Vestigiality

As a rudiment (Latin rudimentum " beginning," " first attempt ", " sample " ) is referred to in biology in the phylogeny ( phylogeny ) partially or entirely functionless become characteristic ( organ, organ part, organ structure or behavior). Rudiments appear in contrast to atavism, which only occur in some individuals, at many or all individuals of a species. Rudiments can generally occur in all organisms and are considered classic evolutionary evidence. The regression process is the Rudimentation. She went from a functional stage of the feature. Some Rudimentationen are also associated with a change in function, such as the example appendix / appendix is described.

Rudimentary organs in humans and animals

The back formed organs lose the course of evolution of living things in relation to the lifestyle change its original features, but they can still have tasks (for example, lymphatic function in the human vermiform appendix ). Usually the rudiments prepare more grief than good. In humans, these are the wisdom teeth (now deformity, inflammation ), appendix (today: " appendicitis " ), ear muscles, ear bump, parceled abdominal muscles.

An example of only a partial loss of function of the pineal gland in mammals and in humans. In earlier stages of development it was significant as a light- sensitive Parietalorgan ( "third eye "). Directly through the skin, as now in some amphibians, birds and reptiles Today, it is important in mammals for the melatonin secretion and the day - night cycle.

Rudiments in humans

  • Stunted wisdom teeth ( breakthrough until after the age of 17 ). Origin: All original placental mammals possessed in each half of the jaw three incisors, one canine, four front molars and three molars. Their dental formula is therefore 3 x 1 x 4 x 3, their number of teeth was 44
  • In comparison with the cutting edge and back teeth of relatively large and acute canine. Origin: ingestion of raw meat and a social signal in the context of agonistic behavior and display behavior.
  • Rest of the nictitating membrane. Origin: serving as a third eyelid in related mammals.
  • Appendicitis with appendix. Origin: Rest of a previously larger intestine appendix for the digestion of indigestible food. Here there is a change of function, since lymphoid tissue was found in the cecum, so that the appendix is today counted among the lymphoid organs. So he is now a part of the immune system.
  • Coccyx: rudiment of a tail spine.
  • Functionless muscles of the ear cups. Origin: served for the movement and orientation of the ears.
  • Segmented, parceled abdominal muscles. Origin: segmentation of the body.
  • Body in humans. Origin: fur.

Rudiments in animals

  • Tiny remnants of the pelvic girdle in whales, Origin of landlebigen ancestors
  • Remains of the upper and lower leg when bowhead
  • Remnants of hind limbs with giant snakes
  • Shades of eye regression in cave animals
  • Housing remains in slugs
  • Eyes in the mole
  • Shoulder and pelvic girdle remains at blindworms
  • Stub -shaped wing radicals in the Kiwi
  • Nails on the fins at sea lion and walrus
  • Splint bones in the horse are rudimentary metacarpal or metatarsal bone

Rudiments of plants

An example here is the Rudimentation the stamens at the Rachenblütlern ( Scrophulariacea ). In this takes within a progression series, the number of stamens from the original five in Verbascum about four in digitalis Two at Veronica officinalis from, but the non-functioning systems of the remaining stamens are still trained.

Rudimentary behavior

Many of the reflexes of human infants represent rudimentary behavior that was once essential for survival in the phylogenetic development. This applies for example to the grasp reflex. In monkeys, babies, it allows the clawing of the newborn in the fur of his mother, while this works its way from branch to branch or moves on all fours on the floor. In human baby's grasp reflex for adherence to the largely hairless body of his mother is useless, which also travels not to four but on two legs and the infant without this contributes in the arm. The human grasp reflex is already formed after the 32nd week of pregnancy, its function appears even more devious in the womb. The time of occurrence of the reflex, however, corresponds to the human gestation period of related species (for example, bonobos 220-250 days ), that is, he is to this day formed at that time of development, from which it was essential for survival in the ancestors.

Phylogenetics Organ (anatomy) Segmentation (biology) Accessory bone Ulrich Kutschera
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