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From Cold-Blooded To Warm-Blooded

( Originally Published 1940 )

We have seen in Chapter 40, there was once a time when all living organisms were asexual. Those self-satisfied people, wrapped in smug ignorance, who pose as apostles of morality, must secretly rejoice to think of this stage when this was the only mode of reproduction guaranteed free from all sexual desire! When there was nothing but cell-division.

In these primeval times the lower algae and fungi represented the highest forms of vegetable life,(1) but even then these aquatic and moisture-loving flora must have shown quite graceful lines; for although the flora in that far-off age was not yet crowned with flowers, the lower forms were richly varied, and water-plants, because their weight is supported by the water, could at least attain a higher degree of elegance than land-plants, which are constantly exposed to the wind. But since all sexuality was absent, a certain coldness must have reigned, something like simulated death, or perhaps one might better say, like the Sleeping Beauty waiting for Prince Charming.

The later fusion of two similar cells, as in the conjugatae, looks already a little more promising. For here there was already a fusion, such as is the ideal of all lovers; and it was still without any inequality of rights or any other inequality, for both parties to the fusion were then equal in character and form. But this sort of equality was a little monotonous.

The appearance of hermaphridism is far more seductive: a difference of sex, but each of the partners can function as either husband or wife, or sometimes both at once! And still no pride of sex or sexual rivalry; for all individuals are still double-sexed, not simply temporarily as we men are in our embryonic stage, but perfectly formed, in a double ecstasy.

That our earth-worms and garden-snails are not insensible to love, we can perceive from their untiring patience in mating, and their loving behaviour before copulation; snails seem never tired of kissing each other! But then their kissing had another significance besides the symbolical one, for in these species, the genital organs lie near their heads! And they can make love to each other half the day without making a sound, revelling the whole time in double ecstasy. For them there is no question as to which is the more blessed, to give or to receive, for they both do both at once!

And yet it is far more romantic, if less Arcadian, when the division of the sexes compels each partner to seek a mate of the opposite sex. And how much more has variety in the Iove-life occurred since that time! In the plants it is still unconscious, in the lower animals only half-conscious, and the higher we mount in the scale of animal evolution the more conscious it becomes.

But a very long time elapsed before the slightest trace of tenderness was perceptible in the sexual relations.

At first copulation signified only the voluntary expulsion of the reproductive cells with the mutual help of the other partner, an evacuation, when the tension had become too great; nothing but a purely excretory function. A little while after fertilisation, the female laid the fertilised eggs in a quiet, sunny, safe place, where she would not be disturbed during this lonely excretory function, and did not trouble any further about them. And these eggs hatched out in due time by the sun in a spot as sheltered and as safe, as if the place had been chosen with motherly foresight for the well-being of the new brood.

It is scarcely possible to observe parents caring for their offspring earlier in the evolutionary scale than the vertebrates. Even in some fishes there is already evidence of paternal care in the building and guarding of nests. Some reptiles cover their eggs with moss and leaves; some of the snakes coil themselves up over their heap of eggs as if to protect them; mother-crocodiles sometimes carry their young about with them.

Nor is there in the lower species any trace of enduring friendship or lasting love between the two parents; they separate after copulation and trouble about each other no further. Frogs and most fishes do not even have any internal mode of copulation, but both sexes simply shed their sexual product into water. But they perform their excretory function in communistic voluptuousness; the fishes by swimming close together in shoals, the frogs very pedantically by assuming the traditional attitude of a pairing couple, but really like the fish with external massage only.

Thus the reproductive cells are simply shed into water by both sexes, generally in a sheltered and sunny spot, where the reproductive process may proceed undisturbed and unlimited.

A few of the water-toads stay together from the time of copulation until the Iaying of the eggs; and the male of the Surinam toad (pipa Americana), assists the female to lay her eggs.

But it is only in warm-blooded animals that we find really affectionate care bestowed on the young, of sitting on the eggs or warming the young that have been born alive; parents often living together and affording each other mutual help, especially in the birds. The tender affection that a pair of birds will show for each other, and the care that they take first of the eggs and then of their young might put many a human couple to shame. In mammals it is mostly the mother which does everything for her young ones, and must even sometimes shield them from the brutality of their father, but sometimes it is the father that protects the whole family.

Thus we see here two new important factors coming into operation at the same time in the history of evolution: a higher development of the sexual life and the occurrence of warm-bloodedness. We may now enquire whether there is any connection between these two factors. I am of opinion that an interchange of cause and effect cannot be denied.

In the course of evolution so long as the excretion of reproductive cells, mating and laying eggs were comparatively simple matters, the parents needed but little mutual help: and because this most powerful and intimate stimulus of life-energy was Iacking, the increased oxidation it would have caused was also lacking and the animals remained cold-blooded.

Warm-bloodedness must vice versa stimulate sexuality. We have already seen (chapter 32) that increase of temperature is a most effective sexual stimulant, and in Chapter 29 that in the procreative act the mutual warmth of the parents plays an essential part. But mutual warmth is found agreeable in other circumstances also, not only as a protection against chill, but also as a reminiscence of former mating and a foretaste of the next, and so altruistic. And the protective warmth of the parents' bodies is indeed indispensable for the young brood.

Let us first try thoroughly to realise what is the position of a warm-blooded organism. Warm-blooded means that the organism has a temperature considerably higher than its surroundings and so is always in danger of losing its body-heat. Against this a warm skin-covering or nest can only provide a relative protection, i.e., a postponement of the cooling. In the life of wild animals, and also that of men up to the time of the discovery of fire, the mutual warmth of bodies in contact was the only regular and permanent source of heat, whenever the animal could not maintain the usual and necessary heat though its own resources; the ingestion of food and the oxidation in the lungs, e.g., during the night and in the winter-time.

So then the companionship of the parents among warm-blooded creatures grew to be a lasting delight, which indeed attained its height in the procreative act, but was still at all times an emotional delight. The procreative act is now the climax of emotion. Thus the sexual impulse has been directed into emotional paths.

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