Search results
Results from the WOW.Com Content Network
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]
Arrows show the vestigial structure called Darwin's tubercle. In the context of human evolution, vestigiality involves those traits occurring in humans that have lost all or most of their original function through evolution. Although structures called vestigial often appear functionless, they may retain lesser functions or develop minor new ones.
Atavisms have been observed in humans, such as with infants born with vestigial tails (called a "coccygeal process", "coccygeal projection", or "caudal appendage"). [8] Atavism can also be seen in humans who possess large teeth, like those of other primates. [ 9 ]
The DNA structure at left (schematic shown) will self-assemble into the structure visualized by atomic force microscopy at right. DNA nanotechnology is the field that seeks to design nanoscale structures using the molecular recognition properties of DNA molecules.
The existence of vestigial organs can be explained in terms of changes in the environment or modes of life of the species. Those organs are typically functional in the ancestral species but are now either semi-functional, nonfunctional, or re-purposed. Scientific literature concerning vestigial structures abounds.
Structural inheritance was discovered by Tracy Sonneborn, and other researchers, during his study on protozoa in the late 1930s. Sonneborn demonstrated during his research on Paramecium that the structure of the cortex was not dependent on genes, or the liquid cytoplasm, but in the cortical structure of the surface of the ciliates.
As of 2007, only two monophyletic groups of organisms are known to contain plastids with a vestigial nucleus or nucleomorph: the cryptomonads [3] of the supergroup Cryptista and the chlorarachniophytes [4] of the supergroup Rhizaria, both of which have examples of sequenced nucleomorph genomes.
For example, in an aligned DNA sequence matrix, all of the A, G, C, T or implied gaps at a given nucleotide site are homologous in this way. Character state identity is the hypothesis that the particular condition in two or more taxa is "the same" as far as our character coding scheme is concerned.