regional sweating in eskimos compared to caucasians

Regional Sweating in Eskimos Compared to Caucasians

Nouthcrn Medicnd Reseal-c-h Unit, Metkic.al Sen~ic.es, Ednronton, Alberta l '5MSA4

Northerrl M ~ d i c a i Unit, IJrzi~.l~raity o~'1l4arzitoba. Winnipeg, hfanitoha RSEOWZ

AND

Received December LO, 1973

SCHAEFER, O., HILDES, J. A., GREIDANUS, P., and 1 2 ~ ~ ~ ~ , D. 1974. Regional sweating in Eskimos corrlpared to Caucasians. Can. J . khysiol. Pharmacol. 52,968-965.

After pharnaacological stimulation, prints of functioning sweat glands were obtained from 17 skin sites on the face, body, and limbs of 37 adult rraale Eskimos and 21 Caucasian controls.

Erkimos showed greater numbers and greater activity of functioning sweat glands on exposed parts sf the face such as nose and cheeks, while responding with significantly less sweat gland activity on all body surfaces that are nornnally heavily clothed in winter. 'Trtinks, arnas, hands. legs, and feet showed a progressive reduction of sueat gland response in the order of one-half on the triaisk to one-fifth on feet when contparing mean sweat gland counts per square centimeter in Eskinlos and cont~ols. The comparative reduction of sweat gland response in the Eskimos progressed in the same order as the distance of the part from the body core, and as the risk of the part to freezing. There- fore, this reduction of sweat gland activity may represent a morphologicnB and/or ft~nc- tional adaption to enviranment;al conditions including climate and clothing.

SCHAEFER, O., HILDES, J . A., GREIDANUS, P. et Lnu~c;, D. 8974. Regional sweating ila Eskinac~s compared to Gaa~casians. Can. J . PhysioI. Pharmacol. 52: 940-965.

Aprks stirnelfation pharmacologiq~ae des glandes smdoripares, nous avons mcsurC la tlensitk des glandes en iictivit6 en 17 zones du visage, dir corps et des mernbrcs chez 17 eskin~os miles ea adulles, et ckez 21 caucasiea~s contrhles. Chcz les eskimos, ies glandes sudoa-ipares sont plus non~breuses c t plus actives au niveau dcs zones exposCcs del visage comnae le nez et les jo~ies qu'au nivea~a des zones d~a corps chaetdemel-at vetues en hiver. Le tronc, les bras, les mairas, les jambes et les pieds rno11t1-ent- une riduction progressive de la rkpsnse des glandes sudoripares de l'ordre cil'lrne demie at1 niveau dta tronc el d9uane cinquikme ara nivearn des pieds lsrsqlae 190n compare le nombre n-acdyan de glandes seadoripares par centimktre carp6 chez les eskinsass et les caucasiens. C'kez Ies eskimos, cette rEductisn de l'nctiviti sudsripare Cvolue era Eonction cte la distmce du lronc, et Ggalernent en fonction tlu risque cle gel de la pnrtie consid&r@e. Cette rGducrion repre- senterait lame adaptation morpkologique et/ou fonctionnelle aux conditions environnantes donl les conditions climatiques et vestimentaires.

ITraduit par le joa~rnall

Introduction Cold adaptation of Eskimos and other

northern pcoples has been the subject of physiological studies (Harnmcl 19641, but it is well recognized that such adaptation5 are probably of ~nrtlch greater significance in the naked or near naked absrigi~nal races such as the Aus- tralians Aborigines (Sclscdander et al. 11 958), and the Kalahari Bushmen (Hamrnel eb al. 1962), whereas human existence in the Arctic appears to depcnd more am clothirag and shelter technc~lsgy than on msrpholc~gical and physis-

logical aciaptations. Ira fact, the thermal re- sponses of Eskin~os in a stam~lard cold C X P O S I B F ~

appear paradoxically opposite to those of naked races mentioned in that, rather t h a n relying on a vasoconstrictive insulative response, the Klski~nos respond with high lacat productic~rn and maintaira blosd flow to the peripheral tissues, particularly the laarlds (Hammel 1904; Hildes el a/. 196 1 ) .

Indeed it has been recognized by Burton and Edholm ( 9 955) that if thc Eskimos have a thermal problem it I? one of heat rather tltsa1.n

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SCWAEFER ET AL.: REGIONAL SWEATING IN ESKHMOS 96 g

FIG. 1 . Typical sweat gland prints. ( a and b ) Prints from truncal sites (abdomen) of Eskimos ( a ) and Caucasian ( b ) subjects, respectively. ( c and d ) Prints from face (cheek) of Eskimos ( e ) after 10 rng bethanechol, ( d ) after 5 rng bethanechol.

cold during prolonged bursts of high activity while hunting, when he has to remain fully clothed. E&cicnt heat dissipation by evaporation of sweat requires free access of air, which Eskimo winter clothing allows only for the face 2nd to a very limited degree to parts sf the trunk and arms but practically not at all to the Begs. Much sweating on body surfaces where it can not evaporate would not only be ineffective but the ensuing soaking of fur clothing with sweat wokrid be most un- comfortable or even endanger the Arctic hunter's life.

We have observed personally om m a y oc- casions that Eskiraos sweat profusely on the face when warm but the rest of the body re- mains comparatively dry (Sc~~aefer, 0.: un- published observations), suggesting an adaptation of preferential regional sweat gland activity to their Arctic habitat and clothing. A study was designed to test this hypothesis by corn- paring regi6;lai sweat gland activity in healthy adult Eskimos ts Caucasians.

Methods and Sabjects We studied 58 males (28-55 years), 3'7 Eskirnos

and 21 Caucasian contro1s. SOPIP@ of the Eskimos were tested in hospital ~ ih i l e conaralescing and the remainder ;at Igloolik, N.W.T., an Eskimo village. The Caucasian controls (students. physicians, 0r orderlies) also underwent tests both in hospital and under field conditions in Iglsolik.

For this particular purpose sf detecting regional

differences in sweat gland activity, the method recommended by IVeiner and Eourie ( 1969) seemed suitable except that there were technical di&cralties in using thermal stimulation to evoke. sweating under Parctic field conditions, since it requires immersion of one arm and leg in water tanks with a controlled temperature. Therefore, we used a pharmacological stim~ltls to activate the sweat glands, a suksutanecseas dose of kedhanechol, a parasyra~pathomirnetie agent. The ~astaal dose was 5 mg but we found, particularly in the cooler environment during the field tests, that this often required supplementation by a repeat dose if sweating was not noticeable in 7-15 min. The plastic impression method described by Snrarman and Thornson (1952) was also found less suitable in field conditions than the older starch-iodine method as modified by Randall (1946). This im- volves pir-rting the skin area to be tested with a 4 % iodine tincture and pressing a starch-impregnated 4 x 10 cm piece of bond paper to the skin after a short interval to :allow for evaporation of the tincture. P;ctive sweat glands are shown as yellowish brown dots. 'Fypical prints are shown in Fig. 1.

Preliminary studies were landertaken at the Charles Camsell Hospital in Edmonton using seven Cau- casian and eight Eskimo subjects, in each of whom the response to immersion sf one arm and k g in water at 43-44 "C was compared with that of a subcutaneous insection of 5 I ~ P of bethanechol.

I h,

Sweating occurrecl earlier and was more profuse after thermal stin~ulatiora in both racial groups, indi- cating submaxinlaE sweat gland stimulation in most subjectsaafter 5 mg of kcthanechol. The number of active sweat glands recorded after the pharrnaco- logical stirnulrss was in all test sites 20-40% lower. Since, however, both methods appeared to show quite similar differences of regional sweat gland response between Eskimos and Caucasians we felt justified to use, in field tests, only the less cumber-

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962 CAN. J . PHYSIOL. PHARMACOE. VOL. 5 2 , 1974

some pharmacological stimulation method, Indeed reqtaired compared with the contro1s (averaging 2 s subtnaxirnai stimulation of sweating might sirnttlate in the Eskimos vs. 5 s in the controls). Csnversely Arctic life conditions more closely and a comparison print application time on trunk and extremities tended of sweating response under such cvnditisrns would, to be considerably longer in Eskimos thm in Cau- therefore: be of greater relevance. casians with the greatest difference recorded over

Site of Sampling We folIowed the directions given by Weiner and

Eoalrie (1969) for selection and preparation of body sites to be counted but added an additional site, the nose, whisk we had previously observed in Eskimos to be the usual site where sweating starts and where it is mast profuse (see Fig. 2 ) . Countirzg Mechuck

Analysis of bond paper prints was performed independently by two observers, using a low power stereoscopic microscope. Each observer ccbusated 4 c m 9 n different parts of each print and the mean count per square centimeter for each site was tabu- lated. There was no consistent or large difference found between the observers.

A nsoun t of Sweating No attempt was made to measure the quantity of

the dorsram of the h o t (32 s vs. 10 s). Although actual recordings of timing and duration

sf optimal print application to the 17 teat sites were started too late in the test series and remained too incomplete to warrant statistical comparisons, they were in line with our observations in this respect: we had to begin printing of facial sites in Eskimos sooner and apply prints for shorter periods than in Caucasians, whereas the reverse was true for test sires OR trunk and extremities. These observations fend to emphasize differences in numbers of responding sweat glands to be discussed BpcButv. The profuse sweating typically seen in Eskimos on the face while the rest of the body appeased relatively dry is demon- strated in Fig. 2, which also shows a number of iodine-tincture prepared trunkaI test sites.

Results and Discnssioas sweat prodiiced as this was impossible under %eld ~h~ number of glands activated in coaaditisns. We observed, however, that Eskimos pro- duced much Inore copious quantities of sweat on the of the skin areas studied after face so tkat a shorter time of mint a ~ d i c a t i o n was dc~n biifh either 5 10 nag b e h n e ~ h ~ l in the

1 L I

Eskimos and control subTects are shown in

FIG. 2. Eskimo 20 min after bethagaechol injec- tion. Note profuse sweat pearls on face while body remained relatively dry. Darker strips on body are test sites painted with 4% iodine tincture.

Table 1 . Since use of the- 10 rng bethanechd dose led in most Eskimos to such profuse and precipitate facial sweating tkat blotchy con- fluent sweat @and prints resulted (see Fig. I c and d ) making counting more difficult and less accurate, we compare in Table 2 test results from Eskimos and contrsIs who have received a dose of 5 rng bethanechol. Both tables show, with miner exceptions, similar rcsults, namely equal QP greater numbers sf active sweat glands in facial test sites in Eski- mos and significantly kswer numbers on most sites on trunk and extrcmitics, The differences appear greater and statistically more significant despite smaller numbers sf subjects when only subjects stimulated with the single 5 mg beeh- anechol dose are compared.

Fig. 3 shows on a ~~milogar i th rn i~ chart the reIative rates sf sweat gland activation in Eskimos compared ts the means found in Caucasian controls in the 1'7 sites tested. A markedly lower sweat gland' response was shown by Eskimos on all skin sites tested on trunk and extremities: in the order of only 10-20% on the most peripheral and most cold-exposed feet and lateral Ieg surfaces and of 40-6596 on the trunk when compared to corresponding sites of the controls. The differences were highly significant for eight of

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9 64 CAN. 9. PHYSIOL. PHARMACOI,. VOL. 5 2 , 1974

RELATlVE REGIONAL SWEAT GLAND ACTIVITY OF 17 MALE ADULT ESKIMOS, DEPICTED AS % OF MEANS FOUND IN 20 CAUCASIAN CONTROL SUBJ.

NOSE (p ( 0 05 )

CHEST (p ( 0 0 2 ) 4BDOMEN ( p ( 0 0 1 ) UPPER BACK MID BACK BUTTOCK

UPPER ARM (p (001) FOREARM ( p ( 0 0 2 ) HAND (p(OOi j

THIGH MEDIAL THIGH ANTER. (p (0.001 ) THIGH L4TERAL (p (Q001 J LEG MEDIAL !p (0 0 2 j LEG LATERAL ( p ( 0 001) FOOT ( ~ ( 0 0 1 )

FIG. 3. A semilogaritkrnic scale was used for better graphical expression of numerical relations of regional sweat-gland response of Eskinnos compared to Caucasian controls who provide the standard (100%). Note that Eskinlos had higher sweat-gland counts only in perioral areas of the face, whereas they h:ad Bower counts in all other body regions, most nmarkedly so for lower extrenaities.

objectionable and obtaining of usable prints technically too difficult.

The sweat gland response on the cheeks, which in Eskimc~s more often than the nose are frostbitten, was only in~significantly greater in Eskimos than Caucasians (+37% ) ? whereas the forehcad which, with the traditional hair- cut of Eskimo men, is covered up to the eyebrows by a thick front lock the mean number of responding sweat glands was insignifi- cantly lower ( -25% 1.

Fig. 4 compares the mean numbers of sweat glands activated on trunk, arm, legs, hands, and feet in relation to facial sweating in both racial groups. In order to compare distribution of sweating in the Eskinlo to that of the Caucasian controls we calculated for each group the ratios of sweating cpn the trunk, arms, hands, legs, and feet to that of the face. Then in each case the ratio of the Eskimo ratio to the corresponding Caucasian ratio was calculated and shown on the right-hand side of Fig. 4. It may be seen that the Eskimo- Caucasian trunk to face relationship is % : 2.6 (or 39%) and that relative to Caucasians Eskimo sweating is steadily reduced as one proceeds peripherally. Thc Eskimo-Caucasian feet to face sweating ratio is 1 16.6 (15 ?h ).

This gradient of comparative regional dif-

ferences in sweat gland activity of Eskimos parallels the distance from body core and danger of freezing. Facial sweat response differences appear to reflect presence or absence of fur and hair cover in traditional Eskimo clothing.

We may conclude, therefore, that regional distribution of functioning sweat glands and order of arousal to activity diEered significantly in Eskimos from that seen in Caucasian controls. The observed peculiarities of sweating in Eskimos appear to suit very well their en- vironnaental climatic and clothing conditions and may, therefore, constitute iillportant mor- plsological and functional adaptations.

Kawahata and Adanls (1961) found a barely significant (6) < 0,051 lower number of active sweat glands after maximal heat chamber stimulation in Eskimo women cf. Caucasian females. Only two Eskimo inen were tested and had slightly Bower counts than white men, but not enough subjects were tested to allow valid cor.eclusions for Eskimo men. Facial and body sites tested arc not reported separately but only the calculated total body sweat gland numn bers and isneans per square centimeter are listed. 'The validity of this calculated overall body mean for their interracial comparison is open to question in our opinion because: ( Q )

thcy arrived at their total body means taking into account 20 different facial and body sites tested in Negroes and Caucasians, while their Eskiislo subjects had only 8 face and body sites tested, and ( h ) swcat gland response in Esk in l~~s cf. Caucasians may differ inversely for facial and other body sites. as our own in- vestigations indicate, and by partial cancella- tion result in dimiilished differences of calculated means for the entire body.

Of interest in this regard arc also Kawahata's earlier findings of greater numbers of reacting sweat glands in Japanese born and raised in tropical climates cf. Northern Japanese, and in Japanesc when compared to Russians living in Northern Manchuria (Kawakata f 950) , and Japanese and Aino's living on Hokkaido Island in Northern Japan (Kawahata and Akamoto 1951).

Summary Highly significant differences were demon-

strated in nunabers and degree of response to

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SCHAEFER ET AL.: REGIONAL SWEATING IN ESKIMOS

RELATlONSHlP OF SWEAT GLAND ACTIVITY ON TRUNK AND EXTREMITIES VERSUS FACE ESKIMO

ESKIMO , CAUCASIAN CAUCASIAN BODY - FACE

FACE : 76 3 .. . .. ..... ' . ....,, . . . . . . . . . . . . . . . . . . . .. ...........,.... . . . . . . . . . . .. . . . . .. .. .. ,607 "EL

-.--- + TRUNK : I 2 6

ARMS : I 3 3

HANDS

LEGS

FEET I 6 6

NUMBER OF WEAT GLANDS PER SQUARE CENTIMETER

FIG. 4. The lower sweat-glaiad response of Eskin~cps on trunk and extrenaities becomes even more striking when expressed as a relation to facial sweat-gland response. Comparing these relations in Eskimos to that of Caucasian contro8s the relative reduction in Fskimos varied from 1:2.6 over the trunk to 1:6.6 over the feet, if we take the relation of sweat-gland density face to body sites in our Caucasian controls as 6: 1 standard.

pharmacological stimulation of sweat glands when comparing various body surface areas in Eskimos and Caucasians. Eskimos showed greatcr numbers and greater activity of functioning sweat glands in the face while their body surfaces, which are usually covered by fur clothing, had significantly lower numbers of activated sweat glands.

The dcgrec of difference of regional sweating response in Eskimos vs. Caucasian controls was approximately 1 : 2 on the trunk, 1 : 3 on upper extremities, 1 : 4 on lower extremities, and 1 : 5 ovcr the feet, paralleling the order of distance from the body core and dangcr of freezing.

Reduction of sweat gland response in heavily clothed parts of the body, and particularly in the most peripheral and frost-endangered legs and feet fits very well the macro- and microclimatic conditions of traditional Eskimo life and clothing. This may represent an example of morphological or functional adaptation to vital priorities of life in the Arctic. The increase of sweat gland response on the exposed areas of the face is somewhat less impressive and may leave the Eskimos with a heat dissipation

BURTON, A. C., and EDHOEM, 0. G. 1455. Man in a cold environment. Edward Arnold Publishers Ltd., London,

HAMPAEL, W. T. 8964. Terrestrial aninnals in cold: recent studies or primitive Inan. Handbook of physiology. Sect. No. 4. Adaptations to the environment. Edifed hy D. B. Dill, E. F. Adolph, and C. G. Wilber. American Physiological Society, Washington, D.C. pp. 413-434.

HAMMEL,, H. T., HHP.I>ES, J . A., JACKSON, D. C., and ANIIERSON, H. T. 1962. Therrnal and metabolic response of the Kalahari Bushmen to moderate cold exposure at night. Tech. Report No. 62-44. Arctic Aeromedical Laboratory, Ladd Airforce Base.

HILLES, J . A., IRVINC;, L., and HART, J. S. 6961. Estinaa- tion of heat flow from hands of Eskimos by calori- metry. J. Appl. Physiol. 16, 617--623.

KAWAHATA, ti. 1950. J . Mie Med. Coil. 1, 25. K A W A ~ ~ ~ A . ~ A , A., and ADAMS, T. 8961. Racial variations

of sweat glalnd distribution. Proc. Soc. Exp. Riol. Med. 106, 862.

KAWAIIATA, A., and AKAMOTO, H. 1951. Jap. J . PhysioB. 2, 166.

RANDALL,, W. C. 1946. Quantitative and regional distribution of sweat glands in man. J . Clin. Invest. 25,61-68.

SC~~~OZ.ANL)ER, P. I;., HAMMEL, 6-1. T., HART, J. S., LE MESSURIER, D. H., and STEEN, 3 . 1958. <:old adaptation in Australian Aborigines. J. AppH. Physiol. 13, 21 1--218.

SIJTARPAAN, 0. O., and THOMSON, M. L. 1952. A new technique for enunaerating active sweat glands in man. J. Physiol. 117, 51-52.

pro-blem, perhaps assuming greater impoitance W L I N L I ~ , J . S.. and LOURIE, J. A. 1969. IBP Handbook

under the changed microclimatic conditions No. 9. Human biology: a guide to field ~methods. Blackwell Scientific Publications Ltcl., Oxford and

modern Eskimos live in. Edinburgh. pp. 429-439.

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regional sweating in eskimos compared to caucasians

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