Hominin skeletal remains from the Dinaledi Chamber, South Africa, represent a minimum of 15 individuals of the extinct species Homo naledi. We examined the dental material from this sample in order to assess the life-history stages of individuals in the sample, in particular to determine the minimum number of individuals in the sample as a whole, and within each of six age classes. We found evidence of individuals within every age class: infant, early juvenile, late juvenile, subadult, young adult and old adult. The Dinaledi Chamber sample is notable in comparison to other samples of human, chimpanzee and fossil hominins in that it has a relatively high representation of juvenile remains, as compared to infants and adults. With 15 individuals, the sample size presented by the Dinaledi dental material is too small to test the hypothesis of attritional versus catastrophic accumulation. The data here provide a basis for further investigation of individual associations within this commingled assemblage, and provide an important comparative data set as a basis for the consideration of life history in H. naledi and other extinct hominin populations. SIGNIFICANCE: • We identified a minimum number individuals so far recovered in the assemblage and document the use of molar eruptions as biomarkers of life-history stages to sort the individuals into age classes. • We provide a demographic profile of individuals from the chamber and establish a comparative data set for life history in extinct hominin populations.

The mineral content of bone can be determined by measuring the absorption by bone of a monochromatic, low-energy photon beam which originates in a radioactive source (iodine-125 at 27.3 kev or americium-241 at 59.6 kev). The intensity of the beam transmitted by the bone is measured by counting with a scintillation detector. Since the photon source and detector are well collimated, errors resulting from scattered radiation are reduced. From measurements of the intensity of the transmitted beam, made at intervals across the bone, the total mineral content of the bone can be determined. The results are accurate and reproducible to within about 3 percent.

The mineral content of bone can be determined by measuring the absorption by bone of a monochromatic, low-energy photon beam which originates in a radioactive source (iodine-125 at 27.3 kev or americium-241 at 59.6 kev). The intensity of the beam transmitted by the bone is measured by counting with a scintillation detector. Since the photon source and detector are well collimated, errors resulting from scattered radiation are reduced. From measurements of the intensity of the transmitted beam, made at intervals across the bone, the total mineral content of the bone can be determined. The results are accurate and reproducible to within about 3 percent.