Observational realities frequently conflict with attempts to correlate brain size and intelligence. In a scientific paper a scientist states, "After correcting for body height or body surface area, men's brains are about 100 g heavier than female brains in both racial groups." After adjusting for size, male brains are 7% larger, but there is not even a 3% difference in intelligence between males and females. Elephants have brains several times larger than human brains, but elephants are not as intelligent as humans. Removing half of a human brain in a hemispherectomy operation has no major effect on intelligence, as discussed in the posts here. Crows have high intelligence despite tiny brains, and a lack of a neocortex.
Sometimes it is argued that the real measure of cognitive ability is brain connectivity (the degree to which brain cells are connected with each other). It has been suggested that maybe humans are smarter than other mammals because our neurons are better connected. But a new study indicates that the brains of humans are not better connected than the btains of other animals. The study is announced on the Science Daily web site with this headline: "MRI scans of the brains of 130 mammals, including humans, indicate equal connectivity."
We read the following:
"Researchers at Tel Aviv University, led by Prof. Yaniv Assaf of the School of Neurobiology, Biochemistry and Biophysics and the Sagol School of Neuroscience and Prof. Yossi Yovel of the School of Zoology, the Sagol School of Neuroscience, and the Steinhardt Museum of Natural History, conducted a first-of-its-kind study designed to investigate brain connectivity in 130 mammalian species. The intriguing results, contradicting widespread conjectures, revealed that brain connectivity levels are equal in all mammals, including humans."
A Professor Assaf is quoted as stating, ""Many scientists have assumed that connectivity in the human brain is significantly higher compared to other animals, as a possible explanation for the superior functioning of the 'human animal.'" But it turns out that this assumption (a natural one from the idea that your brain is the source of your mind) just isn't true.
So we have the brain connectivity of mice, the brain connectivity of cows, the brain connectivity of sheep. This is another reason for believing that the human mind (so vastly superior to the mind of such animals) is not produced by the human brain.