No More Confusion: Three Categories of Biological Redundancy, Simplified
As I wrote here yesterday (“Intelligent Design Clarifies Biological Redundancy”), biological redundancy is defined as the existence of two very similar mechanisms in an organism such that if one is deleted, the organism experiences little to no effect on fitness under standard laboratory conditions.
I looked at how the neo-Darwinian perspective can generate confusing predictions about biological redundancy by predicting loads of “junk” or “waiting to evolve” DNA. Intelligent design clarifies the confusion by anticipating function for most genetic material 一 the result of a “good design” hypothesis. Today I will look at how ID further clarifies the categories of biological redundancy by refocusing on function.
Different Types of Biological Redundancy
Apart from the confusion as to whether biological redundancy is meaningful or important, another ambiguity is that there are subtly different types of biological redundancy. Martin Nowak in his 1997 paper, which I’ve already referenced, distinguishes three types of redundancy:
- True redundancy: Where an individual with a redundant genotype is not fitter than one in which one of the redundant genes has been knocked out.
- Generic redundancy: The redundant individual is only occasionally fitter than the nonredundant individual.
- Almost redundancy: The redundant genotype is always slightly fitter than any genotype where one of the redundant genes has been knocked out.
Unfortunately, Nowak’s wording describes the categories in terms of organismal fitness, leading readers to attribute the existence of redundant genes to survival of the fittest rather than the obvious function they afford. The purpose of these genes is thus obscured.
A New View of Biological Redundancy
A design theorist might rewrite these categories, and I’ve taken a stab at doing so below. Here the emphasis is removed from fitness and restored to function. Notice how much easier the categories are to understand.
- True redundancy: Backup devices to prevent failure when key system components fail.
- Generic redundancy: Anticipatory systems for rare conditions.
- Almost redundancy: Optimization machinery for organismal robustness.
Rewriting the categories of biological redundancy in terms of function clarifies their purpose and contribution. As indicated by the category descriptions above, genetic redundancy can prevent system failure when a key component fails, can anticipate rare conditions, and can allow an organism to function optimally under a variety of conditions. These descriptions more easily elucidate the purpose of redundancy, clarifying where you’d expect to find it in biology. In my next post I will give an example of each type and discuss how one can use design triangulation to anticipate redundancy from these categories.