Neoteny is usually first learned in biology classes by studying the Amphibian class. Neotenia is a developmental delay in a number of species in which the possibility of sexual reproduction occurs before adulthood. Neotenia is usually seen in a living example of amphibians, worms, or arthropods. But a number of anthropologists argue that man is also a product of neoteny.
The most famous example of neoteny
If in ontogenesis (this is a process of individual development), an organism lives in two environments (for example, in water and on land), then neoteny can contribute to the survival of the species. After metamorphosis (transformation into an adult animal), larvae living in water go to land, as is seen in amphibians (amphibians). If there is not enough food on land, adults can die. But aquatic larvae are sometimes able to proceed to sexual reproduction, bypassing the stage of metamorphosis. This helps to keep the look.
Axolotl is an example of neoteny cited in all textbooks. This is a larva of an ambist, a family from the order of caudate amphibians. They live on the North American continent in nature and around the world in the aquariums of pet lovers.
Most species of ambistos do not pass the stage of transformation into an adult animal. In this case, the external gills, so similar to curls, disappear; lungs appear, eyelids appear on the eyes. Axolotl, whose photo is always tender, can turn into an adult, already less attractive individual. This requires a hormonal vaccine, which will launch the stage of metamorphosis.
Neotenia is the engine of evolution
There is a neotenic hypothesis of the origin of the Subcranial subtype. This subtype includes the lancelet, with which the study of chordates begins in school. There is a second subtype of chordates - shells. Their larvae, unlike adult shells, are very similar to a lancelet. It is possible that, as a result of neoteny, the larvae of the tunicans switched to reproduction, giving rise to a new subtype of cranial.
There is an opinion suggested by de Beer that neoteny is the reason for the appearance of insects - the largest group of animals. The insects owe their origin to the larvae of millipedes.
Botanists also tend to suggest neotenic progress in the plant kingdom. For example, the transition from tree forms to grassy. Longline neoteny is the process of the appearance of annual herbs when juvenile, lower tiers that do not grow to tree-like, “adult” forms begin to multiply. L. A. Takhtadzhyan spoke of “breaking off” ontogenesis, that is, the preservation of juvenile (youthful) traits in adult organisms. This process was the evolutionary basis for the emergence and development of angiosperms.
Where are we from
Many researchers - V. M. Artsikhovsky, E. Mayr, A. D. Takhtadzhyan - note that the main thing in the process of neoteny is not that the larvae begin to multiply, but that the adult stages retain the juvenile form. In the 70s of the XX century B. Campbell proposed his version of the emergence of man - a delay in the development of a number of characters in monkeys led to the preservation of their children's traits in a new branch of primates, the ancestors of humans.
A man really resembles a baby chimpanzee more than an adult animal:
- features of the shape of the skull (weakly pronounced arches of the eyebrows, etc.);
- hair structure and their accelerated growth on the head;
- relative sizes of teeth and jaws;
- disproportionately enlarged cerebral hemispheres immediately after birth.
The importance is attached to the ethological (behavioral) characteristics of young and adult animals. It is assumed that the curiosity and playfulness of the cubs is genetically entrenched in a new evolutionary branch. The hominids (a family of progressive primates) felt great sympathy for partners who possessed childhood traits in their behavior.
A. Markov in a book on human evolution suggested that selection for friendliness (a childhood trait) could lead to juvenile thinking and a number of morphological (external) features. This reduced aggression within groups of hominids and contributed to their progressive development.
Total
Neoteny and its significance for evolution continues to be the subject of study. New ideas about the origin of the world, and in particular plants, animals and humans, appear even today. Classical examples with axolotl (photo in the article) are supplemented by amazing hypotheses about the appearance of our ancestors.