Replication code and data for the publication "Comparing measured dietary variation within and between tropical hunter-gatherer groups to the Paleo Diet" appearing in the American Journal of Clinical Nutritian. Files include: 1) R replication code (5 files that should be run sequentially in numerical order). 2) "raw_diet_data.csv": 1 file that is ingested by the R code and used for the main analyses. 3) "lipid_classes.csv" and "nutriants_by_source_raw.csv": 2 files that are ingested by the R code and used for the supplementary analyses. 4) "wc2.1_30s_bio_1.tif": 1 file of GeoTiff data on annual mean temperature from the WorldClim v. 2.1 dataset (http://www.worldclim.com/version2) that is ingested by the R code. 5) "table_1.csv": a cleaned version of the data used in analyses that is output by the R code. 6) "table_hg_diet_data.csv" and "table_seasonal_diet_data.csv": 2 files containing seasonal and HG diet data that were not used in analyses, which are output by the R code.
During locomotion, each step generates a shock wave that travels through the body toward the head. Without mechanisms for attenuation, repeated shocks can lead to pathology. Shock attenuation (SA) in the lower limb has been well studied, but little is known about how posture affects SA in the spine. To test the hypothesis that lumbar lordosis (LL) contributes to SA, 27 adults (14 male, 13 female) walked and ran on a treadmill. Two lightweight, tri-axial accelerometers were affixed to the skin overlying T12/L1 and L5/S1. Sagittal plane accelerations were analyzed using power spectral density analysis, and lumbar SA was assessed within the impact-related frequency range. 3-D kinematics quantified dynamic and resting LL. To examine the effects of intervertebral discs on spinal SA, supine MRI scans were used to measure disc morphology. Results showed no associations between LL and SA during walking, but LL correlated with SA during running (p<0.01, R2=0.30) resulting in as much as 64% reduction in shock signal power among individuals with the highest LL. Patterns of lumbar spinal motion partially explain differences in SA: larger amplitudes of LL angular displacement and slower angular displacement velocity during running were associated with greater lumbar SA (p=0.008, R2=0.41). Intervertebral discs were associated with greater SA during running (p=0.02, R2=0.22), but after controlling for disc thickness, LL remained strongly associated with SA (p=0.001, R2=0.44). These findings support the hypothesis that LL plays an important role in attenuating impact shocks transmitted through the human spine during high-impact, dynamic activities such as running.
