Why is the glossy cockatoo so brainy? part 3

 (writing in progress)
 
...continued from https://www.inaturalist.org/journal/milewski/67970-why-is-the-glossy-cockatoo-so-brainy-part-2#

The glossy cockatoo (Calyptorhynchus lathami) is remarkably specialised for an almost exclusive diet of casuarina seeds. In terms of diet, this species is one of the most specialised birds on Earth. I discussed this from the perspective of a kind of avian counterpart in Australasia for squirrels, which are absent from Australia with no marsupials or Australian rodents in any way convergent with squirrels.
 
Here I would like to add an aspect of this remarkable cockatoo: its surprising social intelligence towards the human species.
 
I have previously detailed how engaging various spp. of cockatoos can be in captivity. And I’ve mentioned that this does not seem to reflect encephalisation alone, because cockatoos such as the Indonesian Cacatua moluccensis only score about 6/10 relative to the global fauna of psittaciform birds in terms of braininess, yet are unparalleled in the complexity and individuality of their relationship to a human keeper.
 
If you told me there was an animal, weighing about half a kilogram, in the Australian vegetation dominated by casuarinas, that specialises on virtually nothing but casuarina seed, and then asked me to predict how intelligent this animal would be in its relationship with humans, I would probably chuckle at your naivety. This is because eating seeds of one family of plants is so monotonous that the foraging niche of the consumer in question can hardly require much braininess.

And yet I would be wrong, because in fact the glossy cockatoo is among the brainiest of birds, and brainier than expected in its brainy order, the Psittaciformes. And even compared with other cockatoos it is regarded as an exceptionally worthwhile species by aviarists.
 
The mean body mass of the glossy cockatoo is 430 g and its mean brain volume is 9.78 ml.

How brainy is this, relative to the world’s parrot-like birds?
 
I examined the data-set of Iwaniuk by looking at all the various psittaciforms, on all landmasses, that have body masses of around 0.5 kg. At this body mass, psittaciforms vary from the small-brained New Guinean forms Psittrichas and Eclectus to the extremely large-brained Rhynchopsitta of Mexico – which parallels the glossy cockatoo in the sense that it specialises on a diet of pine seeds, likewise extracted from cones. That is an interesting coincidence.

The genera Amazona (America), Cacatua (Australia) and Psittacus (Africa) are all moderately encephalised. The last-mentiined genus is the most encephalised, in this way approaching the smallest species of Calyptorhynchus – which is in fact the glossy cockatoo.

Ranked from most encephalised to least encephalised at body masses of about 500 g, we have the following:
-Rhynchopsitta brain vol. ca 11.2 (Mexico),
-Calyptorhynchus lathami (the glossy cockatoo, which is the smallest species in its genus) ca 9.8,

• Psittacus (which is the genus to which Alex belongs and thus made famous for its speech by Irene Pepperberg) ca 9.75, and
   - Cacatua spp. occurring in Australia and Indonesia (but excluding the brainiest corellas, which have greater body masses than this), ca 8.5-10.6
   
  All of the above score 5/10 or more on a scale of 1-10 for the braininess of the world’s psittaciforms.
   
  Next we have:

• Amazona (America and the Caribbean), ca 9,
• Lophochroa leadbeateri (the corella-like species penetrating the nutrient-poorest parts of semi-arid interior Australia), ca 8.5,

• Psittrichas of New Guinea, ca 7.8, and
   - Eclectus of New Guinea, ca 7.5.
   
  All the above values are, of course, mean brain volumes in ml.
   
  Please note that the glossy cockatoo, despite having such a specialised and simple diet requiring minimal versatility, turns out to be brainier than most corellas, and at least as brainy as the genus to which Alex the famous African grey parrot belongs.
   
  It is noteworthy that the glossy cockatoo has similar body mass to Lophochroa leadbeateri (which is the species penetrating farthest into the nutrient-poor interior of Australia), with mean values respectively of 430 g and 460 g. It is thus clear that the former species is the brainier: 9.78 g vs 8.47 g.
   
  In summary, the above data establish clearly that the glossy cockatoo has above-average braininess for a psittaciform species worldwide, and also for a cockatoo.
   
  Now let me quote from Rosemary Low (1993), ‘Cockatoos in Aviculture’, re the glossy cockatoo in captivity:
   
  “I cannot think of any cockatoo – or, indeed, scarcely any other parrot – which is so endearing and affectionate. I make no apologies for repeating an opinion which perfectly describes this species: ...hand-reared males of the Glossy Black Cockatoo are the ultimate experience in bird ownership. They possess an extraordinary rapport with their human owners which is not possible to translate into words, other than to say that they are the ‘dolphins of the bird world’...Perhaps rearing and owning a male Glossy may be the ultimate enlightenment of scientists who treat with disdain any suggestion of intelligence in birds (Courtney, in Low, 1992a). It is not only with their ‘owner’ that Glossy Cockatoos are so remarkably affectionate. An encounter I had with a male belonging to Neville and Enid Connors will long remain in my memory. This male had briefly observed me on three or four occasions during the two days before I entered his aviary...When I entered, the male instantly flew down to stand on my foot. I picked him up and he displayed, standing on my arm, spreading his tail...depressing his back and making the distinctive double call which Glossy Cockatoos use prior to copulation. He kept this up for some minutes. It was a wonderful feeling to be the recipient of this handsome bird’s striking display.”
   
  By contrast, the same author in the same book states the following about Lophochroa leadbeateri:
   
  “Despite its beauty, ...is seldom favoured as a pet, because it lacks the endearing qualities of most cockatoos and appears to be less intelligent.”
   
  So there we have it:
  A bird that does nothing more complicated in its trophic niche that eat the same small seeds throughout its life, taken from the same family of trees and shrubs, and a bird that lives on a continent poor in predators; yet a bird with not only exceptional braininess but also an encephalisation to match noteworthy parrot taxa such as the African grey parrot. And, even more than the African grey and the various corellas, an ability to relate intimately and emotionally to the human species in captivity.

To help readers mull on this topic, I suggest that a key to understanding this bird is lifespan.

Cockatoos are exceptionally long-lived, being capable (like humans) of exceeding 100 years old. It makes basic sense that any species which has evolved to live this long despite having what is - in the scheme of things animal – a rapid metabolism would also tend to be intelligent.

I am unsure how this intelligence is applied in the natural life of the glossy cockatoo. However, it is easy to see that a bird is not going to live for so long without being able to learn from its mistakes and to modify its behaviour according to circumstances.

So, to put this in the context of an infertile land with plants that give as little to animals as possible:
This foraging niche is the epitome of simplicity. However, more important is the unrelenting frugality of the environment. This frugality explains the adaptiveness of slow pace of life. This is in turn manifested partly in great longevity.

It makes sense that any animal that has a slow pace of life will tend to ‘last long’. So environmental ‘stinginess’ leads to long life, which in turn leads to a need to be intelligent.

To summarise:
One can argue that a combination of nutrient-poverty and consumption mainly by fire means that those animals that do evolve in such ecosystems manage to achieve the whole package of slow-pace-of-life by virtue of the natural complementarity of longevity and intelligence. I.e. the glossy cockatoo is smart because it has a slow pace of life emphasising survival over reproduction, and it has a slow pace of life because its resource base is so unrelentingly poor.

Casuarina is the medium whereby this poverty is channeled. This genus is so stingy with its seeds (as with all other parts of its body) that there would be no niche for a seed-eater on it, were it not for the fact that the serotiny (adapted to fire) means that the seeds are held for several years in the cones attached to the branches – which means they can be raided by the bird.

FOLLOWING PARAGRAPHS NEED TO BE REORDERED (still in email reply sequence)

The only extremely intelligent animals I can think of, that are not dexterous in the strict sense of the word, are dolphins. However, dolphins do show great dexterity in the sense that their movements are extremely fine-tuned considering their lack of anything resembling hands or tentacles. So in my view dolphins would indeed conform to the broader concept of dexterity.
 
One could even possibly argue that casuarinas, being so unrelentingly stingy and mean towards animals, have evolved a particular design, in their cones and branches, which prevents unintelligent, non-dexterous seed-eaters from predating the seeds while these seeds are held inside the closed cones (remember that Allocasuarina is serotinous as well as bradysporous).
 
I think the key here is trying to imagine two kinds of granivores. The first is an insect which simply perches on the cone and chomps at it, extracting seed after seed. The second is an arboreal mouse or mouse-like marsupial (functionally equivalent to a small squirrel but not using manual dexterity as squirrels do) which scampers along the branches and simply ‘gnaws’ into the woody cones, extracting the seeds by means of its tongue and teeth.
 
It’s not immediately obvious to me why the latter type of granivore, in particular, could not predate casuarina seeds. However, perhaps a) the branches sway too much (one of the things one soon notices, when watching the glossy cockatoo foraging on a windy day, is how the bird, perched on the branch, is whipped back and forth, often in a kind of arc, which challenges its ability to cling to the tree and use movements precise enough to get at the seeds), or b) the system of ligneous baffles and barriers in the detailed design of the casuarina cone make it oddly difficult just to dismantle the cone by gross damage.
 
You raised the broader question of the puzzling association between the concept of dexterity and the concept of rightness. One can see, in a general sense, how ‘getting it right’ could apply to both the mechanics of an operation and the abstract quality of an operation. This is indeed an interesting question of etymology. It can surely be no coincidence that the original Latin association between ‘dexter’ (right-hand side) and dexterity has survived the permutation of the language into French, in which the right-hand side is spelt ‘droit’ (hardly resembling ‘dexter’) and once again the association with rightness in an abstract sense is conveyed by the French-originating word ‘adroit’.
 
It is indeed easy to see that the glossy cockatoo achieves a kind of ‘adroitness’ in being able to carve a specialised niche for itself in eating from a group of plants, namely casuarinas, that are resolutely and unrelentingly mean towards all other animals.
 
However, all of this depends on us being able to show that there is something about these particular cones that would defy a simpler-minded, less dexterous combination of mouthparts and ‘hands’ (in the cockatoo’s case, actually feet).
 
 Ajm: 
• Humans are extremely dexterous with our hands. Octopi are extremely dexterous with their tentacles. Glossy cockatoos perhaps are more dexterous than other cockatoos given their need to extract such small seeds. The video I watched did surprise me with regards to how dexterous they were. Does one need intelligence to be dexterous? Being dexterous requires a lot of rapid computation e.g. deciding which way to move many parts in space in order to achieve an outcome. It’s in essence very complicated physics.
 
I suppose the next question becomes: are there any non-intelligent dexterous organisms?
 
It’s interesting that dexterous used to mean ‘mentally adroit’. Google states: early 17th century (in the sense ‘mentally adroit’): from Latin dexter ‘on the right’ 
 
Avm: 
As perhaps the most intelligent organism known, we humans have a certain evolutionary theory of intelligence. Here I present a body of observation – of a form of parrot-like bird - that undermines this theory and calls for a wider conceptual framework.
 
Intelligence allows animals to be versatile and adaptable in their behaviour, finding ways to solve environmental problems. This is borne out by human mastery of tools, which makes us the best example of a technological animal. Intelligence also allows animals to live complex social lives, as seen not only in humans but also in non-technological primates such as baboons.
 
So it seems reasonable to theorise that the most intelligent animals, beyond the primate lineages, would be found in groups likewise combining versatility (perhaps in adaptation to complex and changeable environments) and extreme sociality.
 
However reasonable this theoretical prediction might be, it does not seem to explain zoological reality particularly well. And as I’ll show below, one particular species of cockatoo refutes it so much that fresh research initiatives are warranted.
 
Among land mammals, perhaps the most intelligent species besides primates are modern elephants. These proboscideans do support the human-based theoretical model fairly well, because they use their extremely specialised proboscis much like a tool-kit, and they do have complex societies based on longevity and matriarchy. However, no proboscidean is brainy enough to provide a strong test of our theory, and extreme body-size further complicates this comparison.
 
Among cetaceans such as certain dolphins, there is such extreme braininess that the possible analogies with humans are fascinating. However, dolphins cannot rival humans in societal compexity, and technology is hardly relevant to them because of their aquatic specialisation and limited ability to manipulate objects. While the great intelligence of dolphins is undeniable, this lineage tends to refute our adaptive theory of the evolution of intelligence rather than supporting it.
 
Cephalopods such as octopi are also puzzling. Although certain squids are gregarious, we have little evidence for complex society in any cephalopod. The best-known examples of cephalopod intelligence, in octopi, refute our theory because individuals usually live for only one year, relying on reproduction rather than learning for the survival of the species. It’s true that having many tentacles may demans a certain mental complexity, and it is also true that octopi can be remarkably versatile and complex in their mastery of e.g. disguise, whicn involves nuances of posture, locomotion, colour-change and even short-term modifications of skin structure that can be viewed as analogous with ‘technology’. However, cephalopods again overall hardly support our theory.
 
Turning to birds, there are two main lineages of flying vertebrates that excel in intelligence: corvids and psittaciforms. Crows and their relatives certainly are social, and some species make, store, modify and use tools as part of what are essentially omnivorous niches – thus providing significant analogy with human intelligence although the precise expression of this intelligence can seem so otherworldly corvids have traditionally been interpreted as sinister. As for parrot-like birds, there is clear analogy with humans in terms of great longevity, and certain species can be extremely gregarious. Furthermore, although parrots are not known for their use of tools there is a quasi-technological skill to the use of a beak with uniquely complicated hinges and occlusions, in combination with dexterous feet. So birds do seem, overall, to lend support for the theory of the evolution of intelligence based on the human species.
 
The trouble with psittaciform birds is that the most intelligent species among them are not particularly comparable with humans – which brings me to my particular example, namely the glossy cockatoo (Calyptorhynchus lathami).
 
Imagine an island continent, with relatively few predators and a general tameness in its birds, almost reminiscent of the Galapagos. Imagine that this continent is also the flattest and nutrient-poorest landmass on Earth, with much of its area semi-arid. Imagine, within this continent, a particular type of low forest dominated by grey-green, perpetually leafless, dull-looking trees called casuarinas, which are extremely adapted to a combination of infertility and drought. Imagine that these plants have an ecological strategy in which they conserve their meagre resources by being extremely stingy and miserly towards all animals; their foliage is essentially inedible, they produce no nectar of fruit-pulp, and their living wood is too hard for borers. Imagine the seeds of these plants, which are small compared to the superficially similar conifers of other parts of the world and are held in small woody cones. Imagine that 

(writing in progress)

הועלה ב-יולי 6, 2022 01:21 לפנה"צ על ידי milewski