complete hereditary memories. They all knew their natural food, where to look for it, and how best to utilise it. They had a clear knowledge of environmental dangers. The larger African eagles - their worst natural foe - were instinctively recognised, and were guarded against in the only possible manner - that is, by dodging under thick branches. Beasts of prey were also hereditarily recognised, but here hereditary memory was not as clearly directed as in the non-primate gregarious mammals. A donkey, for instance, when seen for the first time, caused just as much terror as a leopard. The sexual sense was invariably correctly directed by hereditary memory.

There is, in fact, not a very great difference between them and the higher

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gregarious mammals as far as the activity of the instinctive mentality is concerned. But the difference becomes more than conspicuous when we come to consider the degree of development attained by the causal memory. The vervet is certainly not as ‘clever’ as the chacma. It is slower to accumulate individual memories and its comprehension of causality in the individual memory is not as perfect as in the chacma.

If in the vervet the ‘dual control’ is so equally divided that it is almost impossible to say to which side the balance swings, then it is in the chacma that the process of submergence of the instinctive mentality first becomes clearly apparent. Here for the first time individual memory assumes dominant control of the mind. And there is a further singular difference between the chacma and the vervet in respect of the instinctive mentality. In the vervet there is great uniformity of instinctive behaviour; in the chacma there is great individual variation: that is to say, all the artificially reared vervets showed the same degree of hereditary memory. In the chacma, individuals are found that are almost as completely equipped with hereditary memories as the vervet; but a large percentage lack even the most essential ones. Generally speaking, it is the ‘clever’ chacma that is without phyletic memories. The ‘stupid’ ones are sometimes highly instinctive.