I am beginning to suspect that it is surprisingly common for intelligent, competent adults to somehow make it through the world for a few decades while missing some ordinary skill, like mailing a physical letter, folding a fitted sheet, depositing a check, or reading a bus schedule. Since these tasks are often presented atomically - or, worse, embedded implicitly into other instructions - and it is often possible to get around the need for them, this ignorance is not self-correcting. One can Google "how to deposit a check" and similar phrases, but the sorts of instructions that crop up are often misleading, rely on entangled and potentially similarly-deficient knowledge to be understandable, or are not so much instructions as they are tips and tricks and warnings for people who already know the basic procedure. Asking other people is more effective because they can respond to requests for clarification (and physically pointing at stuff is useful too), but embarrassing, since lacking these skills as an adult is stigmatized. (They are rarely even considered skills by people who have had them for a while.)
This seems like a bad situation. And - if I am correct and gaps like these are common - then it is something of a collective action problem to handle gap-filling without undue social drama. Supposedly, we're good at collective action problems, us rationalists, right? So I propose a thread for the purpose here, with the stipulation that all replies to gap announcements are to be constructive attempts at conveying the relevant procedural knowledge. No asking "how did you manage to be X years old without knowing that?" - if the gap-haver wishes to volunteer the information, that is fine, but asking is to be considered poor form.
(And yes, I have one. It's this: how in the world do people go about the supposedly atomic action of investing in the stock market? Here I am, sitting at my computer, and suppose I want a share of Apple - there isn't a button that says "Buy Our Stock" on their website. There goes my one idea. Where do I go and what do I do there?)
So... here's the thing. You and wedrifid are doing something that has me concerned.
Specifically, you're putting me into a position where, for consistency, I feel compelled to argue a case for something that I myself don't currently have a hugely high degree of confidence in... simply because you're not actually providing in your arguments, any information which I could either specifically agree or disagree with.
IOW, comments like, "quack", "laughable", and "noise" do not give me any information about your epistemology, and therefore light up on my board "[citation needed]" just as much as it did for what I've been reading from D'Adamo.
So, it would be nice if you could identify specific concerns instead... who knows, I might agree with them!
OTOH, my consistent experience is that just because somebody has a stupid-sounding theory, doesn't mean their advice doesn't actually work. (Likewise, people who have good theories are often lousy at giving usable advice.)
Heck, take Seth Roberts as an example here: the entire idea of drinking oil or sugar water to lose weight is also "laughable", "noise" and "quack"... and yet it still seems to work for plenty of people.
Heck, there are elements of Roberts' theory that don't make sense to me, from a "fewest elements to make the circuit" point of view. (For example, I don't think "set point" is a real thing; I think it's more likely an epiphenomenon of something else.)
But that doesn't mean I wouldn't recommend it... just that I'd avoid recommending it to people who jump to conclusions first and ask questions later. ;-)
Anyway... specifics, please. Otherwise, I'll simply bow out of this discussion on the assumption that you don't actually have any new evidence to present.
IOW, a knee-jerk dismissal on grounds of ridiculousness isn't an independent data point for Bayesian analysis. Citing papers disproving D'Adamo's hypotheses, on the other hand, would be quite welcome.
(I've actually googled around for criticisms of both his blood type and genotype work, and have yet to find a single cite that doesn't have a more-recent countercite; the vast majority of criticism, however, appears to be of the, "that's so silly I won't even bother to argue the idea seriously" variety. Maybe this is evidence that he's a quack, but at least his responses to the critiques include some citations in his favor.)
A big red flag is that where I expected to see an analysis of what mixture of the various ancestral types a person is, I see a declaration that the person fits into one of 6 little boxes. This despite the fact these types describe multiple features, controlled by different genes, in a sexually reproducing population that represents all types. Now, not all genes are selected for independantly, genes nearby on the same chromosone can be correletated. But a model of which dietary traits correspond to which easily measurable traits should be more complicated than assigning a cluster of dietary traits to a cluster of easily measured traits.