It also does not explain why birds are better at language tasks than cats. Cat brains are much larger. The training rewards in the lab are the same. And, yet, cats significantly underperform parrots at every single language-related task we can come up with. Why? Because the parrots have had a greater evolutionary pressure to be good at language-style tasks—and, as a result, they have evolved task-specific neurological algorithms to make it easier.
Cat brains are much larger, but physical size is irrelevant. What matters is neuron/synapse count.
According to my ULM theory—the most likely explanation for the superior learning ability of parrots is a larger number of neurons/synapses in their general learning modules - (whatever the equivalent of the cortex is in birds) and thus more computational power available for general learning.
Stop right now, and consider this bet—I will bet that parrots have more neurons/synapses in their cortex-equivalent brain regions than cats.
We show that in parrots and songbirds the total brain mass as well as telencephalic mass scales approximately linearly with the total number of neurons, i.e. neuronal density does not change significantly as brains get larger. The neuronal densities in the telencephalon exceed those observed in the cerebral cortex of primates by a factor of 2-8. As a result, the numbers of telencephalic neurons in the brains of the largest birds examined (raven, kea and macaw) equal or exceed those observed in the cerebral cortex of many species of monkeys.
Finally, our findings of comparable numbers of neurons in the cerebral cortex of medium-sized primates and in the telencephalon of large parrots and songbirds (particularly corvids) strongly suggest that large numbers of forebrain neurons, and hence a large computational capacity, underpin the behavioral and cognitive complexity reported for parrots and songbirds, despite their small brain size.
The telencephalon is believed to be the equivalent of the cortex in birds. The cortex of the smallest monkeys have about 400 million neurons, whereas the cat’s cortex has about 300 million neurons. A medium sized monkey such as a night monkey has more than 1 billion cortical neurons.
Interesting! I didn’t know that, and that makes a lot of sense.
If I were to restate my objection more strongly, I’d say that parrots also seem to exceed chimps in language capabilities (chimps having six billion cortical neurons). The reason I didn’t bring this up originally is that chimp language research is a horrible, horrible field full of a lot of bad science, so it’s difficult to be too confident in that result.
Plenty of people will tell you that signing chimps are just as capable as Alex the parrot—they just need a little bit of interpretation from the handler, and get too nervous to perform well when the handler isn’t working with them. Personally, I think that sounds a lot like why psychics suddenly stop working when James Randi shows up, but obviously the situation is a little more complicated.
I’d strongly suggest the movie project nim, if you haven’t seen it. In some respects chimpanzee intelligence develops faster than that of a human child, but it also planes off much earlier. Their childhood development period is much shorter.
To first approximation, general intelligence in animals can be predicted by number of neurons/synapses in general learning modules, but this isn’t the only factor. I don’t have an exact figure, but that poster article suggests parrots have perhaps 1-3 billion ish cortical neuron equivalent.
The next most important factor is probably degree of neotany or learning window. Human intelligence develops over the span of 20 years. Parrots seem exceptional in terms of lifespan and are thus perhaps more human like—where they maintain a childlike state for much longer. We know from machine learning that the ‘learning rate’ is a super important hyperparameter—learning faster has a huge advantage, but if you learn too fast you get inferior long term results for your capacity. Learning slowly is obviously more costly, but it can generate more efficient circuits in the long term.
I inferred/guessed that parrots have very long neotenic learning windows, and the articles on Alex seem to confirm this.
Alex reached a vocabulary of about 100 words by age 29, a few year’s before his untimely death. The trainer—Irene Pepperberg - claims that Alex was still learning and had not reached peak capability. She rated Alex’s intelligence as roughly equivalent to that of a 5 year old. This about makes sense if the parrot has roughly 1/6th our number of cortical neurons, but has similar learning efficiency and long learning window.
To really compare chimp vs parrot learning ability, we’d need more than a handful of samples. There is also a large selection effect here—because parrots make reasonably good pets, whereas chimps are terrible dangerous pets. So we haven’t tested chimps as much. Alex is more likely to be a very bright parrot, whereas the handful of chimps we have tested are more likely to be average.
Not much to add here, except that it’s unlikely that Alex is an exceptional example of a parrot. The researcher purchased him from a pet store at random to try to eliminate that objection.
The neuronal densities in the telencephalon exceed those observed in the cerebral cortex of primates by a factor of 2-8.
This is curious. I wonder if bird brains are also more energy efficient as a result of the greater neuronal densities (since that implies shorter wires). According to Ratio of central nervous system to body metabolism in vertebrates: its constancy and functional basis the metabolism of the brain of Corvus sp (unknown species of genus Corvus, which includes the ravens) is 0.52 cm^3 O2/min whereas the metabolism of the brain of a macaque monkey is 3.4 cm^3 O2/min. Presumably the macaque monkey has more non-cortical neurons which account for some the difference, but this still seems impressive if the Corvus sp and macaque monkey have a similar number of telencephalic/cortical neurons (1.4B for the macaque according to this paper). Unfortunately I can’t find the full paper of the abstract you linked to to check the details.
I wonder if bird brains are also more energy efficient as a result of the greater neuronal densities (since that implies shorter wires).
Yes—that seems to be the point of that poster I found earlier.
From an evolutionary point of view it makes sense—birds are under tremendous optimization pressure for mass efficiency. Hummingbirds are a great example of how far evolution can push flight and weight efficiency.
Primate/human brains also appear to have more density optimization than say elephants or cetaceans, but it is interesting that birds are even so much more density efficient. Presumably there are some other tradeoffs—perhaps the bird brain design is too hot to scale up to large sizes, and uses too much resources, etc.
Unfortunately I can’t find the full paper of the abstract you linked to to check the details.
It was a recent poster—so perhaps it is still a paper in progress? They claim to have ran the defractionator experiments on bird brains, so they should have estimates of the actual neuron counts to back up their general claims, but they didn’t provide those in the abstract. Perhaps the data exists somewhere as an image from the actual presentation. Oh well.
Cat brains are much larger, but physical size is irrelevant. What matters is neuron/synapse count.
According to my ULM theory—the most likely explanation for the superior learning ability of parrots is a larger number of neurons/synapses in their general learning modules - (whatever the equivalent of the cortex is in birds) and thus more computational power available for general learning.
Stop right now, and consider this bet—I will bet that parrots have more neurons/synapses in their cortex-equivalent brain regions than cats.
Now a little google searching leads to this blog article which summarizes this recent research—Complex brains for complex cognition—neuronal scaling rules for bird brains,
From the abstract:
The telencephalon is believed to be the equivalent of the cortex in birds. The cortex of the smallest monkeys have about 400 million neurons, whereas the cat’s cortex has about 300 million neurons. A medium sized monkey such as a night monkey has more than 1 billion cortical neurons.
Interesting! I didn’t know that, and that makes a lot of sense.
If I were to restate my objection more strongly, I’d say that parrots also seem to exceed chimps in language capabilities (chimps having six billion cortical neurons). The reason I didn’t bring this up originally is that chimp language research is a horrible, horrible field full of a lot of bad science, so it’s difficult to be too confident in that result.
Plenty of people will tell you that signing chimps are just as capable as Alex the parrot—they just need a little bit of interpretation from the handler, and get too nervous to perform well when the handler isn’t working with them. Personally, I think that sounds a lot like why psychics suddenly stop working when James Randi shows up, but obviously the situation is a little more complicated.
I’d strongly suggest the movie project nim, if you haven’t seen it. In some respects chimpanzee intelligence develops faster than that of a human child, but it also planes off much earlier. Their childhood development period is much shorter.
To first approximation, general intelligence in animals can be predicted by number of neurons/synapses in general learning modules, but this isn’t the only factor. I don’t have an exact figure, but that poster article suggests parrots have perhaps 1-3 billion ish cortical neuron equivalent.
The next most important factor is probably degree of neotany or learning window. Human intelligence develops over the span of 20 years. Parrots seem exceptional in terms of lifespan and are thus perhaps more human like—where they maintain a childlike state for much longer. We know from machine learning that the ‘learning rate’ is a super important hyperparameter—learning faster has a huge advantage, but if you learn too fast you get inferior long term results for your capacity. Learning slowly is obviously more costly, but it can generate more efficient circuits in the long term.
I inferred/guessed that parrots have very long neotenic learning windows, and the articles on Alex seem to confirm this.
Alex reached a vocabulary of about 100 words by age 29, a few year’s before his untimely death. The trainer—Irene Pepperberg - claims that Alex was still learning and had not reached peak capability. She rated Alex’s intelligence as roughly equivalent to that of a 5 year old. This about makes sense if the parrot has roughly 1/6th our number of cortical neurons, but has similar learning efficiency and long learning window.
To really compare chimp vs parrot learning ability, we’d need more than a handful of samples. There is also a large selection effect here—because parrots make reasonably good pets, whereas chimps are terrible dangerous pets. So we haven’t tested chimps as much. Alex is more likely to be a very bright parrot, whereas the handful of chimps we have tested are more likely to be average.
Not much to add here, except that it’s unlikely that Alex is an exceptional example of a parrot. The researcher purchased him from a pet store at random to try to eliminate that objection.
This is curious. I wonder if bird brains are also more energy efficient as a result of the greater neuronal densities (since that implies shorter wires). According to Ratio of central nervous system to body metabolism in vertebrates: its constancy and functional basis the metabolism of the brain of Corvus sp (unknown species of genus Corvus, which includes the ravens) is 0.52 cm^3 O2/min whereas the metabolism of the brain of a macaque monkey is 3.4 cm^3 O2/min. Presumably the macaque monkey has more non-cortical neurons which account for some the difference, but this still seems impressive if the Corvus sp and macaque monkey have a similar number of telencephalic/cortical neurons (1.4B for the macaque according to this paper). Unfortunately I can’t find the full paper of the abstract you linked to to check the details.
Yes—that seems to be the point of that poster I found earlier.
From an evolutionary point of view it makes sense—birds are under tremendous optimization pressure for mass efficiency. Hummingbirds are a great example of how far evolution can push flight and weight efficiency.
Primate/human brains also appear to have more density optimization than say elephants or cetaceans, but it is interesting that birds are even so much more density efficient. Presumably there are some other tradeoffs—perhaps the bird brain design is too hot to scale up to large sizes, and uses too much resources, etc.
It was a recent poster—so perhaps it is still a paper in progress? They claim to have ran the defractionator experiments on bird brains, so they should have estimates of the actual neuron counts to back up their general claims, but they didn’t provide those in the abstract. Perhaps the data exists somewhere as an image from the actual presentation. Oh well.