cultFST: cultFST

In alastair-JL/AnthroTools: Some custom tools for anthropology

cultFST

Description

Cultural FST is a proportion of between-group cultural variance to the total cultural variance in a particular trait. AnthroTools uses the formula: CFST = [ni/(ni + nj)(pi - phat)^2 + nj/(ni + nj)(pj - phat)^2]/[phat(1 - phat)] where ni and nj are the frequency of individuals in groups i and j, respectively, pi is the proportion of i who exhibit a trait, and pj is the propotion of j that exhibits the trait, and phat is the cross-group sharedness (i.e., (xi + xj)/(ni + nj).

Usage

  cultFST(ni, nj, xi, xj)

Arguments

ni	Number of individuals in group i
nj	Number of individuals in group j
xi	Frequency of target trait in group i
xj	Frequency of target train in group j

Value

This function returns the Cultural FST value for two groups. If all of the variance lies between the groups, FST = 1. If all of the variance exists within groups, FST = 0.

Note

This function is only to be applied to two groups. Use the fstmatrix() function for multiple groups.

References

Bell, A. V., Richerson, P. J., & McElreath, R. (2009). Culture rather than genes provides greater scope for the evolution of large-scale human prosociality. Proceedings of the National Academy of Sciences, 106(42), 17671-17674.

Handley, C., & Mathew, S. (2020). Human large-scale cooperation as a product of competition between cultural groups. Nature communications, 11(1), 702.

Wright, S. (1965). The interpretation of population structure by F-statistics with special regard to systems of mating. Evolution, 395-420.

Examples

  # Miscellaneous examples
  cultFST(100, 100, 100, 0) # n = 100 for both groups, i exhibits 100, j exhibits 0
  cultFST(100, 100, 50, 50) # n = 100 for both groups, i exhibits 50, j exhibits 50
  cultFST(100, 100, 0, 100) # n = 100 for both groups, i exhibits 0, j exhibits 100
  cultFST(100, 100, 46, 2) # n = 100 for both groups, i exhibits 46, j exhibits 2
  
  # Plot values of CF_ST across levels of xj and xi.
  par(mar = c(4, 4, 1, 1), mfrow = c(1, 1))
  plot(NA, xlim = c(0, 100), ylim = c(0, 1),
       xlab = expression(italic('x'['j'])), ylab = expression(italic('CF'['ST'])))
  lines(cultFST(100, 100, 0, 1:100), lty = 1, lwd = 1.5)
  lines(cultFST(100, 100, 25, 1:100), lty = 2, lwd = 1.5)
  lines(cultFST(100, 100, 50, 1:100), lty = 3, lwd = 1.5)
  lines(cultFST(100, 100, 75, 1:100), lty = 4, lwd = 1.5)
  lines(cultFST(100, 100, 100, 1:100), lty = 5, lwd = 1.5)
  legend(37, 1, c("0", "25", "50", "75", "100"), title = expression(italic('x'['i'])*' ='), 
         lty = 1:5, cex = .9)

alastair-JL/AnthroTools documentation built on Feb. 4, 2025, 8:44 p.m.