Growth and development are both fundamental components of demographic structure and life history strategy. Together with information about developmental timing they ultimately contribute to a better understanding of Neanderthal extinction. Primate molar tooth development tracks the pace of life history evolution most closely, and tooth histology reveals a record of birth as well as the timing of crown and root growth. High-resolution micro-computed tomography now allows us to image complex structures and uncover subtle differences in adult tooth morphology that are determined early in embryonic development. Here we show that the timing of molar crown and root completion in Neanderthals matches those known for modern humans but that a more complex enamel-dentine junction morphology and a late peak in root extension rate sets them apart. Previous predictions about Neanderthal growth, based only on anterior tooth surfaces, were necessarily speculative. These data are the first on internal molar microstructure; they firmly place key Neanderthal life history variables within those known for modern humans.

No abstract

The evidence for macroscopic life during the Palaeoproterozoic era (2.5-1.6 Gyr ago) is controversial. Except for the nearly 2-Gyr-old coil-shaped fossil Grypania spiralis, which may have been eukaryotic, evidence for morphological and taxonomic biodiversification of macroorganisms only occurs towards the beginning of the Mesoproterozoic era (1.6-1.0 Gyr). Here we report the discovery of centimetre-sized structures from the 2.1-Gyr-old black shales of the Palaeoproterozoic Francevillian B Formation in Gabon, which we interpret as highly organized and spatially discrete populations of colonial organisms. The structures are up to 12 cm in size and have characteristic shapes, with a simple but distinct ground pattern of flexible sheets and, usually, a permeating radial fabric. Geochemical analyses suggest that the sediments were deposited under an oxygenated water column. Carbon and sulphur isotopic data indicate that the structures were distinct biogenic objects, fossilized by pyritization early in the formation of the rock. The growth patterns deduced from the fossil morphologies suggest that the organisms showed cell-to-cell signalling and coordinated responses, as is commonly associated with multicellular organization. The Gabon fossils, occurring after the 2.45-2.32-Gyr increase in atmospheric oxygen concentration, may be seen as ancient representatives of multicellular life, which expanded so rapidly 1.5 Gyr later, in the Cambrian explosion.

Extant African great apes and humans are thought to have diverged from each other in the Late Miocene. However, few hominoid fossils are known from Africa during this period. Here we describe a new genus of great ape (Nakalipithecus nakayamai gen. et sp. nov.) recently discovered from the early Late Miocene of Nakali, Kenya. The new genus resembles Ouranopithecus macedoniensis (9.6 -8.7 Ma, Greece) in size and some features but retains less specialized characters, such as less inflated cusps and better-developed cingula on cheek teeth, and it was recovered from a slightly older age (9.9 -9.8 Ma). Although the affinity of Ouranopithecus to the extant African apes and humans has often been inferred, the former is known only from southeastern Europe. The discovery of N. nakayamai in East Africa, therefore, provides new evidence on the origins of African great apes and humans. N. nakayamai could be close to the last common ancestor of the extant African apes and humans. In addition, the associated primate fauna from Nakali shows that hominoids and other noncercopithecoid catarrhines retained higher diversity into the early Late Miocene in East Africa than previously recognized.hominoid evolution

No abstract

No abstract

No abstract

Neandertals differ from recent and terminal Pleistocene human populations in their patterns of dental development, endostructural (internal structure) organization, and relative tissue proportions. Although significant changes in craniofacial and postcranial morphology have been found between the Middle Paleolithic and earlier Upper Paleolithic modern humans of western Eurasia and the terminal Pleistocene and Holocene inhabitants of the same region, most studies of dental maturation and structural morphology have compared Neandertals only to later Holocene humans. To assess whether earlier modern humans contrasted with later modern populations and possibly approached the Neandertal pattern, we used high-resolution microtomography to analyze the remarkably complete mixed dentition of the early Upper Paleolithic (Gravettian) child from Abrigo do Lagar Velho, Portugal, and compared it to a Neandertal sample, the late Upper Paleolithic (Magdalenian) child of La Madeleine, and a worldwide extant human sample. Some aspects of the dental maturational pattern and tooth endostructural organization of Lagar Velho 1 are absent from extant populations and the Magdalenian specimen and are currently documented only among Neandertals. Therefore, a simple Neandertal versus modern human dichotomy is inadequate to accommodate the morphostructural and developmental variation represented by Middle Paleolithic and earlier Upper Paleolithic populations. These data reinforce the complex nature of Neandertal-modern human similarities and differences, and document ongoing human evolution after the global establishment of modern human morphology.