1.3: Hybrids and Immutability

On the Origins of New Forms of Life

1.3: Hybrids and Immutability

EUGENE M. MCCARTHY, PHD GENETICS, ΦΒΚ

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The schoolmen took their worldview from Aristotle, not from observation. (Artist: Laurentius de Voltolina)

Although many religious people still claim "species" are eternal and unchanging, no such idea is expressed in the Bible. It says only that animals and plants were created "in the Beginning," not that they remained the same thereafter. Modern religious thinkers who adhere to the notion of immutability obtained it from the schoolmen, who in their turn, took it from Aristotle, a pagan, who did make such a claim (On the Generation of Animals, fourth century BCE):

For since it is impossible that such a class of things as animals should be of an eternal nature, therefore that which comes into being is eternal in the only way possible. Now it is impossible for it to be eternal as an individual (though of course the real essence of things is in the individual)—were it such it would be eternal—but it is possible for it as a species.¹

The scholastic philosophers adhered to this notion of immutability, just as they did to most other things Aristotle said. Thus, Aquinas, the greatest of the schoolmen, confirms the idea of immutability:

Therefore, since in things corruptible none is everlasting and permanent except the species, it follows that the chief purpose of nature is the good of the species, for the preservation of which natural generation is ordained.²

The assumption that there truly were "natural species," immutably established by the "Author of Nature," continued to hold sway on into the scientific era. Thus, in his Essay toward a Natural History of the Earth (1695), which is as much religious diatribe as natural history, John Woodward boasts

Woodward
1665-1728

I will prove ... that the Animal and Vegetable Productions of the Antediluvian Earth did not in any way differ from those of the present Earth. That there were then the very same kinds of Animals and Vegetables, and the same subordinate Species under each kind that now there is. That they were of the same stature and size, as well as of the same shape; their Parts of the same Fabrick, Texture, Constitution, and Colour, as are those of the Animals and Vegetables at this day in being.³

Often, in connection with such assertions, it was claimed that God, or a personified Nature viewed as a sentient force, had made hybrids sterile in order to prevent the various types that made up the divine creation from blending together. The marriage of these two claims — though both were unsubstantiated by observation (see discussion of hybridization in next section) — is encountered again and again in the writings of a broad range of authors of the early scientific period. Thus, Oliver Goldsmith in his preface to Brooke's Natural History (1763: 251) assures his readers that hybrids can never disrupt the natural order:

Goldsmith
1728-1774

Jean-Jacques Rousseau

Rousseau
1712–1778

Happily for mankind, the most intricate enquiries are generally the most useless. Modest nature has concealed her secret operations from rash presumption; it may suffice man to be certain, that she always acts with uniformity and success. Tho' we cannot discover how animals are generated, we know that every species is still transmitted down without mixture, and that the same characteristic marks which distinguished them in the times of Aristotle and Pliny, divide them to this day. Creatures of different kinds may be brought to produce between them, indeed an animal partaking something of each, yet different from either, but here the confusion ends; for this new being, this monster of nature, is incapable of continuing the breed, and is marked with perpetual sterility.⁴

Jean-Jacques Rousseau (Émile, The Creed of a Savoyard Priest, 1762) gives his readers a similar account of Dame Nature's plan:

The mere generation of living organic bodies is the despair of the human mind; the insurmountable barrier raised by nature between the various species, so that they should not mix with one another, is the clearest proof of her intention. She is not content to have established order. She has taken adequate measures to prevent the disturbance of that order.⁵

In the 1700s, many considered not only animal hybrids, but even plant hybrids, widely taken for granted today, as unnatural. For example, Chambers Cyclopedia of English Literature (1727-1741) listed the following definition: "Mules, among gardeners, denote a sort of vegetable monsters, produced by putting the farina fæcundans [i.e., pollen] of one species of plant into the pistil or utricle of the other."⁶ Zirkle (1935: 1) notes that

as late as the eighteenth century hybridization was not altogether reputable and a number of the early plant breeders felt called upon to justify their attempts at crossing different species. There seems to have been a widespread belief that sexual intercourse between diverse types was an immoral perversion and that the production of new forms of life was an impious affront to the Deity, a tacit criticism of the original work of Creation.

This notion that nature proscribed hybrid animals and plants to preserve the natural order is of ancient origin. The Roman poet Lucretius (On the Nature of Things, V, first century BCE) gave clear expression to the idea:

The kinds of herbage and corn and joyous trees which even now spring in plenty out of the earth yet cannot be produced with the several sorts plaited into one, but each thing goes on after its own fashion and all preserve their distinctive differences according to a fixed law of nature.⁷

In Latin, the word hybrida was applied not only to hybrid animals and plants, but also to anything that violated natural law. Thus, Lewis and Short (Latin Dictionary) give the following definition of the word from which our hybrid is derived: "unbridled, lawless, unnatural; hence, of animals produced from two different species, a mongrel, hybrid." In the same place, they note hybrida is probably kindred to hubris (ὕβρις), used by the ancient Greeks to designate any violation of the natural order, especially one involving sexual matters.⁸ Apparently, hybrids fell under the heading of hubris because hybrids resulted from a form of sexual contact deemed to breach that order.⁹ There was a religious significance attached to such matters since the Greeks believed acts of hubris brought down the curse of the gods.

Jews, too, from an early date viewed hybrids as a desecration of a natural order laid down by God. Writing in the first century CE, the Jewish scholar Philo Judaeus (The Special Laws, III, 46) asserts that

So great are the provisions made in the law to ensure that men should admit no unlawful matings, that it ordains that even cattle are not to be crossed with others of a different species. No Jewish shepherd will allow a billy goat to mount a ewe or a ram, a nanny, or a bull, a mare, or if he does, he will be punished as an offender against the decree of Nature (which is careful to preserve the primary species without adulteration).

Many even in the modern era have expressed this idea that God abhors transgressions of natural law. For example, in his Notes on the Miracles of Our Lord (1846), Anglican Archbishop Richard Chevenix Trench comments that "the unnatural, the contrary to order, is of itself ungodly."¹⁰ Such ideas are even widened at times to encompass not only hybrid animals and plants, but also hybridity of a purely abstract and non-biological nature. For example, an early film critic, Victor Oscar Freeburg claimed lasting art can never result when media are mixed:

Buffon
1707-1788

Nature abhors a mixture of species and therefore does not allow hybrid animals to perpetuate themselves by reproduction. The history of the development of aesthetic taste shows the same abhorrence for hybrid art. Hybrid art is not pure and therefore cannot endure as art. Some of the Greeks, for example, tried the cross-breeding of the arts by painting complexions on their statues, but the resulting hybrid, half painting and half sculpture could not endure as art and is remembered in history only as an interesting mistake.¹¹

It must be said, however, that throughout much of the history of science there have been those who rejected the claim that hybrids are unnatural and consistently sterile. In his Histoire naturelle, the great naturalist Comte Georges-Louis Leclerc de Buffon (1707-1788) expressed his (correct) opinion that hybrids vary in fertility depending on the cross from which they are derived: "In mixed species, that is to say in those animals that, like the mule, come from two different species, there are, as in the pure species, different degrees of fertility."¹² Another early example is the botanist Christian Julius Wilhelm Schiede, who in 1825 wrote an entire book on the subject of hybrid plants occurring naturally in Germany and Italy.¹³ NEXT PAGE >>

1.Book II, Ch. 1. See Hutchins (1952b: vol. II, 272). On this point, however, as on many other points, Aristotle was inconsistent. Elsewhere (Generation of Animals, 747A15) he claimed animal hybrids are typically of normal fertility: “It is known that with one exception all the animals that are produced as the result of such unions copulate with each other and unite in their turn and are able to produce young of both sexes. Mules are the one exception. They are sterile and do not generate either by union with each other or with other animals.”
2. First Part, Question 98, Art. 1; Hutchins (1952a: 517
3. Woodward (1695: 246-247).
4. Goldsmith (1763).
5.Rousseau (1928).
6.Quoted (s.v. mule) in the Oxford English Dictionary.
7.Hutchins (1952h: 73).
8.The word hybrida appears in Latin in the sense of a cross-bred human being by the end of the Roman Republic (prior to 50 BCE). Thus, Julius Caesar (Bellum Africum, 19.3) used hybrida to describe half-breed soldiers in an opposing army. A decade later, in his satires (I.7.2), Horace (30 BCE) also uses hybrida in this sense. Some scholars have suggested hybrida was originally used in Latin in the narrow sense of hybrids between tame and feral pigs (see OED, s.v. hybrid), but this argument is based on usages in Pliny the Elder, and later authors dating a century or more after those just cited. The restriction in sense therefore is probably unwarranted. For a detailed discussion of this topic see Warren (1884). The Romans introduced the letter y during the late Republic to transliterate Greek υ into Latin (Wheelock 1963: xxxi). Apparently, the ς of υβρις became the d of hybrida because the transliteration was based on a declined form of υβρις such as υβριδος (accusative singular). The substitution of the common Latin feminine ending -a completed the transition.
9.Encyclopedia Britannica (1967: vol. XI, 921).
10.Trench (1846: 15).
11.Freeburg (1918: 166).
12.Cuvier et al., eds., (1839–1844: vol. IV, 4462). Translated by E. M. McCarthy. Original French: "Dans les espèces mixtes, c'est-à-dire dans celles des animaux qui, comme le mulet, proviennent de deux espèces différentes, il y a, comme dans les espèces pures, des degrés différents de fécondité ou plutót d'infécondité."
13.Schiede (1825). Lasch (1829) also listed naturally occurring hybrids.

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