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Equation 3 · Part 6 · Humanity Has Always Been a Human–Technology System

Symbol M_ji

x˙i=xi(fi−fˉ)+∑jMjixj−∑jMijxi,\dot{x}_i = x_i(f_i-\bar f) + \sum_j M_{ji}x_j - \sum_j M_{ij}x_i,
MjiM_{ji}

What this part means

MjM_ji is one of the signed contributions combined to compute the quantity on the left.

Its job in the formula

MjM_ji is one of the signed contributions combined to compute the quantity on the left.

The passage around this formula

A minimal cultural-selection model can represent the frequency xix_i of a variant i as x˙i=xi(fi−fˉ)+∑jMjixj−∑jMijxi\dot{x}_i = x_i(f_i-\bar f) + \sum_j M_{ji}x_j - \sum_j M_{ij}x_i. where fif_i is context-dependent cultural fitness and MijM_{ij} represents transformation or transmission from variant i to j . The equation is illustrative, not a claim that beliefs have fixed genes or that cultural change is reducible to one replicator law. Unlike alleles, cultural variants can be intentionally modified, horizontally transmitted, blended, externally stored, and adopted because of prestige, conformity, coercion, or institutional mandate.

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Learn the underlying idea

A subscript is a label attached below a symbol. It often selects a time step, component, category, or member of a sequence.

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Sources cited in the article section

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