To take examples:—(1) the white lotus (Nymphæa lotus) is as decidedly characteristic of the decorative art of Ancient Egypt as the frigate-bird is of that of the Solomon Islands or of the Massim district of British New Guinea; but these are not peculiar to these districts, as both the lotus and the frigate-bird motives extend beyond the regions named.
(2) The employment of highly conventionalised and degenerate human figures to cover comparatively large areas is, so far as I am aware, peculiar to the Hervey Group,[205] as also is the device of nature-printed ferns on tapa in certain Polynesian islands.
(3) The absence of the frigate-bird as a decorative motive throughout the greater part of British New Guinea is as important a fact as its presence in a comparatively small district. The absence of scroll designs, and practically of sigmoid lines, in Torres Straits and Daudai and throughout the greater part of the Central District of British New Guinea, is as significant as their occurrence in the Massim district; or their general absence in Eastern Polynesia with their prevalence in New Zealand.
What is known as a zonal distribution in organisms only occurs in anthropology when a district is inhabited by different peoples that live concentrically to one another. Such, for example, as the Negritto populations which inhabit the centre of the Mollaccan Peninsula or the centre of some of the islands of the Malay Archipelago and are surrounded by Malay peoples; here we have a core, so to speak, of one type of decorative art surrounded by a different type.
Discontinuous distribution occurs in art as well as zoology, and the solution of each problem must be attempted from the scientific standpoint.
A good example of such a problem is to be found in the distribution of the fret and scroll patterns to which I have frequently alluded. Further study is necessary before we can say definitely whether a given fret or meander pattern has been independently evolved, or whether it has spread from elsewhere. In our study the problem is more complicated than in zoology, for a multiple origin of a given design or pattern is always possible and often probable, whereas this is not known to occur for a single species of animal. Discontinuity in distribution in ethnography may mean either that the form has a multiple origin or that it has migrated without establishing itself in the intermediate districts, or that it has disappeared from those districts.
It is evident that every pattern or set of patterns in the first instance has to be separately studied in a limited area, in order to determine whether it is of indigenous or foreign origin. No casual application of general principles will suffice, for it is possible that in certain cases a design may be apparently fairly uniformly distributed over a certain area, and on the face of it one might be tempted to regard this as a case of uniform distribution, whereas on a more minute examination it may be found that the designs are analogues and not homologues, that they have spread from different centres of origin, and thus the apparent uniformity of distribution may be essentially invalid. I suspect this is largely the case in the meander and scroll patterns.
We often find that a particular type of decoration occurs over a certain area, but within the limits of that district there are several distinct varieties. Students at home usually have a great difficulty in studying this problem owing to the very imperfect and unsatisfactory way in which objects are labelled by collectors. In my memoir on The Decorative Art of British New Guinea I have attempted to work out the local varieties both of form and decoration of the lime spatulas of the Massim district. According to the material at my disposal, it does seem that certain types are characteristic of, if not peculiar to, particular groups of islands. The more or less complete isolation of tribes or peoples, owing to geographical conditions or inter-tribal wars, is sufficient to account for local types and insular varieties, even when the people all belong to the one stock. If that stock is a mixed one, variations are much more likely to occur than if it is a pure race or a people that have become homogeneous by prolonged isolation.
Local types may, however, be due to the presence of a colony from another district. There are numerous examples of this in Melanesia, where colonies of Polynesians have arrived from more eastern island groups in Oceania, and as I have pointed out, there are Melanesian colonies in British New Guinea. To use a geological term, these are ethnological outliers.