Age‐related changes of digital endocranial volume during human ontogeny: Results from an osteological reference collection

Abstract

Endocranial volume (EV) estimation is widely used in physical anthropology for assessing brain size differences between taxa and monitoring the emergence of brain growth patterns in modern humans. However, to date, no reference data are available for modern human EV ontogeny. We measured 94 skulls with known sex and age (ranging from 0 to 7.5 years) from the osteological collection of Strasbourg University (OCSU) by using an accurate digital active contour model algorithm on 3D virtual models, reconstructed by CT. The OCSU data also allow us to propose improved equations for estimating EV in immature individuals from dry skull diameters (length, width, and height). Aside from the EV, the average proportional endocranial volume (PEV), corresponding to the ratio of EV at a given age to the average EV in the corresponding adult population, was also computed. EV nearly doubles during the first year of life, and later continues to expand more slowly, at least until 7 years of age. No sex differences can be demonstrated between the EV distributions of boys and girls in this sample. However, although PEV at birth is identical in girls and boys, it later displays significantly higher values in the girls of our series. PEV obtained at birth is 22%, which is quite different from values established for the brain itself from autopsied individuals, or MRI data. This suggests that assessments of EV and PEV values in fossil specimens should be conducted by using identical measures in comparative samples of extant humans and apes.

A neonatal perspective on Homo erectus brain growth

“…Despite the different sources and brain size measurement (see below), the small Taï sample (n ¼ 9) falls within the larger Yerkes dataset (n ¼ 49) for all ages considered. Although sex is known for nearly all individuals, we do not consider sex in our analysis as sex is unknown for the fossil sample and was not found to contribute significantly to ontogenetic variation in the chimpanzee and human samples (Coqueugniot and Hublin, 2012). Captive chimpanzee (Herndon et al, 1999) and wild gorilla (McFarlin et al, 2013) ECVs were estimated from masses using equations provided in Smith et al (1995:157): ECV ¼ (brain mass) *1.05 (Jerison, 1973), and ECV ¼ 0.94*(brain mass) 1.02 (Martin, 1990).…”

“…Age at death is known for all individuals in the extant sample. In addition, the human (Coqueugniot and Hublin, 2012) and gorilla (McFarlin et al, 2013) samples are from single populations, thus reducing potential population effects. Chimpanzee data are from the Taï Forest and the Yerkes National Primate Research Center (Herndon et al, 1999;DeSilva and Lesnik, 2006).…”

Earliest Cranio-Encephalic Trauma from the Levantine Middle Palaeolithic: 3D Reappraisal of the Qafzeh 11 Skull, Consequences of Pediatric Brain Damage on Individual Life Condition and Social Care

“…The endocranial volume of Qafzeh 11 ranges from 1283.44 to 1333.18 cc using updated formulas [18]. Previously, values ranging from 1251±48 cc to 1303±46 cc [6] were obtained using other equations [27].…”

“…EV was firstly calculated using equations recently proposed [18]; then an attempt of direct EV measurement on virtual endocast (see below) was performed although the skull base is damaged. For comparison, we used a modern data set issued from a digital bone library of immature skulls [18]. This sample comes from the identified osteological collection of Strasbourg University, France [19].…”

Endocasts: Possibilities and Limitations for the Interpretation of Human Brain Evolution

“…Humans, having the largest brains among primates, show a special pattern of brain growth: although gestation differs only by a few weeks [Kappeler and Pereira, 2003], human newborns have brains that are about two times larger than those of great apes, yet they have achieved a smaller per-centage of their total brain growth prenatally compared to great apes, they maintain their high fetal growth rates for about 2 years, and then keep growing their brain at lower rates for a longer duration than chimpanzees and other apes [Schultz, 1940[Schultz, , 1941Count, 1947;Holt et al, 1975;Jordaan, 1976;Gould, 1977;Passingham, 1982;Martin, 1983;Dienske, 1986;Smith and Tompkins, 1995;Coqueugniot et al, 2004;Leigh, 2004;DeSilva and Lesnik, 2006;Hublin and Coqueugniot, 2006;DeSilva and Lesnik, 2008;Coqueugniot and Hublin, 2012;Neubauer et al, 2012a;McFarlin et al, 2013; but see Jolicoeur et al, 1988;Fragaszy and Bard, 1997;Vrba, 1998;Rice, 2002;Fragaszy et al, 2004;Leigh, 2004;Kennedy, 2005;Vinicius, 2005]. In this respect, it has been claimed that brain growth has been shifted postnatally in humans and that human neonates are thereby developmentally delayed as compared to the newborns of other related species.…”