The study doesn't show this: it compares humans (who happen to live in cities) to primates (who definitely don't live in cities). It doesn't compare between human populations.
Ironically, cities (particularly affluent ones, but in general) probably have better access to fresh and healthy produce than do medium or low-income rural areas. Some of that is supply and demand (the economics of moving bulk produce favor large population clusters), and some of it is pricing (affluent consumers prefer cities and suburbs on average). You can see these trends in the USDA's Food Atlas[1], which shows lots of rural areas with poor access to produce.
Ironically, cities (particularly affluent ones, but in general) probably have better access to fresh and healthy produce than do medium or low-income rural areas. Some of that is supply and demand (the economics of moving bulk produce favor large population clusters), and some of it is pricing (affluent consumers prefer cities and suburbs on average). You can see these trends in the USDA's Food Atlas[1], which shows lots of rural areas with poor access to produce.
[1]: https://www.ers.usda.gov/data-products/food-access-research-...