XXVII.2.4 The evidence for opportunism in biological evolution, i.e. the occurrence of suboptimal or clearly flawed designs of some organs, also demonstrates the existence of biological evolution itself

I already stated previously (I.12) that evolution cannot plan ahead and always create structures that are suitable for an organism at a particular moment.The functional approaches that evolution “selected” at a certain moment can prove to be disadvantageous after some time when the particular organ completely develops in evolution.Consequently, organisms have a great many organs that are obviously suboptimal or even completely senseless in their design from the viewpoint of their present-day function.We have already mentioned the example of the eye in vertebrates with nerve fibers located in front of the retina in the optical pathway of beams and innervation of the pharynx in giraffes with a senseless many-meter-long loop reaching as far as the aorta.The frequent occurrence of these senseless structures indicates that the organisms were certainly not created according to a pre-established plan, but developed by the “blind” opportunist process of biological evolution.

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The classical Darwinian theory of evolution can explain the evolution of adaptive traits only in asexual organisms. The frozen plasticity theory is much more general: It can also explain the origin and evolution of adaptive traits in both asexual and sexual organisms Read more
Draft translation from: Evoluční biologie, 2. vydání (Evolutionary biology, 2nd edition), J. Flegr, Academia Prague 2009. The translation was not done by biologist, therefore any suggestion concerning proper scientific terminology and language usage are highly welcomed. You can send your comments to flegratcesnet [dot] cz. Thank you.