Gitksan medicinal plants-cultural choice and efficacy

The use of plants for healing by any cultural group is integrally related to local concepts of the nature of disease, the nature of plants, and the world view of the culture. The physical and chemical properties of the plants themselves also bear on their selection by people for medicines, as does the array of plants available for people to choose from. I have used a biobehavioral approach to analysis of Gitksan medicinal plant use, examining both what is known of the plants and their pharmacological properties, and Gitksan healing perspectives and practices, to attempt to understand why people are selecting certain plants as medicines.

The Gitksan (Fig. 1) live in northwestern British Columbia in a heavily forested region. Many of their medicines are made from barks of trees or shrubs. The most frequent type of Gitksan medicine preparation is the mixed decoction of barks called haldow k um g an, which means "wood medicine" or "bush medicine". Needles or leaves such as pine (Pinus contorta Dougl.) or spruce (Picea × lutzii) tips are also used, pounded with pitch or grease for salves and in mixed decoctions drunk as medicinal teas. Whole herb plants may also be used for decoctions or poultices. Roots or rhizomes such as cow parsnip root (Heracleum lanatum Michx.) may be applied as poultices to sore joints or fractures, and inner barks may be used as wound dressings. Plants are also burned as smudges and used in the sweat hut anguxw'uutx; Gitksan healing practice includes steam baths with herbal washes or herbs burned on the hot rocks. Plants can be used as charms for protection or luck. Internal, external or spiritual cleansing may be a goal of plant use. Purgative and emetic preparations are often referred to in English as "cleansers".

Gitksan ethnomedical concepts spring from an understanding of humans as a part of all nature, and in reciprocal relations with all other entities, including sources of foods and potentially medicinal plants. Gitksan healing is holistic. Other key concepts are that of balance -avoidance of excess, and respect, for self and for others, which are seen as important in living a good life and in maintaining health. As an aspect of respect, attitude is important in collection and use of plants, which are seen as entities with their own intrinsic power to help and heal, or to withhold help.

Gitksan medicines are often slow acting, and may be integrated into life over prolonged periods. Use of tonics to promote health and prevent sickness is common. For the Gitksan, the underlying cause of much illness is seen to be spiritual, or a result of imbalance. The concepts of purification and cleansing are significant in both healing and gaining power. For a person who is ill, cleansing allows a return to balance and reinstatement of health. For a person who seeks supernatural power, cleansing removes dirt and impurity and may enable the seeker to gain power; "dirt" is specifically cited as a barrier to power in some teachings.

There are material and non-material aspects to all things in the Gitksan view. As a corollary to this, smudging or burning to release non-material essences is a culturally important mode of using some medicinal plants, especially those which are seen to have spiritual efficacy.

Formerly the Gitksan used elaborate shamanic curing ceremonies in conjunction with herbal medications, fasting, cleansing, prayer, and means of ensuring luck and personal power. There were shamanic healing specialists called halaaydim swanaasxw, who relied on ritual and non-material means to diagnose and cure illness in public ceremonials [1, 2]. There is still use of some ritual or spiritual types of healing, especially within family contexts, as well as adoption of newer spiritual healing methods like Christian prayer meetings and Revivals.

The present analysis of Gitksan medicinal plant use is derived from my ongoing fieldwork with the Gitksan from the period 1985–1998. Information on plant uses and traditional healing was gathered from 60 people in more or less formal contexts. Thirty-one consultants were women, and twenty-nine were men. The majority (49) were over 50 at the time of interviewing. Ethnomedical data were gathered in the course of interviews on the topic of plant uses, and in several interviews specifically on the topics of shamanic practice and traditional healing. Perspectives on health and healing were also shared in the course of informal conversation. The project was initially undertaken while working for the Gitksan-Wet'suwet'en Education Society, and everyone who participated was informed of the nature of the project. Participation was strictly voluntary, and the consultant's wishes were followed in terms of what information was recorded and whether it could be shared. Subsequently, I obtained ethics clearance from the University of Alberta while a graduate student there for the continuation of the project. Since that time I have continued to consult with individual Elders and teachers, and with the Gitxsan Tribal Council [Now Hereditary Chief's Office]. Original tapes and other materials are on deposit in Hazelton, BC in the Hereditary Chief's Office library. Plant specimens have been deposited in the Herbarium of the Botany Division of the Royal British Columbia Museum, and in the Vascular Plant and Cryptogamic Herbaria of the University of Alberta (see list of specimens in Table 5). The identifications have not been confirmed by taxonomic specialists. Earlier works which report on aspects of Gitksan ethnobotany and medicinal plant use include [3, 1, 4], and the recently published work of Harlan Smith [5]. A more complete discussion of methodology will be found in [2].

In my analysis of Gitksan medicinal plant use, I have combined the biobehavioral methods of Carol Browner, Bernard Ortiz de Montellano and Arthur Rubel [6]with the informant consensus approach pioneered by Robert Trotter and Michael Logan [7] in a study of Hispanic folk medicine in Texas. I also use what I call "intercultural consensus" as an additional approach to confirmation of plant uses, which is helpful in areas where extensive trade and intercultural contact make it impossible to assume that each culture may have independently chosen healing plants and techniques for their use.

Given the difficulty of ensuring that use of plants could not have been learned by contact with neighbouring groups who use the plant, David Young and his colleagues at the University of Alberta have tried to look at use of the same plants in widely separate geographic localities (Alberta and China) (Young et al. unpublished manuscript.). Such an approach limits analysis to plant species of very wide distributions, but many plants of medicinal interest are more restricted in range. Devil's club (Oplopanax horridus (Sm.) T.&G. ex Miq.) exemplifies the problems of restricted range in confirmation of efficacy by independent use by other cultural groups, as its range is restricted to northwestern North America, a region which has seen extensive cultural interchange over a long period of time. I have attempted instead to ascertain relative intercultural consensus in the use of plants for medicine as an analogue to intracultural consultant consensus for confirmation of the likely empirical efficacy of plant remedies (cf. [7]).

Intercultural consensus is agreement in which plants are valued for medicinal use, and similarity of reported uses between cultures which are in contact through such activities as trade, feasting and intermarriage. Heinrich et al. [8] approach intercultural comparison in a more geographically restricted and structured format in their work on medicinal plant choice in four Mexican indigenous groups, but their approach requires a series of parallel studies with the same methodology and classification of symptomology to be applicable. My method of determining intercultural consensus has been to map records of similar use of a given plant for medicine by all groups for which information is available within the range of the plant within my map area of northwestern North America from the Columbia River to the mainland of Alaska (Figure 1). [9], personal field notes, informal communication with colleagues, and references in Johnson [2] were used in this analysis. This approach is intended to supplement truly independent records of use by groups not in any direct contact, which can be obtained for plants with wide ranges in North America or globally.

The methodology of Browner and her associates involves examining the degree to which empirical criteria confirm the probable efficacy of the ethnomedical use or practice based on a biomedically grounded understanding of human physiology in the context of the ethnomedical concepts of the cultural group. While an approach grounded in physiology and phytochemistry is not the only way to assess healing efficacy, it is a useful perspective and helps cross cultural comparison. Their lowest level of empirical confirmation is Level 1, which requires "reports of parallel usage in populations among whom diffusion is unlikely" suggesting that "chemical activity exists" [6]:686.

Most of the medicinal plants used by the Gitksan are also used by at least one other culture in a similar manner, where direct diffusion is not known to have occurred, and are confirmed at Level 1 (Table 1). (In one instance a plant use that was not confirmed by another cultural group may be confirmed by the presence of an antiinflammatory compound that likely would be helpful in treatment of fractures, even though no other groups used it in a similar way). This tabulation includes use by both distant groups where true independent discovery can be assumed, and groups from the general northwestern region of North America, where chains of contact and cultural and cosmological similarities may have influenced choice and use of medicinal plants. The use of eleven of these plants is also confirmed at Level 2 or higher by the presence of active phytochemicals or bioassays which show potentially therapeutic activities (Table 2).

Consultant consensus analysis of interview reports from 29 Gitksan consultants revealed eight medicinal plants which were mentioned by five or more individuals (Table 3). I have grouped use of spruce and use of pine in this tabulation, because many of their uses are interchangeable. These data are derived from unstructured interview notes, and therefore are likely an underestimate of the actual degree of consensus among knowledgeable Gitksan. The 29 consultants, including both men and women, came from all of the Gitksan villages and therefore represent a broad sample of current Gitksan medicinal plant knowledge.

The eight plants most frequently mentioned by Gitksan consultants are, interestingly, all confirmed at Level 2 or greater for at least some of their traditional uses (Table 2). Though these data are suggestive, the phytochemical data are rarely sufficient to indicate amounts likely to be taken in actual use, nor are many of the plants adequately analysed to know what may be in them. Similarly, many phytochemicals known to occur in plants have never been investigated for their pharmacological activities. Nonetheless, confirmation at Level 2 or higher is indicative possible modes of physiologic action of traditional plant medicines. Intercultural consensus also supports likely efficacy of these plants, as all are used by half or more of the cultural groups in British Columbia and adjacent portions of Washington and Alaska west of the Rocky Mountains. I would now like to turn to a detailed discussion of these plants. Sources for the data presented in Figures 2, 3, 4, 5, 6, 7, 8, 9 are listed in Table 4.

In summary, consultant consensus, intercultural consensus, and evidence of biological activity all converge to support the likely efficacy of the eight most frequently mentioned medicinal plants used by the Gitksan. It is my contention that plants found to be efficaceous in healing, within the framework of local understandings of health and illness, will be retained in local ethnomedical tradition. One of the interesting results of the study is demonstration of the richness and diversity of individual healing knowledge and practice within Gitksan society. Limitations in the completeness of data, both for the Gitksan and for other cultural groups, make a rigorous quantitative analysis of intercultural consensus impossible at this time. Similarly, although indications of similar use by nearby or distant other cultural groups supports the likely efficacy of traditional herbal remedies, lack of such confirmation does not necessarily rule out effectiveness. Some factor of cultural selectivity seems to be responsible for the lack of recorded Gitksan use of other medicinal plants which are widely used and known to contain active phytochemicals, though random variations in knowledge, sampling error and erosion of traditional knowledge may also be implicated in the lack of records of use of certain plants. Assuming that the non-use is genuine, and not an artifact of research methods and contexts, many factors might be responsible for their non-use, ranging from the purely stochastic, to symbolic or contextual. Ethnomedical models must be taken into account, as well as the availability of other remedies which might produce a similar effect to the unused plant.