The twins are essential to understanding the influence of heredity and environment in development. A study in mice has shown how the experience changes the brain. The animals, genetically identical, are born equal but soon become differentiated. It is the emergence of individuality.
Francis Galton coined the terms "nature and nurture" to explain the effects of heredity and environment . Since then the debate continues as fruitful.
For each trait of a living being, to what extent does the environment and to what extent genes influence? In the end things are clear: how good food we have, one can measure four meters. Likewise, if someone never hears about, not learn the language . We need a genetic endowment and environment in which develop.
Galton was also a pioneer in twin studies. If we can control one of the variables, we study the influence of the other. Two twins have identical genetic endowment. We can therefore attribute the differences between them to environmental factors.
Human twins are a fantastic source of information. Twins But other animals. Specifically, what are the strains of mice. If you have a strain of mice identical, we can rule out the effects of genetics. The strains of genetically identical mice have become an essential tool in the investigation. How do you get?
The way to achieve a strain of genetically identical mice is crossing them with sister brother for generations. Over 20 generations of sib mating is achieved strain in which practically all genes are equal. When reaching the 150 crosses generations, are considered 100% homozygous. The mice were mated in real factories. , Over 450 strains of mice and 230 rats.
The first part of the development of a living being is independent of the activity. That is, the genes are expressed automatically. Reached a certain maturity, in the case of mammals even without being born, development is mediated by genes but also for the activity. That is, early on, the atmosphere begins to influence.
In this study , scientists placed a group of genetically identical mice in a cage with all sorts of attractions. The mice moved freely and could play with multiple toys. The mice had a radio frequency RFID tag so that all their movements were recorded.
Even in identical twins reared together, there is always observable differences that reflect the influence of individual responses. These differences are manifested in brain neuron development.
40 identical mice reared together showed behaviors that were diverging over time. Some more than others explored. There is an area of the brain called the hippocampus where new neurons in adult form, called neurogenesis. The results showed that mice had greater more active neurogenesis.
Although a common environment and identical genes, mice showed highly individualized behavior patterns, reacting to its environment differently.
These differences were associated with differences in the generation of new neurons in the hippocampus, a brain region that supports learning and memory.
The results suggest that the experience influences aging of the human mind, that an enriched environment promotes the development of individuality
These results are consistent with those of the famous study of taxi drivers in London have to know all the streets of his city, taxi drivers have a larger hippocampus than usual.
Maybe someday we finish solving the equation heritage-friendly. The use of twins is an essential tool.