Somewhat intertwined with miasmatic concepts were various hypotheses that postulated the "bad seeds" as contagia. Such entities could be passed from one person to another through the air, water, soil, or fomites such as clothing, bedding, utensils, or other belongings of the sick. Hence the development of such measures as quarantine and the burning of the possessions of the dead during outbreaks of plague as well as other epidemics. Even in times when the medical scholars were theorizing and practicing humoral explanations of disease the general public seemed more inclined toward contagia principles, whether it be the isolation of lepers or deserting the sick in time of plague. Such thinking was also behind some of the attempts at germ warfare by a few American colonists as they left the clothing of smallpox victims in Indian villages. Smallpox became another weapon, because of the greater susceptibility of the Indians to this disease with which they previously had no contact.

Contagia could be passed from one person to another
through the air, water, soil, or fomites such as clothing, bedding, utensils, or other belongings
of the sick.

From the time of the great plagues of the fourteenth to seventeenth centuries there were numerous suggestions of particulate contagia that had some of the characteristics of living creatures - such as reproduction. Acceptance of this concept by the medical and scientific world of the time was made difficult by preconceived notions. Before the advent of the microscope and other technologies, such "living things" could not be demonstrated. Their possible existence was, therefore, often ridiculed. Thus John Astruc, physician to Louis XIV (1638-1715), reviewed the numerous theories regarding the cause of syphilis and commented on "living contagia" as follows:

Furthermore, even when such creatures could be seen, as in the case of parasitic worm infections, the general acceptance of the concept of spontaneous generation led many to the conclusion that these things were the result of the disease and not the cause. Such "chicken or egg" confusion continued in many circles even after the microscope entered the picture.

D. Germ Theory

After numerous tantalizing suggestions that living organisms could be responsible for disease, the germ theory became firmly established during the last quarter of the nineteenth century. Following in the footsteps of some of the lesser lights of the seventeenth century, scholars so ridiculed by Astruc, disease investigators became more accepting of the possibility that disease could "[depend] upon little living things." By the middle of the nineteenth century John Snow, in his classic studies on the epidemiology of cholera, concluded that this disease was caused by a specific poison, that the poison particles were dispersed in the water with sewage, and caused cholera by multiplying in the next victim after ingestion in contaminated water. By these hypotheses and the development of microscopic and cultural techniques by Louis Pasteur, Robert Koch, and others, the Germ Theory of Disease became the major paradigm in the medical world and in the thinking of the general population. Few people would have any problem with Ogden Nash:

A mighty creature is the germ
Though smaller than a pachyderm.
His customary dwelling place
Is deep within the human race
His childish pride he often pleases
By giving people strange diseases.
Do you, my poppet, feel infirm"
You probably contain a germ.

So we arrived at the point, only a century ago, where much of the sickness and disease in plants, animals, and humans could be attributed to various infectious organisms or "germs": bacteria, viruses, fungi, and parasites. Just as "natural selection," at this same time, seemed to be answering questions regarding the origin of species, so "germs" of various types were answering questions regarding the origin of disease.

E. Too Many Germs and Other Problems

But following the establishment of a theory there is often the tendency to claim more than the theory justifies. At the time of Pasteur and Koch, whose work was mainly with bacteria, there appeared claims for the presumed discovery of the bacteria that caused various diseases. Most of these discoveries - such as those for cholera, typhoid fever, tuberculosis, and leprosy - were correct. Others, however, were wrong. Thus Haemophilus influenzae was proclaimed as the cause of influenza, a disease later shown to be caused by a virus. Likewise Bacillus malariae was championed as the cause of malaria until it was clearly demonstrated that this affliction was a mosquito borne disease caused by several species of protozoans of the genus Plasmodium. Furthermore, we accept the fact that medical investigators have identified numerous diseases that are not caused by infectious organisms: diseases that may result from hereditary defects, from poor nutrition, from environmental factors, etc.

In this process we often find that the rationalistic theories of the ancients were not 100% wrong. Thus, while we accept the reality of a diversity of very different diseases and different causes, we have also come to appreciate the intricate balances (homeostasis) that are involved in normal biological processes and that diseases - infectious or noninfectious " - are usually associated with an upset in these balances. But, of course, there are more than a mere four humors to balance!

In addition to disease production by environmental factors such as asbestos, benzene, tobacco, and lead we have come to appreciate that a complex network of the components of the environment plays a significant role in the occurrence and the course of infectious, "germ" related diseases. G. Melvyn Howe summarizes this interplay of a variety of factors.

And the human component was emphasized by Henry Sigerist:

So, in considering disease from a rationalistic perspective we now recognize a variety of specific diseases, interrelated to normal biochemical balances, and influenced by a variety of environmental factors. We've also come to appreciate the role of the emotional state in the ability of an individual to respond to infectious agents. We now must deal with a "germ theory of disease" that has many more factors - at both the individual and the community levels - than just a germ and a person made sick and a simple "bug/drug" association for prevention or cure.

A. Spontaneous Generation

From the ancient Greeks to the nineteenth century it was commonly assumed that various living organisms developed spontaneously from specific environmental situations. Thus crocodiles developed from the mud of the Nile River, birds appeared suddenly from swamps and marshes, frogs from mud, maggots from flesh, and mice from various types of filth. The experiments of Francisco Redi in the seventeenth century proved that maggots were the larval stages of flies that laid their eggs on flesh. Spontaneous generation almost disappeared as a viable rationalistic option until the development of the microscope led to revival of this type of thinking for at least the tiny forms of life. But then the work of Pasteur and others convincingly disproved this explanation of the origins of even microscopic living things.

B. Fixity of Species

With the advent of global exploration, the collecting of large numbers of specimens lead to

attempts to systematically catalog the vast array of plants and animals. Living things were sorted and assigned to groups in systems that resembled the sorting of mail at the post office or as we might classify motor vehicles into a hierarchy of concept-related categories. In the eighteenth century the Swedish botanist Carolus Linnaeus formalized classification, especially in his 1758 publication Systema Naturae. From this work developed not only the highly useful binomial system of nomenclature, but also the hypothesis that each species has remained very much as when originally created. Hence we get two related terms: "fixity of species" and "special creation." (It is important to remember regarding the latter concept that "special" does not refer to divine purpose but rather to the creation of particular "species.") Such a concept, supported by Linnaeus and others, appealed to many Christians, and the "species" of science became equated with the "kinds" of Genesis. However, anyone with any experience with the taxonomic process quickly realizes that "species" is a manmade category of convenience: biologists are still arguing over the definition of "species" (some of the dogmatic statements to the contrary in popular literature notwithstanding.)

C. Catastrophism

Concurrent with the attempts, on the basis of the developing species concept and the description of hierarchical schemes for establishing inter-species relationships, was the accumulation of a fossil record and indication of large time spans. The occurrence of a vast array of fossil plants and animals stimulated discussion of these time relationships. How and when did these fossils get in the rocks and how are they to be related to the living world of today? One view of this phenomenon that gained popularity among both scientists and theologians was that of catastrophes. Some sought explanation in a single catastrophe, usually based on the biblical flood. Others saw the fossil record as indicating a series of catastrophes with subsequent re-creations. Still others de-emphasized the importance of "catastrophes" and, especially after Darwin, focussed on a gradualism through long periods of time. In recent years, some paleontologists have, by the hypotheses of "punctuated equilibria," modified steady gradualism with interspersed periods of relatively rapid change. Furthermore, meteoric impacts have been blamed for the catastrophic demise of the dinosaurs.

D. Natural Selection

Amidst the various attempts to explain species diversity on the basis of spontaneous generation, fixity of species, and catastrophism, there were numerous suggestions that somehow life forms as we know them today may have at least some ancestral relationships. Species within a given genus, or genera within a family, may have had common ancestors and at least some of these ancestors could be represented in the fossil record. Such ideas had been postulated by some of the ancient philosophers. Jean Baptiste Lamarck, early in the nineteenth century, suggested that individually acquired characteristics could be passed on and developed further in succeeding generations. However, none of these mechanisms appeared viable as a basic theory to explain species diversity. There was no substantial evidence for the inheritance of these acquired characteristics.

Then in 1859 appeared Charles Darwin's On the Origin of Species by Means of Natural Selection. This mechanism for an "evolution" quickly became accepted as the major explanation of species diversity and interrelationships. As with many dramatic and sweeping theories, controversy soon erupted. However, as documented by David Livingstone⁷ and James Moore⁸ this was not simply a conflict between scientists and theologians, as it is so often erroneously portrayed. Some of Darwin's most vigorous opponents were scientists such as Louis Agassiz; some of his supporters were conservative, Calvinist theologians such as Benjamin Warfield and James Orr. 

But what is this "natural selection" First we need to be aware of what it is not. Some evolutionists and some anti-evolutionists imply that natural selection is opposed to supernatural selection or special creation. However, if one even skims Darwin's volume, it is obvious that natural selection is primarily in contrast to artificial selection, a process much used in Darwin's time (and before) for the selective breeding of plants and animals. Such a process has been developing even further in recent years through genetic engineering.

Darwinian "natural selection" is based on several basic principles that are of a relatively noncontroversial nature. It is the extrapolation to a sweeping general evolutionary theory that becomes more questionable.

1. High Reproductive Rates

While it may be an encouragement to recognize that insignificant people or ideas can accomplish much, the observation that "mighty oaks from little acorns grow" has limitations. Anyone who has an oak tree in their backyard realizes that if all of the acorns produced were to survive, the earth would be completely buried in oak trees in a short time. A single female mackerel produces 400,000 to 500,000 eggs each year; an Atlantic cod can develop 9 million eggs; and a freshwater carp almost 2 million. The human intestinal roundworm (Ascaris) releases up to 200,000 eggs per day and, on the basis of its longevity, a single female can produce 73 million eggs during its life span.

2. Limiting factors

Although the earth experiences occasional episodes of overpopulation, such as hordes of locusts or gypsy moths, plants and animals usually exhibit relatively stable population levels. The numbers of individuals are controlled by a variety of factors: limited food supplies, predators, and parasites. So, in these situations of high productivity, only a small percentage of eggs or seeds reach reproductive maturity. Even in species with more modest reproductive potential a majority of offspring do not survive.

3. Genetic Diversity

Except for identical twins and clones, no two individuals are exactly alike in their inherited characteristics. While many hereditary features, especially new ones (mutations), are harmful - and hence lower chances of survival under normal circumstances - others can be helpful if changes occur in the physical or biological environment. Any feature that would enhance disease resistance, the ability to flee or hide from predators, or make use of another food supply would enhance the chances of survival of a given population.

The interplay of overproduction, genetic diversity, and the various limiting factors became the basis of Darwin's proposal for the "origin of species by natural selection."

E. Too Much Natural Selection

Like the Germ Theory of Disease, "natural selection" tended to become the ultimate answer to questions concerning species diversity and phylogenetic relationships. Natural selection, together with the fossil record, was soon developed, by Darwin and others, into the general theory of evolution. Such a concept was readily accepted by an increasingly rationalistic society as an explanation which made divine control or origin unnecessary. There was some scientific opposition to Darwin's ideas of evolution by natural selection on the basis of Darwin's erroneous ideas regarding the mechanisms of heredity. Several scientific and theological writers used this faulty understanding of genetics in their attempts to discredit natural selection in particular and evolution in general. There was some theological opposition on the basis of literal interpretations of Genesis and a fear that "natural" was eliminating "supernatural." However, natural selection soon received recognition as the major, if not only, method of all of evolution.

Furthermore, the emphasis on limiting factors and species survival led to concepts such as "the survival of the fittest," which for many portrayed only "nature, red in tooth and claw." Totalitarian political philosophies along with an extreme free enterprise capitalism led to "Social Darwinism." Such nonscientific, philosophic speculation and theorizing became the basis of the evolutionism that dominates current attitudes towards the natural world. "Nature" and "Evolution" are obviously the gods of many of the otherwise educational, awesome, and spectacular TV programs (and of their narrators) that describe what for Christians must be thought of as God's creative and sustaining handiwork. This same "Nature" is even the god of some of our TV meteorologists!

Concluding Comments

Where does God and Scripture fit into all this rationalistic theorizing and theological interpretation" Christians have taken various positions on natural selection and on broader evolutionary theory. Some have denied both: some have accepted theistic neo-Darwinism: many have taken numerous other positions from among those outlined by David Wilcox⁹ and Craig Nelson.¹⁰ On the other hand, we have too often allowed our over-rigid commitment to one interpretation of Scripture to be the means of evaluating the current fad theory in science. Such either/or approaches and stiff-necked rigidity hinder us from moving toward both scientific and theological truth.

Any biologist who has had hands-on experience with the identification and classification of "species" knows that the criteria for defining "species," "genus," "family," etc. vary with the experts and change from year to year. For example, the major group of parasitic worms which I have studied since graduate student days is the Acanthocephala, or spiny headed worms. During the lifetime of my major professor their status changed from genus to family to class to phylum. The major reason for such tentativeness is that "species" or any other category of living things exhibit remarkable diversity and explanations of such diversity are often difficult.¹¹

On the basis of laboratory and field studies, natural selection can be accepted as a major factor in plant and animal diversity. Microevolution or special evolution should be no problem to any Christian, even those committed to recent creationism. Further changes that appear to require long periods of time (macroevolution or general evolution) may also take place, at least in part, through natural selection. But these interrelationships are impossible to firm up with certainty and the suggested pathways are constantly changing. Other still unknown mechanisms, some perhaps no longer operating, may also have been involved. As Christians, while it is still basic that God did it, we can still speculate on how he has done it as we study what he is doing now. To accept natural selection does not deny God. To insist on God as the explanation for only the unknown is an unbiblical God-of-the-gaps deism. To ignore God in natural processes (natural selection or infectious disease) is also unbiblical.

In the Germ Theory of Disease I have not found much Christian opposition to these naturalistic explanations of how living organisms get sick. In accounts of community response to serious epidemics there has been some tension between the emphasis on practical procedures, such as sanitary improvements or quarantines, and spiritual activities such as fasting and prayer. Some of this tension has not always been accompanied by Christian love and compassion and has certainly been as negative a witness as some of the heated, emotional evolution/creation debates. For example, an editorial in the Western Sunday School Messenger during the cholera epidemic of 1832 stated:

And another writer thanked God that the cholera remained, "almost exclusively confined to the lower classes of intemperate dissolute and filthy people huddled together like swine in their polluted habitations."¹³ It is sad that we have heard similar cruel and self-righteous comments from some Christians in regard to AIDS victims, all of whom are not homosexuals or drug addicts. And even when they are, Christian compassion may lead some of them to repentance and salvation.

But Christians have often been in the forefront of care and compassion for the sick, even in disastrous, personally dangerous epidemic situations. William McNeill could write:

In addition to these social/theological implications of disease, there have been some theoretical theological implications of germ theory. While not so prominent in scientific/theological controversies as evolution and creation, numerous speakers and writers on disease have, in this author's experience, often implied that it is either God or germs. Just as natural selection and genetics have given us rationalistic explanations of the origin of species that make theological interpretations unnecessary, so our understanding of germs (bacteria, viruses, etc.) often remove God from individual sickness and from epidemics. As one anonymous writer put it: "In the nineteenth century man lost his fear of God and acquired a fear of microbes." Howard Haggard expressed similar conclusions when he wrote:

In contrast to Christian suspicion of rationalistic, nontheistic descriptions of the origin of species, it seems that perhaps we all too often treat individual sickness and even epidemics on a purely rationalistic, even nontheistic basis. We talk only in terms of immunization procedures, antibiotics and the latest chemotherapy. We need to avoid the harsh condemnation of the sick as quoted above or as spoken by Job's unhelpful "friends." We need to reaffirm that our Creator and Sustainer controls the disease processes, whether personal or community. Perhaps the AIDS epidemic and its obvious dependence on human sin will help us to remember the role of Almighty God in the processes of speciation and mutations, whether in the "origin of species" - or in the origin of epidemics. Our God, who controls the heavens, the winds, and the seas, is certainly in control of climate changes (even man-induced!) and species variation. Our God, who inflicts war, famine, and pestilence on sinful humans, certainly controls the occurrence and behavior of bacteria, amebae, worms, and viruses. For both Natural Selection and Germ Theory we need to humbly remember God's sovereign rule as well as the limitations of human theories.

²Lucretius. On the Nature of Things, Book VI, Section 8 "Plague and Disease."

³ Duffy, John. op cit. Also Rosenberg, Charles. 1962, The Cholera Years: The United States in 1832, 1849 and 1866, Chicago, University of Chicago Press.

⁴Haggard, Howard. 1929, Devils, Drugs, and Doctors, Cardinal Giant paperback edition (1959), p. 258.

⁵Howe, G Melvyn. 1977, A World Geography of Human Diseases, New York, Academic Press.

⁶Sigerist, Henry E. 1943, Civilization and Disease, Chicago, University of Chicago Press, p. 3.

⁷Livingstone, David. 1987, Darwin's Forgotten Defenders, Grand Rapids, Eerdmans.

⁸Moore, James R. 1979, The Post Darwinian Controversies, Cambridge, Cambridge University Press.

⁹Wilcox, David. 1986, "A Taxonomy of Creation", Journal of the American Scientific Affiliation 38:4, pp. 244-250.

¹⁰Nelson, Craig. 1986, "Creation, Evolution, or Both", in: Hanson, Robert (ed), Science and Creation, New York, Macmillan.

¹¹Bullock, Wilbur L. 1969, "Morphological Features as Tools and as Pitfalls in Acanthocephalan Systematics", in Schmidt, Gerald D. (ed), Problems in Systematics of Parasites, pp. 9-45.

¹²Rosenberg, Charles. op cit, p. 44.

¹³Rosenberg, Charles. op cit, p. 42.

¹⁴McNeill, William. 1976, Plagues and People, New York, Anchor Press/Doubleday, p. 121.