Wednesday, 9 April 2014

Killer whales, dead seals and an active social life.

What makes humans special? This question at one point had a number of distinct answers, tool-making, language, emotions, sense of self, and so served as the perfect opening-line into many an article on the distinctive nature of humans, but they more we learn about our animal brethren, the less clear this distinction becomes. Is it that we are the only species that would think of such a question?


The encroaching realization that our uniqueness wasn't as unique as we had envisaged, was not taken as that disappointing by all, as some saw this as an opportunity to better understand what it is to be human. But the more we learn about animals, specifically mammals, the more we learn about how their isn't just one way of being, to which all other animals are striving towards, all less successfully than us, but that there are many ways to exist in this world. Some of which, could be viewed as superior to the human approach. And this evidence doesn't always have to come from primates, which are somewhat boring from an evolutionary perspective, given their linear narrative. Cetaceans (whales and dolphins) are much more interesting from an evolutionary perspective, having come from the sea, lived on land and returned to the sea but it is the Orca, or to use it’s more appropriate name, The Killer Whale, that can provide some fascinating insight on social interaction.

The complexity of the social structure of the killer whale is only matched by elephants and higher primates, such as humans. These societies are based on matrilines, consisting of the matriarch and her descendants, with 4 or 5 matrilines loosely grouped together as pods, with the next step-up the social hierarchy being clans, which are composed of pods of similar dialects. All members of a pod use similar calls, known as a dialect, which are complex and stable overtime. New-borns produce similar calls to their mother but have a much more limited repertoire, but in the days after the birth of a calf, pods have been observed to increase their use of calls, which may be an attempt to create a better environment for the calf to learn. Killer whales hunt a wide variety of animals, but often pods focus on one or a few species, with the associated techniques varying in skill, for example killer whales in Argentina, hunt seals by deliberately beaching themselves, a somewhat unnatural act for these animals and not one exhibited by any other clan.  Killer whales will share their food with one another at all times, with one pod having being documented as supporting a crippled whale, which has a missing fin, by hunting for it and feeding it.

Post-mortem MRI studies of the killer have found three areas of the killer whales brain that are enlarged with respect to human brains, the operculum, the insular cortex and the limbic lobe.  The operculum and the insular cortex are correlated with speech and audition in humans, and it has been considered that this area serves a similar function in killer whales. The structural difference of sounds between pods, has a dialectical variation and there is evidence that this communication may be a learned behavioural trait, with the level of complexity depending on the culture of the pod. The more specialized a pods feeding pattern, they more variety they exhibit in their sound production.

In mammals the limbic system has been identified as the emotional-processing area, in dolphins and whales part of this system have gotten smaller but adjacent parts, the paralimbic region, and are much larger and more elaborate than the human brain. This extra lobe of tissue sits adjacent to their limbic-system and neocortex, suggesting this lobe plays a role in processing emotions and thinking, with the neuro-scientist who conducted the MRI, Lori Marino suggesting that something evolved in the cetacean brain which did not occur in the human brain, giving it a complex range of emotions. Further evidence can be seen in the fact that, spindle cells, associated with the limbic system processing of social organization and empathy, were once thought to be unique to the great apes but have since been found in whale species including orcas. In fact the relative number of spindle cells in killer whales is larger than that of even the human brain.These claims about the emotional depths of killer whales is not based purely on neuroscience though, studies of these mammals in the wild suggest a level of social cohesion not found amongst other mammals, the sleeping behaviour hints at these close bonds, the members of a pod will form a tight circle and their breathing and movements will synchronise.

Their ability to coordinate and plan behaviour can be seen in this clip, which I think is one of the scariest yet fascinating things I have ever watched. But this social cohesion goes beyond the ability to collectively out-smart a seal and it has been suggested that killer whales may have a distributed sense of self. Years of study on how they communicate amongst themselves, by use of vocal and non-vocal cues, how they respond when a member of the group is injured and behaviour such as mass stranding’s, according to Lori Marino, suggest that there may be something about their sense of self that is not an individual sense but depends very much on the social group.It was long held that the ‘sense of self’ was a uniquely human characteristic but elephants, primates and cetaceans have all reacted to seeing a red dot on their own reflection, so this would no longer seem to hold true. It may also be that another sense exists, the distributed sense of self, which is only found in cetaceans and suggest that bonds are so close in a matrilines that they have a combined ‘self’.  

The Killer Whales are apex predators and so some aspects of their behaviour may not be seen as all that inspiring. But there are some characteristics that they exhibit, such as their social cohesion, which are truly impressive and arguably greater than that exhibited by humans. Whilst some research from nature will undoubtedly shine a light on the how and why of human nature, should we only be concerned by our past and present but is our future not a valid concern? Perhaps research from our animal brethren will show us our true limitations and perhaps how these could be overcome.  

2 comments:

  1. The spindle cells you mention are a fascinating case of convergent evolution, having arisen in unrelated lines of descent. Recently they were also found in Elephants. The conclusion that they evolve in the context of certain kinds of very rich social embedding that is shared by apes, elephants and cetaceans seems inescapable.

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    1. The more evidence that emerges about the lives of Elephants & Cetaceans, the more blurred the lines become between Man and the animal kingdom. To hark back to my first love, in Archaeology, homo-sapiens were seen as unique & distinct as their culture included a funerary ritual, but it would seem that elephants engage in funerary practices too.

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