The Plantaris and the Question of Vestigial Muscles in Man

Evolutionists continue to propose a few of our smaller and least understood muscles as being vestiges of once useful organs left over from putative evolutionary ancestors. For example, the plantaris muscle in the calf of the leg is still widely regarded to be vestigial by reason of its slender diameter and seemingly minor contribution to the two more massive muscles with which it is associated. The plantaris joins with the much larger soleus and gastrocnemius muscles to form the triceps surae, which plantarflexes the foot through the Achilles tendon. Growing evidence reveals however, that each of the three muscles of the triceps surae has special properties that contribute to the overall function of this important muscle group. The remarkably short and slender plantaris muscle with its long slender tendon serves a proprioceptive function that provides a kinesthetic sense of limb position and muscle contraction.

Problems with vestigial organs

plantaris and gastrocnemius

Figure 1. Changes in relative length between the parallel-working combination of a muscle with a short belly and a long tendon (plantaris) and a muscle with a long belly and a short tendon (gastrocnemius). The relative difference in lengthening of the plantaris is 40% compared with only 15% for the gastrocnemius (after Peck et al.).3

The presumed existence of vestigial organs is often cited as visible evidence for macroevolution. Vestigial organs have been used as particularly attractive examples of evolution in science textbooks and the popular press because they are so easily understood. If the human body can be shown to have truly useless organs that are a known vestige of once useful organs in a non-human ancestor, this would be evidence for non-human ancestry.

The problem with declaring any organ to be without function is our inability to distinguish between an organ that truly has no function, and one for which a real function is simply unknown. The human ego (and even scientists have one) often finds it more satisfying to conclude that an organ has no use than to admit that we simply do not know its use. Even worse, an organ deemed to be without use is unlikely to be a subject of further biomedical research. Fortunately, many scientists have ignored the claims of evolutionists regarding vestigial organs, and thus the advance of empirical science has revealed at least one known function for nearly every type of organ, tissue, and cell of the body. Of the nearly 200 vestigial organs once claimed to exist in the human body, only a few continue to be seriously discussed as vestigial….

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