Geometry Lines and Genealogy
In genealogy, we speak of lines as our descent from a particular ancestor. The father of geometry, Euclid, first defined a line as “breadthless length.” [1] In Euclidean geometry, a line has no dimension: no breadth, and no defined length. I could argue that genealogical lines, or lineages, have breadth: our siblings and cousins. But, generally, when genealogists research a lineage, it is a direct line of descent connecting children to parents, going as far into the past as records permit. But what about the genealogical brick wall? Or a descendant that has no children? Does that mean genealogical lines are not lines but segments or rays?
Segments and Rays
While geometry defines a line as infinite, segments are lines with defined endpoints. Consider a lineage that begins with you and ends with a, so-called, genealogy brick wall. This is an ancestor whose parentage cannot be determined. I have previously argued that genealogy is like long line topology. [2] There is always another generation, even if that generation is not found in the records, they exist. So, brick wall ancestors are only an end point on paper. In fact, their lineage continues into the past, we just cannot document it. While this example seems to have one defined endpoint, you, in fact your descendants continue the lineage into the infinity of the future.
Let’s consider the ray, it is defined in geometry as semi-infinite. It has a finite point from which it originates and then goes into the infinite. Could this be the case of a childless person? Their personal lineages go in just one direction, the infinite past. Hmm… Technically, that sounds right. I have no children myself, so rather than referencing my lineage, should I call it my rayage? Probably not, but it’s a fun idea for a mathematical analogy to genealogy.
SOURCES:
1. Webpage, Wikipedia, Line (geometry); https://en.wikipedia.org/wiki/Line_(geometry)
2. Blog post, Family Finds, Long Line; https://barblafara.com/long-line/
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