Use of coca leaf in southern Peru: adaptation or addiction

Sections

Abstract
Introduction
Coca use in the Andes
TABLE 1- Daily coca leaf llipta consumption in ten families resident in Nunoa
TABLE 2 Responses of habitual and non-habitual coca users after 24 hours of chewing or abstaining from coca
FIGURE I
TABLE 3 - Performance of matched habitual and non-habitual coca users during work. Means for coca using trials
TABLE 4 Resting and maximum values for maximal working test
FIGURE 2
Coca use or cocaine addiction
Overview
Bibliography

Details

Author: Joel M. HANNA , Conrad A. HORNICK
Pages: 63 to 74
Creation Date: 1977/01/01

Use of coca leaf in southern Peru: adaptation or addiction

Joel M. HANNA
Conrad A. HORNICK
Department of Physiology, University of Hawaii, Honolulu, HI 96822

Abstract

Use of coca leaves among the Quechua Indians of the Peruvian altiplano is considered from the biological and social perspectives. Biologically, coca use seems to reduce the loss of body heat in the cold and to enhance working ability to a small degree. It may also have some nutritional value. Socially, coca is well integrated into the economic and social systems, providing functions in both spheres. The equation of coca use with cocaine addiction is also considered and a simple equivalence is rejected.

Introduction

Coca ( Erythroxylin coca) was among the earliest plants to be domesticated in South America (Lanning 1967). The practice of chewing coca leaves is especially widespread among the Indians of the altiplano or high plateau. The Quechua, Aymara, and other highland indigenes ascribe many uses to coca leaves as did the Inca before them. Coca has been used for more than four thousand years (Lanning 1967, Martin 1970). Today coca is used in religious ceremony, divination, sacrifice, medical practice, and is believed by the Indians to be helpful in maintaining their adaptation to the high plateau. Coca is believed to reduce hunger and fatigue, and also to promote a feeling of warmth in the user (Little 1971, Hanna 1974).

Coca is ingested by placing a number of leaves in the mouth and chewing them in a wad or quid which is held in the cheek and periodically rechewed. The juice and up to 70 per cent of the leaves may be swallowed (Cuiffardi 1949). The general physiological stimulation observed in coca users for about an hour after chewing (Zapata Ortiz 1944:159; Risemberg 1944; Chambochumbi 1949), has been equated by some investigators with stimulation produced by cocaine and as a result, coca leaf chewing and cocaine addiction have been regarded as one and the same problem (Wolff 1952).

If in fact coca chewers among the Indians of the altiplano are addicted to cocaine, it does not appear to have a serious effect on community life since the insatiable desire for the drug, paranoia and mental deterioration characteristic of cocaine addiction (Traut and Takman 1965, Sutherland 1970) are not witnessed in the behaviour of the coqueros in their daily lives (Monge 1952, Hanna 1974). The intention of this paper is to further investigate the systemic input of coca use into the biocultural adjustment these people have made with their environment.

Coca use in the Andes

Significant modification in behaviour and physiology of Indians using coca has not been obvious. Monge (1952) found no overt symptoms among coca users and reported that the habit was willingly abandoned by a group of users when ingestion of coca leaves was replaced by well balanced meals. Monge concluded that coca use was an intrinsic part of the Indian's adaptation to high altitude life. A similar conclusion was reached by other researchers (Mortimer 1901, Cardenas 1952, and Slutes 1963) who reported coca use harmless and resulting in no profound, observable changes when chewed by the high altitude indigenes. During two years of residence on the altiplano, one of us (JMH) also observed no significant changes in the behaviour of native users in a variety of situations, nor did it seem difficult for even habitual users to abandon the practice.

Although coca chewing seems to produce no overt response among high altitude natives, there does appear to be a strong relationship between the prevalence of coca use and altitude. Monge (1952) reported coca use at 15,000 ft nearly universal, while at 8,000 ft it was used only rarely and hardly at all by people living at sea level. A more recent study by Buck, Sasaki, and Anderson (1968) supports this contention, with the following percentages of the adult population using coca regularly: 72 per cent at 11,500 ft, 28 per cent at 5,600 ft, 29 per cent at 3,500 ft, and 3 per cent at sea level. However, this relationship is not conclusive and has been interpreted by some investigators as simply due to the proximity of coca plantations (Gutierrez-Norriga 1949a), while others (Monge 1952) have hypothesized that chewing coca may in fact be a response to the difficulties encountered in living at high altitudes. The natives themselves, as mentioned earlier, believe that coca relieves hunger, reduces fatigue, and promotes warmth. This belief is so strong that they may refuse to perform normal labour without it and in fact consume more coca during the cold season (Little 1970:236, Stein 1961:169). Another variable confounding a simple interpretation of this altitude gradient is the fact that the Indians of the high plateau are living within an aboriginal culture in which coca use has always played an important role, while in the westernized cities at lower elevations no tradition of coca chewing exists. Therefore, coca use may be the continuation of a cultural tradition among high altitude natives, or alternatively the incorporation of a plant into the diet may constitute a more efficient adaptation to the high altitude stresses of hunger, cold and fatigue.

Although the Indians "almost universally" refer to coca as a food (Martin 1970), the potential nutritive value of coca leaves has generally been overlooked by most investigators (Cardenas 1952, Wolff 1952). However, Baker and Mazess (1963) found the alkaline llipta which is chewed with the leaves to be a significant source of calcium in the Indian's diet. Recent work by James A. Duke (personal comm.), has altered the nutritional view. Upon analysis, he reports that Bolivian coca leaves contain a significant number of essential nutrients.

In order to gain a better perspective on the physiological and cultural inputs of coca use in the South American native highland populations, a study of coca use in the town of Nunoa in southern Peru was undertaken. 1

To estimate daily consumption by habitual users of coca, families with habitual users were given 50gm bags of coca for each user along with a weighed amount of the alkaline llipta. The day following distribution, the bags were collected and the remaining coca and llipta was weighed. The results are noted in table 1.

Mean daily coca consumption per adult was calculated to be 58gm, with men chewing a little more than women. This figure is within the range of a survey conducted by Baker and Mazess in Nunoa which estimated daily coca use at 25 to 75 gm per day (Baker and Mazess 1963), but it may be a little high with recipients taking advantage of the free coca. The use of llipta also was slightly above their estimate of 2 to 4 gm per day.

1

Aspects of life in Nunoa have been described by Baker et al. (1968) and Baker 1969.

TABLE 1- Daily coca leaf llipta consumption in ten families resident in Nunoa

 

N

Age (yr)

Ht (cm)

Wt (kg)

Coca (g/day)

Llipta (g/day)

Male mean
10 39 151 51 62.5 5.9
S.D.
  19 10 10 23.2 4.2
Female mean
12 40 115 45 54.1 6.4
S.D.
  18 4 8 23.3 4.6

A series of tests contrasting conqueros with non-users (less than 1 chew per week) was carried out in order to test physiological responses of highland natives to these average amounts of coca ingestion. From a group of 20 applicants six heavy users and five non-users were selected. On alternating days half of the group chewed coca while half abstained. Habitual users were given any quantity of coca that they requested, while non-users were given 50 gm of leaves and asked to chew all of it. Llipta was given with the coca. Subjects were tested for oxygen intake, heart rate, and blood pressure. The results are summarized in table 2.

TABLE 2 Responses of habitual and non-habitual coca users after 24 hours of chewing or abstaining from coca

 

Habitual

Non-habitual

N
6 5
Retests
3 4
Total
9 9
Age (year)
30 23
 

With

Without

With

Without

Vo 2(1/min)a, b
0.31(0.1)c 0.32(0.01) 0.30(0.00) 0.30(0.00)
HR (f/min)
81(12) 80(10) 78(10) 77(7)
Systolic (mm)
119(9) 122(14) 115(11) 110(8)
Diastolic (mm)
83(6) 83(10) 77(6) 83(7)

Vo 2is oxygen intake per minute; HR is heart rate; Systolic and Diastolic are blood pressure measurements.

None of the group differences is statistically significant.

Means and standard deviations are indicated.

As can be seen, there were no significant differences between coca users and controls in either the user or non-user categories. Further studies were undertaken to test native claims of increased work capacity and feeling of warmth following coca ingestion.

FIGURE I

Full size image: 17 kB

The results of coca use on oxygen intake (Vo 2) and heart rate. Work level is 350 kg-M/min, 2 is 525, 3 is 875 and 4 is 1150. Level 5 is heart rate 4 minutes and 6 is 30 minutes after the cessation of work.

Seven coca chewers and five non-users were selected for the exercise test (Hanna 1971a). One user and three non-users were tested twice to round off the "sample population" at 8 users and 8 non-users. They were tested after resting an hour on 2 separate days. One day they used coca (about 50gm for non-users, any desired amount for users) the other day they abstained. Subjects were tested on a Monark bicycle ergometer. The tests consisted of three minutes of effort at each of four increasing work loads. Three subjects did not finish all 4 levels, so statistics were computed only for levels 1 through 3. Variables observed were oxygen intake, ventilation, heart rate, and blood pressure. Analysis of variance showed no statistical difference in blood pressure and ventilation between trials. Oxygen consumption and heart rates are shown in figure 1.

An analysis of variance over the first three levels showed no statistical difference in oxygen intake. This suggests that coca use did not change work efficiency or the energy required for a given task. Heart rates shown in figure 1 illustrate a significant difference between coca and non-coca runs (0.01

< little have to seems but coca, of effect stimulatory a from result may This>

TABLE 3 - Performance of matched habitual and non-habitual coca users during work. Means for coca using trials

 

Habitual non-users

Habitual users

Fa

N
5 5  
Age (year)
24.8 26.2
nsb
Height (cm)
155.4 152.2
nsb
Weight (kg)
53.8 52.4
nsb
Vo 2(1/min)c
1.64 1.61
nsb
HR (f/m)
139.9 141.5
nsb

F = ns is non-significant.

Paired "t" used for first three characteristics.

Mean Vo 2and HR for first three levels of work where Vo 2is oxygen uptake in litres/minute and HR is heart rate per minute.

TABLE 4 Resting and maximum values for maximal working test

 

Rest

 

Maximal

 
 

No Coca

Coca

t a

No Coca

Coca

 
Vo 2(l/min)> c
0.31 0.33
ns
2.56 2.58
ns
Aerobic Capacity (cc/kg/min)
-
-
ns
46.8 46.2
ns
HR (f/min)
82.7 80.8
ns
183.6 182.5
ns
SP (mm)
118.2 119.4
ns
152.9 155.7
ns
DP (mm)
80.7 83.1
ns
88.9 89.2
ns
Duration (min)
-
-
ns
5.2 5.6
ns> b

HR is heart rate in beats per minute; SP and DP are systolic and diastolic blood pressures and duration is length of exercise in minutes. on the performance of work. A multiway analysis of variance matching users with non-users for height and weight was performed, and demonstrated no significant differences between them suggesting that the tachycardia following coca chewing is characteristic of both users and non-users alike. This work is illustrated in table 3.

The final work-test run was designed to examine the effect of coca chewing on maximal effort in both users and non-users. The test was run on a bicycle ergometer with a high load which was increased each minute until the subject was completely exhausted. Maximal oxygen intake, heart rate and pre- and post-trial blood pressures were recorded. As shown in table 4, none of the differences are statistically significant, although longer riding times of about 20 seconds (1.0< t<0.05) were recorded for coca use trials.

FIGURE 2

FINGER.

Full size image: 15 kB, FINGER.

Minutes

of exposure

------ No coca at 15.5C

____ Coca

The result of coca use on body temperature. Finger and toe temperatures are significantly lower after coca use. The resulting economy of body heat content is seen in rectal temperwature.

Summarizing the above with regard to work performance, we may note that coca chewing resulted in acceleration of the heart rate and a slightly increased endurance time.

Another claim the Indians make for coca use is that it makes them feel warm (Little 1970). To examine this assertion, a study was conducted to observe possible changes in physiological response to cold after coca leaf ingestion (Hanna 1971b). Fourteen male subjects were chosen, 9 of whom were habitual coca users. Each subject was tested once with coca and once without it on each of two separate days. After resting under blankets for an hour, the men, dressed only in shorts, were exposed to 15.5 °C (60 °F) for two hours. Temperatures were measured for the body surface and core (rectal) over the two hour exposure time. The results are illustrated in figure 2. An analysis of variance demonstrated a significant difference between tests with and without coca. Chewing coca leaves resulted in lower peripheral temperatures, but also during the second hour of exposure a higher core temperature was maintained in subjects chewing coca. Thus coca use resulted in more intense vasoconstriction of the periphery and lead to a reduced heat loss from the core.

To summarize this work with respect to physiological and environmental parameters, evidence suggests the Indians' assertion that chewing coca warms them, quells hunger, and reduces fatigue may be valid. Although the mechanisms by which all these effects are realized have not been clearly demonstrated, the work reported above has shown oral ingestion of coca to result in: first, a mild vasoconstriction resulting in reduced heat loss from the extremities and a higher core temperature; elevated heart rate and a slightly increased endurance time under working conditions; and perhaps a significant nutritional input.

High nutritional value, a higher core temperature and a reduced sense of fatigue derived from chewing coca leaves can be seen as having significant adaptive value in an environment such as the Andean plateau where cold, hard work, and a marginal diet are common. When viewed from this perspective, the general correlation between coca use and altitude noted by earlier investigators can be looked at as demographic evidence in support of coca chewing as an adaptive behaviour to the environmental stresses imposed by life at high altitude.

Consideration of the socio-economic aspects of coca use among the indigenes of the altiplano further illustrates the integral role this plant has assumed in the lives of the people over the passing centuries (Hanna 1974). The coca-producing areas are located in the foothills on the eastern slope of the Andes. Communication between these areas and the altiplano is limited due to the ruggedness of the terrain. However, trade networks exist, extending the ecological resource base of the natives of both the altiplano and the foothills. Each year men (some-times with their families) travel to the foothills, taking with them animals, meat, potatoes, and cereals from the altiplano. These can be traded for coca as well as other tropical products to be used and sold when they return to Nunoa.

Bargaining for their coca outside the national government's formal distribution network, the natives who make this journey increase the value of their crops inasmuch as the goods are worth far more in the foothills than they would be if sold to a local Nunoa merchant. This multiplier effect acts on the goods from the foothills also, as they increase in value when transported to Nunoa. Coca leaves may also function as a substitute currency with stores exchanging goods for coca at fixed rates, and wages being paid in coca for various tasks.

Economically speaking, the coca trade brings the otherwise self-sufficient Indians into touch with other segments of society and thus involves them in the national market. The trade potential of farm goods which may be converted to coca leaves and consumer goods represents an incentive to the Indian farmers to keep up their production.

Socially, coca has played an important part in Indian life since pre-Columbian days, when the Inca employed it in divination, sacrifice, as a prize in athletic contests and as a mark of special favour (Martin 1970). For the modern Indian such as the Aymara of Bolivia, coca is chewed at all ceremonial occasions, at wakes, weddings, divinations, sacrifices and initiation ceremonies. Aside from its traditional economic, social and religious usages, the applications of coca as a herbal remedy in folk medicine are legion. It is employed as a veritable panacea for ailments ranging from headache to broken bones (Martin 1970).

Coca use or cocaine addiction

Whether or not coca is efficacious in all these treatments has not been clinically demonstrated, however a purified version of one of its alkaloids, cocaine, became very popular in western medicine for the treatment of a wide variety of ills (Hoffmann 1975). Cocaine use was pharmaceutically restricted when it was found that it causes psychological addiction. Also, other local anesthetics, such as procaine, which exhibit similar analgesic properties, but do not act as powerful cortical stimulants have been synthesized.

The equation of coca chewing with an addiction to cocaine (Zapata Ortiz 1944, Risemberg 1944) is principally based upon reported similarities between the physiological responses exhibited by people who ingested the two substances. Zapata Ortiz (1944) also noted severe withdrawal symptoms in habitual users who abstained from coca. However, subsequent studies (Monge 1952, Martin 1970, Salser 1970, Hanna 1974) contradict this observation and in fact withdrawal symptoms of this nature (vomiting, diarrhoea, general distress etc.) are characteristic of narcotic withdrawal rather than cocaine withdrawal (Goodman 1965, Isbell 1967, Hoffmann 1975). In the decades of study devoted to the elucidation of the action of coca leaves and cocaine on the human body, no clinical evidence has come to light other than the study of Zapata Ortiz, which would indicate any physical addiction. The chills, vomiting, etc. reported are similar to withdrawal symptoms shown by those addicted to the opiates morphine or heroin (Hoffmann 1975).

The action of cocaine is similar to that of the amphetamines. Some authorities have postulated that both cocaine and the amphetamines may have similar actions in maintaining circulating levels of catecholamines in the blood (Isbell 1967). Neither cocaine, nor coca leaves is an opiate in action, nor have they been shown to produce physical dependence.

Although physical dependence has not been demonstrated, cocaine is indeed a dangerous drug and susceptible individuals can develop a strong psychological craving for the "high" it engenders.

The ability of cocaine to cause excitation of the central nervous system seems to constitute its principal attraction for drug-dependent individuals (Hoffmann 1975).

Hence before we equate the chewing of coca leaves by the aboriginal Indians of the altiplano with the habit of a cocaine addict, it would be wise to examine current knowledge regarding patterns of use, motivations of users, and effects of drugs.

Beginning with patterns of usage we may observe that cocaine is generally sniffed or injected directly into the bloodstream, whereas coca leaves are most often chewed. This is significant with regard to the bioavailability of the drug in question, that is the rate and quantity of drug reaching the site of its action (Garrett 1974). The primary site of action for cocaine is the central nervous system, where it acts as a powerful cortical stimulant (Goodman 1965). Transsection of the spine in laboratory animals has demonstrated that other effects of cocaine (tachycardia) are mediated via the central nervous system. Thus to yield its systemic effects cocaine must get into the bloodstream and ultimately into the brain. Cocaine is a local anaesthetic and most systemic effects of local anaesthetics are due to high plasma levels of a drug resulting from excessive use or rapid absorption (Campbell and Adriani 1958). But the oral route for cocaine uptake as in the chewing of coca leaves is most inefficient because when given orally, cocaine is largely hydrolized in the gastrointestinal tract and rendered ineffective (Goodman 1965). After cocaine is absorbed through the gastrointestinal tract it passes through the liver which in humans is the principal site of cocaine detoxication. Thus it is not surprising that neither cortical stimulation nor toxic effects are evident in the coca chewer, since the amount of cocaine passing into the bloodstream is insignificant in relation to the amount entering the organism (Montesinos 1965). In an earlier study Monge also observed that "quantities of cocaine found in the blood as a result of chewing the coca leaf are really insignificant" (Monge 1952).

In concluding our observations on patterns of usage, we should like to point out that in earlier laboratory studies (Zapata Ortiz 1944, Risemberg 1944) which equated the effects of cocaine with those of coca chewing, dosages were often administered at one time which were largely in excess of the average daily consumption observed in the altiplano. Using Montesinos' (1965) figure of 350 mg as the maximal amount of cocaine which could be extracted from 50 grams of leaves, broken down into three chews in a day, with a conservative estimate of 75 per cent hydrolysis by the gastrointestinal tract secretions, less than 0.03 gm would even get to the liver on the first pass. When we contrast this with Goodman's (1965) estimate of cocaine addicts using as much as 10,000 mg in a day employing direct injection into the bloodstream, it seems obvious that the resulting physiological effects should be unequivocally distinct.

Cocaine and coca chewing both are reported to promote warmth and reduce both fatigue and hunger. Upon first review of the data, many investigators have concluded that the effects we are witnessing must be the result of the same chemical. However, the above considerations with regard to the effective concentrations in the blood seem to warrant further investigation. In an earlier study (Hanna 1974) it was suggested that arecoline may have been the active factor involved in general stimulation and hyperactivity. Another likely possibility is the alkaloid nicotine, reported to be present in coca leaves by several researchers (Martin 1970, Duke n.p.). Similarities exist between the pharmacological action of nicotine and acetylcholine. In small doses, nicotine acts as a stimulant and in larger ones as a depressant, thereby mimicking the presumed action of cocaine (Robson and Stacey 1968). Nicotine may act as a stimulant both on the central nervous system and on voluntary muscle; it also affects the circulation through the vasomotor and vagus centres and as little as 0.2 mg of nicotine is reported to reflexly abolish hunger contractions of the stomach for 15 to 60 minutes (Grollman 1965). An ethnological parallel germaine to our argument here is that of the Central Australian aborigines, who employ nicotine in their adaptation to cold and fatigue much as the Amer-indians do coca. They chew the leaves of the plant Ruboisia mixed with tobacco into a bolus or quid in their mouths. The principal active alkaloids here are nicotine and nornicotine which are reportedly effective in combating hunger, cold, and fatigue (Hicks 1963, Grollman 1965). The common problem of weight gain due to increased appetite upon stopping cigarette smoking may corroborate this.

Returning to the motivations of the users, the distinction between coca chewing and cocaine addiction apparently centres on the intense cortical stimulation produced by cocaine. It is not likely that people are paying high prices for cocaine to reduce their appetite, or to keep them warm. On the other hand, even when given the opportunity to chew quantities of coca which might produce cocaine euphoria, habituated coqueros did not choose to do so. In sum, the motivations of the users of cocaine and coca leaves seem to be very different and the effects produced by chewing coca leaves may be the result of an alkaloid or alkaloids other than cocaine. We should also mark the lack of mental deterioration among the Indians of the altiplano, which has been reported as concomitant effect of ingesting 150 mg of cocaine daily (Musser and Shubkagel 1965, Sutherland 1970).

Overview

Coca use among the Indians of South America is seen to be physiologically beneficial in terms of their adaptation to hunger, cold and fatigue at high altitudes. Economic, social, and dietary advantages have also been pointed out. The principal physiological changes which have led earlier investigators to equate cocaine addiction with the chewing of coca leaves, quite possibly were produced by other alkaloids present. The addictive properties of cocaine are believed to be the result of its action on the cerebral cortex, an effect which the other alkaloids present do not have (Goodman 1965). In conclusion, the chewing of coca leaves does not seem to result in obvious physical and mental deterioration among the Indians. However, the ingestion of harmful alkaloids and probably pesticides as well (Duke n.p.) cannot be judged a safe practice. These observations are not cited to obscure the potential danger of the toxic alkaloids ingested by coca chewers, but rather to underscore the need for a thorough awareness of the interlocking nature of the components of a people's long standing adaptation to their environment.

Bibliography

Baker, P.T., "Ecological and Physiological Adaptations in Indigenous South Americans with Special Reference to the Physical Environment", in The Biology of Human Adaptability, P.T. Baker, and J.S. Weiner, eds. Oxford: Oxford University Press, 1966.

Baker, P.T. and M.A. Little, Man in the Andes: A Multidisciplinary Study in High Altitude Quechua, Dowden, Hutchinson and Ross, Stroudsburg, Pennsylvania, in press, 1976.

Baker, P.T. and R. Mazess, "Calcium: Unusual Sources in the Highland Peruvian Diet" Science 142: 1466-1467, 1963.

Buck, A., T. Sasaki, and R. Anderson, Health and Disease in Four Peruvian Villages, Baltimore: Johns Hopkins, 1968.

Use of coca leaf in southern Peru 73

Cárdenas, M., "Psychological Aspects of Coca Addiction", Bulletin on Narcotics, IV:2, 6-9, 1952.

Chambochumbi, M.N., "Effectos de la coca sobre el metabolismo basal en sujetos no habituados", Revista de Farmacologia y Medicina Experimental 2:94-113, 1949.

Cuiffardi, T.E., "Dosis de alcaloides que ingieren los habituados a la coca", Revista de Farmacologia y Medicina Experimental 1:216-231, 1949. "Contribucion a la quimica del Cocaismo", Revista de Farmacologia y Medicina Experimental 2:18-93, 1948.

Duke, J.A., Nutritional Value of Coca (Erythroxylum coca lam), unpublished.

Garett, E.R., Classical Pharmacokinetics, T. Teorell, R.L. Dedrick, P. G. Condliffe (eds.) Plenum Press N.Y., 1974.

Goodman, L.S. and A. Gilman, The Pharmacological Basis of Therapeutics, 3rd ed. Macmillan, N.Y., 1965.

Gutierrez-Noriega, C., "Acción de la cocaína sobre la resistencia a la fatiga en el perro", Revista de Medicina Experimental 3:239-243, 1944.

_____, "Errores sobre la interpretación del cocaismo en las grandes alturas", Revista de Farmacologia y Medicina Experimental 1:100-123, 1949 a.

_____,"El habito de la coca en E1 Peru", America Indigena 9:143-154, 1949 b.

Hanna, J.M., "Further Studies on the Effects of Coca Chewing on Exercise", Human Biology 43:200-209, 1971 a.

_____, "Responses of Quechua Indians to Coca Ingestion during cold exposure", American Journal of Physical Anthropology 34:273-278, 1971 b.

_____, "Coca Leaf Use in Southern Peru: Some Biosocial Aspects", American Anthropologist, vol. 76:2 pp. 281-296, 1974.

Berbst, R. and P. Schellenberg, "Cocain and Muskelarbeit II: Weitere Untersuchungen über die Beeinflussung des Gasstoffwechsels" , Arbeitphysiol. 4(3):203-216, 1931.

Hicks, C.S., "Climatic Adaptation and Drug Habituation of the Central Australian Aborigine", Perspectives in Biology and Medicine. 7:39, 1931.

Isbell, H., "Pharmacological Factors in Drug Dependence", in Advances in Experimental Biology and Medicine, vol. 20 pp. 35-47, 1967.

Karpovich, P.V., The Physiology of Muscular Activity. Philadelphia: Saunders, 1966.

LaBarre, W., The Aymara Indians of the Lake Titicaca Plateau, Bolivia. Memoir No. 68. American Anthropological Association (Menosha, 1948).

Lanning, E., Peru before the Incas. Englewood Cliffs, N.J.: Prentice-Hall, 1967.

Little, M. A., "Effects of Alcohol and Coca on Foot Temperature Responses of Highland Peruvians during a Localized Cold Exposure", American Journal of Physical Anthropology 32(2):233-242, 1970.

Martin, R.T., "The Role of Coca in the History, Religion and Medicine of South American Indians", Economic Botany 24:422-437, 1970.

Mazess, R., and P. Baker., "Diet of Quechua Indians Living at High Altitude: Nunoa, Peru", American Journal of Clinical Nutrition 15:341-351, 1964.

Monge, M.C., "The need for studying the problem of coca leaf chewing", Bulletin on Narcotics, IV:4, 13-15, 1952.

Montesinos, A.F., "Metabolism of Cocaine", Bulletin on Narcotics, XVII:2, 11-17, 1965.

Picon-Reategui, E., "The Effect of Coca Chewing on Metabolic Balance in Peruvian High Altitude Natives", Occasional Papers in Anthropology No.1. The Pennsylvania State University, University Park, PA. 556-563, 1968.

Risemberg, M.F., "Acción de la coca y la cocaína en sujetos habituados", Revista de Medicina Experimental 3:317-328, 1944.

Robson, J.M. and R.S. Stacey, Recent Advances in Pharmacology, Little Brown and Company (Boston, 1968).

74 Bulletin on Narcotics, Vol. XXIX, No. 1, January-March 1977Slutes, R., "Botanical Sources of New World Narcotics", Psychodelic Review 1:145-166, 1963.

Sutherland, V.C., A Synopsis of Pharmacology. W.B. Saunders Co., Phila., 1970.

Traunt, A. and B. Takman, " Local Anesthetics, Ch. 11 ".in Drill's Pharmacology in Medicine (34d ed.), J. DiPalma (ed.) McGraw-Hill, New York, pp. 133-156, 1965.

Wolff, P.O., "General Considerations on the Problem of Coca Leaf Chewing", Bulletin on Narcotics, IV:2, 2-5, 1952.

Zapata Ortiz, B., "Modificaciones psycológicas y fisiológicas producidas por la coca y la cocaína en los coqueros", Revista de Medicina Experimental 5:132-162, 1944.

000

None of the differences are statistically significant at 5 per cent or better. A paired samples t-test with 6 df was used.

0.1 < t<0.05.

Vo 2is minute oxygen uptake in litres; aerobic capacity is oxygen consumed per kg body weight;