Quick search gave the following:
Pack in more neurons
These countless folds allow humans to pack in more neurons which, in turn, can mean more advanced brains with increased cognitive abilities, Ronan said. However, folded brains are hardly ubiquitous, as most animals’ brains aren’t folded.
Why Do Our Brains Have Folds? | Live Science
www.livescience.com/62892-why-brains-have-folds.html
www.livescience.com/62892-why-brains-have-folds.html
The folds of a brain are called gyri and the grooves are called sulci. These morphological features are produced by the folding of the cortex, the part of our brain responsible for higher cognitive processes like memories, language and consciousness.
Question of the Week: Why do brains have wrinkles?
blogs.ucl.ac.uk/researchers-in-museums/2017/04/27/why-do-brains-have-wrinkles/
blogs.ucl.ac.uk/researchers-in-museums/2017/04/27/why-do-brains-have-wrinkl…
and
The neocortex—the outermost layer of the brain characterized by the squiggly sulci, or brain folds—is the region that gives all primates their exceptional intelligence. In both chimps and humans, this brain region continues to grow and organize for years after birth, allowing us to learn and develop socially.
Humans can outlearn chimps thanks to more flexible brain genetics …
This article is interesting:
https://www.thoughtco.com/most-intelligent-animals-4157712
IT notes that elephants have a LARGER brain, but the same number of neurons as a human brain.
Dolphins have more folds then humans, but it doesn’t give a size comparison, they are are the only animal to pass the mirror test of self awareness.
IT appears that intelligence is more about the number of cells specific to the cortical area and not the overall brain - nice picture in here of various animal brains and you can see how the folds are different. The money quote: “The researchers say the number of neurons in an animal’s cerebral cortex is a hallmark of intelligence. The brain of a Golden Retriever was found to have more cortical neurons than a brown bear despite being three times smaller.” Pictured far down the page are relative animal brain sizes with noteable differences in folding and the link: https://www.dailymail.co.uk/sciencetech/article-5131945/Dogs-really-smarter-cats-research-suggests.html
* * * Brains / intelligence ~ neuron density in cerebral cortex * * *