The greatest change in brain structure across human evolution relates to the frontal lobe. Frontal lobes are tiny in many smaller mammals, such as tree shrews and hedgehogs. In higher-order mammals, like cats and dogs, they are still smaller than in humans and also considerably less convoluted. As mentioned above, the convolutions on the cortex provide more surface area for dendrites to expand. Relatedly, our species has the most complex and sophisticated cognitive capacities on earth. That is not to say that other animals do not use some form of thought— chimpanzees use tools to solve problems and gorillas can be taught the rudiments of language. Nonetheless, as far as we know, no other species really comes close to us with regard to intelligence.