trait of the cave-man, or the beast, may reappear in a child of Twentieth Century civilisation.
Darwin, in The Descent of Man, Chapter II, gives many instances of "atavism," or breeding back, by human beings to apish and even quadrupedal characteristics. Alluding to a case cited by Mr. J. Wood, in which a man had seven muscles "proper to certain apes," Darwin says:
It is quite incredible that a man should through mere accident abnormally resemble certain apes in no less than seven of his muscles, if there had been no genetic connection between them. On the other hand, if man is descended from some apelike creature, no valid reason can be assigned why certain muscles should not suddenly reappear after an interval of many thousand generations, in the same manner as with horses, asses, and mules, dark-coloured stripes suddenly reappear on the legs and shoulders after an interval of hundreds, or, more probably, of thousands of generations.
Dr. Lydston, in The Diseases of Society (Lippincott: 1904) says:
The outcropping of ancestral types of mentality is observed to underlie many of the manifestations of vice and crime. These ancestral types or traits may revert farther back even than the savage progenitors of civilised man, and approximate those of the lower animals who, in their turn, stand behind the savage in the line of descent.
This "reversion to older and lower types," or "breeding back," is important, because it is the source of much crime – the origin of very many "Bottom Dogs," as we shall see. But at present we need only notice that heredity, or breed, reaches back through immense distances of time; so that a man inherits not only from savage ancestors, but also from the brutes. And man has no power to choose his breed, has no choice of ancestors, but must take the qualities of body and mind they hand down to him, be those qualities good or bad.
Descent, or breed, does not work regularly. Any trait of any ancestor, beast or man, near or remote, may crop up suddenly in any new generation. A child may bear little likeness to its father or mother: it may be more like its great-grandfather, its uncle, or its aunt.
It is as though every dead fore-parent back to the dimmest horizon of time, were liable to put a ghostly finger in the pie, to mend or mar it.
Let us now use a simple illustration of the workings of heredity, variation, and atavism, or breeding back.
There is no need to trouble ourselves with the scientific explanations. What we have to understand is that children inherit qualities from their ancestors; that children vary from their ancestors and from each other; and that old types or old qualities may crop out suddenly and unexpectedly in a new generation. Knowing, as we do, that children inherit from their parents and fore-parents, the rest may be made, quite plain without a single scientific word.
In our illustration we will take for parents and children bottles, and for hereditary qualities beads of different colours.
Now, take a bottle of red beads, and call it male. Take a bottle of blue beads, and call it female.
From each bottle take a portion of beads; mix them in a third bottle and call it "child."
We have now a child of a red father and a blue mother; and we find that this child is not all red, nor all blue, but part red and part blue.
It is like the father, for it has red beads; it is like the mother, for it has blue beads.
It is unlike the father, for the father has no blue, and it is unlike the mother, for the mother has no red.
Here we have a simple illustration of "heredity" and "variation."
Now, could we blame the "child" bottle for having red and blue beads in it; or could we blame the "child" bottle for having no yellow and no green beads in it?
But that is an example of a simple mixture of two ancestral strains. We have to do with mixtures of millions of strains.
Let us carry our illustration forward another generation.
Take our blue and red "child" and marry him to the child of a black bottle and a yellow bottle.
This gives us a marriage between Red-Blue and Black-Yellow.
The "child" bottle mixed from these two bottles of double colours will contain four colours.
He will "inherit" from grandfather Red and grandmother Blue, from grandfather Black and grandmother Yellow, and from father Red-Blue and mother Black-Yellow.
He will be like the six fore-parents, but different from each of them.
Can we blame this "child" bottle for being made up of red, blue, black, and yellow? Can we blame it for having no purple nor white beads in its composition? No. These colours were mixed for the child, and not by it.
How could there be white or purple beads in this bottle, when there were no white nor purple beads in the bottles from which it was filled?
But what of the variation amongst brothers and sisters?
That is easily understood. If the four colours in the ancestral bottles are evenly mixed, the grandchildren bottles will vary from their ancestors, but not from each other.
As we know that brothers and sisters do vary from each other, we must conclude that the hereditary qualities are not evenly mixed.
For the scientific explanation of this fact I must refer you to The Germ Plasm, by Weissmann.
For our purposes it is enough to know that brothers and sisters do vary from each other, and that they so vary because the ancestral qualities are not evenly distributed amongst the "sperms" and the "ova." On this head our own knowledge and observation do not leave any room for doubt.
It is as if in the case of our marriage of Red-Blue and Black-Yellow there were three child-bottles, of which one got more red and yellow, one more blue and red, and one more yellow and blue than the others. So that the three brother-bottles would differ from their fore-parents and from each other.
And as it would be foolish to blame the second bottle for having less red in it than the first, so it is foolish to blame a human child for having less intellect or less industry than his brothers.
If you refer to the masterly description of the impregnation of the ova given in Haeckel's great work, The Evolution of Man, you will find that the heredity of brothers is largely a matter of accident. See the plate and explanation on page 130 in the first volume.
The "variation" in brothers and sisters is like the variation in the mixing of beads in our bottles.
It is as though we made several tartan plaids of the same four colours, but in different patterns.
It is like dealing hands of cards from a shuffled pack. There are four suits, but one hand may be rich in clubs, another in diamonds.
And who in a game of whist would blame his partner for holding no trumps in his hand? The partner could only play the trumps dealt out to him.
In no way can a child control the pre-natal shuffling or dealing of the ancestral pack.
Now, as to atavism, or breeding back. In the ancestral bottles called men and women there are millions of different kinds of beads. And it sometimes happens that a particular kind of bead (or quality) which has lain dormant for a long time – perhaps for a thousand years – will crop up in a new mixing that goes to make a "child-bottle,"
