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The human brain contains 86 billion neurons, with 16 billion neurons in the cerebral cortex. [ 2 ] [ 1 ] Neuron counts constitute an important source of insight on the topic of neuroscience and intelligence : the question of how the evolution of a set of components and parameters (~10 11 neurons, ~10 14 synapses) of a complex system leads to ...
Thus, large whales have very small brains compared to their weight, and small rodents like mice have a relatively large brain, giving a brain-to-body mass ratio similar to humans. [4] One explanation could be that as an animal's brain gets larger, the size of the neural cells remains the same, and more nerve cells will cause the brain to ...
Predators tend to have relatively larger brains than the animals they prey on; placental mammals (the great majority) have relatively larger brains than marsupials such as the opossum. A standard measure for assessing an animal's brain size compared to what would be expected from its body size is known as the encephalization quotient. The ...
Mice have a direct brain/body size ratio similar to humans (1/40), while elephants have a comparatively small brain/body size (1/560), despite being quite intelligent animals. [18] Treeshrews have a brain/body mass ratio of (1/10). [19] Several reasons for this trend are possible, one of which is that neural cells have a relative constant size ...
Brain-to-body size scales allometrically. [1] This means that as body size changes, so do other physiological, anatomical, and biochemical connections between the brain and body. [2] Small-bodied mammals tend to have relatively large brains compared to their bodies, while larger mammals (such as whales) have smaller brain-to-body ratios.
Brain of a human (left), compared to that of a black rhinoceros (center) and a common dolphin (right). Elephant brains also show a complexity similar to dolphin brains, and are also more convoluted than that of humans, [20] and with a cortex thicker than that of cetaceans. [21]
Fish typically have quite small brains relative to body size compared with other vertebrates, typically one-fifteenth the brain mass of a similarly sized bird or mammal. [10] However, some fish have relatively large brains, most notably mormyrids and sharks, which have brains about as massive relative to body weight as birds and marsupials. [11]
The human brain stands out among the mammals because of its relative size compared to the rest of the body. The brain of Homo sapiens is about three times larger than that of its closest living relative, the chimpanzee. For a primate of its body size, the relative size of the brain and that of the digestive tract is rather unexpected; the ...