|
What is Hazel Stage?
In searching for a creative name for this business, I began by listing words on a piece of paper. Columns and columns of words I liked, words that described me, etc.
"Hazel" and "Stage" ended up next to each other on the page. I liked the way they sounded together. "Hazel" - for my eyes, "Stage" - for my passion for the theater.
Just out of curiousity, I googled the phrase. I found it used in a wikipedia submission as an example of computational phylogenetics. I don't really know what that is... but I liked the idea of requiring eyes to evolve through a "hazel stage" to get from brown to green.
Below is exactly what I found in Wikipedia: |
| Maximum parsimony, often simply referred to as "parsimony," is a non-parametric statistical method commonly used in computational phylogenetics for estimating phylogenies. Under maximum parsimony, the preferred phylogenetic tree is the tree that requires the least number of evolutionary changes. |
|
|
| Each character is divided into discrete character states, into which the variations observed are classified. Character states are often formulated as descriptors, describing the condition of the character substrate. For example, the character "eye color" might have the states "blue" and "brown." Characters can have two or more states (they can have only one, but these characters lend nothing to a maximum parsimony analysis, and are often excluded). |
|
|
| Coding characters for phylogenetic analysis is not an exact science, and there are numerous complicating issues. Typically, taxa are scored with the same state if they are more similar to one another in that particular attribute than each is to taxa scored with a different state. This is not straightforward when character states are not clearly delineated or when they fail to capture all of the possible variation in a character. How would one score the previously mentioned character for an individual with hazel eyes? Or green? As noted above, character coding is generally based on similarity: Hazel and green eyes might be lumped with blue because they are more similar to that color (being light), and the character could be then recoded as "eye color: light; dark." Alternately, there can be multi-state characters, such as "eye color: brown; hazel, blue; green." |
|
|
Characters can be treated as unordered or ordered. For a binary (two-state) character, this makes little difference. For a multi-state character, unordered characters can be thought of as having an equal "cost" (in terms of number of "evolutionary events") to change from any one state to any other; complementarily, they do not require passing through intermediate states. Ordered characters have a particular sequence in which the states must occur through evolution, such that going between some states requires passing through an intermediate. This can be thought of complementarily as having different costs to pass between different pairs of states. In the eye-color example above, it is possible to leave it unordered, which imposes the same evolutionary "cost" to go from brown-blue, green-blue, green-hazel, etc. Alternately, it could be ordered brown-hazel-green-blue; this would normally imply that it would cost two evolutionary events to go from brown-green, three from brown-blue, but only one from brown-hazel.
This can also be thought of as requiring eyes to evolve through a "hazel stage" to get from brown to green and a "green stage" to get from hazel to blue, etc. |
|
|
| |
