I consider ethics to be an exclusively human concern with no superhuman authority behind it.
Albert Einstein, in Science, Philosophy, and Religion (1941)
n this century, the triumph of the scientific method in illuminating molecular aspects of particular human physiologic and metabolic features has been little short of astounding. Less than ninety years have elapsed since Sir Archibald Garrod's prescient suggestion that "bodily form depends on chemical structure," yet today's medical treatises detail the genetic and biochemical etiologies of thousands of human metabolic conditions. Paralleling these sweeping discoveries of cellular and molecular mechanisms have been major conceptual advances concerning the modes by which natural selection, mutation, genetic drift, sexual reproduction, and other evolutionary genetic processes govern the dynamics of genes. The dominion of the genes clearly includes pervasive influence on our bodily conditions. Yet, when it comes to more "ethereal" human qualities such as intelligence, behavioral disposition, psychological profile, mode of social intercourse, personality, emotion, and ethical sensibility, the extent and even the meaning of genetic influence is fiercely debated.
Genes underlying neurological functions and behavioral dispositions evolve by natural selection just as do those for anatomical and physiological traits. Biologists are well aware that not only physical features but similarities in inherited behavior unite members of a species (and often higher taxonomic units). Adaptive coevolution between a species' behavior and its morphology, physiology, and ecology explains why we don't observe vegetarian
lions or predatory gazelles. Furthermore, if lions had societal codes of ethics, wouldn't these surely reflect an evolved sense of the rightness of predatory behavior, and wouldn't gazellean ethical standards consider grazing as morally proper and meat-eating as sinful?
Perhaps the evident associations between behavior and ecology in the animal world account for the allure of the belief that human social behaviors and even moral perceptions are ensconced in our own evolution-molded genes.1 However, to raise such issues on human nature is to sail between the Scylla of full genetic determinism and the Charybdis of pure cultural influence. Where lies the proper channel for safe passage between these flanking dangers? Does this traditional distinction between nature and nurture even provide a proper framework for intelligent discussions on human behavior and ethics?
Toward the nature end of the philosophical continuum is "genetic determinism," parodied in Figure 6.1. Two aspects of genetic determinism can be distinguished. According to some geneticists and social scientists, behaviors that vary among individuals or ethnic groups are those for which genetic differences are best ascribed. According to others, behavioral characteristics nearly universal to the human species provide surer signatures of evolution-molded genetic influence. Toward the nurture end of the debate is "cultural determinism," which interprets both the varieties and the universalities of human behavior as outcomes of societal influence and asserts that most human behavioral tendencies are not in our genes.2 How can such opposing views be retained in the light of scientific investigations into human behavior? Also, how do scientific views on genetic or cultural determinism of human nature compare to theological stances? Such thorny questions are the topic of this chapter.
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