A Science & Religion Commentary

Lev. 19: 19 You shall keep my statutes. You shall not let your animals breed with a different kind; you shall not sow your field with two kinds of seed; nor shall you put on a garment made of two different materials.

Deut. 22:9-11 You shall not sow your vineyard with a second kind of seed, or the whole yield will have to be forfeited, both the crop that you have sown and the yield of the vineyard itself. You shall not plow with an ox and a donkey yoked together. You shall not wear clothes made of wool and linen woven together.

These two sets of prohibitions from Leviticus and Deuteronomy rarely cause anxiety to Christian interpreters, usually because they are flatly ignored. Levitical laws are sometimes said to be fulfilled in Jesus Christ, sometimes abrogated in the new covenant, and occasionally dismissed as mere cultural intrusions on inspired text. Rarely have Christian commentators taken the time to figure out a reason for ignoring laws that prima facie prohibit blended fabrics, hybrid seed, and other common practices — practices that seem to bring significant benefits and little or no harm.

In recent years, however, these texts have flitted around the edges of innovations such as genetic modification through transgenesis (transfer of genes from one organism to another across species barriers) and xenotransplantation (use of body parts from animals for transplant in humans, such as pigs’ heart valves to treat heart disease). These texts raise uneasiness at such practices to a religious level even though the exact nature of the objection remains elusive.

The Levitical laws which prohibit mixing of species are known in Jewish circles by the term kilayim. Since orthodox Jewish hermeneutics preclude obsolescence as an option for divine law, the tradition has formulated another approach. One line of rabbinical thought discerns no underlying ground for these commands. They are hukah, or statutes without stated reasons.        The only rationale for God’s command is fidelity; they are tests of obedience, not general norms for the operation of creation. The appropriate rule of application, then, is that such laws are to be strictly interpreted, sharply limited to the stated case.

Another approach, however, interprets these divine commands in light of principles of creation. In other words, the structures of creation are used as a hermeneutical principle to ascertain the meaning of the command. The laws of kilayim are ordinances of creation, based upon the divisions God made in the creation of the world. Most prominent among the rabbinical commentators who hold this view is Ramban:

The reason for kilayim is that God created species in the world . . . and gave them the ability to procreate in order that said species should continue forever, [that is,] for as long as God wishes for the world to continue………………… Whoever intermingles two

species changes and denies the Creation, as if he thought that God did not complete the work of His world as much as necessary, and he wishes to aid in the creation of the world, to add creatures to it. … [In nature] the species of animals do not crossbreed, and even [with regard to] close relatives in nature, those that may be born to them    are infertile. We see that as far as this is concerned, the act of crossbreeding species is a repugnant and futile act. (Jerusalem Talmud, Kedoshim on Leviticus 19:19)

This passage by Ramban is cited, for instance, by the Alliance for Bio-integrity as a religious voice in opposition to genetic engineering.

The concept of fixity of species was common in Christian circles prior to Darwin and still can be found in anti-evolutionary circles. God, in creating the world, made creatures according to their kind. These kinds persist, unchanged, for the duration of God’s creative intent. To tamper with the divisional lines within creation is to frustrate God’s intent and to cast aspersions on the divine intelligence. Species divisions are sacred in character. Their violation manifests pride and insults God’s wisdom. One would expect that those who deny evolution on religious grounds would consequently be strongly opposed to genetic engineering. This, however, does not seem to be the case.

Few contemporary Jewish scholars follow Ramban’s interpretation and argue against biotechnology because it involves the mixing of species. The majority of commentators strictly limit the scope of kilayim, permitting hybridization and genetic engineering on one principle or another. Within the Jewish community there is an openness to genetic engineering, born in part out of the principle that God gave man the power to improve upon creation and develop technologies to attain such improvement.

The preferred theological reading of kilayim found among the few Christian commentators who attempt to interpret them stresses the symbolic nature of “non-mixing”. The Levitical law of kilayim symbolizes the divinely imposed duty upon Israel to remain free from contamination by the surrounding peoples. Gordon Wenham, for instance, argues that the symbolism against mixing is abrogated in the New Testament church, an institution where God’s will is that the nations come together. Recent Biblical commentators such as Mary Douglas analyze these laws of purity and impurity as means to order the world and unify experience. Rather than being primarily rules of hygiene, a warning against the adoption of foreign practices, or a means of expressing devotion, the Levitical laws order the world according to a divinely-imposed scheme. Blessing comes through order, and one garners the power inherent in blessing by respecting the order God has placed within creation. With regard to the laws of Leviticus 19, Douglas notes that

We can conclude that holiness is exemplified by completeness. Holiness requires that individuals shall conform to the class to which they belong. And holiness requires that different classes of things shall not be confused. Another set of precepts refines on this last point. Holiness means keeping distinct the categories of creation. It therefore involves correct definition, discrimination and order.

Rolf Bouma is a lecturer in the School for Environment and Sustainability at the University of Michigan. He holds advanced degrees in law and systematic theology, with thesis work in biotechnology and a theology of nature. He has also served as a pastor to congregations.

Copyright The Ministry Theorem, 2012