An article entitled “Architectural Analysis and Intraoperative Measurements Demonstrate the Unique Design of the Multifidus Muscle for Lumbar Spine Stability,” in the current issue of the Journal of Bone and Joint Surgery, nicely refutes Dobzhansky’s pontifical pronouncement that “nothing in biology makes sense except in the light of evolution.”
The abstract is available online, though the full text article requires a subscription. This errant concept has been discussed previously on UD by DonaldM, but I thought it worth revisiting when I saw this example of the absolute lack of any usefulness of any concept of evolution in understanding at least this type of biological form and function.
The most striking thing about this article from a heuristic standpoint is that understanding the muscle under study depends completely on a design perspective, and owes nothing to any understanding of evolution. This is implicity acknowledged by the authors in the wording of their descriptions and conclusions:
“The architectural design … demonstrates that the multifidus muscle is uniquely designed as a stabilizer to produce large forces.”
From the discussion section:
“The large physiological cross-sectional area and relatively short fibers indicate that the multifidus muscle is architecturally designed to produce very large forces over a narrow range of lengths. This design allows the multifidus muscle to function more to stabilize the spine and less to provide motion of the spine.”
“The measurement of sacromere lengths in the present study permitted the discovery of a second important design feature of the multifidus muscle, specifically, that it is designed to operate on the ascending portion and plateau region of the sarcomere length-tension curve. The sarcomere length-tension curve is one of the classic structure-function relationships in all of biology.”(emphases added)
I am not quote mining here. The entire article implicitly supports and acknowledges the idea that the multifidus muscle is elegantly designed.
I do not mean to here suggest that the authors of this study meant it to support Intelligent Design. I do not know them and have no idea what their position is on ID. Quite likely their implied support for ID is unconscious.
However, there is no mention anywhere in the article of any sort of evolutionary story behind the “design” of this muscle, or of the classic relationship in all of biology of the sarcomere length-tension curve.
The investigators managed to come up with a hypothesis, conduct their study, and reach conclusions about this elegantly designed muscle without any consideration of or reference to evolution.
The multifidus muscle makes excellent sense purely from a design perspective, without bringing evolution into it at all. In fact, a design perspective is necessary to understanding the muscle’s architecture and function, specifically the elegant coordination of the fiber arrangements and locations of its bony insertions with the length-tension curve of the sarcomeres.
Any story-telling about the evolutionary origins of the multifidus muscle would be superfluous speculation adding nothing to our understanding of its form and function.
I think it would be fair to say that in this case at least, biology does not make sense except in the light of design.