Definition of the Climatic Niche limits for Homo species
For each hominin species, we built a climatic envelope. We pooled
together all bioclimatic values associated to their fossil occurrences.
Then, we selected the recorded minimum values for MinTemp, MinPrec, and
NPP, and the maximum values for MaxTemp, MaxPrec, and NPP. We repeated
this procedure over 100 replicates. At each replication, the age of each
individual archaeological locality was sampled at random from the
uniform distribution spanning from the estimated minimum to the maximum
locality age. Thus, replication accounts for both ageing uncertainty of
individual archaeological layers and, correspondingly, for climatic
uncertainty around the paleoclimatic estimates concerning the fossil
localities. Finally, for each bioclimatic variable, we took the mean
value from each resulting distribution of temperature, precipitation and
NPP minima and maxima. Taken together, these mean values of bioclimatic
extremes represent a conservative estimate of the climatic range
realized for each hominin species during its history, avoiding putting
too much faith on extreme values attached to individual replicates and
locality.