Oldest evidence of abundant C4 grasses and habitat heterogeneity in eastern Africa.

The assembly of Africa's iconic C4 grassland ecosystems is central to evolutionary interpretations of many mammal lineages, including hominins. C4 grasses are thought to have become ecologically dominant in Africa only after 10 million years ago (Ma). However, paleobotanical records older than 10 Ma are sparse, limiting assessment of the timing and nature of C4 biomass expansion. This study uses a multiproxy design to document vegetation structure from nine Early Miocene mammal site complexes across eastern Africa. Results demonstrate that between ~21 and 16 Ma, C4 grasses were locally abundant, contributing to heterogeneous habitats ranging from forests to wooded grasslands. These data push back the oldest evidence of C4 grass-dominated habitats in Africa-and globally-by more than 10 million years, calling for revised paleoecological interpretations of mammalian evolution.

Enhancing Administrative Claims Data: Feasibility, Validation and Application of Linking Medicare Claims Data and National Marrow Donor Program Search Data.

PURPOSE: Administrative claims data provide real-world service utilization of acute myeloid leukemia (AML) treatment, but lacks insight into treatment delays or barriers. The National Marrow Donor Program (NMDP)/Be The Match Search (Search) data contains information on donor search, but lacks information on treatment received if allogeneic hematopoietic cell transplant (HCT) is not performed. We hypothesized that linking these two data sets would create a rich resource to define factors associated with receiving HCT that could not be evaluated with either data set alone. METHODS: A subset of 2010-2016 Medicare administrative claims data was linked with Search data. A total of 5,351 patients with AML age 65-74 years (HCT = 607, no HCT = 4,744) were identified using Medicare. These patients were then linked to 93,800 records with a donor search between 2009 and 2016. Patient date of birth, sex, disease, ZIP code, transplant center/hospital, and diagnosis date were used for matching. Exploratory analysis was conducted to identify predictors associated with receiving HCT for patients with AML who received a search. RESULTS: The data sets were successfully linked, showing high sensitivity and specificity. The final cohort included 5,085 patients with AML (HCT = 533, no HCT = 4,552). Of 97 patients who received HCT without a matched search, more than 85% received a related donor HCT. Of those not receiving HCT, 609 had a matched NMDP search and 3,943 did not have a matched NMDP search. Multivariate analysis showed time to search, age, diagnosis year, race/ethnicity, and neighborhood education status associated with receiving HCT. CONCLUSION: Methods herein demonstrate the feasibility of linking Search and Medicare data. Similar methods may be applied to answer critical questions regarding barriers to HCT, thereby identifying areas to improve access to care.

Stable isotope paleoecology of Late Pleistocene Middle Stone Age humans from the Lake Victoria basin, Kenya.

Paleoanthropologists have long argued that environmental pressures played a key role in human evolution. However, our understanding of how these pressures mediated the behavioral and biological diversity of early modern humans and their migration patterns within and out of Africa is limited by a lack of archaeological evidence associated with detailed paleoenvironmental data. Here, we present the first stable isotopic data from paleosols and fauna associated with Middle Stone Age (MSA) sites in East Africa. Late Pleistocene (∼100-45 ka, thousands of years ago) sediments on Rusinga and Mfangano Islands in eastern Lake Victoria (Kenya) preserve a taxonomically diverse, non-analog faunal community associated with MSA artifacts. We analyzed the stable carbon and oxygen isotope composition of paleosol carbonate and organic matter and fossil mammalian tooth enamel, including the first analyses for several extinct bovids such as Rusingoryx atopocranion, Damaliscus hypsodon, and an unnamed impala species. Both paleosol carbonate and organic matter data suggest that local habitats associated with human activities were primarily riverine woodland ecosystems. However, mammalian tooth enamel data indicate that most large-bodied mammals consumed a predominantly C4 diet, suggesting an extensive C4 grassland surrounding these riverine woodlands in the region at the time. These data are consistent with other lines of paleoenvironmental evidence that imply a substantially reduced Lake Victoria at this time, and demonstrate that C4 grasslands were significantly expanded into equatorial Africa compared with their present distribution, which could have facilitated dispersal of human populations and other biotic communities. Our results indicate that early populations of Homo sapiens from the Lake Victoria region exploited locally wooded and well-watered habitats within a larger grassland ecosystem.