The brains of Asian and African elephants rank among the highest for absolute and relative mass, cortical expansion and complexity, features comparable only to those of some of the Cetaceans, and the Great Apes, including humans. Averaging 4,783 g, the adult elephant brain is the largest among living and extinct terrestrial mammals.The brain of a newly born elephant is approximately 50% its adult weight, indicating a prolonged developmental period for the brain wherein the environment will significantly shape neuronal microstructure.

One way of comparing the brains of different animals is to use the Encephalization Quotient or EQ. EQ is the ratio of the observed brain mass to the expected brain mass of a typical animal of that size. Looking at brain size in this way, an EQ equal to 1.0 is an average mammalian brain. The larger the brain is relative to body size, the more brain mass is theoretically available for more complex cognitive function - beyond the basic survival tasks, such as breathing, motor skills etc. During the course of evolution, the EQ of the Proboscidea has increased by 10 fold, from 0.2 for extinct Moeritherium, to about 2.0 for extant elephants (Shoshani et al. 2006a).

The EQ for the 16 elephants whose brains have been measured (as of 2006) range from 1.13 to 2.36, with an average of 1.88. Asian elephants appear to have a higher average EQ than African elephants, 2.14 and 1.67, respectively -- although these figures are based on a very small sample size. In species where sexual dimorphism is pronounced, as in elephants, males have lower EQ values than females (EQ Loxodonta africana: male: ~1.3 - female: 2.0). So it is clearly important to know which sex is being measured as this may also affect observed differences between the two species.

The figures for elephants are comparable to the larger primates (e.g. chimpanzee: 2.2-2.4; gorilla: 1.4-1.7; orangutan: 1.6-1.9, although Homo sapiens at 7.0+ is far above all other mammals. The EQ for Cetaceans range from about 1.5 in river dolphins to as high as 5.6 in bottle-nosed dolphins, which is about the same as Australopithicines. Are bottle-nosed dolphins as intelligent as this figure suggests? Scientists agree that intelligence is too complex to be characterised by a single numerical index, and that internal structural complexity is probably a more important factor in the evolution of intelligence.

Brain complexity

The cerebrum and cerebellum of the elephant's brain are extremely convoluted and elephants have the greatest volume of cerebral cortex available for cognitive processing of all land mammals. The relatively large cerebellum in the elephant is probably largely correlated with the fine motor control of the trunk, as the cerebellum is intimately involved in coordination. Elephants have a large and highly convoluted neocortex, which is the outermost ribbon of grey matter one sees when looking at the cerebral hemispheres. The neocortex is the seat of enhanced cognitive skills, such as working memory, planning, spatial orientation, speech and language.

The temporal lobes, which are thought to function in recognition, storage, and retrieval of information related to sensory input, are especially large and enormously complex in elephants. Relative to brain size, the temporal lobes appear to be larger, more convoluted and denser than those of humans. The extremely large temporal lobes may help explain elephants' remarkable capacity for remembering individuals, places and events. Elephants also have a very large and highly convoluted hippocampus, which is linked to the processing of memory and spatial learning. The hippocampus takes up 7% of the central structures of the brain in elephants, as compared to only 5% in humans and may explain their prodigious memories and their ability to navigate over long distances. The neocortex volume relative to the rest of the brain ("neocortex ratio"), has been shown to correlate closely with social group size suggesting that it underwrites the cognitive skills needed for complex social living. Moreover, the finding that neocortical ratio predicts the frequency with which primate species have been found to use tactical deception to solve social problems lends support to this argument. We know that elephants have a very large and convoluted neocortex, further supporting the notion that elephants are processing very elaborated sensory information, as one would expect in higher cognitive processing. Another indicator of intelligence is the absolute number of nerve cells in the brain since more nerve cells indicates the potential for more complicated neural networks. Elephants have a very convoluted cerebral cortex and, although the cell density is lower than in humans, it is estimated to have as many neurons. Much more research is needed before we understand the significance of these cellular characteristics in elephants.

This beautiful image indicates that several researchers (including, Bob Jacobs, Paul Manger, Patrick Hof, and Chet Sherwood) around the world are beginning to unravel the mysteries of the elephant brain. This cortical cell came from the brain of an elephant that was recently preserved for research purposes. Read more in ScienceDirect. Some preliminary research has already emerged and can be found here.

How intelligent are elephants?

In general, elephants are proving to be very intelligent (read more under Elephants are intelligent) but significantly more research is needed. One avenue is to carry out more cognitive studies both in the wild and in captivity. But we also need more information on the brains of elephants. For instance, now that we know elephants are capable of empathy, we might expect to find that their brains include a relatively large insula - which is believed to be crucial to this function in humans.