LATERALIZATION OF INFANT HOLDING IN CHIMPANZEES - NEW DATA DO NOT CONFIRM PREVIOUS FINDINGS

About 80% of human females cradle their infants on the left side of th e body. MANNING & CHAMBERLAIN (1990) found a similar left-side bias fo r chimpanzees and two other ape species. In the present paper, however , only a slight bias was found which was - in contrast - right-sided. The combined results of the two studies do not differ from an homogene ous distribution between 9 and 100% right-sided. When data for 3 ape s pecies and 3 studies are pooled, a significant bias is also absent. Ev en if a left-side bias were present in apes, comparability with humans is limited. The possible functions of a left-side bias in humans (bet ter hearing of the mother's soothing heartbeat and better visual conta ct with the left side of the mother's face) might not apply to chimpan zees. For there are relevant behaviour differences between chimpanzees and humans. These concern different ways of holding and carrying, rar e crying by ape infants, and rare facial orientation in apes. Moreover , most of the ape infants involved were older than the age at which th e human bias is found. For the time being, no convincing evidence for a bias in apes exists.