Biomechanical and taxonomic diversity in the Early Pleistocene in East Africa: Structural analysis of a recently discovered femur shaft from Olduvai Gorge (bed I)

Recent Plio-Pleistocene hominin findings have revealed the complexity of human evolutionary history and the difficulties involved in its interpretation. Moreover, the study of hominin long bone remains is particularly problematic, since it commonly depends on the analysis of fragmentary skeletal elements that in many cases are merely represented by small diaphyseal portions and appear in an isolated fashion in the fossil record. Nevertheless, the study of the postcranial skeleton is particularly important to ascertain locomotor patterns. Here we report on the discovery of a robust hominin femoral fragment (OH 84) at the site of Amin Mturi Korongo dated to 1.84 Ma (Olduvai Bed I). External anatomy and internal bone structure of OH 84 were analyzed and compared with previously published data for modern humans and chimpanzees, as well as for Australopithecus, Paranthropus and Homo specimens ranging from the Late Pliocene to Late Pleistocene. Biomechanical analyses based on transverse cross-sections and the comparison of OH 84 with another robust Olduvai specimen (OH 80) suggest that OH 84 might be tentatively allocated to Paranthropus boisei. More importantly, the identification of a unique combination of traits in OH 84 could indicate both terrestrial bipedalism and an arboreal component in the locomotor repertoire of this individual. If interpreted correctly, OH 84 could thus add to the already mounting evidence of substantial locomotor diversity among Early Pleistocene hominins. Likewise, our results also highlight the difficulties in accurately interpreting the link between form and function in the human fossil record based on fragmentary remains, and ultimately in distinguishing between coeval hominin groups due to the heterogeneous pattern of inter- and intraspecific morphological variability detected among fossil femora.

Solution NMR backbone assignment reveals interaction-free tumbling of human lineage-specific Olduvai protein domains

Olduvai protein domains, encoded primarily by NBPF genes, have been linked to both human brain evolution and cognitive diseases such as autism and schizophrenia. There are six primary domains that comprise the Olduvai family: three conserved domains (CON1-3) and three human lineage-specific domains (HLS1-3), which typically occur as a triplet (HLS1, HLS2 and HLS3). Herein, we present the solution NMR assignment of the backbone chemical shifts of the separate HLS1, 2 and 3 domains of NBPF15. Our data suggest that there is no change in the structure of the separate domains when compared to the full-length triplet (HLS1-HLS2-HLS3). We also demonstrate that there is no direct interaction between the three domains.

A Third Linear Association Between Olduvai (DUF1220) Copy Number and Severity of the Classic Symptoms of Inherited Autism

OBJECTIVE

The authors previously reported that the copy number of sequences encoding an Olduvai protein domain subtype (CON1) shows a linear association with the severity of social deficits and communication impairment in individuals with autism. In this study, using an improved measurement method, the authors replicated this association in an independent population.

METHOD

The authors obtained whole genome sequence (WGS) data and phenotype data on 215 individuals from the Autism Speaks MSSNG project. They derived copy number from WGS data using a modified sequence read-depth technique. A linear mixed-effects model was used to test the association between Olduvai CON1 copy number and symptom severity as measured by the Autism Diagnostic Interview-Revised. The authors then combined data from previous studies (N=524) for final analyses.

RESULTS

A significant linear association was observed between CON1 copy number and social diagnostic score (SDS) (β=0.24) and communicative diagnostic score (CDS) (β=0.23). Using the combined data, the authors present strong significant associations of CON1 dosage with SDS (β=0.18) and CDS (β=0.13). The authors also implicate Olduvai subtypes found in two genes, NBPF1 and NBPF14 (R²=6.2%). Associations were preferentially found in multiplex versus simplex families.

CONCLUSIONS

The finding of a third dose-dependent association between Olduvai sequences and autism severity, preferentially in multiplex families, provides strong evidence that this highly duplicated and underexamined protein domain family plays an important role in inherited autism.