The origin of anatomically modern Homo sapiens and the fate of Neanderthals have been fundamental questions in human evolutionary studies for over a century. A key barrier to the resolution of these questions has been the lack of substantial and accurately dated African hominid fossils from between 100,000 and 300,000 years ago. Here we describe fossilized hominid crania from Herto, Middle Awash, Ethiopia, that fill this gap and provide crucial evidence on the location, timing and contextual circumstances of the emergence of Homo sapiens. Radioisotopically dated to between 160,000 and 154,000 years ago, these new fossils predate classic Neanderthals and lack their derived features. The Herto hominids are morphologically and chronologically intermediate between archaic African fossils and later anatomically modern Late Pleistocene humans. They therefore represent the probable immediate ancestors of anatomically modern humans. Their anatomy and antiquity constitute strong evidence of modern-human emergence in Africa.

A new species, Homo floresiensis, was recently named for Pleistocene hominid remains on Flores, Indonesia. Significant controversy has arisen regarding this species. To address controversial issues and refocus investigations, I examine the affinities of these remains with Homo sapiens. Clarification of problematic issues is sought through an integration of genetic and physiological data on brain ontogeny and evolution. Clarification of the taxonomic value of various ‘primitive’ traits is possible given these data. Based on this evidence and using a H. sapiens morphological template, models are developed to account for the combination of features displayed in the Flores fossils. Given this overview, I find substantial support for the hypothesis that the remains represent a variant of H. sapiens possessing a combined growth hormone–insulin‐like growth factor I axis modification and mutation of the MCPH gene family. Further work will be required to determine the extent to which this variant characterized the population.

Historically, the foramen magnum (FM) has been an integral component of studies on skull ontogeny and evolutionary transformations of cranial form. Although this foramen has been considered a single entity, we hypothesize that it comprises two functional matrices, a ventral matrix and a dorsal matrix. In general, the ventral matrix is related to locomotor functions, whereas the dorsal matrix is related to neurological functions and fluid flow dynamics. To test our hypothesis, we used a large ontogenetic sample of modern human crania (seventh fetal month to adult) to (1) delineate bony size and shape ontogeny for both the foramen and its dorsal and ventral units; (2) delineate the role of synchondroses in the observed growth patterns and rates; and (3) explore the relationship between FM and cranial size, shape, and growth. Detailed growth patterns and rates are established for the bony FM and its ventral and dorsal skeletal units. These data are supplemented by literature and observational data on embryonic and fetal FM ontogeny, soft tissue relationships, anomalous/pathological extremes of size, and craniocervical anatomy and locomotor functions. The hypothesis that the FM is composed of a ventral and a dorsal functional matrix is supported by observed ontogenetic differences between ventral and dorsal skeletal units, as well as by the soft tissue anatomy of these matrices. Further documentation of these matrices has the potential to significantly enhance our understanding of the ontogenetic and evolutionary transformations of skull base morphology. Anat Rec, 294:199-216, 2011. V V C 2010 Wiley-Liss, Inc.Key words: foramen magnum; ontogeny; human variation; functional matricesThe basicranium forms in a zone of interaction between structures with neural, skeletomotor, respiratory, auditory, masticatory, digestive, and visual functions. Because of the complex structural-functional relationships, the morphology of the basicranium reflects compromises resulting from the competing demands of multiple soft tissue units that are responding to essential functions.During basicranial development, the structures traversing the endocranial-ectocranial boundary become encircled by cartilage and, eventually, by bone. The resulting bony foramina of the basicranium respond in Additional Supporting Information may be found in the online version of this article.