Cartilaginous skeleton not necessarily more “primitive”
|December 24, 2016||Posted by News under Design inference, Evolution, News, Tree of life|
A friend writes to tell us of an insightful article in Nature:
It emerges that a dogfish shark’s spine becomes stiffer as the fish swims faster, enabling the animal to swim efficiently at different speeds. The finding could also provide inspiration for the design of robotic biomaterials. (paywall) – Biomaterials: Sharks shift their spine into high gear
Matthew A. Kolmann & Adam P. Summers, Nature, 14 December 2016 | doi:10.1038/nature21102, More.
The friend believes that the shark’s cartilaginous skeleton should not be thought of, as it often is, as primitive, but as an intelligent use of materials that enable high-speed bursts of movement. As the author put it, the skeleton is “an aquatic equivalent of continuously variable transmission, a type of gear-change system found in some motor scooters that is continuously responsive to a wide range of speeds.”
And the cartilage? “It is a type of in-between substance, neither an elastic solid such as rubber or metal, nor a stirrable fluid such as coffee. Instead, cartilage belongs to the category of viscoelastic materials – materials that resist deformation differently when they change length at different rates.”
The authors naturally hope to apply their newfound knowledge to biomaterials. In the meantime, one wonders how many opportunities have been lost to an artificial “tree of life” way of thinking about nature in which, in the hierarchy of the old-fashioned tree of life, bone was just plain better, “more evolved,” somehow.
Is “primitive” one of those phrases, like living fossil, that implies a scenario that, once accepted, need not actually be demonstrated?
Some use the term durable species for living fossils; less colorful but more accurate.
What would a better term than “primitive” be?
See also: Human hand more primitive than chimps’?
Sneezing sponges – existence challenges assumptions about ‘primitive’ organism
Sharks not primitive? Well, if they aren’t, what is?
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