MIS 3 innovative behavior and highland occupation during a stable wet episode in the Lake Tana paleoclimate record, Ethiopia.

Securely dated archaeological sites from key regions and periods are critical for understanding early modern human adaptive responses to past environmental change. Here, we report new radiocarbon dates of > 42,000 cal years BP for an intensive human occupation of Gorgora rockshelter in the Ethiopian Highlands. We also document the development of innovative technologies and symbolic behaviors starting around this time.

A Late Pleistocene human humerus from Rusinga Island, Lake Victoria, Kenya.

In 2010, a hominin right humerus fragment (KNM-RU 58330) was surface collected in a small gully at Nyamita North in the Late Pleistocene Wasiriya Beds of Rusinga Island, Kenya. A combination of stratigraphic and geochronological evidence suggests the specimen is likely between ∼49 and 36 ka in age. The associated fauna is diverse and dominated by semiarid grassland taxa.

An examination of the cross-sectional geometrical properties of the long bone diaphyses of Holocene foragers from Roonka, South Australia.

Objectives: This study examines long bone diaphyseal rigidity and shape of hunter-gatherers at Roonka to make inferences about subsistence strategies and mobility of inhabitants of semi-arid southeastern Australia. Roonka is a cemetery site adjacent to the Lower Murray River, which contains over 200 individuals buried throughout the Holocene. Archaeological evidence indicates that populations living near this river corridor employed mobile, risk averse foraging strategies.

Are human hands and feet affected by climate? A test of Allen's rule.

Objectives: In recent years, several studies have shown that populations from cold, high-latitude regions tend to have relatively shorter limbs than populations from tropical regions, with most of the difference due to the relative length of the zeugopods (i.e., radius, ulna, tibia, fibula).

Exercise-induced bone formation is poorly linked to local strain magnitude in the sheep tibia.

Functional interpretations of limb bone structure frequently assume that diaphyses adjust their shape by adding bone primarily across the plane in which they are habitually loaded in order to minimize loading-induced strains. Here, to test this hypothesis, we characterize the in vivo strain environment of the sheep tibial midshaft during treadmill exercise and examine whether this activity promotes bone formation disproportionately in the direction of loading in diaphyseal regions that experience the highest strains. It is shown that during treadmill exercise, sheep tibiae were bent in an anteroposterior direction, generating maximal tensile and compressive strains on the anterior and posterior shaft surfaces, respectively.

Abrasive, silica phytoliths and the evolution of thick molar enamel in primates, with implications for the diet of Paranthropus boisei.

Background: Primates--including fossil species of apes and hominins--show variation in their degree of molar enamel thickness, a trait long thought to reflect a diet of hard or tough foods. The early hominins demonstrated molar enamel thickness of moderate to extreme degrees, which suggested to most researchers that they ate hard foods obtained on or near the ground, such as nuts, seeds, tubers, and roots. We propose an alternative hypothesis--that the amount of phytoliths in foods correlates with the evolution of thick molar enamel in primates, although this effect is constrained by a species' degree of folivory.

Developmental plasticity in fat patterning of Ache children in response to variation in interbirth intervals: a preliminary test of the roles of external environment and maternal reproductive strategies.

A firm link between small size at birth and later more centralized fat patterning has been established in previous research. Relationships between shortened interbirth intervals and small size at birth suggest that maternal energetic prioritization may be an important, but unexplored determinant of offspring fat patterning. Potential adaptive advantages to centralized fat storage (Baker et al.

Further new hominin fossils from the Kibish Formation, southwestern Ethiopia.

In addition to the new fragments of the Omo I skeleton, renewed fieldwork in the Kibish Formation along the lower reaches of the Omo River in southwestern Ethiopia has yielded new hominin finds from the Kibish Formation. The new finds include four heavily mineralized specimens: a partial left tibia and a fragment of a distal fibular diaphysis from Awoke's Hominid Site (AHS), a parietal fragment, and a portion of a juvenile occipital bone. The AHS tibia and fibula derive from Member I and are contemporaneous with Omo I and II.

A description of the Omo I postcranial skeleton, including newly discovered fossils.

Recent fieldwork in the Kibish Formation has expanded our knowledge of the geological, archaeological, and faunal context of the Omo I skeleton, the earliest known anatomically modern human. In the course of this fieldwork, several additional fragments of the skeleton were recovered: a middle manual phalanx, a distal manual phalanx, a right talus, a large and a small fragment of the left os coxae, a portion of the distal diaphysis of the right femur that conjoins with the distal epiphysis recovered in 1967, and a costal fragment. Some researchers have described the original postcranial fragments of Omo I as anatomically modern but have noted that a variety of aspects of the specimen's morphology depart from the usual anatomy of many recent populations.

Robusticity and sexual dimorphism in the postcranium of modern hunter-gatherers from Australia.

Throughout much of prehistory, humans practiced a hunting and gathering subsistence strategy. Elevated postcranial robusticity and sexually dimorphic mobility patterns are presumed consequences of this strategy, in which males are attributed greater robusticity and mobility than females. Much of the basis for these trends originates from populations where skeletal correlates of activity patterns are known (e.

The aging of Wolff's "law": ontogeny and responses to mechanical loading in cortical bone.

The premise that bones grow and remodel throughout life to adapt to their mechanical environment is often called Wolff's law. Wolff's law, however, is not always true, and in fact comprises a variety of different processes that are best considered separately. Here we review the molecular and physiological mechanisms by which bone senses, transduces, and responds to mechanical loads, and the effects of aging processes on the relationship (if any) between cortical bone form and mechanical function.

Optimization of bone growth and remodeling in response to loading in tapered mammalian limbs.

How bones respond dynamically to mechanical loading through changes in shape and structure is poorly understood, particularly with respect to variations between bones. Structurally, cortical bones adapt in vivo to their mechanical environments primarily by modulating two processes, modeling and Haversian remodeling. Modeling, defined here as the addition of new bone, may occur in response to mechanical stimuli by altering bone shape or size through growth.