Historical Constraints and the Evolution of Development 1049
similar orientation of each polygon along this axis. (In an interesting exception, a few
ancient samples (2000 to 3000 years old by radiocarbon) from Indian middens on
Curacao (see Gould, 1971a), shown in the small polygon marked I on Fig. 10-9,
include far larger shells with sample means well outside the range of modern
variation—as shown by their localized and maximized values on this second axis.)
The first and third axes express different aspects of the jigsaw constraint. By
these methods, we can isolate this interregional component (on truly independent,
mathematically orthogonal axes) from the substantial intraregional variation in size
that obscured the broader geographic pattern in the studies of Hummelinck and de
Vries. We can also assess the relative strengths of these two sources in compositing
the total amount of difference among sample means. Baker's interregional differences
explain about % of the total variation among sample means. And, with the exception
of Bonaire's distinction by a