ween ARCHEOLOGY IN BRITISH GUIANA 185 
Use of these data for determining the time at which contact between 
the two Phases occurred involves several assumptions. Of primary 
importance is the question of whether the relative frequency of trade 
sherds can be considered representative of the relative frequency of 
pottery types manufactured by the donor culture at the time the trade 
took place. In our own culture and in archeological cultures where 
evidence of trade is most familiar, such an assumption would not be 
valid because occupational specialization and systems of marketing, 
with associated attitudes of commercial competition between sellers 
and of securing the best product at the lowest price among buyers, 
provoke various kinds of selection on the part of both the makers and 
the customers. Ethnographic data on the Tropical Forest cultures 
suggest, however, that on a lower level of cultural development selec- 
tion is of quite a different kind, if it occurs at all. Reports on British 
Guiana emphasize tribal specialization in which certain tribes are 
reputed to excel in the manufacture of certain kinds of objects, such 
as pottery, graters, or bows (Im Thurn, 1883, pp. 271-2; Farabee, 
1924, pp. 21, 52, 57). Selection is on a tribal basis and range of 
choice is limited to what the members of the tribe have to offer. 
There is nothing to suggest that the donor tribe makes any modifica- 
tion in the objects to be traded that would differentiate them in quality 
or style from those for home consumption. Since all evidence indi- 
cates that the Abary Phase is a culture of the Tropical Forest level 
of development, we have made the assumption that the relative fre- 
quency of the trade sherds reflects those proportions existing in the 
Mabaruma Phase at the time of contact, and that a correlation between 
the two cultures can be made on the basis of the pottery type repre- 
sented and their relative frequency.® 
For the purpose of establishing such a correlation, only the trade 
sherds can be used. The existence of locally made imitations is im- 
portant in assessing the strength of the influence exerted by the 
Mabaruma Phase ceramics on Abary Phase potters, but the relative 
frequency of the types copied is more likely to reflect Abary Phase 
cultural preferences or the technical and artistic limitations of the 
Abary Phase potters, than are the trade sherds. Any individual pref- 
erence that may have influenced the selection of pottery vessels re- 
ceived by trade can be minimized by using the total trade sherds of 
each type rather than the level to level occurrence in the comparison. 
These totals show Aruka Incised to be the dominant decorated. type, 
with Kaituma Incised and Punctate second, Akawabi Incised and 
6 The validity of this assumption can be tested in the case of the Koriabo Phase, whose 
correlation with the Mabaruma Phase sequence can be checked by the presence of trade 
sherds in Mabaruma Phase sites. In this case, the sherds of Mabaruma Phase origin 
traded to the Koriabo Phase reflect reasonably well what was being made at that time 
(cf. fig. 56 with fig. 31; pl. 20 with pls. 16, 17, 19; pl. 23 with pls. 21, 22, 26). 
