deletions | additions       diff --git a/materials_and_methods.tex b/materials_and_methods.tex  index 3109fb0..045bb23 100644  --- a/materials_and_methods.tex  +++ b/materials_and_methods.tex 
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\textbf{Importance of environmental factors}  To extract as much ecological information as possible from our model, we analyzed the influence of the environmental factors over habitat suitability values at local to  continental scales.   To analyze the influence of environmental factors at the local scale, we firstly defined \textit{local scale} as the average home range of Neanderthals. According to \cite{Daujeard201232},  and based on the transportation of raw lithic materials, the regional mobility range of Neanderthals during the Middle Palaeolithic was around 50 kilometers. We divided the study area in 50 km cells, and we fitted one linear regression model per cell (only when the cell contained more than 30 5km cells) and environmental predictor, using habitat suitability as response variable. We considered the R squared obtained by each predictor to be an indicator of its  local scales. importance (the higher the better), while the coefficient was taken as an indicator of the direction of the relationship. We mapped the results (see Appendix), used a boxplot to assess the importance of the environmental predictors at the presence sites, and evaluated the importance pattern of the most relevant topographic predictor across sites. Cells with p-values less than 0.05 were not used in our analysis.  We applied Random Forest \cite{Breiman20015} using the average suitability of the ensemble as a response variable to analyze the influence of the environmental factors over Neanderthals habitat suitability at the continental scale. The ability of Random Forest to deal with non-linearity makes it perfect to analyse our ensemble, since non-linearity may arise when averaging the results of multiple GLMs. Also, Random Forest is regarded as a robust method to assess variable importance \cite{Cutler20072783}. We used both measures of variable importance available in the randomForest R function (Liaw and Wiener 2012): mean decrease in accuracy and total decrease in node impurities (node impurity: heterogeneity of target categories within a node in a classification tree).  To analyze the influence of environmental factors at the local scale, we firstly defined \textit{local scale} as the average home range of Neanderthals. According to \cite{Daujeard201232}, and based on the transportation of raw lithic materials, the regional mobility range of Neanderthals during the Middle Palaeolithic was around 50 kilometers.