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The mystery of female beauty
Yu and Shepard1 have reported a preferencefor heavy women with high waist-to-hipratios (WHR) in a culturally isolated popu-lation in southeast Peru. Their findings areinteresting because a preference for lowWHR is widespread in westernized popula-tions2–5. However, we disagree with theirargument that cultural invariance is neces-sary for an adaptionist interpretation ofWHR preference.
WHR and waist circumference are posi-tively correlated with testosterone and neg-atively associated with oestrogen6. Womenwith low WHR have better health and fertil-ity than women with high WHR5. However,women in England and Texas with high
scientific correspondence
214 NATURE | VOL 399 | 20 MAY 1999 | www.nature.com
consumption rate on leaves with Bt pollencompared with leaves with untransformedpollen (P40.004).
The low consumption rates of larvae fedon leaves with Bt pollen led to slowergrowth rates: the average weight of larvaethat survived to the end of the experimenton Bt-pollen leaves (0.1650.03 g) was lessthan half the average final weight of larvaethat fed on leaves with no pollen(0.3850.02 g, P40.0001).
These results have potentially profoundimplications for the conservation ofmonarch butterflies. Monarch larvae feedexclusively on milkweed leaves4; the com-mon milkweed, A. syriaca, is the primaryhost plant of monarch butterflies in thenorthern United States and southern Cana-da5. Milkweed frequently occurs in andaround the edges of corn fields, where it isfed on by monarch larvae6. Corn fields
shed pollen for 8–10 days between lateJune and mid-August, which is during thetime when monarch larvae are feeding7.Although the northern range of monarchsis vast, 50% of the summer monarch pop-ulation is concentrated within the mid-western United States, a region referred toas the ‘corn belt’ because of the intensity offield corn production8. The large land areacovered by corn in this region suggests thata substantial portion of available milk-weeds may be within range of corn pollendeposition.
With the amount of Bt corn planted inthe United States projected to increasemarkedly over the next few years9, it isimperative that we gather the data neces-sary to evaluate the risks associated withthis new agrotechnology and to comparethese risks with those posed by pesticidesand other pest-control tactics.John E. Losey, Linda S. Rayor, Maureen E. CarterDepartment of Entomology, Comstock Hall, Cornell University, Ithaca, New York 14853, USAe-mail: [email protected]
1. Ostlie, K. R., Hutchison, W. D. & Hellmich, R. L. Bt Corn and
European Corn Borer (NCR publ. 602, Univ. of Minnesota,
St Paul, 1997).
2. Fearing, P. L., Brown, D., Vlachos, D., Meghji, M. & Privalle, L.
Mol. Breed. 3, 169–176 (1997).
3. Raynor, G. S., Ogden, E. C. & Hayes, J. V. Agron. J. 64, 420–427
(1972).
4. Malcolm, S. B., Cockrell, B. J. & Brower, L. P. in Biology and
Conservation of the Monarch Butterfly (eds Malcolm, S. B. &
Zalucki, M. P.) 253–267 (Natural History Museum of Los
Angeles County, Los Angeles, 1993).
5. Malcolm, S. B., Cockrell, B. J. & Brower, L. P. J. Chem. Ecol. 15,
819–853 (1989).
6. Yenish, J. P., Fry, T. A., Durgan, B. R. & Wyse, D. L. Weed Sci.
45, 44–53 (1997).
7. Brower, L. P. J. Exp. Biol. 199, 93–103 (1996).
8. Wassenaar, L. I. & Hobson, K. A. Proc. Natl Acad. Sci. USA 95,
15436–15439 (1998).
9. Andow, D. A. & Hutchison, W. D. in Now or Never: Serious New
Plans to Save a Natural Pest Control (eds Mellon, M. & Rissler, J.)
19–65 (Union of Concerned Scientists, Cambridge,
Massachusetts, 1998).
Transgenic pollenharms monarch larvae
Although plants transformed with geneticmaterial from the bacterium Bacillusthuringiensis (Bt) are generally thought tohave negligible impact on non-targetorganisms1, Bt corn plants might representa risk because most hybrids express the Bttoxin in pollen2, and corn pollen is dis-persed over at least 60 metres by wind3.Corn pollen is deposited on other plantsnear corn fields and can be ingested by thenon-target organisms that consume theseplants. In a laboratory assay we found thatlarvae of the monarch butterfly, Danausplexippus, reared on milkweed leaves dustedwith pollen from Bt corn, ate less, grewmore slowly and suffered higher mortalitythan larvae reared on leaves dusted withuntransformed corn pollen or on leaveswithout pollen.
Pollen for our assay was collected fromN4640-Bt corn and an unrelated, untrans-formed hybrid, and was applied by gentlytapping a spatula of pollen over milkweed(Asclepias curassavica) leaves that had beenlightly misted with water. Pollen densitywas set to visually match densities on milk-weed leaves collected from corn fields. Peti-oles of individual leaves were placed inwater-filled tubes that were taped into plas-tic boxes. Five three-day-old monarch lar-vae from our captive colony were placed oneach leaf, and each treatment was replicatedfive times. Milkweed leaf consumption,monarch larval survival and final larvalweight were recorded over four days.
Larval survival (56%) after four days offeeding on leaves dusted with Bt pollen wassignificantly lower than survival either onleaves dusted with untransformed pollen oron control leaves with no pollen (both100%, P40.008) (Fig. 1a). Because therewas no mortality on leaves dusted withuntransformed pollen, all of the mortalityon leaves dusted with Bt pollen seems to bedue to the effects of the Bt toxin.
There was a significant effect of cornpollen on monarch feeding behaviour(P40.0001) (Fig. 1b). The mean cumula-tive proportion of leaves consumed perlarva was significantly lower on leaves dustedwith Bt pollen (0.5750.14, P40.001) andon leaves dusted with untransformed pollen(1.1250.09, P40.007) compared withconsumption on control leaves withoutpollen (1.6150.09). The reduced rates oflarval feeding on pollen-dusted leavesmight represent a gustatory response of thishighly specific herbivore to the presence ofa ‘non-host’ stimulus. However, such aputative feeding deterrence alone could not explain the nearly twofold decrease in
FFiigguurree 11 Survival and leaf consumption of second-to third-instar monarch larvae on each of three milk-weed leaf treatments: leaves with no pollen (lightblue), leaves treated with untransformed corn pollen(green) and leaves dusted with pollen from Bt corn(dark blue). a, Mean (5s.e.m.) survival based on theproportion of larvae surviving in five replicates ofeach treatment. b, Mean (5s.e.m.) cumulative leafconsumption based on the total amount of leaf areaconsumed per larva in five replicates of each treat-ment. The amount of leaf area consumed per larvain each experimental unit was calculated for eachtime interval by dividing the amount of leaf areaconsumed in that interval by the number of larvaealive during the time interval. Cumulative consump-tion was calculated by summing the leaf area con-sumed per larva at each interval. Colours of linescorrespond to those of the bars in a.
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© 1999 Macmillan Magazines Ltd
WHR and thick waists tend to have moresons7,8, and a preference for women withhigh WHR might result in selection forincreased testosterone levels in children.Men in societies that prize sons over daugh-ters and in which strength is an advantagemight therefore be expected to show a pref-erence for high WHR.
We present data from a rural Jamaicanpopulation showing that: (1) in agreementwith the data from England and Texas7,8,there is a positive association between awoman’s waist circumference and her num-ber of sons; and (2) a high WHR in womenis associated with a marker for high testos-terone (a low ratio of the lengths of the sec-ond and fourth digits, or D2/D4; ref. 9) intheir children.
Our Jamaican sample was drawn fromSouthfield in the parish of St Elizabeth andwas part of a large long-term study of devel-opmental stability (the Jamaican SymmetryProject). We measured 141 women whose
mean age was 34.6357.23 s.d. years. Thewaist was measured at the narrowest por-tion between the ribs and the iliac crest,and hips were measured at the level of thegreatest protrusion of the buttocks. All sub-jects were standing and wore light outdoorclothing.
Photocopies of children’s hands wereused to measure digit length (95 subjects,mean age 8.0051.43 s.d. years, were askedto place hands palm-down on the glassplaten). Digits were measured from thecrease proximal to the palm to the tip of the digit9. Repeated measurements on thephotocopies and comparisons with X-raysof the hands indicated that there was a highconcordance with the photocopied mea-surements. The mean D2/D4 ratio for theright hand was 0.9350.03, and 0.9450.04for the left.
The waist circumference of mothers wassignificantly and positively related to thenumber of sons (Fig. 1a) but not to thenumber of daughters. The relation betweena woman’s waist circumference and thenumber of her sons remained significantafter the effect of the age of the mother waspartialled out (partial correlation, numberof sons and waist circumference: r40.18,P40.03; and age of mother: r40.30,P40.0005).
Similar, but weaker, relationships werepresent between hip circumference andWHR and the number of sons. Waist andhip circumference and WHR were posi-tively but not significantly related to theproportion of sons (Table 1). The D2/D4
ratio was significantly and negatively relatedto WHR in the right and left hands; that is,women with high WHR tended to havechildren with low D2/D4 ratios (Table 1 andFig. 1b). As a low D2/D4 ratio is indicative ofa high testosterone level in adults, thisprobably means that women with highwaist-to-hip ratios have children with hightestosterone.
Of course, our Jamaican sample is west-ernized and we have no data on WHR pref-erences in adults. However, the positiverelation between waist circumferenceand/or WHR and a tendency to producesons has now been demonstrated in threepopulations and may well be universal.The high testosterone found in the chil-dren of high-WHR women might relate tomuscular strength (it is already known thathigh-WHR women have heavier and taller
babies than low-WHR women10). Thismight explain why traditional societies inwhich sons are valued over daughters mayprefer tubular women, which is consistentwith an adaptionist interpretation of thesepreferences.J. T. Manning*, R. L. Trivers†, D. Singh‡,R. Thornhill§*School of Biological Sciences,University of Liverpool, Liverpool L69 3BX, UKe-mail: [email protected]†Department of Anthropology, Rutgers University,New Brunswick, New Jersey 08901-1414, USA‡Department of Psychology, University of Texas,Austin, Texas 78712, USA§Department of Biology, University of New Mexico,Albuquerque, New Mexico 87131-1091, USA
1. Yu, D. W. & Shepard, G. H. Nature 396, 321–322 (1998).
2. Singh, D. J. Pers. Soc. Psychol. 65, 293–307 (1993).
3. Singh, D. Hum. Nat. 6, 51–68 (1995).
4. Furnham, A., Tan, T. & McManus, C. Pers. Indiv. Diff. 22,
539–549 (1997).
5. Henss, R. Pers. Indiv. Diff. 19, 479–488 (1995).
6. Evans, D. J., Hoffmann, R. G., Kalkhoff, R. K. & Kissebah, A. H.
J. Clin. Endocrinol. Metab. 57, 304–310 (1983).
7. Manning, J. T., Anderton, R. & Washington, S. M. J. Hum. Evol.
31, 41–47 (1996).
8. Singh, D. & Zambarano, R. J. Hum. Biol. 69, 545–556 (1997).
9. Manning, J. T., Scutt, D., Wilson, J. & Lewis-Jones, D. I. Hum.
Reprod. 13, 3000–3004 (1998).
10.Brown, J. E. et al. Epidemiology 7, 62–66 (1996).
Evolutionary psychology suggests that awoman’s sexual attractiveness might bebased on cues of reproductive potential. Ithas been proposed that a major determi-nant of physical attractiveness is the ratiobetween her waist and hip measurements(the waist-to-hip ratio, or WHR): for exam-ple, a woman with a curvaceous body and aWHR of 0.7 is considered to be optimallyattractive1–3, presumably because this WHRis the result of a fat distribution that maxi-mizes reproductive potential4. It followsthat the preference for a curvaceous bodyshape in women should be universal amongmen and not be culturally based, becausenatural selection presumably favours cuesindicative of the most fertile body shape.
Yu and Shepard have challenged thishypothesis5. They tested the preferences of aculturally isolated tribe of Peruvian Indians(the Matsigenka) by using a set of line-drawn figures of women who varied inapparent body-mass index (BMI) andWHR1. They claim that their results indi-cate a preference by this tribe for a tubularbody shape, rather than the curvaceousshape favoured in the United States5. How-ever, we believe that the conclusions of Yuand Shepard are undermined by a flawedassumption.
The drawings used by Yu and Shepardare arranged in three series5: underweight,normal and overweight. Within each series,the BMI of each of the four figures is sup-posed to be held constant, while the WHRis varied by narrowing the waist. However,we believe that this assumption is false
scientific correspondence
NATURE | VOL 399 | 20 MAY 1999 | www.nature.com 215
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FFiigguurree 11 Relations between female body shape andthe number of sons and testosterone levels in theirchildren. a, Number of sons and waist circumfer-ence in 141 Jamaican women; b, D2/D4 ratio for theleft hands of 95 Jamaican children and the WHR oftheir mothers. The lines are least-squares lines ofbest fit: a, y40.023x10.34; b, y410.155x&1.059.
Table 1 Effects on offspring of WHC and WHR of Jamaican women
Trait No. of sons No. of Proportion D2/D4 D2/D4
daughters of sons right hand left hand
r P r P r P r P r P
Waist circumference 0.21 0.01 0.02 0.79 0.17 0.052 10.15 0.15 10.18 0.08
Hip circumference 0.14 0.09 0.07 0.41 0.16 0.06 10.02 0.87 10.01 0.92
WHR 0.15 0.08 0.05 0.56 0.10 0.27 10.20 0.048 10.29 0.004The relations are shown between measurements of waist and hip circumference (WHC) and waist-to-hip ratio (WHR)for Jamaican women, and the proportion of sons (arcsine transformed, n4141 women) and the number of sons anddaughters (n4141 women) they have, and the D2/D4 ratio in the left and right hands of their children (n495 women).r, Coefficient of correlation; P, probability of wrongly rejecting the null hypothesis.
