Animal Breeding the Law That Like Produces Like
Animal Breeding the Law That Like Produces Like Breeding, like everything else in the domain of nature, is governed by laws. How far the action of these is modified by the conditions which precede and accompany such action is not fully known, nor is it ever to be. Nor would it be correct to say that all the laws or principles which relate to this great subject have even been discovered.
But some of them have, and happily enough may be gleaned regarding them to enable the breeder to prosecute his work with at least a fair measure of certainty and success.
Fundamental Laws. —Of the laws or principles which govern breeding there may be considered as fundamental, viz. :
- The law that begets like.
- The law or principle of variation; and
- The law or principle known as atavism. Varying in their Action. —Much has yet to be learned about these laws.
They are only understood in part since none of them, as now understood, is unvarying or uniform in its action. In practice it can never be known with absolute certainty which of them will dominate in determining the character of the offspring. It sometimes happens that the progeny of two parents will be possessed of high excellence in one instance, while in the next the progeny of the same will be only ordinary if not indeed inferior.
The result is doubtless the outcome of the action of law in both instances, but why law should produce results so dissimilar when the conditions are as nearly alike as man can make them, is one of the inscrutable things that man will probably never be able to discover.
It is true, nevertheless, that man is by no means helpless in determining what the results from mating animals will be. No results have taught him much and will doubtless teach him more in the future. It has been noticed that the first law is more uniform in its action than the second and the second than the third.
Uniformity in the action of the law that like produces like increases with the purity of the breeding, the duration of the period of such breeding, and also up to a certain limit with the closeness of the relationship of the animals so bred.
The intensity of action in the second law would seem to increase with the increase in the distance from the conditions just mentioned. And it will be correct to say that the law of atavism weakens as the starting point in pure breeding is receded from.
By properly utilizing such knowledge the breeder can do much toward se- curing uniformity in results. An excellent illustration of this is seen in the frontispiece representing the Eed Poll cow “Pretty Girl 4292” with heifer calves at 5 and IT months respectively, by “Pando 1254.” The property of Capt. V. T. Hills, Delaware, O.
The First Law Defined. —The law that like pro- duces like implies that the characters of parents will appear in their offspring, or to put it differently, that the offspring will bear a close resemblance to the parents in all essentials. Because of this it may be said that this law is the great sheet anchor of the breeder. It is the compass without which he could never enter the harbor of success. The law that like produces like pervades all animated nature.
It dominates the animal kingdom, and it would seem to be but a little less potent in the domain of plant life. When the parents are much alike in breeding and in all essential characteristics, this law is sufficiently uniform in its action to justify the breeder in looking for progeny similarly endowed. But where parents, unlike in these respects, are mated, it would be unreasonable to look for progeny the counterpart, to any marked degree, of both parents. In fact, it could not be.
The most that nature could do in that case would be to produce progeny that would bear resemblances to both parents. Those resemblances could not exist equally in all features of the progeny, since they differ in the parents. But even where the mating is eminently correct, there are some exceptions to uniformity of action in this law.
Were it otherwise, there would not be the same room for the existence of the law of variation, nor would there be any necessity for examples to illustrate it and proofs to support it. Had it been unvarying in its action, it is probable that it would not have received any other attention than the mere recognition of its existence.
This Law Early Recognized. —We are too prone to conclude that, but little was known with reference to the art of breeding until within a comparatively recent period. Such a view is not correct. The short cut to improvement through in-and-in breeding does not appear to have been practiced before the time of Bakewell. But the existence of the law has unquestionably been recognized for an exceedingly long period.
It is equally certain that many of its principles were well understood. Evidence of the same is found in the breeding operations conducted by the patriarch Jacob. The narrative of the management of his father-in-law’s flocks makes it clear that much attention had been given to the subject at least eighteen centuries before the modern era.
The influence of external objects in determining color had been recognized so far that the patriarch was enabled to turn the knowledge to excellent account, which is to say, so far as his own personal interests were concerned. The statement of holy writ with reference to the color of the males in actual service as seen in the vision, is a clear recognition of the law now under discussion.
Further evidence is furnished in the monstrous forms that were bred for the amusement of the Roman people about the time that the decline of the empire began. The very fact that such monstrosities were then produced tends to show that experimental crossing had been practiced long before that era.
The pedigrees kept by the Arabs of their horses centuries before the era of pedigrees began among Anglo-Saxon peoples furnish additional evidence of the certainty of the comparatively early recognition of the law that like produces like by that nation of wanderers, and of the importance which they attached to it. The justification of pedigrees could not exist in the absence of such a law.
Illustrations in the Human Family. —When ap- plied to the human family the law that like produces like finds ample illustration in the distinctive peculiarities of feature common to the different races.
Each of the five different races into which mankind has been divided has distinctive peculiarities. These are such as relate to physical form, color, and intellectual development: It is further illustrated by the differences and resemblances observable in sub-divisions within each race, and more especially in those sub-divisions in which there has been no mingling of – alien blood.
While the various tribes of North American Indigenous people which dwelt amid the forests possessed in common certain peculiarities, as, for instance, the copper color and the straight hair, each individual tribe possessed peculiarities common to all the individuals thereof and yet different from those in other tribes. Yet, again, it is illustrated in the resemblances discernible in very many instances between the members of the same family.
So strong are these resemblances that oftentimes the family relationship of each can thus be discerned- These resemblances cannot be accidental. Admit the existence and the potency of the law that like produces like, am. The explanation is easy. Deny it and no satisfactory explanation can be given.
Uniformity in Results. —The degree of uniformity in the results obtained in breeding will be dependent on the methods of the breeder. In no instance will they be absolutely uniform or else there could be no law of variation. But so generally uniform will these results be that the skillful breeder may carry on his operations with no little certainty.
But before he can succeed thus, he must, in the first place, breed to a standard of excellence. Such a standard must determine his choice of breeding animals. It must guide him in mating them. It must be ever present while selections are being made. It, too, must determine which shall be discarded.
Second, he must set a proper value on improved blood. The value of such blood as a factor in breeding has already been referred to in Chapter L and is further discussed below in the present chapter. And third, he helps me understand the art of selection and the principles of management. The question of selection is discussed in Chapter XXIV. The principles of management are so comprehensive that they cannot be stated here.
The author hopes to discuss these sometime in the future, when writing about feeding.
Benefits Arising from this Law. —The following- are chief among the practical benefits that may result to breeders because of the existence of the law that likes produces like: First, it makes it possible for them to effect improvement until a certain standard of excellence is reached. The standard thus set may be placed Adhere they are pleased to place it.
The standard of no breed in existence has been raised to the level to which it is possible to bring it. Standard bred horses have been brought nearest to the limit of improvement, but there are no good reasons for supposing that the speed of such horses will not be farther increased. Second, it makes it possible for breeders to maintain improvement.
In all animated nature there would seem to be an inherent tendency in the direction of deterioration in the absence of influences, natural or artificial, such as the tendency to secure the survival of the fittest.
And to prevent such deterioration it would seem to be necessary that these influences are continually operative. This statement may and doubtless will be challenged, and in- certain instances with much show of truth, but in the judgment of the author, the history of the animal and vegetable kingdoms since man left Eden, will sustain it.
But the law is sufficiently uniform and constant in its action to enable the breeder to more than counteract such tendencies when the work is properly conducted. Third, it makes it possible to form new breeds and to mold new types. A mature person can accomplish both because of the existence of this law. Turn loose into nature’s domain a number of cattle comprising representatives of several of the improved breeds and where the conditions are such that they can be maintained without the aid of man, and in time nature will mold them into a new breed.
Give her enough time and the resemblances between the progeny of those diverse breeds will be striking. Take some of those animals and again relegate them to the care of nature where the conditions are different, and the type will be changed. These modifications would be impossible were it not for the fact that in animal breeding, when alien blood is excluded, the tendencies toward assimilation would seem to be decidedly stronger than toward variation.
What nature, unaided, can do can be done more quickly when man comes to the aid of nature, and makes a more rigorous selection than nature could make without the aid of man.
Benefits from Want of Uniformity in this Law. —The exceptions to the want of uniformity in this law have been taken advantage of,
1, to improve the standard of the breed, and
2, to form certain breeds and mold certain types which could not otherwise have been called into existence.
These statements, though apparently contradictory to those just given, are not really so. While the evolution of breeds is the outcome of general uniformity in the action of the law that like produces like when aided by selection, it is equally true that some breeds could never have been evolved at all but for the absence of such absolute uniformity.
Such are the polled breeds of cattle and certain of the improved breeds of sheep from which the horns have been eliminated. Nor could the level of improvement have been raised had none of the progeny varied to the extent of exceeding their parents in desirable development.
The discussion of this question will be further considered in Chapter IV. It may also be proper to mention here that variations in type within a pure breed are seldom to be desired, since, when made to the extent of practically supplanting a type previously existing, they necessitate a change in the standard of excellence.
The more diversity in type found within a breed the greater the want for unity and harmony among the breeders, and when such conditions exist the interests of the breed suffer in proportion as these are present.
Transmission in Mixed Breeding.—In cross- breeding and grading where different types are mated, the result is in a sense a mean between the two. The progeny cannot be exactly like either. The characteristics of both parents are transmitted in part, but they are seldom transmitted equally. There is in nearly all instances a preponderance in resemblance to one parent or the other, arising in a great measure, at least, from the greater prepotency of that parent which is most closely resembled in the progeny. Prepotency is discussed in Chapter IX.
Influences that Affect the Action of this Law.— The influences that affect the action of the law that like produces like are strong: First, in proportion to the purity of the breeding in one or both parents. This will be readily apparent from what has been said in Chapter L, page 8, when treating of breeding from parents whose ancestors have long been bred without any admixture of alien blood.
The influence of alien blood must prove a disturbing factor to potency in transmission, since it is alien, and the degree of such disturbance will be proportionate to the degree in which alien blood is present, and to the degree in which it fails to harmonize with the dominant blood elements in the animals.
In other words, it will increase the tendency to variation in transmission.
Second, it will be strong in proportion to the period during which the animals have been bred pure. This, at least, is true up to a certain limit of duration. Whether a time comes when antiquity in the purity of the breeding ceases to affect the influences concerned in transmission has not been determined.
In other words, it has not been determined whether purity of breeding for a thousand years is a greater power than purity of breeding for five hundred years.
If there is a time, as would seem probable, when duration in purity of breeding ceases appreciably to affect transmission, that time has not been determined, and if it could be, it would probably not be the same in all breeds.
Experience has shown that one hundred years of pure breeding assures much potency in transmission, as evidenced in more than one of the dark-faced breeds of sheep.
Third, it is strong in proportion to the closeness of the blood relationship in the parents. For instance, the progeny of animals closely related usually have a closer resemblance to the parents and to one another than the progeny of animals of the same breed but not closely related.
The blood elements in the former would seem to have a stronger affinity; but why has not been fully explained. This fact, however, has been turned into good account by the originators of new breeds. (See Chapter XXVII.
Fourth, it Avill be strong in proportion to the nearness of the resemblance of the parents to one another in structure and form and in all leading characteristics. Conversely, it will be weak in pro- portion as the opposites of these are present in the parents.
It is evident that the more nearly the parents resemble one another in the features named, and in fact in all features, the less will be the gap to be bridged over in the process of assimilation through transmission. For instance, a well-developed hind flank is more likely to be present in the progeny when this feature of form is correct in both parents than when it is correct only in one.
Potency in transmission, therefore, will be strong in proportion to the in- tensity of the sum of all these influences acting in conjunction.
Features of Resemblance in the Offspring.—The resemblance of the offspring to the parents produced by the action of this law is not, by any means, confined to external form, although the evidence of such resemblance are thus most readily observed. It ex- tends to every physical feature of the organization, as, for instance, structure, function, color, hair, and handling qualities.
The rounded out, cylindrical form of Aberdeen polled cattle illustrates transmission in structure. The progeny of these has this form of body in contrast to the squarer body of the Shorthorn because the parents have the same. The easy action of the limbs in the trotting horse and the more labored action in the limbs of the draft horse are illustrations of transmission in function.
The black and white color in Holstein cattle, the white hairs never mingling with the black, illustrates transmission in color. The long, wavy hair possessed, more or less, by all Galloways and the short hair that characterizes Jerseys illustrate transmission as to the nature of the hair. The strong, harsh hide in the scrub, and the soft, pliant hide in the Guernsey, illustrate transmission in handling qualities.
This resemblance also extends to habit and to the mental traits which frequently control habit and govern the disposition. A cow whose ancestors have grazed on the range for generations, will go dry in five or six months from the date of calving, while the period of lactation in the cow whose ancestors have been in the dairy for an equal number of generations will be not less than ten months.
The difference illustrates transmission in habit. The young collie dog instinctively takes to the heels in driving because its ancestors have done so from time immemorial. The lambs of sheep used to the corral take kindly to the same, while those of other sheep are restless for a time under such restraint.
These are illustrations of mental traits which control habit. The progeny of a bull, naturally vicious, are also likely to possess this trait in at least some degree. The calf of a cow whose ancestors have been in the dairy for generations can usually be taught to drink in a day, while the calf of a cow whose ancestors had roamed for several generations on the range would pretty certainly require several days to accomplish the same end. These are illustrations of mental traits that govern the disposition.
Furthermore, this resemblance extends to ab normal qualities including diseases. The transmission of abnormal qualities is discussed in Chapter VI. and of diseases in Chapter VII.
Transmission Seldom Equal in Parents.—Theoretically one half of the characters possessed by the progeny when the conditions are apparently equal will be inherited from each parent. In fact, however, such a result is probably very seldom found.
Though the qualities are apparently equal, they will probably not be so in reality. One will almost certainly be more prepotent than the other, while the evidences of this difference may not be apparent in the external individuality of each.
The same is sometimes true of inherent vigor. When a preponderance of these and kindred influences are present, they will certainly ac- cord to the parent possessing the same, an excess of influence in transmission, and yet, such preponderance may not be known beforehand.
The deduction, therefore, is legitimate, that the sum of the characters inherited from one parent seldom or never equals the sum of the same inherited from the other. –
Just use your name and valid email address – I will never sell or share your email address with anyone. Never. You may unsubscribe anytime.
Copyright © 2021-2022 https://1-stop-sporting-goods.com All Rights Reserved