Stanford Encyclopedia of Philosophy
Field of reference: Biology
"Epigenetics in the broad sense refers to two kinds of inheritance. (1) Cellular epigenetic inheritance through mitotic cells and transgenerational epigenetic inheritance through meiotic cells. Transgenerational heredity of DNA methylation has been observed in unicellular organisms, plants, and mammals, suggesting that transgenerational epigenetic inheritance may be more prevalent than often suspected (Jablonka & Raz 2009). (2) Hereditary effects that by-pass the germline, for example through early developmental inputs that lead to regeneration of previous developmental conditions (e.g., hormonal and neural conditions) and other forms of phenotypic transmission, such as the transmission of symbionts and parasites, e.g., gut bacteria (Jablonka & Raz 2009)."
| שייך לנושאים: 1-13 - חינוך אינטגרלי, -מקורות מדעיים, השפעת הסביבה, 3. השפעת הסביבה = חוק |
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Oxford Journals
Field of reference: Biology
Description: The appearance of a particular organ is the product of the genotype and the epigenotype, reacting with the external environment’.
"Historically, the term ‘epigenetics’ is attributed to Conrad Waddington (1905–75) who in the late 1930s remarked ‘It is, surely, obvious that the fertilized egg contains constituents which have definite properties which allow only a certain limited number of reactions to occur; in so far as this is true, one may say that development proceeds on a basis of the “preformed” qualities of the fertilized egg. But equally it is clear that the interaction of these constituents gives rise to new types of tissue and organ which were not present originally, and in so far development must be considered as “epigenetic” ’ [1]. He further remarked that ‘One might say that the set of organizers and organizing relations to which a certain piece of tissue will be subject during development make up its “epigenetic constitution” or “epigenotype”; then the appearance of a particular organ is the product of the genotype and the epigenotype, reacting with the external environment’."
| שייך לנושאים: 1-13 - חינוך אינטגרלי, -מקורות מדעיים, השפעת הסביבה, 3. השפעת הסביבה = חוק |
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Dr. Peter J. D'Adamo
Field of reference: Biology
Description: Conrad Waddington an embryologist used a metaphor called an "epigenetic landscape" describing the development of an individual organism, or part of, such as an organ. cell. or tissue and the effects of development according to its reactions with the external environment.
"Epigenetics is the study of reversible heritable changes in gene function that occur without a change in the sequence of nuclear DNA. It is also the study of the processes involved in the unfolding development of an organism. In both cases, the object of study includes how gene regulatory information that is not expressed in DNA sequences is transmitted from one generation to the next – that is “in addition to” the genetic information encoded in the DNA. In its simplest manifestation, epigenetics is defined as any genetic mechanism that results in phenotypic variation without altering the base-pair nucleotide sequence of the genes. (3)Waddington used an important visual metaphor to describe the development of an individual organism –or part of an organism, such as an organ, tissue or even a specific cell. He likened it to a ball rolling down an undulating, dissected landscape predetermined by the genetic architecture that lay underneath. This he called an epigenetic landscape. This epigenetic landscape is a metaphor for how gene regulation modulates development. One is asked to imagine a number of marbles rolling down a hill towards a wall. The marbles will compete for the grooves on the slope, and come to rest at the lowest points. These points represent the eventual cell fates, that is, tissue types. A key theme in this work is that the final form of an organism does not develop entirely and exclusively from a blueprint specified in the genetic program, but rather is a result of the way the genes interact with the environment throughout the developmental process. (4-5)Waddington suggested that these concurrent interacting influences of genotype and environment could best be conceptualized as an epigenetic landscape, a domain of multiple hills and valleys; and that the growth and development of the organism could be likened to a marble making its way downhill. “Well-worn” or “beaten” paths pathways along which the course of development of an organism normally unfolds were termed chreodes. In the epigenetic landscape, chreodes are the developmental trajectories in the landscape and the epigenetic landscape itself represents the probability distribution of the developmental outcomes. In essence, the balls are much more likely to wind up at the base of a deeper valley, than stuck on some shelf or side valley. As the ball rolls down the landscape, it can be buffered by external or internal influences and perturbations; but it tends to return to the base valley, the chreode. (6,7) The resistance of phenotypic variations to environmental or genetic influences is calledcanalization. Another way of thinking about it: Canalization is a measure of the ability of a population to produce the same phenotype regardless of variability of its environment or genotype. In Waddington’s epigenetic landscape a canalized trait would be a valley enclosed by high ridges, safely guiding the phenotype to its “fate.” This phenotypic buffering of the developmental systems can produce a “wild-type” phenotype (or what might more accurately be called a phenotypic mean) in the face of various mutations or environmental insults.In many ways, canalization is the opposite of phenotype plasticity, since it works to insure that phenotypic variation is limited to the degrees that the same phenotype is produced regardless of genotypic or environmental changes. Traits that are highly canalized show little capacity for variation."
| שייך לנושאים: 1-13 - חינוך אינטגרלי, -מקורות מדעיים, השפעת הסביבה, 3. השפעת הסביבה = חוק |
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World Health Organization
Field of reference: Psychology/Health
Description: Importance of the right environment on the brain development of a child.
“The more stimulating the early environment, the more a child develops and learns. Language and cognitive development are especially important during the first six months to three years of life. When children spend their early years in a less stimulating, or less emotionally and physically supportive environment, brain development is affected and leads to cognitive, social and behavioural delays. Later in life, these children will have difficulty dealing with complex situations and environments. High levels of adversity and stress during early childhood can increase the risk of stress-related disease and learning problems well into the adult years.”
| שייך לנושאים: 1-13 - חינוך אינטגרלי, -מקורות מדעיים, השפעת הסביבה, 3. השפעת הסביבה = חוק |
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World Health Organization
Field of reference: Psychology, Health
Description: Importance of a caring and responsive environment in a child development.
“To reach their potential, young children need to spend time in a caring, responsive environment that protects them from neglect and inappropriate disapproval and punishment.Parents and families are the key to early child development, but need support to provide the right environment. Children benefit when national governments adopt “family friendly” social protection policies that guarantee adequate family income, maternity benefits, financial support, and allow for parents and caregivers to devote time and attention to young children.Globally, societies that invest in children and families in the early years – whether rich or poor – have the most literate and numerate populations. These are also the societies that have the best health status and lowest levels of health inequality in the world.”
| שייך לנושאים: 1-13 - חינוך אינטגרלי, -מקורות מדעיים, השפעת הסביבה, 3. השפעת הסביבה = חוק |
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