>    
>    Possibly as the taller people are the ones with fewer generations of
>    ancestors eating Neolithic foods. As we know, humans shrank in height after
>    Neolithic foods were introduced. But why do larger dogs die younger?

The simplest answer is that humans are not dogs, especially in not
being purpose-bred for function and fancy by their masters. Also
their biochemistry is rather different, and no doubt have their own
set of genetically-linked problems under a Neolithic diet.