Several are mentioned in the article, eg:

  While meat was definitely a caloric bonanza for early humans, recent primate studies offer evidence that sugary fruits continued to be a critical “brain food.” A 2017 paper looked at 140 primate species and compared their brain sizes with their diets. 

  “What [that study] showed very clearly was that the fruit-eaters, the frugivores, had 25 percent bigger brains, on average, than the folivores, the leaf-eaters,” Brand-Miller says. The fruit-eaters also had bigger brains than the omnivores, which ate meat. 

A central role for dietary sugars in human evolution - https://www.science.org/doi/10.1126/science.aed8437

the paper centrally discussed.

Funny how science deniers will downvote anything that doesn’t fit their world view