No. 3662 PRIMATE BIOLOGY—NAPIER 9 
Ruch (1959) and Fiennes (1967) would reveal a great deal of informa- 
tion on the proved and potential usefulness of particular species for 
particular problems. A comprehensive account of the research poten- 
tial of the 197 species of primates is beyond the scope of the present 
article. 
Choice of a suitable primate for a specific project, therefore, must 
depend on hearsay, on the published reports of other workers, or, 
in the last instance, on trial and error. Finally, selection will be 
influenced by pragmatic considerations that relate to available space, 
available resources, and available primate species. There are no hard 
and fast principles by which suitable animals may be selected except 
that of phylogeny, which, at best, can act only as a general guide. 
The phylogenetic article of faith is simply stated: The experimental 
results that are most likely to be meaningful in a human context are 
those carried out on animals that have the closest genetic relationship 
(and, therefore, phylogenetic proximity) to man. 
The phylogeny of the primates is shown diagramatically in figure 1, 
wherein primate families and their component genera have been 
arranged in terms of their relative closeness to man. 
Prosim1ans.—The Prosimians comprise six families, which are 
arranged as follows: Tupaiidae, Lorisidae, Daubentoniidae, Indriidae, 
Lemuridae, and Tarsiidae (Napier and Napier, 1967). The use of 
prosimians as laboratory animals has been discussed recently by 
Manley (1967), Montagna (1967), and Hill (in press). 
Treeshrews (Tupaiidae) are not unequivocally primates. Opinions 
differ strongly at the present time as to whether they should be so 
regarded. The attitude taken by the author is that, whether technically 
they are primates or not, they are thought to be so close to the phyletic 
root of the order (at a time when all primates were insectivores, so to 
speak) that they should be retained in the Primates, if only as a 
permanent reminder of the generalized mammalian origins of the 
stock. Treeshrews have not been used widely as laboratory animals 
except in strictly physiological experiments, but with the new in- 
formation emerging on breeding behavior (Martin, 1966), they may 
well attract more attention. 
Among the Lorisidae, galagos are potentially the most useful. 
Their relatively short gestation period (Galago crassicaudatus: 130— 
135 days; G. senegalensis: 144-146 days) and the not uncommon occur- 
rence of twin births mark them as possibles. A number of primate 
centers and research laboratories are breeding these animals success- 
fully. The melanistic race, G. c. argentatus, is tougher and heavier 
than the brownish G. c. crassicaudatus and may prove to be more 
hardy in captivity; it is possible that it may be a good subject for an 
open-air colony situation. 
288-067—68——2 
