We were lucky to have sightings involving several Striped dolphins (Stenella coeruleoalba) these last two weeks, which allows us to assume that larger pods may be foraging around the archipelago. Striped dolphins are notorious for travelling in very large groups known as “super pods” across the worlds oceans. These enormous aggregations consist of hundreds of animals and often contain other dolphin species.
If we consider how it must be for each individual animal when they move in these large, fast groups we begin to understand why the animals are more reliant on their acoustics than they are on their vision. Imagine swimming amongst several other peers at 30 km/h and coordinating your own movement with that of others around you. It’s obvious that communication is everything in such situations and that this input of information must be processed quickly. It’s not easy to understand the ways dolphins perceive their environment because their habitat is very different to ours and their lives are much faster. If we seriously wish to attempt to imagine the fast lifestyle of these cetaceans we have must consider the architecture of their brain and what structural differences it has to our own.
If you are seriously interested in the structure of a dolphin’s brain, I strongly recommend the works of neuroscientist Lori Marino. As a specialist in biopsychology and neuroanatomy, Marino gained a prominent status amongst behavioural scientists and published hundreds of papers in her field. Within the scope of a massive study where she collected over 200 dolphin skulls to determine the evolution of their brains, she managed to reconstruct 3D models of dolphin brains from up to 47 million years ago. The study showed a body to brain ratio downsizing. At the beginning of their evolutionary development, the mass of the dolphin brain was much smaller in relation to its body and evolution drove it to dramatically expand in size over time. Simultaneously, their bodies shrank, their teeth became smaller and they developed high frequency acoustics. Marino also managed to prove self-awareness in Bottlenose dolphins (Tursiops truncatus) together with her colleague Diana Reiss by means of a mirror test. The fact that the far-out abstraction of dolphins possesing an „idea of self“ had been proven marvelled the scientific world and Marino’s profound credentials made it hard for others to dismiss her research despite the controversial implications it presented.
If we further look into the dolphins brain we realise that the wiring is very different to ours but just as complex. If not, I dare to say, even more complex. Their neocortex, the layered part of the mammalian brain that is responsible for sophisticated behavior, has 5 layers instead of six. Dolphins lack layer 4 which is where all the input from the lower part of the brain is integrated, meaning the way information enters a dolphins brain is completely different to ours. Moreover, in contrast to our thick neocortex, the dolphins neocortex has a higher surface area with more crimps and wrinkles. Dolphins also integrate sound and visual input in practically the same area (in humans this is separated by several lobes) making it a fast-processing brain made for speed. Both humans and dolphins posess a group of very sophisticated brain cells known as Economo neurons, also referred to as VENs. Besides being extremely fast, these neurons are also responsible for important aspects of socializing such as empathising, joking etc and a loss in such neurons is closely associated with dementia in humans. VENs help transfer large parcels of information around at high speeds and allow us (and dolphins) to keep track of family and acquaintances. This helps explain the extroverted nature of dolphins and how they are able to juggle alliances within their groups.
I could go on and on but I think you get the picture.
When asked during an interview whether they would be the dominant lifeforms on earth had they inhabited the land, Marino subtlely answered „While they don’t build rockets, their level of sociality is so sophisticated I don’t think they have anything to learn from us. The fact that they have co-inhabited the ocean and not destroyed themselves really speaks to the fact that they have figured out a way to do this in a way we haven’t“.
Of course opinions on the subject differ but, considering her research and what it has uncovered, Marino’s answer definitely delivers food for thought.
By Paula Thake
Sightings of the day
17:00 Bottlenose dolphins, Striped dolphins
09:00 Striped dolphins
12:00 Striped dolphins
15:30 Bottlenose dolphins