Human ecology and general ecology: On theory and methods

INTRODUCTION

Human and natural sciences have much to offer to and to profit from general ecological theory. Human ecology is transdisciplinary in essence, but so far, no proper methodology is available for the complex analysis it requires. My prognosis is that no single method will be able to satisfy the needs or to attend to, the requirements, particularities and differences in outlook of the distinct fields of knowledge involved in human-ecological research. Human ecologists must learn the basic principles, particular methods and special techniques of both natural and human sciences, striving to acquire a global understanding, rather than compartmentalized knowledge of, complex problems. The future of the profession lies in the preparation of technical and political advisors in matters related to human impacts upon the environment. Those professionals must be able to provide global overviews, identify important factors, and suggest appropriate courses of action for eliminating or minimizing ecological problems. Human ecology differs in many aspects from plant-and animal ecology. Culture in man is a powerful ecological factor: it pervades all human actions and decisions. Primitive, rural, urban, and marginal populations show different degrees and types of relationships with the environment, and their analysis must bear this important aspect in mind. They represent distinct ecological taxa or categories. As to man's impact upon nature and natural resources, a novel concept of responsibility must be reached, where subpopulations, at whatever level, must be responsible for the economical use and preservation of resources at their sources, wherever they come from: in the immediate vicinity, as in primitive geosystems, or in distant systems, when imported by technologically advanced urban communities.

Key words:

ecoly, human ecology, evolution, human evolution, culture, ecosystems, geosystems.

  Introduction  4

  The taxonomic referential  5

  Ecological units  7

  Human cultural evolution  11

  Primitive populations  12

  Rural populations  13

  Urban populations  18

  Evolution or ecology  24

  Human ecology and general ecology: ecosystems and geosystems  25

  On methods  27

  Concluding remarks  31

  Notes  35

  Glossary of technical terms  36

  Bibliography  37

  ON METHODS  41

Introduction

Human ecology is the most humanistic among the sciences. In its broadest definition it embraces the totality of human knowledge, as it aims to unravel the relationships of man with the biosphere. Similar claims might be made by geography - the study of our spaceship with its passengers, and by anthropology - the study of man. A more manageable and circumscribed definition limits its objective to the study of man's relationships with, physical, social and cultural adaptations to, and impact upon, the environment.

Throughout this text I will use nature for natural productions, and resources or natural resources to indicate exploited natural products. Petrol, for example, having remained unexplored for most of human history was a natural product, only becoming a natural resource after we begun to bore wells and use it. Environment is employed in its widest sense, as the sum of all factors, biotic, abiotic, cultural, and social, which affect an organism, and is affected by him. as a source of energy and of chemical compounds.

The scope of human ecology as here defined is vast enough, and truly systemic and transdisciplinary in essence, as we shall see.

The human species has achieved a progressive independence from environmental constrains. Limiting factors, as the seasonallity of primary production, the availability of nutrients and water, variations in temperature and light, predators and parasites, have all been put under control and made permanently accessible, suitable and artificially modulated, or successfully controlled.

From its original foyer in the African savannas, Homo sapiens spread across oceans and continents to colonize the Earth. Man-the-hunter became farmer, then the builder of urban settlements, and successful in establishing new types of relationships within the biosphere (IUCN, 1964).

The taxonomic referential

The classification of organisms in Linnaeus' hierarchical system proposed in the XVIIIth Century - the Century of the Systems - was intended as an inventory of the types or kinds of organisms as created by God: a sort of passenger manifest of Noah's Arch, plus the fishes and vermin not allowed on board. Nowadays, taxonomists strive to reveal phylogenetic relationships, but not ecological affinity. So, systematics do not provide us with a key for the understanding of the structure of ecosystems. To achieve this kind of knowledge, we must identify the niche or the rôle of organisms in its community. The basic unity in ecology is the ecosystem, i.e, the biotic community plus its abiotic environment, not the species, which is constituted by populations of individuals alike and capable of interbreeding. So, in the study of human ecology, the basic units would be those biotic communities where man is present. Man's rôle in an ecosystem, i.e., in the recycling of nutrients and energytransfer, and the extent of man's impact upon the local (or distant) environment will depend on the technological development of each local human population.

During the historical period of epic oceanic explorations and early circumnavigation of the globe that began with the establishment of the School of Sagres, in Portugal, and that lasted from the XVth to the XVIIIth century, new land masses were discovered, teeming with unknown plants, animals, and strange men. This historical period coincided with the Renaissance in Europe and was marked by a change from scholastic to Cartesian truths; from the certainty of revelation to the doubts of

scientific inquiries; from deductive reasoning to independ inductive generalizations and of freedom of thought. The New World had no place in the Scriptures, and there was no explanation for the presence of man in isolated continents, far from Mount Ararat, where the Arch is said to have come aground. Answers to this riddle had to be reached by reasoning, not by consultation to biblical writings, inviting some curious theories that suggested a reconfiguration of the continents and made references to the lost tribes of Israel. (Abreu, 1930; Vásquez de E., 1948). In the XVth century, Pope Paulus III decreed, in the encyclical Veritas Ipsa, that natives from the New World were human beings, and belonged to the species that would be officially named Homo sapiens by Linnaeus (with six varietas), 200 years later. Differences in skin colour, the shape of the head and the contour of facial features were explained in terms of climatic influence and Lamarckian inheritance. One hundred years before Linnaeus, Archbishop James Usher of Armagh established that man had been created in the year 4004 BC One hundred years after Linnaeus, this date is still accepted by some Christian new denominations, in spite of the discoveries in the fields of geology, stratigraphy, paleontology and archeology.

Modern taxonomy, and the international set of rules for the nomenclature and classification of organisms in a hierarchical system, established by the Swedish naturalist in the XVIIIth century, introduced order in the chaos of the natural productions described by scientists of the Renaissance and Baroque periods.

The allocation of organisms to slots or pigeonhole in a hierarchical phylogenetic system is intended to show kinship or gentic relationships, i.e., common origin or phyletic descent. The taxonomic referential or framework is of little use to show ecological affinities, and vice-versa. Carter (1951) commenting on this subject, mentioned the association of two or more species, remarking that No one, layman or naturalist, would wish to include the different kinds of animals that form one of these

associations in a single species. The concept of species is based on populations of whole ontogenies of a single organism. As Moran (1990) rightly stated, One thing did emerge from the work of systems ecologists: the structural and functional characteristics of ecosystems may not be inferred from those of species, communities, or populations. Of course, this is one of the fundamental principles of the systems theory as understood by Ludwig Bertalanffy (1968).

Ecological units

Much of the discussions concerning the relationships of human ecology with general ecology arise either from an attempt to smooth the differences, or from a failure to distinguish ecological from taxonomic relationships. Rappaport (1990) tried his best to retain the ecosystem concept in anthropology, at the same time suggesting the adoption of a regional system concept, in human ecology. Regional systems would be composed of interactions among ecologically similar populations, that is, distinct populations of the same species occupying similar or equivalent ecological niches. In his argument, there are two important partial misconceptions. One arises from his definition, when he considers ecosystems as essentially, systems of matter and energy exchanges among unlike species. The second concerns local populations, and transhumance. In ecology, individuals of different sex and age may integrate distinct ecosystems and biomes, and occupy different ecological niches. And the geographical and ecological distribution of a species is, in most instances, discontinuous, fragmented in a checkerboard of local, mendelian or interbreeding populations, also known as demes (Gilmour & Gregor, 1939; Huxley, 1942). Individuals move from one sub population to another, maintaining a genetic flow, as the young abandon their parents, and adult transhumants search for other territories to control, and new home ranges to satisfy their trophic and reproductive needs.

But the confusion of issues involving taxonomic concepts and the ecological referential does not stop here. In many groups of animals, males and females of the same species differ drastically in morphology, habits, and habitat. It is not uncommon for an entomologist to describe males and females of one species as distinct taxa. They may live in distinct habitats and exploit different niches. The case of organisms that go through radical metamorphosis during their ontogenetic development is enlightening. Amphibian tadpoles are mostly aquatic gill-breathing animals; mosquito larvae are also fresh-water and detritivorous. As de Beer (1954) pointed out, It is a corollary of such adaptations that the better the larva is suited for its mode of life, the greater will be the difference between it and its adult. Coupled with paedogenesis, this is indeed a pathway for divergence and evolution by a process called paedomorphosis, as shown by Hardy (1954) and de Beer (1954). Adult frogs breath through lungs and live on dry land. Adult mosquitoes breath through tracheae, the females are blood- sucking while the males feed on plant juices. The sea provide a number of other interesting examples. Many marine invertebrates have planktonic and free-swimming larvae, while the adults are sessile and benthonic. In these instances, young and adults of the same species live in different biomes and are part of very distinct biotic communities. Selective pressures tend to force them to adapt more and more to their respective habitats, and diverge in shape and habits. Fresh water communities may harbour mosquito larvae and tadpoles, but no adult gnats or frogs, in their food-webs.

In human ecology, the relationships of technologically primitive or pre-industrial groups and those of city dwellers with their respective environments, is not equivalent. All human beings belong to the same taxonomic species, but distinct human populations impact differently upon their environment: they may be viewed as ecological taxa. (Avila-Pires et al., 2000).

Ecosystem theory carries with it a concept of dynamic equilibrium. By the end of the XIXth century, the old notion of the perfect balance of created nature was replaced by the idea of the dynamic relationships of organisms with biotic and abiotic environmental factors. Creationism postulated that species were created to fit natural slots in an organized world. Nature was viewed as the result and evidence of an ordered and planned act of God. Adaptations appeared by design, and variations were considered to be providentially provided for minute adjustments. All nature lived in the permanent state of an planned climax. The idea of an evolutionary process guided by the hazards of natural selection of arbitrary and random variations, while homeostasis emerged from chaos, with no allowance for design or finality, changed our whole view of nature and led eventually to the new science of ecology.

As Charles Darwin implied, and David Wallace (1984) aptly recognized, ...humanity is not destined for anything. Evolution has always been open to new possibilities, which is why it has been so chaotic and devious.

Ecosystem theory is also based upon the process of nutrient recycling and energy transfer in biotic communities, resulting in sustentability. Most discussions about the rôle of ecosystem theory in human ecology emphasize the interaction of factors as being the fundamental aspect of ecology, but the distinctive characteristic of ecological theory lies in the recycling of nutrients, and the transfer of energy along successive trophic levels.

We are forced to recognize that, while accepting that there is a recognizable field called human ecology, there is no such a thing as a human ecosystem. Homo sapiens is a taxonomic unit but not an ecological one.