Sex Differences in Left-Side Infant Holding: Results from “Family Album” Photographs

J. T. Manning Department of Environmental and Evolutionary Biology, The University of Liverpool, Liverpool, England

Humans tend to cradle infants on the left side of the body. However, it is controversial as to whether left-side cradling is characteristic of women and not of men. Photographic surveys of women and men holding infants have suffered because of underrepresen- tation of men and lack of accurate information of infants’ age. Sampling from “family albums” overcomes these difficulties. A sample of photographs of 1119 women and 577 men indicated (a) left-holding frequencies of 61% women and 47% men, (b) women tended to pose with younger infants, (c) left-side holding was greatest for very young infants (3 months or less) but women showed consistently higher left-side holding for all infant age groups, (d) the distribution of frequency of cradling per individual is skewed towards left-holding for women but for men it is rectangular or perhaps skewed towards right-holding, and (e) there may be family trends in left-holding for women.

INTRODUCTION

H uman females tend to cradle infants on the left side of the body (Salk 1960, 1973; Weiland 1964; Rheingold and Keene 1965). Left-side cradling appears to be independent of the handedness of the mother (Salk 1973), is cross-cultural (Bol-

ton 1978; Briiser 1981; Saling and Cooke 1984) and has been observed in gorillas and chimpanzees (Manning and Chamberlain 1990).

This paper is concerned with a controversial aspect of left-side cradling, i.e., whether it is shown by human females but not males. Studies on infant carrying in Sri Lankan (Bri_iser 1981) and North American populations (Lock- ard et al. 1979) have suggested a strong left-side preference in women but not in men. This is supported by a photographic survey of Western, Eastern, and American Indian cultures (Richards and Finger 1975) and by observa-

Received October 24, 1990; revised March 7, 1991.

Address reprint requests to: J.T. Manning, Ph.D., Dept. of Environmental and Evolutionary Biology, The University of Liverpool, P.O. Box 147, Liverpool L69 3BX, England.

Ethology and Sociobiology 12: 337-343 (1991) 0 Elsevier Science Publishing Co., Inc., 1991 655 Avenue of the Americas, New York, NY 10010

0162-3095/91/$3.50

338 J. T. Manning

tions of doll holding in female and male children (De Chateau and Andersson 1976). On the other hand, a survey of photographs from developmental psy- chology textbooks resulted in almost identical left-side preferences for men and women (Harris and Fitzgerald 1985), while De Chateau (1983) and Dag- enbach et al. (1988) found few differences in left-side holding tendencies among mothers and fathers of newborn infants.

Common problems with photographic surveys are (a) adult males tend to be underrepresented in samples of photographs of infant holding, e.g., Harris and Fitzgerald’s (1985) sample of 216 photographs consisted of 164 female and 52 male adults holding children and (b) accurate information as to age of the infants is not usually available. This is important as Lockard et al. (1979) and Dagenbach et al. (1988) have shown the left-side tendency decreases with infant’s age. In order to overcome these difficulties this sur- vey uses photographs from “family albums.”

METHOD

The photographs were observed in “family album” collections of colleagues and students in the Departments of Continuing Education and Education of the University of Liverpool. Individuals supplying photographs were told the work was an investigation of adult/infant interaction and that they were not to select photographs in any way.

Each photograph was categorized by the sex and age of the child, the sex of the adult, the relationship of the adult to the child, and whether the child was positioned to the left or right side. In all cases age was estimated by the owner of the “album.” When multiple photographs were obviously of the same pose at the same time only one was counted. Photographs show- ing the child breast-feeding, bottle-feeding, or positioned in the middle of the adult’s body were excluded.

RESULTS

The sample number was 1696, which consisted of 1119 photographs of adult women and 577 of adult men. For the women 61% were left-holding and for the men the figure was 47%. This difference is highly significant; X2 = 27.7, p < 0.001. Controlling the age of the child, Figure 1 shows that females tended to pose with younger children than males. For example, 73% of female adults held children l-year-old or less, while for adult males the figure was 50%. However this does not account for the higher frequencies of left- side holding shown by women. When we consider left-holding frequencies against the age of the child (Fig. 2) we see that the left-side tendency remains consistently higher for female adults when compared to males.

Because some family albums were large there was an opportunity to

Sex Differences in Infant Holding 339

10

t o-

SO r 540

2 Ill D30

$ i II20

IL I

females

IO- r-tl o-

O-3m #3-6m 86-12m f-2yr ,2yr

male=

AQE OF CHILO

FIGURE 1. The age distribution of children held by women and by men. Female adults are more likely to pose with a child ~12 months (73% of sample of 1119 photographs) than male adults (50% of a sample of 577 photographs).

observe multiple photographs of a number of female and male adults. Figure 3 shows the frequency of left-side holding for 47 female adults and 19 males where six or more photographs were available. It can be seen that for females there were left-holders and right-holders. Moreover, the distribution is skewed strongly towards left-holders with the mode at 71%-80% left-hold- ing. On the other hand the male distribution tends to be concentrated towards right-holding with a mode of 41%-50% left-holding.

The large albums produced data on mothers, fathers, grandmothers, etc. For example there were 17 pairs of mothers and fathers for which six or more photographs were available. However, there was no relationship between their left-holding frequencies (r, = 0.01). On the other hand, six pairs of mothers and maternal grandmothers had a left-holding correlation

340 J. T. Manning

1

7u-

I

60.

SO

40-

30-

20.

IO-

o-

female5

+

male9

t

10

t u 0 0 -3m *3-6m

0 . . . . 86 -12m

k +

t

I u-2 yr I a2yr

AQE OF CHILD

FIGURE 2. Left-side child holding frequencies per age group of child. Female adults show consistently higher left-side holding values than males for all age groups of children. The vertical bars represent standard deviation.

Sex Differences in Infant Holding 341

Eo-

femelem

! L

1

ii

wz= i II IL L 10 I-

"oL-------- 100

% LEFT HOLOINQ

PER INDIVIDUAL FIGURE 3. Left-side holding frequencies for 47 female adults and 19 male adults represented by six or more photographs. For females the distribution tend to be skewed towards left-side holding and departs significantly from a rectangular dis- tribution (goodness of fit, X2 = 16.97, p < 0.05). The male distribution tends to be skewed towards right-holding but does not depart significantly from a rectangular distribution (goodness of fit, X2 = 12.7, p > 0.05). A median test shows that the samples differ significantly from each other (X2 = 4.29, p < 0.05).

of rS = 0.5. Reducing the number of photographs required per adult to four

or more gives 10 pairs of mothers and maternal grandmothers with a left-

holding correlation of r, = 0.41. The numbers are small but photograph

albums offer a source of data on family trends and this particular association

may be worth further investigation.

DISCUSSION

The results of this photographic survey lends support to the view that left-

side holding is primarily a behavior of human females and not of males.

342 J. T. Manning

However, any further work on sex differences should control for infant age as the highest levels of left-side cradling were observed at three months or less, and males tend to hold older infants. This is in agreement with the results of Lockard et al. (1979). The photographic survey of Harris and Fitzgerald (1985) may have failed to show any sex differences in left-holding because they did not control for infant age. However, the lack of sex dif- ferences in the results of De Chateau (1983) and Dagenbach et al. (1988) are more puzzling. Both studies involved observing the cradling behavior of husbands and wives. It may be that the husband is often influenced by his wife’s side-preference. However there is no support for this from the present work.

If we accept sex differences in infant cradling do exist, how then are they best explained? Lockard et al. (1979), Manning and Chamberlain (1990), and Alvarez (1990) have favored a hemispheric bias explanation. Much of the sensory input from the adult’s left visual and auditory fields is processed in the right hemisphere (Nolte 1988). It is also well established that emotional processing is associated with the right hemisphere (Leventhal and Tomarken 1986) and that this seems to be particularly so in human females (Burton and Levy 1989). Extensive studies of Western and Middle Eastern art have shown that the left-holding tendency changes in strength depending on the historical period, the artist, and the culture (Finger 1975; Grtisser 1983). However, Alvarez (1990) has argued that social factors can affect hemi- spheric specialization and that these changes are not inconsistent with the brain lateralization hypothesis.

Left-side cradling may therefore facilitate the mother’s ability to mon- itor her infant’s emotional state. If correct this is but a proximate answer. What were the evolutionary pressures which caused female left-sided cradling and right hemisphere bias for affective processes? Babchuk et al. (1985) have argued that females dominate childcare in nonhuman and human pri- mates. This “primary caretaker” hypothesis predicts that as a response to high infant mortality rates females should evolve the ability to promptly and accurately recognize infant emotional cues. In support of this Babchuk et al. (1985) have shown that females are more rapid than males in their discrimination of infant facial expressions and that previous childcare ex- perience had no effect on this sex difference. Left-side cradling and right hemisphere specialization for affective processes also seem to be better de- veloped in women than in men. They may therefore be another part of the adaptive response to the “primary caretaking” role of women in primitive human societies.

REFERENCES

Alvarez, G. Child-holding patterns and hemispheric bias. Evidence from Pre-Columbian art.

Erhology and Sociobiology 11: 75-82, 1990.

Sex Differences in Infant Holding 343

Babchuk, W.A., Hames, R.B., and Thompson, R.A. Sex differences in the recognition of

infant facial expressions of emotion: the primary caretaker hypothesis. Ethology and Sociobiology 6: 89-101, 1985.

Bolton, R. Child holding patterns. Current Anthropology 19: 134-135, 1978.

Brtiser, E. Child transport in Sri Lanka. Current Anrhropology 22: 288-290, 1981.

Burton, L.A., and Levy, .I. Sex differences in the lateralised processing of facial emotion.

Brain and Cognition 11: 2 10-228, 1989.

Dagenbach, D., Harris, L.J., and Fitzgerald, H.E. A longitudinal study of lateral biases in

parents’ cradling and holding of infants. Infant Menfal Health Journal 9: 219-233, 1988.

De Chateau, P. Left-side preference for holding and carrying newborn infants: parental holding

and carrying during the first week of life. Journal of Nervous and Mental Diseases 171: 241-245, 1983.

-, and Andersson, Y. Left-side preference in holding and carrying newborn infants. II. Doll-

holding and carrying from 2 to 16 years. Developmental Medicine and Child Neurology 18: 738-744, 1976.

Finger, S. Child-holding patterns in Western art. Child Development 46: 267-271, 1975. Grtlsser, O.-J. Mother-child holding patterns in Western art: a developmental study. Ethology

and Sociobiology 4: 89-94, 1983. Harris, L.J., and Fitzgerald, H.E. Lateral cradling preferences in men and women: Results

from a photographic study. Journal of General Psychology 112: 185-189, 1985. Leventhal, H., and Tomarken, A.J. Emotion: today’s problems. Annual Review ofPsychology

37: 565-610, 1986. Lockard, J.S., Daley, P.C., and Gunderson, V. Maternal and paternal differences in infant

carry: U.S. and African data. American Naturalist 113: 235-246, 1979.

Manning, J.T., and Chamberlain, A.T. The left-side cradling preference in great apes. Animal Behaviour 39: 1224-1227, 1990.

Nolte, J. The Human Brain, 2nd Edition, St. Louis: Mosby, 1988.

Rheingold, H.L., and Keene, G.C. Transport of the human young. In Determinants ofinfants’ behaviour, Volume 3, B.M. Foss (Ed.). London: Methuen, 1965, pp. 87-110.

Richards, J.L., and Finger, S. Mother-child holding patterns: a cross-cultural photographic

survey. Child Development 46: 1001-1004, 1975. Saling, M.M., and Cooke, W.L. Cradling and transport of infants by South African mothers:

a cross-cultural study. Current Anthropology 25: 333-335, 1984. Salk, L. The effects of the normal heartbeat sound on the behaviour of the newborn infant:

implications for mental health. World Mental Health 12: 168-175, 1960. -. The role of the heartbeat in the relations between mother and infant. Scientific American

228: 24-29, 1973. Weiland, I.H. Heartbeat rhythm and maternal behaviour. Journal of the American Academy

ofChild Psychiatry 3: 161-164, 1964.