Nevertheless, the relationship between the Δ 13 C of wheat and barley became marginally significant ( p =0.08) after samples from one site (Horum Höyük, whose kernels suggest a much better water status for barley) were discarded ( Supplementary Fig. 3 ).
Discussion Following the aforementioned environmental and genetic changes, yield estimates during the Neolithic were in general lower than 0.8 t ha −1 , but showed an increasing trend with time associated with a higher kernel weight up to the 8 th millennium cal BP, reaching values of around 1.2 t ha −1 in wheat ( Supplementary Fig. 5 ).