When I read this segment, I was compelled to comment:

A key component of the debate between Robin Hanson and myself was the question of locality. Consider: If there are increasing returns on knowledge given constant human brains—this being the main assumption that many non-intelligence-explosion, general technological-hypergrowth models rely on, with said assumption seemingly well-supported by exponential technology-driven productivity growth—then why isn’t the leading human nation vastly ahead of the runner-up economy? Shouldn’t the economy with the most knowledge be rising further and further ahead of its next-leading competitor, as its increasing returns compound?
The obvious answer is that knowledge is not contained within the borders of one country; improvements within one country soon make their way across borders. China is experiencing greater growth per annum than Australia, on the order of 8% versus 3% RGDP growth.92 This is not because technology development in general has diminishing marginal returns. It is because China is experiencing very fast knowledge-driven growth as it catches up to already-produced knowledge that it can cheaply import.

There actually are historical examples of this happening between civilizations that had relatively little information transfer between them. Pre-Columbian America was far behind Europe, as was sub-Saharan Africa. China's economic and technological development has also been relatively isolated from Europe until relatively recently; there were times where it was more advanced and times where it was less advanced.