Explain scientifically whether humans and humpback whales share a close evolutionary relationship

Science sits at the heart of WDC and our work to help save whales and dolphins, both to conserve these amazing and fascinating creatures but also to protect the welfare and rights of each and every individual.

Whales and dolphins exhibit a wide range of fascinating behaviours, from hunting, spy-hoping and tail slapping, to surfing waves and using tools. There are also well substantiated reports of whales and dolphins grieving for their dead, even rescuing humans.

Whale and dolphin species tend to exhibit a high degree of social behaviour, including cooperation, which helps to ensure that groups thrive. Examples of cooperation include bubble-net feeding in humpback whales and the co-operative behaviour between bottlenose dolphins and fishermen reported in various parts of the world.

Read a comprehensive review of what the many complex aspects of whale and dolphin behaviour mean for the conservation.

So what secrets about whale and dolphin behaviour and intelligence can be gleaned from investigating the large brains of our mammalian cousins?

In recent years, the study of whale and dolphin brains has provided some amazing insights into how these complex beings have evolved and the processing skills for which their brains have adapted.

Whale and dolphin brains are big. Sperms whales have the largest brain on the planet, weighing around 7.8kg. The average bottlenose dolphin brain weighs around 1,700g, whereas the average adult human brain weighs around 1,300g. Does brain size tell us that these species are smarter than us? Well, not necessarily.

Scientists use a ratio of relative brain to body mass, known as Encephalisation Quotient (or EQ). For more information on the origin and evolution of large brains in toothed whales see Marino et al. 2004.

In the quest to unravel the intelligence of other species, just as important as absolute brain size is brain structure. As a result of the fact that dolphins have evolved in, and adapted to, an aquatic environment there are some striking difference between dolphin and human brain structure. Dr Lori Marino, a leading researcher into whale and dolphin brain anatomy notes that the brains of these species have evolved ‘along a different neuroanatomical trajectory’ to human brains, but provide ‘an example of an alternative evolutionary route to complex intelligence on earth’.

Marino further notes: ‘In particular, the cetacean cerebral cortex (the part of the brain involved in higher-order cognition) evolved along a very different trajectory than other mammals, resulting in a highly unusual arrangement of functional areas and an entirely unique structure, the paralimbic lobe. Yet, despite the vast differences in cortical organization cetaceans and humans (as well as great apes) share a number of complex cognitive abilities, such as self-recognition.  Cetaceans and humans, therefore, are a striking example of evolutionary convergence in psychology among mammals.   These similarities, importantly, mean that cetaceans, like humans, are vulnerable to emotional and social stresses that can lead to considerable harm.  This important point is critical for guiding the ethics of how we interact with and treat cetaceans'.

See ‘Brain Structure and Intelligence in Cetaceans’ by Lori Marino in Whales and Dolphin: cognition, culture, conservation and human perceptions.

One very important piece of evidence which emerged in recent years is the existence in some whale and dolphin species of special brain cells known as spindle cells or Von Economo neurones.

Spindle cells are thought to be responsible for ‘rapid intuitive choice in complex social situations’ and are associated with emotions such as empathy. Until relatively recently it was believed that these special brain cells were only found in the brains of humans and some primates. Research now shows that spindle cells are present in the brains of the following whale and dolphin species:

• Humpback whales
• Fin whales
• Sperm whales
• Orcas
• Belugas
• Bottlenose dolphins and
• Risso’s dolphins

Scientists have also discovered the presence of spindle cells in the brains of African and Asian elephants, also known for their complex social behaviours.

The existence of spindle cells, coupled with the revelation that bottlenose dolphins have a sense of self, as shown by the use of a mirror to investigate their own bodies (a behavioural indicator of self-awareness), provides compelling evidence that these are intelligent, sentient and sapient species.

Overall, as Marino et al. 2007 note: ‘cetaceans continue to provide an enormous body of empirical evidence for complex behavior, learning, sociality, and culture’.

Marino even speculates that: ‘It may be that many cetacean species [whales and dolphins] have achieved a level of social-emotional sophistication not achieved by other animals, including humans’.

Even more compelling is the recent discovery that bottlenose dolphins may be more precocious than human infants. Research indicates that bottlenose dolphins are first able to recognise themselves in a mirror at ages earlier than generally reported for children and at ages much earlier than reported for chimpanzees.

‘Brain Structure and Intelligence in Cetacean’ by Lori Marino in Whales and Dolphin: cognition, culture, conservation and human perceptions.

For more information on the origin and evolution of large brains in toothed whales see Marino et al. 2004.

It has been argued, quite plausibly, that if a species can communicate in sophisticated and novel ways then this implies a certain degree of intelligence. Whales and dolphins communicate in many ways with each other, from the body language of posturing, to the high pitched ‘signature whistles’ of bottlenose dolphins.
Perhaps one of the best studied forms of communication in whales is the extraordinary and haunting song of the humpback whale, first described by Roger Payne and Scott McVay in 1971.

The song of male humpback whales is one of the most complex non-human communications ever studied.  Its exact purpose remains something of a mystery, but it is believed to be associated with reproduction (either competition between males, or perhaps in relation to mate selection). Remarkably, there is also strong evidence that these amazing songs are transmitted culturally (see Culture section below and Noad et al. 2000).

A variety of communication techniques in bottlenose dolphins, orcas and sperm whales have also been studied extensively. A range of different acoustic communications have been discovered from greeting and alarm calls to the rhythmic sets of clicks emitted by sperm whales in what are termed ‘codas’.

One of the most well-known studies of dolphin communication was conducted in 1986 by Louis Herman (in Dolphin Cognition and Behaviour: a comparative approach (Comparative Cognition and Neuroscience Series). During this research, captive bottlenose dolphins were taught a basic sign language and a computer-generated language consisting of various sounds. What was remarkable about this study was that it demonstrated that as well as understanding simple sentences and new or unusual combinations of words, the dolphins actually showed understanding of syntax (or sentence structure), an advanced linguistic concept.

This discovery is all the more remarkable when one considers that we humans have spent decades trying to unravel the possible languages of other species, and yet the dolphins were able to understand the syntax of a human generated language.

Adding further to the complexity of dolphin communication is the theory that it is possible for an eavesdropping dolphin to understand information from the returning echoes generated by others of the same species.

The jury is still out on how or if eavesdropping is an important part of social life for dolphins. However, this potentially presents yet another fascinating way in which dolphins may be interacting and communicating with each other.

The use of tools by other species indicates the ability to physically manipulate the world in order to get something an individual wants or need, or perhaps even just for fun (as for example with the bubble rings produced by bottlenose dolphins). Tool use has long been seen as a marker of intelligence, but can also be associated with social learning and culture. There are examples of tool use in several species other than primates. In two quite separate regions of the world, bottlenose dolphins exhibit two excellent examples of tool use for foraging.

In Shark Bay, Western Australia, female Indo-Pacific bottlenose dolphins have regularly been observed carrying sponges on their jaws. The sponges are collected and then used to protect them whilst they forage for food in the sediment and in crevices on the sea floor. This activity is known as ‘sponging’.

Another great example of manipulating the world is provided by bottlenose dolphins along the coast of Florida who use mud to create a trap for fish.

But perhaps one of the best known and most spectacular examples of manipulation of the environment is exhibited during the cooperative foraging strategy used by humpback whales, which results in a bubble nets that encircles large schools of fish. This complex behaviour requires cooperation, anticipation of the action of others, social learning, understanding acoustic cues and probably a good deal of patience whilst the technique is learnt and perfected.

Two of the leading experts in the field of culture in whale and dolphin societies, Hal Whitehead and Luke Rendell, define culture as ‘information or behaviour - shared by a population or subpopulation - which is acquired from conspecifics through some form of social learning’. In this case ‘sub-population’ is used to describe a social group of individuals, rather than necessarily a genetically or geographically distinct group. Examples of cultural transmission include humpback whale song, which is ‘transmitted’ between groups of males, between geographic locations and even between seasons, in a manner similar to the way in which a ‘pop song’ catches on in our own cultures. Other examples of cultural transmission or social learning, include the radically different foraging techniques seen in some groups of orcas and even the use of sponges as tools exhibited by some bottlenose dolphins, as discussed earlier.

There are even some whales that have started a new behaviour called ‘tread-water’ or ‘trap’ feeding: this has been observed both in humpback and Bryde’s whales. The whales rest vertically in the water column with their mouths wide open, waiting for fish to swim into their ‘trap’.

We do not yet know whether the whales learn this behaviour individually, or from each other, but watch this space…. Over time and with careful research we will learn more about this fascinating new behaviour, which if socially learnt could develop into a new foraging culture.

Why is culture an important part of the rights debate? The existence of unique cultures within some populations of whales and dolphins demonstrates not only that these are intelligent beings, who are able to transmit information to each other, both between and within generations, but it also shows that there are important codes of conduct within cultural groups. These sophisticated societies cannot simply be evaluated by their population size alone. Acknowledging that species other than our own have complex cultural structures requires us to look more closely at these populations and the way that we protect them, as species and populations, but also as cultural units and individuals.

So, there you have it. Just some of the evidence that makes whales and dolphins special, and deserving of the recognition of their individual rights. If you agree, then please sign the Declaration of Rights for Cetaceans: whales and dolphins.