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Darwin Correspondence Project

To T. H. Huxley   [before 18 May 1868]1

Marmosets— cause of loss of post. molar.2

Hylobates— males vocal organs most developed? Do not take much trouble— perhaps Blyth will know—3


The date is established by the relationship between this letter and the letter from Edward Blyth, 18 May 1868.
In Descent 1: 26, CD commented that posterior molar or wisdom teeth seemed to be becoming rudimentary in ‘the more civilised races’ of humans, possibly owing to a change in diet, and that these teeth were smaller than the other molars in humans, chimpanzees, and orang-utans. Marmosets belong to the family Callitrichidae, the members of which have one fewer molar on each side of both jaws than most other primates (Nowak 1999).
Edward Blyth had mentioned the ‘voice’ of gibbons (Hylobates) in his letter of [3 April 1868]. See letter from Edward Blyth, 18 May 1868 and n. 2.


Descent: The descent of man, and selection in relation to sex. By Charles Darwin. 2 vols. London: John Murray. 1871.

Nowak, Ronald M. 1999. Walker’s mammals of the world. 6th edition. 2 vols. Baltimore and London: The Johns Hopkins University Press.


Questions on marmosets and the vocal organs of Hylobates.

Letter details

Letter no.
Charles Robert Darwin
Thomas Henry Huxley
Sent from
Source of text
Imperial College of Science, Technology and Medicine Archives (Huxley 5: 373)
Physical description
Amem 1p

Please cite as

Darwin Correspondence Project, “Letter no. 6148,” accessed on 20 January 2021,

Also published in The Correspondence of Charles Darwin, vol. 16