Table 2 GLS spatial models with different predictor variables ranked according to how well they fit the data based on mean ΔAIC values from across the 20 sub-samples of data.

From: Duration of agriculture and distance from the steppe predict the evolution of large-scale human societies in Afro-Eurasia

Rank

Intercept

Duration of agriculture

Agricultural productivity

Elevation (std)

Distance from steppe

Steppe × agriculture

Mean ΔAIC

1

−0.15 (0.01)

0.24 (0.04)

  

0.47 (0.02)

0.15 (0.02)

0.23

2

−0.15 (0.01)

0.24 (0.04)

0.00 (0.01)

0.01 (0.01)

0.46 (0.02)

0.15 (0.02)

1.85

3

−0.09 (0.01)

0.32 (0.04)

  

0.38 (0.02)

 

6.56

4

−0.09 (0.01)

0.32 (0.04)

0.00 (0.01)

0.01 (0.01)

0.38 (0.02)

 

8.10

5

−0.19 (0.02)

0.37 (0.05)

    

26.08

6

−0.13 (0.02)

   

0.49 (0.02)

 

33.76

7

−0.28 (0.02)

     

58.78

8

−0.28 (0.02)

  

0.01 (0.01)

  

59.22

9

−0.28 (0.02)

 

0.00 (0.01)

   

59.85

  1. Standardised coefficients (β) are presented to indicate the relative strength of each predictor. The best-fitting model contains duration of agriculture and distance from the steppe, and the interaction between these two variables. Only one other model falls within 2 mean AIC units of the best-fitting model and this also includes small effects of agricultural productivity and elevation.
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