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A small number of truth seekers, notably Svâmi Prajnânpad, have simply described the laws of life as follows (from the book [Petit Régis, Une approche scientifique du silence]).
* Svâmi Prajnânpad, the truth, emotion / feeling, to think / to see
Svâmi Prajnânpad (alias Svâmiji, 1891-1974) was a Bengali Brahmin who had received dual training, classical Vedantic and modern scientific trainings.
A master of wisdom and lucidity, his rigorous approach is a dive into the heart of the unconscious which reveals the difficulties hindering the silence of mental. No God, no ritual, no paradise.
André Comte-Sponville said about him : "This master is content to see, to be one with what he indifferently calls truth or reality, which is neutral, neither good nor bad, neither pleasant nor painful, and promised only change or death." [PDS 2]
According to the specific vocabulary of his teaching [EHM 1] :
* Inner peace, truth, science
* Ego, attachment, mental, identification
* Thought, emotion, desire
* To be
* Spirituality
[ARI 1] Association pour le Rayonnement Culturel Indien, Citation de Mata Amritanandamayi, La Lettre N 3 de l'ARCI, 2ème trimestre 1987
[BTC 1] Bouchet Christian, Gurdjieff - qui suis-je, Pardès 2001
[CSA 1] Comte-Sponville André, De l'autre côté du désespoir - Introduction à la pensée de Svâmi Prajnânpad, Accarias-L'Originel 1997
[CSO 1] Cambessédès Olivier, Le quotidien avec un maître Svami Prajnanpad, Accarias L'Originel 1995
[DAF 1] Desjardins Arnaud et Farcet Gilles, Confidences impersonnelles, Critérion 1991
[DAF 2] Desjardins Arnaud et Farcet Gilles, Regards sages sur un monde fou, La Table Ronde 1997
[DAL 3] Desjardins Arnaud et Loiseleur-Desjardins Véronique, La voie et ses pièges, La Table Ronde 1992
[DAL 4] Desjardins Arnaud et Loiseleur-Desjardins Véronique, L'ami spirituel, La Table Ronde 1996
[DEA 1] Delaye Alain, Sagesses concordantes - Quatre maîtres pour notre temps : Etty Hillesum, Vilama Thakar, Svâmi Prajnânpad, Krishnamurti, Volume I, Accarias-L'Originel 2003, 2011
[DSA 7] Desjardins Arnaud, A la recherche du Soi 1 - Adhyatma yoga, La Table Ronde 1977
[DSA 8] Desjardins Arnaud, A la recherche du Soi 2 - Le vedanta et l'inconscient, La Table Ronde 1978
[DSA 9] Desjardins Arnaud, A la recherche du Soi 3 - Au-delà du moi, La Table Ronde 1979
[DSA 10] Desjardins Arnaud, A la recherche du Soi 4 - Tu es cela, La Table Ronde 1980
[DSA 15] Desjardins Arnaud, La voie du coeur, La Table Ronde 1987
[DSA 17] Desjardins Arnaud, Zen et Vedanta - Commentaire du Sin sin ming, La Table Ronde 1995
[DSA 19] Desjardins Arnaud, Retour à l'essentiel, La Table Ronde 2002
[DSA 21] Desjardins Arnaud, Bienvenue sur la voie, La Table Ronde 2005
[DSA 23] Desjardins Arnaud, Lettres à une jeune disciple, La Table Ronde 2006
[DSD 1] Desjardins Denise, De naissance en naissance, La Table Ronde 1977
[DSD 3] Desjardins Denise, Mère sainte et courtisane, La Table Ronde 1983
[DSD 7] Desjardins Denise, La route et le chemin - Carnet de voyage et d'ascèse, La Table Ronde 1995
[DSD 9] Desjardins Denise, Conteurs, Saints et Sages - Des Pères du désert à Swâmi Prajnânpad, La Table Ronde 1998
[DSD 10] Desjardins Denise, Petit traité de l'action, La Table Ronde 1999
[EHM 1] Edelmann Eric, Humbert Olivier et Dr Massin Christophe, Swâmi Prajnânpad et les lyings, La Table Ronde 2000
[FTG 1] Farcet Gilles, Arnaud Desjardins ou l'aventure de la sagesse, La Table Ronde 1987
[FTG 3] Farcet Gilles, La transmission selon Arnaud Desjardins, Le Relié 2009
[GKG 1] Guéshé Kelsang Gyatso, Vivre une vie pleine de sens - Mourir dans la joie, Tharpa France 2017
[GKG 2] Guéshé Kelsang Gyatso, Transformez votre vie. Un voyage plein de félicité, Tharpa France 2009
[LRF 1] Leboyer Frédérick, Portrait d'un homme remarquable - Svami Prajnanpad, Critérion 1991
[LRV 1] Loiseleur-Desjardins Véronique, Anthologie de la non dualité, La Table Ronde 1981
[MAM 1] Mâ Ananda Moyî, L'enseignement de Mâ Ananda Moyî, traduit par Josette Herbert, Albin Michel 1974
[MRD 1] Marol et Roumanoff Daniel, Sois sage, La Table Ronde 1994
[NIL 1] Nduwumwami Louis, Krishnamurti et l'éducation, Du Rocher 1991
[OPD 1] Ouspensky Petr Demianovitch, L'homme et son évolution possible, Denoël 1961 puis Accarias L'Originel 1999
[OPD 2] Ouspensky Petr Demianovitch, Fragments d'un enseignement inconnu, Stock 1974
[PDS 1] Prajnanpad Svami, L'art de voir, Lettres à ses disciples - Tome 1, Traduction de Colette et Daniel Roumanoff, Accarias-L'Originel 1988
[PDS 2] Prajnanpad Svami, Les yeux ouverts, Lettres à ses disciples - Tome 2, Traduction de Colette et Daniel Roumanoff, Accarias-L'Originel 1989
[PDS 3] Prajnanpad Svami, La vérité du bonheur, Lettres à ses disciples - Tome 3, Traduction de Colette et Daniel Roumanoff, Accarias L'Originel 1990
[PDS 4] Prajnanpad Svami, A B C d'une sagesse, Paroles choisies par Daniel Roumanoff, La Table Ronde 1998 puis Albin Michel 2009
[PDS 5] Prajnanpad Svami, L'éternel présent - Questions et réponses - Entretiens avec Pierre Wack, Traduction de Daniel Roumanoff, Accarias-L'Originel 2002
[PDS 6] Prajnanpad Svami, Les formules de Swâmi Prajnânpad commentées par Arnaud Desjardins, Formules et commentaires rassemblés par Véronique Desjardins, La Table Ronde 2003
[PDS 7] Prajnanpad Svami, Le but de la vie - Un été plein de sagesse, Entretiens avec Roland de QuatreBarbes été 1966, traduits par Daniel Roumanoff, Accarias-L'Originel 2005
[PDS 8] Prajnanpad Svami, Svâmi Prajnânpad pris au mot - Les Aphorismes, Recueillis et traduits par Frédérick Leboyer, Accarias-L'Originel 2006
[PDS 9] Prajnanpad Svami, Ceci Ici A présent - Seule et unique réalité, Entretiens avec Frédérick Leboyer (première série, janvier et février 1963), Traduction de Colette et Daniel Roumanoff, Accarias-L'Originel 2006
[PDS 10] Prajnanpad Svami, La connaissance de soi - Citations commentées des Upanishad et histoires (tome 1), Mises en forme par Daniel Roumanoff, Accarias-L'Originel 2008
[PSP 1] Prakash Sumangal et Prajnanpad Svami, L'expérience de l'unité, Traduction de Colette et Daniel Roumanoff, Accarias-L'Originel 1986 puis 2013
[RFD 1] Roumanoff Daniel, Svâmi Prajnânpad - Tome 1 Un maître contemporain - Manque et plénitude, La Table Ronde 1989, puis regroupé avec le Tome 3 chez Albin Michel 2009 sous le titre "Tome 1 Les lois de la vie"
[RFD 2] Roumanoff Daniel, Svâmi Prajnânpad - Tome 2 Le quotidien illuminé, La Table Ronde 1990, puis Albin Michel 2009
[RFD 3] Roumanoff Daniel, Svâmi Prajnânpad - Tome 3 Une synthèse Orient Occident, La Table Ronde 1991, puis regroupé avec le Tome 1 chez Albin Michel 2009 sous le titre "Tome 1 Les lois de la vie"
[RFD 4] Roumanoff Daniel, Candide au pays des Gourous - Journal d'un explorateur de l'Inde spirituelle, Dervy 1990
[RFD 5] Roumanoff Daniel, Svâmi Prajnânpad - Biographie, La Table Ronde 1993
[RFD 6] Roumanoff Daniel, Psychanalyse et sagesse orientale - Une lecture indienne de l'inconscient, Accarias L'Originel 1996
[SNR 1] Srinivasan Ramanuja, Entretiens avec Svami Prajnanpad, Traduction de Colette Roumanoff, Accarias-L'Originel 1984
This chapter explores the different facets of hypnosis, including its side effects and potential dangers, the world of show hypnosis, self-hypnosis techniques, as well as the legal and ethical aspects that govern its use.
E2.1. Definition :
Hypnosis is an ancient technique dating back more than 6000 years in the Orient and to the end of the 18th century for modern hypnosis. It produces a modified state of consciousness located between wakefulness and sleep.
More precisely, it allows to induce by speech a particular state of consciousness characterized by indifference to the outside and a greatly increased capacity to receive suggestions (in particular the voice of the hypnotist) [ANM][INS][ MAB].
At the psychological level, hypnosis induces a state of deep relaxation based on freely given suggestion [AFI].
At the neurological level, hypnosis involves a change in brain activity, including a decrease in activity in regions associated with processing sensory information and an increase in activity in regions associated with attention and suggestion [MAB].
Hypnosis is used in different medical sectors [MIN] :
- anesthesia (hypnosedation), to reduce the stress of the operation, or even allow certain operations without resorting to general anesthesia, which is replaced by a sedative medication and quality local anesthesia ;
- pain management (hypnoanalgesia), particularly in obstetrics to reduce labor pain ;
- psychotherapeutics (hypnotherapy), to help people achieve a state of deep relaxation allowing them to work on their problems (fear, stress, blockage, etc.) without causing unwanted side effects.
E2.2. Side effects :
Side effects of hypnosis are as follows :
- Temporary and mild effects : headaches, fears, sadness, disorientation, etc. [CFH1][MAB]
- Rare but serious effects : hallucinations, altered memories, personality change, depression, suicidal impulses, etc. [CFH1]
These side effects are not always the consequence of hypnosis as such. They may arise due to the pre-existing vulnerability of the subject, the practitioner's inexperience in dealing with psychotherapeutic problems, the use of inappropriate suggestions, the inability to erase non-therapeutic suggestions or to fully redirect the patient through adequate debriefing [CFH1].
These reactions occur more often in certain contexts such as show hypnosis, or when the training and experience of the practitioner are insufficient [CFH1].
E2.3. Dangers :
The dangers of hypnosis are as follows :
- Incompetent or clumsy hypnotist : he can in particular plunge a person back into a past trauma without knowing how to manage the situation [ATK].
- Absence of prior diagnosis : a practitioner who does not know how to use the hypnosis tool without prior clinical, psychological or somatic knowledge, will not be able to distinguish between the psychological expression of a serious pathology and a disorder that may be sensitive to a hypnotic approach. Thus, anxiety can be a sign of a pulmonary embolism, a myocardial infarction and many other severe disorders. It is therefore appropriate for the practitioner who is going to use hypnosis to be able to have explored all the possible causes of the disorder, or failing that, to have verified with the patient's treating physician that the pathology has been explored and diagnosed or that the psychosomatic origin has been demonstrated [CFH1].
- Non-compliance with medical contraindications : hypnosis should not be practiced on people with heart disease, epilepsy or serious psychopathology (delusions, psychosis, paranoia, etc.) [CFH1][MAB].
- False memories : the unconscious can produce coherent but false responses, often in an attempt to relieve suffering. Hypnosis accentuates this phenomenon [CFH3][BEN].
Any practitioner must refuse any patient request aimed at rediscovering forgotten memories [CFH3] or verifying the reality of a memory (for example, women who believe they were abused as children) [BEN].
- Poor management of emotional reactions after hypnosis, which can lead to persistent discomfort [CFH1][UNI][ATK].
E2.4. Show hypnosis :
Show (or street or fair) hypnosis is a hypnosis technique close to therapeutic hypnosis, practiced for commercial or occult purposes which has nothing to do with the patient's interest [ATK].
Unlike therapeutic hypnosis, the show hypnotist does not establish rapport with the subject, adopt an authoritative and directive approach, do not debrief individually and do not interrupt the hypnotic trance if necessary [CFH2].
The individual on stage volunteered to play the game and showed particular skills in the trance state during the pre-test carried out by the hypnotist. Added to this is the group effect which reduces the unconscious resistance of the individual [UNI]. The show then consists of attracting the audience by producing spectacular reactions (for example, seeing a subject think he is a chicken on a wall) [GRO].
Many people hypnotized on stage say that, although they are aware of being ridiculed, they paid to go on stage, people watch them and they have an astonishing experience [SAR].
Show hypnosis presents dangers that therapeutic hypnosis does not have: dangers in particular for people with with heart disease, epilepsy, serious pathology or psychologically fragile [CFH1][MAB]. Added to this is the non-management of possible emotional reactions upon exiting hypnosis [CFH1][UNI][ATK].
E2.5. Self-hypnosis :
Self-hypnosis is hypnosis practiced alone, without the help of a practitioner. Like meditation, self-hypnosis is a physical and mental relaxation technique. But unlike meditation :
- The purpose is therapeutic (resolution of a problem) and not spiritual (search for inner peace).
- Relaxation involves an active suggestion or visualization (and not a simple caring attention to the experience of the moment) aimed at achieving a specific objective, such as stress management or improving self-confidence.
- Awareness of the external world disappears in favor of an internal look, while in meditation consciousness is both internal (thoughts, emotions, sensations) and external (perceptions of the environment). The person being hypnotized feels like they are dissociated, with one part of them observing what the other part of themselves is doing, while the meditator is aware of everything that is happening in and around them [PIC].
E2.6. Legal framework :
In France, there is no legal framework to regulate the practice of hypnosis. There is only teaching of hypnosis at the university, associative and private level, as well as various ethical codes of hypnosis.
Two types of hypnosis practices can be distinguished [SEN] :
- Therapeutic hypnosis is practiced by health professionals in the medical field (doctors, psychiatrists, psychotherapists and clinical psychologists) and paramedical field (dentists, midwives, nurses, physiotherapists, occupational therapists and psychomotor therapists).
- Hypnosis known as "better being" is practiced by other professionals under various names : hypnotherapist, hypnopractitioner, hypnologist, hypnosis psychopractitioner, brief therapy practitioner, etc. They must not use certain reserved words such as : "psychotherapist", "patient", "consultation", "diagnosis", "prescription", under penalty of "illegal practice of medicine". We therefore do not speak of "patient" but of "client".
In France the exercise of therapeutic hypnosis in a context other than medical is similar to the illegal exercise of medicine (No. 09-81.778 of the Criminal Chamber of March 9, 2010, and article L.4161-1 of the public health code) [SEN][CFH4].
E2.7. Ethics of hypnosis :
The Confederation Francophone Hypnosis and Brief Therapies (CFHTB) published in 2003 an ethical code of hypnosis based on medical ethics, the principles of which are as follows [CFH4] :
1. The best interests and well-being of the patient are the highest priority.
2. Hypnosis is considered a complement to other forms of clinical or supportive scientific practices.
3. The hypno-practitioner will limit his scientific or supporting clinical use of hypnosis to the areas of competence recognized by the regulations of his profession or the uses relating to it.
4. The hypno-practitioner undertakes not to use hypnosis or brief therapy as a form of distraction or spectacle.
5. In all cases, the transition to the practice of hypnosis will remain conditional on obtaining a complete qualification in the professional field considered.
6. The communication of information relating to hypnosis to the various media is accepted to the extent that it is based on precise scientific knowledge.
E2.8. Sources relating to hypnosis :
[AFI] AFIS, L'hypnose : charlatanisme ou avancée médicale ?.
[ANM] Académie nationale de médecine, Thérapies complémentaires - acupuncture, hypnose,
ostéopathie, tai-chi - leur place parmi les ressources de soins, rapport de la séance du 5 mars 2013.
[ATK] Jean-Marc Atkins, Quels sont les dangers de l'hypnose (ericksonienne) ?
[BEN] Jean-Marc Benhaiem, L'hypnose ne permet pas de retrouver la mémoire de faits réels..., Huffpost
[CFH1] CFHTB, Confédération Francophone Hypnose et Thérapies Brèves, Risques et dangers de l'hypnose
[CFH2] CFHTB, Confédération Francophone Hypnose et Thérapies Brèves, Risques et dangers de l'hypnose : hypnose de spectacle
[CFH3] CFHTB, Confédération Francophone Hypnose et Thérapies Brèves, Risques et dangers de l'hypnose : les faux-souvenirs
[CFH4] CFHTB, Confédération Francophone Hypnose et Thérapies Brèves, Livre blanc de l'hypnose clinique et thérapeutique
[FTB] I2FTB, Quel cadre légal quand on fait de l'hypnose ou PNL ?
[GRO] Laurent Gross, EMDR, Hypnose ericksonienne, médicale et thérapeutique à Paris
[IFH] IFH, Institut Français d'Hypnose, Lexique en hypnose thérapeutique
[INS] Inserm, Evaluation de l'efficacité de la pratique de l'hypnose - 2015
[MAB] Emmanuel Mabin, e-academy.fr, Mieux comprendre l'hypnose
[MIN] Ministère de la Santé et de la Prévention
[PIC] Caroline Pico, Similitudes et différences entre hypnose et méditation
[SAR] Corinne Sarazin, Les dangers de l'hypnose eriksonienne ou autre
[SEN] Sénat, Réponse du Ministère des solidarités et de la santé publiée le 14/02/2019
[UNI] Unitheque, Quels sont les métiers de l'hypnose ?
Smell and taste are the two senses that aroused the least interest from scientific researchers until the 1960s.
Today, we know that the sensory perception of smells and flavors is a subtle mix between universal principles, personal perception and culture.
E3.1. Smells
Smells are molecules detected chemically by olfactory receptors located in the nasal cavity.
They can take two distinct routes : a direct route, called orthonasal, located in the nose (concept of "smell") or an indirect route, called retro-nasal, located in the back of the throat (concept of "aroma" released by food in the mouth).
There is to date no universal consensus on the categorization of smells. Only perfumery and oenology have produced specific classifications.
The table below allows you to simply categorize smells according to their effects (unpleasant/pleasant) and their origins (mineral, plant, animal, human).
Sources relating to smells :
Claude Boisson, "La dénomination des odeurs : variations et régularités linguistiques", Intellectica, 1997/1, 24, pp. 29-49.
Sophie David, Danièle Dubois, Catherine Rouby, Benoist Schaal, "L'expression des odeurs en français : analyse lexicale et représentation cognitive", Intellectica, 1997/1, 24, pp. 51-83.
Dico du Vin, Odeurs du vin, nouvelle classification, Dico-du-Vin 2023.
Danièle Dubois, "Des catégories d'odorants à la sémantique des odeurs", Terrain, 47 | 2006, 89-106.
Camille Gaubert, 03.05.2022, "Notre perception des odeurs n'est que très peu liée à notre culture", Cerveau et Psy.
André Holley, "Le physiologiste et la catégorisation des odeurs", Intellectica, 1997/1, 24, pp. 21-27.
L'Atelier du Vin, Guide des arômes du vin et de leur perception en oenologie.
Hervé-Pierre Lambert, "L'imaginaire, les neurosciences et l'olfactif : confirmations et extrapolations", IRIS, 33 | 2012, 37-51.
C. Sulmont-Rossé, I. Urdapilleta, "De la mise en mots des odeurs", chapitre 28 (pp. 373-382) du livre : Odorat et Goût : de la neurobiologie des sens chimiques aux applications agronomiques, industrielles et médicales, Edition QUAE.
Luc a Poyo Vallina, 24 nov. 2022, "Les 10 principales odeurs perçues par l'odorat humain", Divain, .
Wikipedia, Rétro-olfaction.
E3.2. Flavors
Flavors are molecules detected chemically by taste receptors located on the taste buds of the tongue.
Other sensations in the mouth, also called "flavors" in the broad sense, do not involve the taste buds and are sensory (olfactory, auditory, visual) and somesthetic (thermal, tactile, proprioceptive (position and movement) and nociceptive (pain)).
The table below describes the basic flavors, "flavors" being taken in the broad sense. They can then combine with each other to form more elaborate taste sensations.
Sources relating to flavors :
Le Thi Maï Allafort, Connaissez-vous les mots du goût ? Lorsque les textures font le plaisir !, Marie Claire.
Christine Belloir, Récepteurs gustatifs humains : étude des relations structure-fonction, Thèse 2019, Université de Bourgogne.
Diane Boivineau, Evaluation gnoso-praxique linguale des enfants avec trouble structurel du langage oral, Mémoire 2013/2014, Université Paris VI.
Loïc Briand, "La chimie du goût", CultureSciences-Chimie.
Juliette Defossez, Vers un langage du goût : approche expérimentale d'une communication multimodale à destination des mangeurs, Thèse 2014, Université de Bourgogne.
Audrey Dufour, 24/01/2017, "Comment reconnaît-on les saveurs ?", La Croix.
Goûts et Papilles, C'est quoi le goût ? Odeur, saveur, flaveur....
FasterCapital, Au-delà du goût : comment la texture influence notre perception des aliments.
Claire Gresser, Contribution à l'étude de la composante trigéminale dans la posture cervico-faciale, Thèse 2005, Université de Lorraine.
Tanya Lewis, 5 octobre 2021, "Ce que les piments peuvent nous apprendre sur la douleur", Pour la Science.
Christophe Otte, Olivier Otte, Régulation des dysfonctions maxillo-faciales de l'enfant, Clinique OPS.
Dale Purves, George J. Augustine, David Fitzpatrick, Lawrence C. Katz, Anthony-Samuel LaMantia, James O. McNamara, Neurosciences - Les sens chimiques, DeBoeck
Rapport du groupe PNNS - Qualité gustative des aliments et environnement des repas : restauration scolaire, hospitalière et aide alimentaire, décembre 2010.
Si on me coupait la langue, pourrais-je toujours savourer mes repas ?, La sensation trigéminale.
Wikipedia, Goût.
Wikipedia, Thermorécepteur.
E4.1. Introduction :
Genetics is the science that studies the organization, functioning, regulation and modification of genes, both in their transmission from one generation to another and in their expression within the same individual.
It includes six major scientific fields [PER][CHA] :
1. Genome organization and cell manufacturing
Each cell in the human body contains a complete copy of the organism's genetic material (the genome), carried by DNA (Deoxyribonucleic Acid).
This genome contains all the instructions necessary to produce all of the body's proteins. However, in practice, each cell expresses only a portion of the genes, depending on its specialization. For example, a muscle cell will produce mainly contractile proteins, and few or no proteins specific to neurons or immune cells.
Proteins play an essential role in the body. On the one hand, they perform structural functions by maintaining and repairing tissues. On the other hand, they act as regulators of vital functions, notably participating in genetic regulation (histones and transcription factors), hormonal regulation (hormones), digestive regulation (enzymes), oxygen transport in the blood (hemoglobin), and immune defense (antibodies).
Each cell thus produces two main types of proteins :
- Effector (or target) proteins, such as structural proteins, transport proteins, hormones, enzymes, that perform the body's cellular and physiological functions.
- Regulatory proteins, such as histones and transcription factors, that control gene expression.
Once produced, proteins are transported to their sites of action (cells, organs, tissues). Some, like hormones, travel through the blood to reach distant organs.
2. Genetic Regulation
Genetic regulation is the control of gene expression, particularly through modulation of DNA accessibility, without modifying the DNA sequence.
The main players in this mechanism are :
- Non-coding DNA sequences (not translated into proteins), which consist mainly of Non-coding genes and Intergenic sequences.
- Regulatory proteins, which are of two main types : Histones ensuring the compaction of the DNA around them and therefore the modulation of its accessibility, and Transcription factors which bind to non-coding DNA sequences to activate or repress gene expression.
- Epigenetic modifications, which are reversible additions of chemical groups to DNA molecules and also to histone tails, altering DNA accessibility and therefore the body's response to internal and external stimuli.
- Long non-coding RNAs, which act as indirect regulators, for example, guiding proteins to specific regions of DNA.
3. Genetic Variation
Genetic variation is the production of genetic differences. The main mechanisms are as follows :
- Mutation : Lasting modification of the DNA sequence at the gene, chromosome, or entire genome level.
- Recombination (crossing-over) : Exchange of DNA segments between homologous chromosomes during meiosis, creating new genetic combinations.
- Polymorphism : Coexistence of several normal genetic forms in a population, as demonstrated by the ABO blood group system in humans, which produces a diversity of groups (A, B, AB, O, etc.).
- Transposition : Change in the position of a DNA segment within the genome.
- Genetic drift : Random change in the frequencies of different forms of a gene in a small population, often due to chance events (catastrophes, isolation) that reduce the number of individuals.
- Migration (or gene flow) : movement of individuals from one population to another, resulting in the arrival or departure of certain gene forms in the host population.
- Random mating : reproduction where partners are chosen at random, promoting genetic mixing within the population.
4. Genetic Repair
Genetic repair is the correction of errors or damage in DNA. The main mechanisms, classified by increasing severity of the damage, are as follows :
- Direct repair : For a slightly damaged base
- Base excision repair (BER) : For an absent or severely damaged base
- Copy error repair (MMR) : For an erroneous sequence following DNA replication
- Nucleotide excision repair (NER) : For a damaged sequence
- Single-strand break repair (SSB repair) : For a broken strand, with the intact second strand serving as a template
- Double-strand break repair (DSB repair) : For a broken double strand
5. Genetic Transmission
Genetic transmission is the transmission of hereditary information at the individual level (between cells of the same organism) or transgenerationally (from one generation to the next). The main mechanisms are as follows :
- Replication : Faithful copying of DNA before each cell division.
- Mitosis : Cell division of somatic (body) cells producing two identical daughter cells with the same number of chromosomes as the parent cell.
- Meiosis : Cell division of germ (reproductive) cells producing two gametes (egg and sperm), each containing half the number of chromosomes. This division does not fragment the genetic information but intelligently redistributes it between the gametes through shuffling and control mechanisms, allowing fertilization to reconstitute a complete and unique genetic heritage.
- Fertilization : Fusion of two gametes (egg and sperm) to form an egg cell (zygote) with a full chromosome number.
- Mendelian inheritance : Transmission of hereditary traits via genes located on nuclear chromosomes (therefore inherited from both parents), according to Mendel's laws.
- Non-Mendelian inheritance : Transmission of hereditary traits that do not follow Mendel's laws, either due to the location of genes outside the nuclear chromosomes (such as mitochondrial DNA inherited only from the mother, or chloroplast DNA), or due to specific mechanisms affecting nuclear genes (such as parental imprinting, incomplete dominance, dynamic mutation, sex-linkage).
- Epigenetic transmission : Transmission, at the individual or transgenerational level, of regulatory marks of gene expression, without modification of the DNA sequence.
6. Natural Selection
Natural selection is an evolutionary mechanism that sorts individuals according to their ability to survive and reproduce.
Given the hereditary variations between individuals, natural selection favors certain traits within this diversity : individuals carrying genetic characteristics that are advantageous for their survival and reproduction in a given environment produce more offspring.
This concept of natural selection evolved historically in four stages (illustrated by the giraffe) :
- Lamarck (inheritance of acquired traits, 1809) : The giraffe lengthens its neck to reach high leaves and passes this acquired trait on to its offspring.
- Darwin (natural selection, 1859) : In giraffes, those born with longer necks through random individual variation survive better and reproduce more, thus producing more offspring.
- Neo-Darwinism (modern genetics, Collective, 1930-1940) : In giraffes, those born with longer necks due to random genetic mutations (not environmentally driven) survive better and reproduce more, thus producing more offspring.
- Epigenetics (regulation of gene expression, Waddington, 1942) : In giraffes, in addition to random genetic mutations, difficulty reaching high leaves could alter the expression of genes involved in neck growth, without changing the DNA sequence. These epigenetic modifications could be temporarily passed on to their offspring.
In summary :
Cellular functioning, through its major functions (organization, production, regulation, variation, repair, transmission), subtly illustrates the dynamic balance between assimilation and accommodation, as described by Jean Piaget.
Like the intelligence of living organisms which constantly adjusts its patterns to integrate or transform experience, the cell assimilates most events according to its genetic and epigenetic programs. But it also knows how to accommodate, that is, adjust or remodel its mechanisms, in the face of novelty or disruption.
This adaptive balance, the driving force of cellular plasticity, provides, on a larger scale, the innovations that are influenced by natural selection.
E4.2. Cell description :
A hierarchical description of the eukaryotic cell (with nucleus) is given as follows [PER][CHA] :
Note : The number shown is relative to the adult human being.
Eukaryotic cell = Plasma membrane + Cytoplasm + Nucleus. Number = 37 trillion
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| Plasma membrane = Envelope separating the interior and exterior of the cell.
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| Cytoplasm = Cytosol + Organelles
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| | Cytosol = Aqueous medium containing ions, nutrients, and enzymes.
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| | Organelles = Free ribosomes + Endoplasmic reticulum + Mitochondria + Golgi apparatus + Lysosomes + Cytoskeleton
| | | Free ribosomes = synthesize proteins from messenger RNA. Number = 10 million
| | | Endoplasmic reticulum (ER) = Synthesizes lipids (smooth ER) and other proteins (rough ER, with attached Ribosomes).
| | | Mitochondria = Produce cellular energy (ATP) through cellular respiration. Contain their own DNA (mitochondrial genome). Number = 100 to 10,000 (according to cell type).
| | | Golgi apparatus = Sorts, packages and transports molecules (mainly proteins and lipids) to their final destination (internal or external to the cell).
| | | Lysosomes = Digest cellular waste. Number = 300 to 500
| | | Cytoskeleton = Maintains cell shape and participates in cell movement.
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| Nucleus = Nuclear membrane + Nucleoplate + Chromatin + Nucleoli
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| | Nuclear membrane = Double envelope separating the interior and exterior of the nucleus.
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| | Nucleoplate = Gelatinous medium containing enzymes and ions.
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| | Chromatin = Nuclear genome + Regulatory proteins + Associated RNAs + Epigenetic modifications
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| | | Nuclear genome = Set of Chromosomes. Number = 23 pairs of chromosomes.
| | | | Chromosome = Compacted DNA molecule (double helix consisting of two antiparallel strands of nucleotides) = Coding genes + Non-coding genes + Intergenic sequences
| | | | | Coding gene = DNA sequence containing the information necessary for protein synthesis. Number = 20,000 coding genes per nuclear genome.
| | | | | Non-coding gene = DNA sequence containing the information necessary primarily for functional RNA synthesis.
| | | | | Intergenic sequences = Non-coding DNA sequences located between two adjacent genes (coding or non-coding). They notably constitute the anchoring platforms for Regulatory proteins and also include a diversity of repeated sequences. Proportion = 90 % of the nuclear genome.
| | | | | Nucleotide = Phosphate group + Deoxyribose sugar + Nitrogenous base. Number = several million per chromosome
| | | | | | Nitrogenous base = Adenine (A), Thymine (T), Cytosine (C), or Guanine (G). Number = 3 billion pairs of nitrogenous bases per nuclear genome.
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| | | Regulatory proteins = Histones + Transcription factors
| | | | Histones = Proteins that compact DNA around themselves and thus modulate its accessibility.
| | | | Transcription factors = Proteins that bind to non-coding DNA sequences to activate or repress gene expression.
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| | | Associated RNAs = Main mediators of gene expression
| | | | Messenger RNA (mRNA) = Copies a coding Gene (the blueprint for protein production) and transports it to the Ribosomes.
| | | | Transfer RNA (tRNA) = Transports amino acids to the Ribosomes and positions them according to the provided blueprint.
| | | | Ribosomal RNA (rRNA) = Forms the backbone of the Ribosomes and assembles amino acids into protein chains according to the provided blueprint.
| | | | microRNA = blocks specific messenger RNA, preventing their translation and thus reducing the production of effector proteins.
| | | | Long non-coding RNA (IncRNA) = Indirect regulator, for example, guiding proteins to specific regions of DNA.
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| | | Epigenetic modifications = Reversible additions of chemical groups to DNA molecules and histones, thus altering DNA accessibility.
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| | Nucleoli = Synthesize ribosomal RNAs. Number = 1 to 5
E4.3. Epigenetics :
Epigenetics constitutes a biological underpinning common to all acquisition-based learning (memory stabilization, brain plasticity, metabolic adaptations). It allows cells to encode lived experience through changes in gene expression without altering the DNA sequence, unlike genetic mutations.
This fundamental mechanism dynamically regulates gene expression according to the physiological or environmental context, thus allowing the organism to adapt effectively to internal and external stimuli, including :
- Climate variations (temperature, humidity)
- Dietary changes (deficiency, excess, nutritional quality)
- Habitat changes (urbanization, pollution, migration)
- Physiological stress (illness, intense exercise)
- Traumatic stress (emotional shock, violence)
This regulation is achieved through reversible chemical modifications, such as :
- DNA methylation, by adding methyl groups to the DNA.
- Modification of regulatory proteins (mainly histones) around which DNA is wrapped.
These modifications dynamically control access to genes and their expression levels, allowing their activation or repression without altering the underlying genetic content.
Two levels of plasticity are distinguished :
Individual plasticity : When stimuli are moderate or transient, the changes remain confined to somatic (body) cells and are not transmitted to subsequent generations.
For example :
- The Arctic fox changes its coat (white in winter and brown in summer). Fox cubs are born with a coat adapted to their season of birth, but their ability to change color then depends on environmental stimuli (study by Zimova M., Mills L.S., Nowak J.J., 2016).
- In humans, skin tanning in response to the sun is a temporary adaptation specific to each individual (study by Slominski A., 2004).
Transgenerational plasticity : When stimuli are intense or prolonged, the changes also affect germ cells (sperm and oocytes). These marks are then transmitted to offspring and influence their phenotypes (behavioral, physiological, and morphological traits) for one to three generations before fading.
For example :
- In water fleas (Daphnia), parental exposure to predator signals induces the development of morphological defenses (helmets or spikes) in the offspring, even if the young have never encountered a predator themselves (study by Tollrian R., 1995).
- Male mice exposed to prolonged cold give birth to offspring better adapted to low temperatures (study by Chan J.C., 2020).
- Male mice conditioned to fear an odor transmit a specific hypersensitivity to that odor to their offspring (study by Dias & Ressler, 2013).
- In humans, malnutrition before pregnancy in the mother or father can have a lasting effect on the child's health, even if the child subsequently grows up in a normal food environment (study by Gete DG., Waller M., Mishra GD., 2020).
In the case of cognitive learning, epigenetics is closely linked to brain plasticity (neural networks) at two complementary coding levels [MER] :
- A structural level : Learning modifies the strength and organization of synaptic connections between neurons, ensuring the storage and consolidation of acquired information (memory).
- A biological level : Learning induces epigenetic modifications in the genome of neuronal cells, which regulate the expression of genes involved in synaptic plasticity and stabilization of neuronal networks.
Warning : Despite the profound impact of intensive cognitive activity (such as musical practice) on brain plasticity and neuronal epigenetics, these changes remain strictly individual. To date, no hereditary mechanism, genetic or epigenetic, has been demonstrated to transmit these adaptations to offspring.
E4.4. RNA :
RNA (RiboNucleic Acid) is the dynamic relay between DNA and all cellular activities, ensuring the transmission, translation and regulation of genetic information within the cell.
All RNAs are synthesized by direct copying of DNA sequences (transcription) through the action of RNA polymerase, a special protein initially present in the cell and then produced by messenger RNA, like all other proteins.
Warning : No RNA is a protein. RNA polymerase, despite its name, is not an RNA but a protein (enzyme) that makes RNA.
A specific type of RNA, messenger RNA (mRNA), is a partial and targeted copy of genetic information, then transmitted to ribosomes (in the cell cytoplasm). Ribosomes then "read" this messenger RNA (coding RNA) as a blueprint for making (synthesizing) proteins.
Other types of RNA, known as non-coding RNA, do not contribute to protein production. They are functional and perform key regulatory functions, such as :
- Blocking specific messenger RNAs to prevent their translation (e.g., microRNAs), thereby reducing the production of effector proteins.
- Controlling access to DNA via epigenetic modifications (e.g., long non-coding RNAs), thereby modulating gene expression without altering the DNA sequence.
E4.5. Sources relative to genetics :
[CHA] ChatGPT, le moteur d'Intelligence Artificielle développé par OpenAI.
[MER] Karine Merienne, Anne-Laurence Boutillier, Régulations épigénétiques et plasticité cérébrale : vers de nouvelles thérapies dans les maladies neurodégénératives ?, 2016.
[PER] Perplexity, le moteur d'Intelligence Artificielle développé par Perplexity AI.
Last page update : May 15, 2026.