Page 90 - J. C. Turner - History and Science of Knots

The Peruvian Quipu 79

of both kinds were found on ancient specimens. Those of the first kind were
found only in the North of the country; those of the second kind only in the
South. Hence it was probably a matter of tradition which method was used,
and every quipu keeper used only one of them.
There was no special sign to indicate an 'empty' digit, like our 0 in 101
for example. The positions were carefully aligned from cord to cord, so that
a space without knots could be associated unambiguously with its position.
There remains ambiguity in the cases of small quipus where a position is empty
on every pendant cord. In these cases, which probably occurred rather seldom,
the length of the spaces might have been considered. Fig. 6 shows a schematic
example.
The Number Zero
Although there was no special sign for zero, we can assume that the Incas
had the concept of nothingness in their number system. They represented
zero by a cord without knots. We can conclude this because the colour code
allowed meaningless cords to be omitted, as the following example illustrates.
Imagine a quipu designed for recording the number of sandals owned by the
people of a village. Each pendant group represents a family, with the number
of the men's sandals on the first cord, the women's on the second and the
children's on the third. The second categorization can be reinforced by using
colours, for example green cords for men, yellow cords for women and red
cords for children. If a family does not have any children, the red cord can be
omitted without ambiguity. A red cord without knots would mean that there
are children in the family, but they do not own any sandals.
As cords without knots, and also repeated colour patterns with single
cords omitted, occur frequently on ancient quipus, we have to assume that it
was on purpose; and this is the most likely explanation. We also know that
another ancient American culture, the Mayas, had the number zero, and it is
possible that the Incas took it over from them.

The Contents
This section deals with the types of information that Incas stored on their
quipus. These include statistical data and astronomical observations; possibly
non-numerical data were also recorded, using number codes.
Statistics
The chroniclers describe the use of quipus for recording statistical numbers.
There was a regular census, as we know from Garcilasso. Every year the
population figures were recorded, divided into provinces, villages, sex, age in
decade intervals, and groups of unmarried, married, and widowers. There were
also regular statistical reports on resources like agricultural produce, herds of