Category: Brains & Intelligence

[Skip to list of Topics for this Category →]

The animal central nervous system is believed to have a single origin, i.e. to be monophyletic. Some of the more basal animal groups completely lack a nervous system (e.g. sponges) or possess a decentralised nervous system, i.e. a loose network of nerves without a brain (e.g. jellyfish). Most animals, however, belong to the Bilateria, which refers to a diverse grouping of bilaterally symmetric organisms that first appeared in adundance in the Cambrian, from around 545 Ma. Genetic information shared by all living bilaterians suggests that their common ancestor had elongated, segmented bodies, and also a nervous system showing segmental organisation, with a ganglion (a conglomerate of nerve cells) in each body segment and an enlarged one at the front end. During the evolution of the distinct bilaterian groups (or 'phyla'), these segmental nervous inputs aggregated and became highly integrated at the anterior, forming a specialised brain. Among the invertebrates, complex brains can be found in the arthropods (including insects and crustaceans) and the cephalopods (octopuses, squids and similar molluscs), the latter having the largest brains of any invertebrates. All vertebrate brains are located in the head and share a common basic structure. During vertebrate evolution, some regions of the brain have undergone dramatic structural changes (e.g. the forebrain), whereas others have preserved their identity across the whole range of vertebrates (e.g. the hypothalamus, which controls many critical biological functions).

Despite its monophyletic origin, the specialisation of the nervous system into enlarged centres for sensory processing, leading ultimately to sentience and complex intelligence, is rampantly convergent. Brains, as such, have evolved independently many times. At this level, however, the convergence is relatively superficial, but there are much more striking convergences that are important in the evolution of such features as memory and learning. Linked to this is the convergent evolution of such structures as the cerebellum in vertebrates and mushroom bodies in insects. Particularly instructive examples exist between vertebrates and cephalopods, e.g. with respect to brain structures, certain aspects of intelligence or personality.

Cognition, i.e. the mental process of gaining knowledge and comprehension, is one of the most familiar of attributes, but one of the most elusive as well. Cognition is associated closely with the concept of intelligence, which, simply put, is the ability to learn and includes such aspects as the adaptation to changing or new environments. There is considerable and controversial divergence of opinion as to the cognitive abilities and capacities of animals. Evidence suggests that complex cognitive abilities are far more widespread among animals than is sometimes thought, but also that, despite very different neural systems, there are a number of surprising similarities between different taxa displaying forms of intelligence. To find cognitive abilities in mammals other than humans is not so surprising, especially in our closest relatives amongst the great apes, but high degrees of intelligence are also found in such groups as the cetaceans (including the dolphins) and elephants. Outside the mammals, certain bird groups (especially the corvids and parrots) are known to possess advanced cognitive abilities, and among the invertebrates remarkable information on cognition has emerged for the octopus (cephalopods) and also some species of bee and wasp (insects). These convergences are not only intrinsically fascinating, but also touch on one of the greatest scientific mysteries - what is the nature of consciousness?

Go to the top of the page


This table lists all the Topics which are part of the Category "Brains & Intelligence"
Topic title Teaser text Availability
Culture and tradition in animals n/a Unavailable
Brain development and complexity in reptiles and mammals n/a Unavailable
Cichlids Cichlids are one of the cause celebr´┐Ż of evolution, and rightly so because these freshwater fish show a remarkable diversity and exemplify many key aspects of adaptive radiation. But why so successful? The answer lies in the versatility of the jaws (and yes, they are convergent). Available
Pressure sensitivity and the tactile sense (excluding the lateral line) The star-nosed mole is famous for, well, its nose, but do you have any idea what these peculiar 'tentacles' are for? The answer is rather touching and, of course, convergent... Available
Intelligence and cognition in birds House sparrows are known to gain access to shopping malls by flying in front of sensors that operate sliding doors, whilst herons have been shown to be adept fishers using baits and lures. Available
Tool use in birds What animals can drop stones into a water-filled tube to bring floating food within reach or bend wire to form a hook? Obviously chimpanzees? No, New Caledonian crows have evolved sophisticated tool use too. Available
Electric fish: insights into convergence Ever seen an electric eel in an aquarium? Don’t dare putting your hand in the tank... Available
Dolphin communication, cognition and sociality Dolphins are one of the most intriguing sources of evolutionary convergence, having cognitive abilities that seem to find many parallels in the great apes, and rather remarkably even extend to tool use. Available
Sleep in animals Suffering from insomnia? Fruit flies do as well... Available
Learning and memory in bees and wasps n/a Unavailable
Cognition in bees and wasps Bees provide surprising insights into not only their cognitive abilities, such as the crucial distinction between same and different, but related features such as learning and memory. Unavailable
Eusociality and communication in bees and wasps The feature of bee communication that has attracted the most attention is the famous bee “dance” that relays information concerning location of productive areas for gathering nectar, pollen or water. Unavailable
Ants: insights into convergence Trap-jaws, silk and agriculture – just a few examples of convergence in the arguably most successful group of insects, the ants… Available
Mirror self-recognition Apart from ourselves, the present roster of animals capable of recongnising themselves includes the bonobo, dolphins, elephants and probably parrots. Unavailable
Tool use in elephants Elephants are well known for their accuracy in throwing objects, and in addition use sticks for a number of purposes. Also of considerable interest is their use of fly-whisks to keep blood-sucking flies at bay. Unavailable
Elephant response to death Elephants are extremely unusual in their reaction to the dying and death of their compatriots, which includes attempts at resuscitation and grieving. Unavailable
Elephants: senses, intelligence and social structure There is evidence that elephants are sensitive to seismic communication, with the large pads of the feet and the trunk tip capable of picking up vibrations transmitted through the ground. Unavailable
Play in birds, mammals and octopus Social play is the hall-mark of the most intelligent of this planet’s species, and there is a particularly striking convergence between birds and mammals. Unavailable
Simple tool use in owls and cephalopods Burrowing owls place pieces of collected dung. These attract insects such as beetles that are then eaten by the owls. Available
Lekking in birds, fish, mammals and cephalopods Complex interactions between males and females prior to mating have evolved independently many times. Amongst the most familiar examples are leks. Unavailable
Electroreception in fish, amphibians and monotremes From an evolutionary point of view, electroreception is particularly intriguing as a sense modality that has been repeatedly lost and reinvented again. Available
Octopus arm function If you want to see a truly remarkable example of convergence, then present an octopus with a piece of food and have a high-speed camera ready… Available
Blood-brain barrier of vertebrates, cephalopods and other invertebrates A very important component of complex brains is an effective barrier between the blood vascular system and the brain, both to regulate electrolyte balance (e.g. potassium) and exclude potentially harmful substances. Unavailable
Learning and memory in vertebrates and cephalopods Convergence in learning (and by implication memory) is important not only because it will give us clues as to the nature of consciousness, but it will also have a bearing on the reality (or otherwise) of pain and suffering in “primitive” animals. Unavailable
Cephalopod brains: convergence with vertebrates Cephalopod brains show some striking convergences with those of vertebrates, including optic lobes and a cerebellum-like region. Unavailable
Octopus and other cephalopods: convergence with vertebrates What could be more different from us than the alien-like octopus? Hold on. Look it in the eye and think again. Available