Due to the fact that most foods have higher strontium/calcium (Sr/Ca) ratios than that of human milk, it is possible to determine the age at which supplementary items entered the infants’ diet and to identify the weaning process in ancient populations. In this study, Sr, Ca and phosphorous content of 90 bone samples belonging to infants, children and adults from İkiztepe settlement dated to the Early Bronze Age were analyzed by inductively coupled plasma mass spectrometry (ICP-MS) method. The Sr/Ca ratio of breastfeeding infants shows the lowest values among a population since they discriminate poorly against Sr in favor of Ca in the gastrointestinal tract. The supplementary food entering the infant diet results in a rapidly increased Sr/Ca ratio. The increasing discrimination against Sr absorption in the gut with age causes a decline in the Sr/Ca ratio. With age, the Sr/Ca ratio increases again and resembles adult values. On the human bones in İkiztepe, it was determined that the infants were breastfed until they reached one year of age, that the entry age for supplementary food was approximately at one year, and that the weaning process was completed at approximately two years of age.

Keywords: İkiztepe, sütten kesme, Sr/Ca oranı, kemik kimyası, Erken Tunç Çağı.