First, the article specifically says they do not know how the seaweed was prepared, so I'm not sure where the "eating it raw" is coming from.
Second, we also still eat seaweed, as many other comments here point out (most of the comments are from the British Isles, so I'll add one that is also available in the Netherlands, where I'm from: salicorna, or "zeekraal"). I'd also like to note that I have never heard of any dish involving sea urchins. I'm sure they exist in the cuisine that you are familiar with, but I'm just mentioning this to point out that you do not speak for the culture of the entire European continent.
With that in mind, I find it rather odd to conclude that it is more likely that the measured seaweed molecules in teeth of ancient humans came from sea urchin stomachs than from seaweed directly. It does not pass Ockham's Razor.
> I'd also like to note that I have never heard of any dish involving sea urchins.
> I'm sure they exist in the cuisine that you are familiar with
You may have heard about a small place called the Mediterranean.
not a place really relevant for European culture if we except three or four empires that shaped the history of the humanity.
Every country touched by the Greeks or Roma knows how sea urchins taste. You could find them easily [1] in coastal areas of Greece, Spain, Morocco, Lybia, Egypt, France, Italy, Portugal, Cyprus... probably also Ireland. I bet that a lot of Asian and American countries have heard of it also by their own means. Japanese pay astronomical prices for them.
Second, we also still eat seaweed, as many other comments here point out (most of the comments are from the British Isles, so I'll add one that is also available in the Netherlands, where I'm from: salicorna, or "zeekraal"). I'd also like to note that I have never heard of any dish involving sea urchins. I'm sure they exist in the cuisine that you are familiar with, but I'm just mentioning this to point out that you do not speak for the culture of the entire European continent.
With that in mind, I find it rather odd to conclude that it is more likely that the measured seaweed molecules in teeth of ancient humans came from sea urchin stomachs than from seaweed directly. It does not pass Ockham's Razor.