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Comment by hyperpallium | Hacker News Reader

By that logic, if humans had them, they would have been found before now, given the amount of time spent looking at human brains.

It seems you have to be looking in the right place, in the right way, for the right thing.

But it's wrong to knock a new discovery - even if not unique to humans, it's still a discovery. Let's celebrate the feature for itself, not benefits that might follow.

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There's probably been orders of magnitude more time spent analyzing rodent brains, simply because there is an effectively unlimited quantity available and an extremely limited quantity of human brains available. Essentially all invasive human brain studies are preceded by animal model studies (usually starting with rodents before proceeding to "higher" animals if that's called for), but conversely not all animal model studies result in a human follow up. Meaning a hell of a lot more rodent brains get put under the microscope. So in general you would expect to find them in rodents first, if the probability of serendipitous discovery is purely a function of time spent conducting unrelated analyses.

I wouldn't expect the number of human autopsies to be more than a few million over the entire history of the human species. Nobody looks at human brains. It's a huge problem.

US alone does over 3 million autopsies a decade so it’s easily 10’s of millions over human history. The issue in terms of science is the vast majority of these have nothing to do with scientific research.

Right, no one is doing mouse autopsies to determine the murder weapon but we don't wholesale kill humans in the quest for scientific research either. Don't discount a medical examiner's job as not being science. They aren't discovering new cells in the body but they are more akin to a GP doctor (versus a clinical research doctor). Just like your GP doctor, they can read the latest medical research, try new techniques and practices, and report experiences at conferences. Or they can work out of a 1950's handbook. But just like an engineer that can't be bothered to adapt to new technology, they are quickly going to fall behind their peers.

We don't remove the brain from someone murdered because they likely didn't give researchers permission to do so. Moreover, to study cells requires some skills not found at the coroner's.

Uniqueness as an artifact caused by limits on current knowledge is a salient point. To give an idea of the state of the art in the understanding of living brains, this page presents a pie chart of known neuron types by species:

http://neuromorpho.org/byspecies.jsp

If an alien stumbled across that data they might surmise that rodents "rule" this planet, followed by fruit flies as their symbiotes/slaves/pets, followed by everyone else.

However, if they had a moral code like ours they might instead surmise that rats, mice, and flies are viewed as expendable to the actual "rulers" of the planet and that these have an aversion to slicing themselves up for science. So they might conclude the rulers to be one of the primates given the existence of three close species: human/chimp/baboon in one family (monkey).

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