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Ileum, caecum and colon of rabbit, showing Appendix vermiformis on fully functional caecum The human vermiform appendix on the vestigial caecum. The appendix was once believed to be a vestige of a redundant organ that in ancestral species had digestive functions, much as it still does in extant species in which intestinal flora hydrolyze cellulose and similar indigestible plant materials. [10]
In humans, the vermiform appendix is sometimes called a vestigial structure as it has lost much of its ancestral digestive function.. Vestigiality is the retention, during the process of evolution, of genetically determined structures or attributes that have lost some or all of the ancestral function in a given species. [1]
Plant fruit: the fleshy nutritious part of plants that animal dispense by eating independently came about in flowering plants and in some gymnosperms like: ginkgo and cycads. [239] Water transport systems, like vascular plant systems, with water conducting vessels, independently came about in horsetails, club mosses, ferns, and gymnosperms. [240]
Pharyngeal clefts resembling gill slits are transiently present during the embryonic stages of tetrapod development. The presence of pharyngeal arches and clefts in the neck of the developing human embryo famously led Ernst Haeckel to postulate that " ontogeny recapitulates phylogeny "; this hypothesis, while false, contains elements of truth ...
This phenomenon is an automatic-response mechanism that activates even before a human becomes consciously aware that a startling, unexpected or unknown sound has been "heard". [2] That this vestigial response occurs even before becoming consciously aware of a startling noise would explain why the function of ear-perking had evolved in animals.
Homeotic genes are genes which regulate the development of anatomical structures in various organisms such as echinoderms, [1] insects, mammals, and plants. Homeotic genes often encode transcription factor proteins, and these proteins affect development by regulating downstream gene networks involved in body patterning.
What makes a human body structure vestigial is that presently it is useless or almost useless, i.e. having no important function. Greensburger ( talk ) 16:49, 1 September 2011 (UTC) [ reply ] The references you listed do not backup your statements, they mention mainly the appendix, and a few other structures.
A diagram that summarizes all well-known paleopolyploidization events. Ancient genome duplications are widespread throughout eukaryotic lineages, particularly in plants. . Studies suggest that the common ancestor of Poaceae, the grass family which includes important crop species such as maize, rice, wheat, and sugar cane, shared a whole genome duplication about