(Major edits added on 2024-11-29.)

Some of my own observations and considerations:

Anecdotal evidence for orca intelligence

(The first three anecdotes were added 2024-11-29.)

1. Orcas leading orca researcher on boat 15miles home through the fog. (See the 80s clip starting from 8:10 in this youtube video.)
2. Orcas can use bait.
3. An orca family hunting a seal can pretend to give up and retreat and when the seal comes out thinking it's safe then BAM one orca stayed behind to catch it. (Told by Lance Barrett-Lennard somewhere in this documentary.^[1])
4. Intimate cooperation between native australian hunter gatherers whale hunters and orcas for whale hunting around 1900: https://en.wikipedia.org/wiki/Killer_whales_of_Eden,_New_South_Wales
5. Orcas being skillful at turning boats around and even sinking a few vessels^[2][3]:  https://en.wikipedia.org/wiki/Iberian_orca_attacks
6. Orcas have a wide variety of cool hunting strategies. (e.g. see videos (1, 2)). I don't know how this compares to human hunter gatherers. (EDIT: Ok I just read Scott Alexander's Book review of "The Secret of our success" and some anecdotes on hunter gatherers there seem much more impressive. (But also plausible to me that other orca hunting techniques are also more sophisticated than the examples but in ways it might not be legible to us.))

(ADDED 2024-11-10^[4]: Tbc, while this is more advanced than I'd a priory expected from animals, the absence of observations of even more clearly stunning techniques is some counterevidence of orcas being smarter than humans. Though I also don't quite point to an example of what I'd expect to see if orcas were actually 250 IQ but what I don't observe, but I also didn't think for long and maybe there would be sth.)

(Mild counterevidence added 2024-12-02:)

• Btw it's worth noting that orcas do sometimes get tangled up in fishing gear or strand (and die of that), though apparently less frequently than other cetaceans, though didn't check precisely whether it's really less per individual.
• Worth noting that there are only 50000-100000 orcas in the world, which is less than for many other cetacean species, though not sure whether it's less in terms of biomass.

Orca language

(EDIT: Perhaps just skip this orca language section. Relevant is that orca language is definitely learned and not innate. Otherwise not much is known, except that we can eyeball the complexity of their calls. You could take a look by listening^[5] here.^[6] I'd say it seems very slightly less complex than in humans (though could be more) and much more complex than what is observed in other land animals.)

(Warning: Low confidence. What I say might be wrong.)

I didn't look deep into research into orca language (not much more than watching this documentary), my impression is that we don't know much yet.

Some observations:

1. Orcas language seems to be learned, not innate. Different regions have different languages and dialects. Scientists seem to analogize it to how humans speak different languages in different countries.
2. For some orca groups that were studied, scientists were able to cluster their calls into 23 or 24 different calls clusters, but still with significant variation of calls within a call cluster.
   1. (I do not know how tightly calls are clustered, or whether there often are outliers.)
3. Orcas communicate a lot. (This might be wrong but I think they spend a significant fraction of their time socializing where they exchange multiple calls per minute.)
4. (Orcas emit clicks and whistles. The clicks are believed to be for spacial navigation (especially in the dark), the whistles for communication.) (EDIT: Actually also pulsed calls, which I initially lumped in with whistles but are emitted in pulses. Those are probably the main medium of communication.)

I'd count (2) as some weakish evidence against orcas having as sophisticated language as humans, however not very strongly. Some considerations:

1. Sentences don't necessarily need to be formed through having temporal sequences of words, but words could also be some different frequency signals or so which are then simultanously overlayed.
2. (The different 24 call types could be all sorts of things. E.g. conveying what we convey through body language, facial expressions, and tone. Or e.g. different sentence structures. Idk.)
3. Their language might be very alien. I only have shitty considerations here but e.g.:
   1. Orca language doesn't need to have at all similar grammar. E.g. could be something as far from our language as logic programming is, though in the end still not nearly that simple.
   2. Orcas might often describe situations in ways we wouldn't describe them. E.g. rather about what movements they and their prey executed or sth.
   3. Orcas might describe more precisely where in 3D water particular orcas and animals were located, and they might have a much more efficient encoding for that than if we tried to communicate this.

More considerations

The onlymain piece of evidence that makes me wonder whether orcas might actually be significantly smarter than humans is their extremely impressive brain. I think it's pretty strong though.

As mentioned, orcas have 2.05 times as many neurons in their neocortex as humans, and when I look through the wikipedia list (where I just trust measured^[7] and not estimated values), it seems to be a decent proxy for how intelligent a species is.

There needs to be some selection pressure for why they have 160 times more neurons in their neocortex than e.g. brown bears (which weigh like 1/8th of an orca or so). Size alone is not nearly a sufficient explanation.

It's plausible that for both humans and orcas the relevant selection pressure mostly came from social dynamics, and it's plausible that there were different environmental pressures. (I'm keen to learn.) It's possible that caused humans to be smart more strongly incentivized our brains to be able to do abstract reasoning, whereas for orcas it might've been useful for some particular skills that generalize less well for doing other stuff.

If I'd only ever seen hunter gatherer humans, even if I could understand their language, I'm not sure I'd expect that species to be able to do science on priors. But humans are able to do it. Somehow our intelligence generalized far outside the distribution we were optimized on. I don't think that doing science is similar to anything we've been optimized on, except that advanced language might be necessary.

On priors I wouldn't really see significant reasons why whatever selection pressures optimized orcas to have their astounding brains, would make their intelligence generalize less well to doing science, than whatever selection pressures produced our impressive human brains.

One thing that would update me significantly downwards on orcas being able to do science is if their prefrontal cortex doesn't contain that many neurons. (I didn't find that information quickly so please lmk if you find it.) Humans have a very large prefrontal cortex compared to other animals. My guess would be that orcas have too, and that they probably still have >1.5 times as many neurons in their prefrontal cortex than humans, and TBH I even wouldn't be totally shocked if it's >2.5 times. (EDIT: The cortex of the cetacean brain is organized differently than in most mammals and AFAIK we currently cannot map functionality very well.)

(Read my comments below to see more thoughts.)

1. ^{^}

   You might need a VPN to canada to watch it.

2. ^{^}

   Btw there is no recorded case of a human having been killed by an orca in the wild, including when they needed to swim when the vessel was sunk. (Even though orcas often eat other mammals.) (I think I even once heard it mention that it seemed like the orcas made sure that no humans died from their attacks, though I don't at all know how active the role of the orcas was there (my guess is not very).)

3. ^{^}

   I'd consider it plausible that they were trying to signal us to please stop fishing that much, but I didn't look nearly deeply enough into it to judge.

4. ^{^}

   Actually I don't remember exactly when I added this. I still think it's true but to a weaker extent than I originally thought.

5. ^{^}

   Or downloading the files and looking at the spectrogram in e.g. audacity.

6. ^{^}

   If you want to take a deeper look, here are more recordings.

7. ^{^}

   Aka optical or isotropic fractionator in the method column.