This leads to e.g. the Gas Turbine just appearing out of nowhere, not depending on any previous technology
The inconsistent definition and the pretty large gaps leads to a lot of oddness. Just look at how sparse anything related to textiles is. "Clothing" just gets one "invention" in 168k B.P., even though a t-shirt and an arctic jacket are obviously very different technologies. New world agriculture is similarly strange. Nodes appear from nowhere and lead nowhere, presumably because there are implicit "nature" edges they didn't want to represent as technology.
[1] https://www.hopefulmons.com/p/what-counts-as-a-technology
This is an interesting example. It's a technology that's very important for staying alive, but not one that you'd expect to contribute to any kind of progress. It's just something you have to do to corn before eating it.
You don't actually need to nixtamalize maize. It's totally edible without and most americans today don't eat nixtamalized corn outside masa. It's just a process to make it more nutritious and importantly, nearly nutritionally complete. For ancient societies, nixtamalizing had a role similar to things like vaccination do for us today. It reduced malnutrition and the economic/social/political effects of disease. The difference I'm trying to highlight is that it probably wasn't understood as such and intentionally done for that purpose. Nixtamalization was culturally encoded as just what you did. Had they had a better understanding of nutrition, they probably would have made more intentional efforts to include the missing vitamins nixtamalization doesn't provide. We often see signs of those missing nutrients in precolumbian skeletons.
This extends to a surprisingly wide variety of ancient technology. Most metallurgy probably wasn't understood in the technical sense we think of it today until quite late. We see that with early glass, where people simply didn't understand what they were doing. Ingredients from specific areas would have specific effects, but sometimes didn't for reasons no one at the time understood. Craft communities would standardize on very specific, ritualized processes that simply couldn't be changed because they didn't have a good mechanistic understanding of the variables involved. One of the downstream effects of this is that poaching craftspeople is a viable strategy (they had the specific "recipe") and also that resources like sand from specific areas in syria and egypt were effectively non-fungible for centuries. You had to trade with whoever controlled that area even if you had the craftspeople.
By implication, this was something that had never been done before.
I'm guessing they had traditional assaying techniques, just with less accuracy than a contemporary chemist.
Andrew Carnegie discovered that certain "bad" ore was that way because its iron content was much higher than usual. Secure in the knowledge that this ore was actually better than "good" ore, he developed the techniques to use it.
Researching those reasons requires a lot of work and most people just want to get to the result step without necessarily understanding why you put the oil in the pan before the egg. They're hungry.
1: For anyone whose Nahuatl is a bit rusty: the English word for nixtmalized corn is “hominy”.
Maybe then you get into arguments about whether the dependencies were "required", but there it's more or less resolvable by relying on what "actually" happened rather than the minimal tree (which is its own exercise)
Still, great project and I'd have loved to see it crowdsourced like wikipedia.
There are obvious exceptions, such as Math, Philosophy (insert all links lead to philosophy here). But even Math is seeing progress in materials science as a component now (computer derived proofs for instance).
Making a really good tech tree is a stupendously hard problem. I once started working on one for a game but gave up once I realized that doing this properly is probably going to take a lifetime or two and there are other things I can do that are more immediately useful.
It's an interesting question. Why couldn't the Romans have invented $X? And the answer is mostly the tech tree. There are probably exceptions around things like germ theory of disease and so forth but it's mostly true.
How would one determine what is sufficiently different to deserve a node?
But 100% agree, incremental improvements are the vast majority of advances.