[4] Darwin, The Descent of Man, 1877, p. 207.

[5] Ibid., p. 208.

[6] The Descent of Man, 1877, pp. 209-211.

[7] The Descent of Man, 1877, p. 220.

[8] The Descent of Man, 1877, p. 496.

[9] Ibid., p. 367.

[10] The Descent of Man, 1877, p. 443.

[11] Ibid., p. 416.

[12] The Descent of Man, 1877, p. 212.

[13] Ibid., p. 523.