Trait (biology)

“ There are those that so believe, as well as those who see in them only the effects of inborn biological impulse. Perhaps these intermediate dubious traits are the results of a blending of nature and nurture, the strength of each factor varying according to each trait or individual examined. ”

“ Living matter is characterised by its innate tendency to exhibit a definite series of the morphological and physiological phenomena which constitute organisation and life. Given a certain range of conditions, and these phenomena remain the same, within narrow limits, for each kind of living thing. They furnish the normal and typical character of the species, and, as such, they are the subject-matter of ordinary biology. ”

“ Though The Origin of Species proved to me that the transmission of acquired characters cannot be the sole factor in organic evolution, as I had assumed in Social Statics and in The Principles of Biology, published in pre-Darwinian days, yet I have never wavered in the belief that it is a factor and an all-important factor. ”

“ Not only are they still in the strictest sense the biological head-quarters: they are also the standard or central type by which we must explain all the rest of nature, both in man and beast, in plant and animal. ”

“ Since the number of hereditary traits is legion, including not only the size and shape of all parts of our bodies inside and out, but our mental peculiarities and moral tendencies as well, there must be a huge number of controlling factors, or determiners, as they are often called. As a matter of fact, there are probably not quite so many determiners as traits, because a single determiner may govern more than one trait. ”

“ Individuals unquestionably exhibit modifications intended not for their own personal benefit, but for that of the species—for instance, the maternal instincts. The modification of a part in the interest of the whole to which it belongs may, perhaps, turn out to have the same essential significance whether the part is an organ or instinct belonging to the synthesis called an individual, or an individual belonging to the synthesis called a species, or a species belonging to some fauna or flora of the globe. ”

“ Finally, we must derive from this philosophy of biology the assurance that the generalizations which it offers to us are grounds upon which we can stand securely in our deductions—of course within the province of biology—respecting man and the human species. ”

“ We know the gross form of the specimens; we know something of their habits during life; and yet how little is this of what there is to be known about them. Who is there of the most learned who can properly explain the meaning of one hundredth part of what these creatures present in form, size, colour, and intimate structure? We have a general idea that their special peculiarities have relation to the two primary essentials of life—the daily bread, and the perpetuation of the species—but we are largely unable to explain the raison d’etre of many of the commonest facts which they present. ”

“ What interpretation is to be put on these truths of classification? We find that organic forms admit of an arrangement everywhere indicating the fact, that along with certain attributes, certain other attributes, which are not directly connected with them, always exist. How are we to account for this fact? And how are we to account for the fact that the attributes possessed in common by the largest assemblages of forms, are the most vitally-important attributes? ”

“ Thus in reasoning from biology to social problems, it is fundamental to remember that man as an animal is tremendously differentiated in functions, and that most of the activities we look upon as distinctively human depend upon the body rather than the germ-cells. ”

“ We are limited, not by the nature of our method, but by the whole nature of the case, to the comparison of organisms such as are manifestly related to one another and belong to the same zoological class. ”

“ Take, for instance, the immense difference in capacity and in character found within the limits of the human race.
In all plants and in all animals the characteristic qualities of species may vary, but within comparatively narrow limits; so also with man, so far as his outer form, his instincts and his animal passions are concerned. ”

“ Would we not have to attribute to each constituent of this living substance the properties which we now attribute to the whole?--that is, the properties which we attribute to masses of protoplasmic units, such as plants, or birds, or human beings?
We look at ourselves and we feel sure that we have a separate and real existence, that we are rationally conscious and are endowed with choice and free will. We can say almost as much for an intelligent bird or dog. ”

“ Dealing with biology in its general principles, it concerns us only to notice how specially sensitive are the substances of which organisms are built up to the varied influences that act upon organisms. ”

“ A trait that is desirable can be perpetuated indefinitely by this means, even though it may be a blending of several hereditary traits, which would separate out in a few generations by ordinary means of propagation. ”

“ It clings to all our conceptions of living things: quite as much, for example, to the evolution of an animal with all its parts from a one-celled germ, or to the connection of brain-cells with the manifestations of intelligence. ”

“ Where the properties of an object are known to be closely interdependent, as in the organisation of plants, animals and societies, we are especially justified in inferring from one case to another. The whole animal Kingdom has certain common characters—the metabolic process, dependence upon oxygen, upon vegetable food (ultimately) , heredity, etc., and, upon this ground, any process (say, the differentiation of species by Natural Selection) that has been established for some kinds of animal is readily extended to others. ”

“ The effects of the struggle to survive, which here prompts a simpler life with resulting degeneracy and there a different life with resulting new developments, are far from being the only causes of morphological obscurations. Fulfilment of certain highly general requirements gives certain common traits to plants of widely divergent classes; and fulfilment of certain other highly general requirements gives certain common traits to animals of widely divergent classes. ”

“ I ought to have made this admission expressly; with the reservation, however, that, as far as I can judge, no theory so well explains or connects these several generalizations (more especially the formation of domestic races in comparison with natural species, the principles of classification, embryonic resemblance, etc.) as the theory, or hypothesis, or guess, if the reviewer so likes to call it, of Natural Selection. Nor has any other satisfactory explanation been ever offered of the almost perfect adaptation of all organic beings to each other, and to their physical conditions of life. ”

“ From the simple organism you ascend step by step to those that are more complex, in order, in the end, genetically to form the most complicate of all—man—out of the materials of nature as a whole. By thus, as it were, imitating nature in creating him, you try to penetrate into his hidden structure. ”

“ The problem is first to be defined.
It is evident that all characters which make up a man or woman, or any other organism, must be either germinal or acquired. It is impossible to conceive of any other category. ”

“ But it is not sufficient to give the explanation of the cause which has brought about the condition of the organs of different animals—a condition which we see to be always the same in those of the same species; we must besides observe the changes of condition produced in the organs of one and the same individual during its life, by the single result of a great change in the special habits in the individuals of its species. ”

“ As we observe the various orders of plants and animals, we find that in the lower forms of life, in vegetable or animal, the male and female principles are embodied in one individual; and that individual, being entirely capable of reproducing the species to which he belongs, stands as a perfect representative of that kind or species. ”

“ Biological truths and their corollaries, presented under these special forms as bases for sociological conclusions, are introductory to a more general biological truth including them—a general biological truth which underlies all rational legislation. I refer to the truth that every species of organism, including the human, is always adapting itself, both directly and indirectly, to its conditions of existence. ”

“ But whether or not I may be able to explain the appearance of the features which distinguish races from each other, and whatever origin may be attributed to them, I shall only take the word character in the sense which is given to it in botany and zoology.
III. An animal species is not characterised solely by the peculiarities manifested by its physical organism. No history of bees or ants omits to speak of their instincts, or to show how these differ in different species. ”

“ Everything combines then to prove my assertion—namely, that it is not the form, either of the body or of its parts, which gives rise to habits, and to the mode of life among animals; but that it is on the contrary the habits, the manner of living, and all the other influencing circumstances which have, after a time, constituted the form of the body and of the parts of animals. With the new forms, new faculties have been acquired, and gradually nature has come to form the animals as we actually see them. ”

“ In brief, the function of substitution possessed by the representative element in the processes of mental selection is the substitute for natural selection in the highest representatives of animal life. ”

“ As comparative anatomy is easily able to show that, physically, man is but the last term of a long series of forms, which lead, by slow gradations, from the highest mammal to the almost formless speck of living protoplasm, which lies on the shadowy boundary between animal and vegetable life; so, comparative psychology, though but a young science, and far short of her elder sister's growth, points to the same conclusion. ”

“ It has, therefore, been proposed entirely to reject descent as an element in the definition of species, and to consider as such any set of individuals which present, either in their external form, or in their internal structure, or in their biological phenomena, any common character, or combination of characters, distinguishing them from all others. ”

“ I could here pass in review all the classes, all the orders, all the genera and species of animals which exist, and make it apparent that the conformation of individuals and of their parts, their organs, their faculties, etc., is entirely the result of circumstances to which the race of each species has been subjected by nature. ”

“ If we contemplate a single specimen of the human race, we find a bodily organism, endowed with life like that of other animals, and acted upon by physical laws throughout the whole period of its existence. ”

“ In order to place the phenomena of instinct upon the same footing, with reference to natural selection, as is held by other manifestations of life, it is only necessary to show that instincts vary, and that these variations may become hereditary. ”

“ To trace out the progressive development of animal life, from its humblest phases; and to mark, as they become visible in the intermediate grades, the first rudiments of organs and instincts which are destined to attain their maximum in the higher ones, embody but a small portion of what it is the naturalist's mission to investigate. ”

“ The persistence of a type, far from being an objection to the manner in which I understand the conditions of life to [258] act, viz.: the formation and maintenance of races, is a confirmation of it.
XIV. In conclusion; like all animal and vegetable species, the human species can vary within certain limits; like plants and animals, man has his varieties and races, which have appeared and been formed by the action of the same causes.
In the human kingdom, as in the two other organic kingdoms, the first causes of variation are, conditions of life and heredity. ”

“ Can we apply this mode of reasoning to the evolution of distinct types of animals out of antecedent and different types? The very nature of the descent or derivation that is to be satisfactorily established requires a connection of lives with lives, just as such a connection is required in making out the pedigree of an individual animal. ”

“ Such a method of evolution and growth is not possible in the vegetable or animal kingdom, where instinct is the only means for the transmission of acquired knowledge. It is this feature that differentiates man from all other created beings. ”

“ But in the meantime I should wish to point out that we ought, above all, to be clear as to what we really mean by the expression ‘acquired character.’ An organism cannot acquire anything unless it already possesses the predisposition to acquire it: acquired characters are therefore no more than local or sometimes general variations which arise under the stimulus provided by certain external influences. ”

“ Under the head of organic behaviour, in the widest acceptation of the term, fall the whole of physiology, the whole of embryological development, nay, more, the whole of organic evolution; while mental evolution, in all its stages, may be regarded as the psychological aspect of that which, from the physiological aspect, is the evolution of nervous systems. Life itself is the behaviour of a particular kind of substance which is found more or less abundantly under natural conditions. ”

“ The fin of the fish, the wing of the bird, and the arm of the man cease to be what they are, if separated from the particular individual to which they respectively belong. The structure and function of the part can be understood only in relation to the needs of the organic whole. The parts of the individual subserve the organic unity. In the course of evolution, both ontogenetic and phylogenetic, parts may arise or drop out for the benefit and advantage of the whole. ”