Varna
Varna means colour or complexion and is referred to assess skin colour. It is important biologically, cosmetically, and socially. Modern literature considers that differences in skin colour among individuals is caused only by variation in pigmentation. This is a result of genetics (inherited from one's biological parents and or individual gene alleles), exposure to the sun, natural and sexual selection, or all of these. Apart from these factors, Ayurveda considers other factors too like daily regimen, excxellence of body tissues, constitution (prakriti) of the person, etc as the factors affecting varna. Equilibrium of dosha is essential for healthy varna. Derangement in the homeostasis of dosha often causes discoloration of varna. Bhrajak pitta[Su. Sa. Sutra Sthana 21/10] [Ast. Hri. Sutra Sthana 12/14] and udanavayu[A. Hri. Sutra Sthana 12/5] carry the physiological functions for maintaining varna. Several medicinal formulations for the enhancement of varna are mentioned in ayurveda texts. E.g. group of ten herbs for improving colour of skin (varnyadashemani) includes Chandana (Santalum album), Tunga (Calophylluminophyllum), Padmaka (Prunus cerasoides), Ushira (Vetiveriazizanioides), Madhuka (Glycyrrhiza glabra), Manjishtha (Rubia cordifolia), Sariva (Hemidesmus indicus), Payasya (Pueraria tuberosa), Sita (Cynodondactylon) and Lata (Cynodon linearis). [Cha. Sa. Sutra Sthana 4/8] This article describes the physiological and pathological aspects of varna and its importance in healthcare.
| Section/Chapter/topic | Concepts / Varna |
|---|---|
| Authors |
Bhojani M.K.1, Yadav Vandana 1 |
| Reviewer | Basisht G.2 |
| Editor | Deole Y.S.3 |
| Affiliations |
1 Department of Kriya Sharira, All India Institute of Ayurveda, New Delhi, India 2 Rheumatologist, Orlando, Florida, U.S.A. 3Department of Kayachikitsa, G.J. Patel Institute of Ayurvedic Studies and Research, New Vallabh Vidyanagar, Anand, Gujarat, India |
| Correspondence email |
meera.samhita@aiia.gov.in, carakasamhita@gmail.com |
| Publisher | Charak Samhita Research, Training and Development Centre, I.T.R.A., Jamnagar, India |
| Date of first publication: | May20, 2023 |
| DOI | 10.47468/CSNE.2023.e01.s09.139 |
Classification
Human skin colour ranges from the darkest brown to the lightest hues. Ayurveda scholars have classified varna based on proportions of mahabhuta composing them as follows:
| S. No | Type of Varna | CharakSamhita ShariraSthana |
CharakSamhita IndriyaSthana |
SushrutaSamhita ShariraSthana |
Colour |
|---|---|---|---|---|---|
| 1 | Gaura | ✓ | ✓ | White/fair complexion | |
| 2 | Krishna | ✓ | ✓ | ✓ | Black/dark complexion |
| 3 | Shyam | ✓ | ✓ | Dark blue/brown | |
| 4 | Shyamavdata | ✓ | Bluish white | ||
| 5 | Avadata | ✓ | White/fair | ||
| 6 | Krishna Shyam | ✓ | Bluish black complexion | ||
| 7 | Gaur Shyam | ✓ | Bluish white cmplexion |
| Varna | Mahabhuta Acc. To Charak | Mahabhuta Acc. To Susruta |
|---|---|---|
| Gaura | Agni+Jala+Akash | Jala+Agni |
| Krishna | Agni+Prithvi+Vayu | Prithvi+Agni |
| Shyam | Akash+Vayu+Agni+Jala+Prithvi | |
| Gaura Shyam | Jala+Akash+Agni | |
| Krishna Shyam | Prithvi+Akash+Agni |
[Cha. Sa. ShariraSthana 8/15],[Cha. Sa. IndriyaSthana 1/8],[Su. Sa. ShariraSthana 2/37]
Inheritance of varna
The disorders of various body systems affect varna. E.g. disorders in rakta dhatu (blood and its components) results in skin discolouration and diseases.[Cha. Sa. Sutra Sthana 28/11-13] [Su. Sa. Sutra Sthana 24/11] Skin diseases have detrimental effect on varna. Rakta dhatu in its optimum quantity and quality leads to superior complexion. Similarly, presence of optimum body and scalp hair, cutaneous blood vessels, too affect the varna. The health of liver, spleen and other digestive organs is important to maintain a normal varna. These organs like heart, liver, spleen are originated from maternal factors, while some like hair, blood vessels, etc are contributed by paternal factors.[Ast. Hri. ShariraSthana 3/4-5] Thus varna of child is believed to be inherited from parents. Contemporary science believes that three classes of genes contribute to normal human color variation through the production of hypopigmented phenotypes or by genetic association with skin type and hair color. The MSH cell surface receptor and the melanosomal P-protein are the two most obvious candidate genes influencing variation in pigmentation phenotype, and may do so by regulating the levels and activities of the melanogenic enzymes tyrosinase, TRP-1 and TRP-2. Varna being regulated by genes may indicate its inheritance from parents.[1]
Effect of gestational diet pattern on varna of baby
The gestational diet and behaviour of mother influence varna of the new born child. Foetus gets nutrition from the mother; hence the diet and regimen of pregnant woman has a strong importance on the varna of offspring. During the gestational period, if the mother indulges in sweet foods such as milk, the colour of the child will be whitish-yellow; indulgence in foods which cause heart burn, such as sesame will lead to black colour of the child; and the use of mixed types of food will result in blue-black colour of the child.[A. Sam. ShariraSthana 1/61][2] A 2003 study found that diet of female mouse can change her offspring's coat colour by permanently modifying DNA methylation.[3] Ayurveda considers that the varna of foetus gets enhanced in sixth month of gestational period and the varna of the mother simultaneously gets decreased during sixth month.[Cha. Sa. ShariraSthana 4/22] The varna of child also depends on the colour of the apparel usedby mother during pregnancy. [Cha. Sa. ShariraSthana 8/12] However, more understanding and researches are needed on this concept. Satmya is the suitability towards the diet and regimens consumed by mother during the period of pregnancy. Satmyaja factors have a great impact in the formation of varna.[Cha. Sa. ShariraSthana 3/11]
Prakriti vis-a-vis varna
Though the complexion of a person is an outcome of many factors such as humidity, temperature, race, occupation, etc. but prakriti (constitution) of individuals pre-dominantly affects his complexion. Since vata dosha is dry, rough and cold in nature due to predominance of vayumahabhuta, vata prakriti individuals are more prone to have lustreless, dry dusky complexion.[Cha. Sa. VimanaSthana 8/98] [Ast. Hri. SharirSthana 3/85] Since pitta dosha is unctuous, hot, and fluid in nature due to predominance of agnimahabhuta, pitta prakriti individuals are prone to have fair complexion, with freckles and blackmoles.[Cha. Sa. VimanaSthana 8/97] [Ast. Hri. ShariraSthana 3/90] Since kapha dosha is unctuous, smooth, soft, cold and clear due to predominance of jalamahabhuta, kapha prakriti individuals are prone to have a pleasing smooth fair complexion with lustre, comparable to gorochan (an auspicious yellow pigment collected from ox), lotus or gold. [Cha. Sa. VimanaSthana 8/96] [Ast. Hri. SharirSthana 3/97] Thus the specific complexion in specific prakriti may be attributed to the composition of their respective predominant dosha. The prakriti depends on genetic constitution of a person. Fewresearches have identified the genome responsible for imparting skin colour. Several genome-wide association studies for pigmentation have now been conducted and identified single nucleotide polymorphism (SNP) markers in known, TYR, TYRP1, OCA2, SLC45A2, SLC24A5, MC1R, ASIP, KITLG and previously unknown SLC24A4, IRF4, TPCN2, candidate genes.[4][5]
Excellence of body tissues (sara) vis-a-vis varna
The excellence of dhatus (body tissues) is studied with reference to sara. Sara is classified into eight categories. Among these eight categories, twak sara (excellence in rasa dhatu) individuals have unctuous, smooth, soft, clear, fine, less numerous, deep rooted and tender hair with lustrous skin.[Cha. Sa. VimanaSthana 8/103] Rasa dhatu is rich in jalamahabhuta imparting smoothness, softness and unctuousness to the skin.
Rakta sara (excellence in rakta dhatu) individuals have unctuousness, red colour, beautiful dazzling appearance of the ears, eyes, face, tongue, nose, lips, sole of the hand and feet, nails, forehead and genital organs.[Cha. Sa. VimanaSthana 8/104] These individuals are believed to have well developed intra-dermal blood capillaries and circulation along with overall excellence in blood vascular system.
Meda sara (excellence in meda dhatu) individuals have unctuousness in complexion, eyes, scalp hair and other parts of the body, nails, teeth, lips, urine and faeces.[Cha. Sa. VimanaSthana 8/106] These individuals have excellence in adipose tissue which is unctuous in nature.
Majja sara (excellence in majja dhatu) individuals too have unctuous complexion.[Cha. Sa. VimanaSthana 8/108] Majja dhatu is predominantly formed of jalamahabhuta.
Shukra sara (excellence in shukra dhatu) individuals have a gentle look, having eyes as if filled with milk, cheerfulness, having teeth which are unctuous, round, strong, even, beautiful, clean and have unctuous complexion with dazzling appearance.[Cha. Sa. VimanaSthana 8/109] Shukra dhatu or reproductive tissues are believed to be formed at the end from essence of all other dhatus. Thus it indicate the excellence of all dhatus.
Effect of dinacharya(daily regimen) on varna
A healthy daily regimen helps in maintaining a healthy varna. These regimens include following:
Consumption of food in proper quantity[Cha. Sa. Sutra Sthana 5/8]
Applying udvartana (massaging the body with soft, fragrant powder) [Ast. Hri. Sutra Sthana 2/15]
Maintaining the three supports of life viz. food, sleep and brahmacharya (avoidance of sexual act physically, mentally and verbally in all ways under any circumstances) in life[Cha. Sa. Sutra Sthana 11/35]
Use of rasayana[Cha. Sa. ChikitsaSthana 1/1/7] (the drug, food or therapy which has capacity to prevent ageing, improve longevity, provide immunity against the diseases, promote mental competence, increase vitality and lustre of the body)
Jatharagni (digestive capacity) is also responsible for complexion [Cha. Sa. ChikitsaSthana 15/3], hence such diet should be consumed which establishes a healthy jatharagni. Importance of diet in imparting good complexion is mentioned.[Cha. Sa. Sutra Sthana 27/349] [Cha. Sa. Sutra Sthana 27/3]. The food that is consumed is digested by jatharagni. This digestion produces nourishment to the dhatus (tissues) of the body. Healthy tissues are responsible for maintenance of healthy skin, thus indicating role of jatharagni in varna.
Ojas & varna
Ojas is the essence of the body tissues (dhatus) [Su. Sa. Sutra Sthana 15/24]. As healthy state of all dhatu keeps the skin healthy.Thusone of the functions of ojas is to maintain varna.[Su. Sa. Sutra Sthana 15/25] The qualitative deterioration (ojavyapat) causes impairment of complexion.[Su. Sa. Sutra Sthana 15/29]
Varna as an atmaja bhava
Ayurveda believes that six procreative factors affect the formation of foetus. One among these factors is atmaja (atma=soul, ja=emerging from) factor. Atmaja factor is belived to affect varna.[Cha. Sa. SharirSthana 3/10]
Importance of concept
Importance in diagnosis & prognosis of disease
The natural complexion indicates a state of health or natural physiological processes inside the body. Sudden spontaneous change in natural complexion may be due to some pathology. Sudden drastic change in natural complexion may also indicate death in near future. Apart from discussing the natural complexion, some of the abnormal complexions like blue, grey, coppery, green and albino (extremely white) are described. [Cha. Sa. IndriyaSthana 1/9] Example, cyanotic complexion is observed in severe right ventricular hypertrophic cardiomyopathy.[6] The abnormalities include if half of the body has natural complexion and the other have abnormal complexion, and both of them are evenly demarcated by a line. These normal and abnormal complexions may simultaneously appear in left and right sides, front and back sides, upper and lower parts or internal and external parts of the body. Natural and abnormal complexions simultaneously appearing in face or other parts of the body, are the morbid signs indicating imminent death.[Cha. Sa. IndriyaSthana 1/10] For example, amelanotic melanomas presenting as red skin lesions are often lethal.[7]
Clinical diagnosis based on varna
Some diseases often have an impact on varna. Thus varna can be used as one of the diagnostic criterias for identification of diseases. Examples are as follows:
- Pandu (anaemia); Pale colour. [Cha. Sa. ChikitsaSthana 16/11]
- Kamla (jaundice): Yellowish [Cha. Sa. ChikitsaSthana 16/35]
- Vitiligo: Depigmented patches over skin.
- Albinism: Depigmentation of skin.
- Cyanosis: Bluish colour (may be due to heart defect).
Contemporary theories
Melanin vis-a-vis varna:
Melanin is produced by melanocytes in a process called melanogenesis. Melanin is made within small membrane–bound packages called melanosomes. As they become full of melanin, they move into the slender arms of melanocytes, from where they are transferred to the keratinocytes. Under normal conditions, melanosomes cover the upper part of the keratinocytes and protect them from genetic damage. One melanocyte supplies melanin to thirty-six keratinocytes according to signals from the keratinocytes. They also regulate melanin production and replication of melanocytes.[8]Individuals have different skin colours mainly because their melanocytes produce different amount and kinds of melanin. The genetic mechanism behind human skin colour is mainly regulated by the enzyme tyrosinase, which creates the colour of the skin, eyes, and hair shades.[9],[10] Differences in skin colour are also attributed to differences in size and distribution of melanosomes in the skin.[11]Both the amount and type of melanin produced is controlled by a number of genes that operate under incomplete dominance.[12] One copy of each of the various genes is inherited from each parent. Each gene can come in several alleles, resulting in the great variety of human skin tones.
Excellence of body tissues (sara) vis-a-vis varna:
The excellence of dhatus (body tissues) is studied with reference to sara. Sara is classified into eight categories. Among these eight categories, twak sara (excellence in rasa dhatu) individuals have unctuous, smooth, soft, clear, fine, less numerous, deep rooted and tender hair with lustrous skin.[Cha. Sa. VimanaSthana 8/103] Rasa dhatu is rich in jalamahabhuta imparting smoothness, softness and unctuousness to the skin.
Rakta sara (excellence in rakta dhatu) individuals have unctuousness, red colour, beautiful dazzling appearance of the ears, eyes, face, tongue, nose, lips, sole of the hand and feet, nails, forehead and genital organs.[Cha. Sa. VimanaSthana 8/104] These individuals are believed to have well developed intra-dermal blood capillaries and circulation along with overall excellence in blood vascular system.
Meda sara (excellence in meda dhatu) individuals have unctuousness in complexion, eyes, scalp hair and other parts of the body, nails, teeth, lips, urine and faeces.[Cha. Sa. VimanaSthana 8/106] These individuals have excellence in adipose tissue which is unctuous in nature.
Majja sara (excellence in majja dhatu) individuals too have unctuous complexion.[Cha. Sa. VimanaSthana 8/108] Majja dhatu is predominantly formed of jalamahabhuta.
Shukra sara (excellence in shukra dhatu) individuals have a gentle look, having eyes as if filled with milk, cheerfulness, having teeth which are unctuous, round, strong, even, beautiful, clean and have unctuous complexion with dazzling appearance.[Cha. Sa. VimanaSthana 8/109] Shukra dhatu or reproductive tissues are believed to be formed at the end from essence of all other dhatus. Thus it indicate the excellence of all dhatus.
Effect of dinacharya(daily regimen) on varna
A healthy daily regimen helps in maintaining a healthy varna. These regimens include following:
Consumption of food in proper quantity[Cha. Sa. Sutra Sthana 5/8]
Applying udvartana (massaging the body with soft, fragrant powder) [Ast. Hri. Sutra Sthana 2/15]
Maintaining the three supports of life viz. food, sleep and brahmacharya (avoidance of sexual act physically, mentally and verbally in all ways under any circumstances) in life[Cha. Sa. Sutra Sthana 11/35]
Use of rasayana[Cha. Sa. ChikitsaSthana 1/1/7] (the drug, food or therapy which has capacity to prevent ageing, improve longevity, provide immunity against the diseases, promote mental competence, increase vitality and lustre of the body).
Jatharagni (digestive capacity) is also responsible for complexion [Cha. Sa. ChikitsaSthana 15/3], hence such diet should be consumed which establishes a healthy jatharagni. Importance of diet in imparting good complexion is mentioned.[Cha. Sa. Sutra Sthana 27/349] [Cha. Sa. Sutra Sthana 27/3]. The food that is consumed is digested by jatharagni. This digestion produces nourishment to the dhatus (tissues) of the body. Healthy tissues are responsible for maintenance of healthy skin, thus indicating role of jatharagni in varna.
Ojas & varna
Ojas is the essence of the body tissues (dhatus) [Su. Sa. Sutra Sthana 15/24]. As healthy state of all dhatu keeps the skin healthy.Thusone of the functions of ojas is to maintain varna.[Su. Sa. Sutra Sthana 15/25] The qualitative deterioration (ojavyapat) causes impairment of complexion.[Su. Sa. Sutra Sthana 15/29]
Varna as an atmaja bhava
Ayurveda believes that six procreative factors affect the formation of foetus. One among these factors is atmaja (atma=soul, ja=emerging from) factor. Atmaja factor is belived to affect varna.[Cha. Sa. SharirSthana 3/10]
Importance of concept
Importance in diagnosis & prognosis of disease:
The natural complexion indicates a state of health or natural physiological processes inside the body. Sudden spontaneous change in natural complexion may be due to some pathology. Sudden drastic change in natural complexion may also indicate death in near future. Apart from discussing the natural complexion, some of the abnormal complexions like blue, grey, coppery, green and albino (extremely white)are described. [Cha. Sa. IndriyaSthana 1/9] Example, cyanotic complexion is observed in severe right ventricular hypertrophic cardiomyopathy.[6] The abnormalities includeif half of the body has natural complexion and the other have abnormal complexion, and both of them are evenly demarcated by a line.These normal and abnormal complexions may simultaneously appear in left and right sides, front and back sides, upper and lower parts or internal and external parts of the body. Natural and abnormal complexions simultaneously appearing in face or other parts of the body, are the morbid signs indicating imminent death.[Cha. Sa. IndriyaSthana 1/10] For example, amelanotic melanomas presenting as red skin lesions are often lethal.[7]
Clinical diagnosis based on varna:
Some diseases often have an impact on varna. Thus varna can be used as one of the diagnostic criterias for identification of diseases. Examples are as follows:
- Pandu (anaemia); Pale colour. [Cha. Sa. ChikitsaSthana 16/11]
- Kamla (jaundice): Yellowish [Cha. Sa. ChikitsaSthana 16/35]
- Vitiligo: Depigmented patches over skin.
- Albinism: Depigmentation of skin.
- Cyanosis: Bluish colour (may be due to heart defect).
Contemporary theories
Melanin vis-a-vis varna:
Melanin is produced by melanocytes in a process called melanogenesis. Melanin is made within small membrane–bound packages called melanosomes. As they become full of melanin, they move into the slender arms of melanocytes, from where they are transferred to the keratinocytes. Under normal conditions, melanosomes cover the upper part of the keratinocytes and protect them from genetic damage. One melanocyte supplies melanin to thirty-six keratinocytes according to signals from the keratinocytes. They also regulate melanin production and replication of melanocytes.[8] Individuals have different skin colours mainly because their melanocytes produce different amount and kinds of melanin.The genetic mechanism behind human skin colour is mainly regulated by the enzyme tyrosinase, which creates the colour of the skin, eyes, and hair shades.[9],[10] Differences in skin colour are also attributed to differences in size and distribution of melanosomes in the skin.[11] Both the amount and type of melanin produced is controlled by a number of genes that operate under incomplete dominance.[12] One copy of each of the various genes is inherited from each parent. Each gene can come in several alleles, resulting in the great variety of human skin tones.
Ultraviolet radiation & Varna:
Melanin controls the amount of ultraviolet radiation penetrating the skin. Moderate amount of ultraviolet radiation is required for production of vitamin D. Its excessive exposure is injurious to health. Thus, people living near equator, like natives of South Asia, Africa,etc, where the intensity of sunlight and ultraviolet radiation is more, have more melanin, hence darker skin. On the other hand, person living near pole are less exposed to sunlight and ultraviolet radiation, leading to less melanin production and hence lighter skin.
Haemoglobin and carotene on varna:
The pigment haemoglobin is responsible for pinkish or reddish colour of skin. While pigment carotene is for orange colour. These skin colours are more apparent in light skin coloured individuals.
Gender & Varna:
Females are usually significantly lighter in skin pigmentation than males. Females need more calcium during pregnancy and lactation. The body synthesizes vitamin D from sunlight, which helps to absorb calcium. Females evolved to have lighter skin so their bodies absorb more calcium.[13]
Assessment parameters
Varna can be assessed with naked eyes. However, the eyes are not able to distinguish between minute differences in skin complexion. Various devices that may be used or were used to assess the varna are the following:
- Fitzpatrick scale: It is a numerical classification schema for human skin colour.
- Von Luschan's chromatic scale: This equipment consists of 36 opaque glass tiles which were compared to the subject's skin, ideally in a place which would not be exposed to the sun (such as under the arm).
- Skin reflectance: These devices are typically pointed at the upper arm or forehead, with the emitted waves then interpreted at various percentages.
- Brown Paper Bag Test: The ‘Brown Paper Bag Test’ is a term in African-American oral history used to describe a colourist discriminatory practice within the African-American community in the 20th century, in which an individual's skin tone is compared to the colour of a brown paper bag.
- Tele-spectroradiometers (TSRs) and spectrophotometers (SPs): TSRs are used for measuring colour appearance such as in cosmetic industry for developing skin colour charts and evaluating skin products. SPs are mainly used for diagnosing skin disease symptom, such as erythema and irritation.
- Skintone Pen TP 20:It is a battery-operated probe to determine skin pigmentation (melanin) on a scale from 0-99.
Current researches
- Cosmetic approach of varna in Ayurveda[14]
The research article discusses the process and principles of varnotpatti (development of varna). Normal varna of an individual has to be considered under two headings: Sahaja (the colour and complexion, which is since birth, falls under this category) and Jatottara (due to exposure external factors like sun-exposure, hot atmosphere, humidity, pollution, etc sometimes the complexion of an individual becomes different from the one he was born with). - Understanding the concept of varnotpattiin Ayurveda[15]
The research article discusses the factors contributing in the formation of varna in foetal life (role of mahabhuta, semen, procreative factors, state of mind of mother, food and behaviour of mother, topography, race and genetics) and factors contributing in the process of varnotpatti after birth (role of digestive capability, food and method of consumption of food, body tissues, biological humors, metabolic wastes, ojas and age). - The concept of varna an Ayurvedic prospective[16]
Apart from other factors, this article also discusses the relation of varna with stress,ACTH and adrenocortical secretion. Almost any type of physical and mental stress can lead within minutes to greatly enhanced secretions of ACTH and consequently cortisol as well (> 20 folds). When ACTH is secreted by the anterior pituitary gland, several other hormones like melanocytes stimulating hormone (MSH), lipotropin, and endotrophin that have similar chemical structures are secreted simultaneously. The reason for this is the gene transcribed to form the RNA molecule that causes ACTH synthesis initially causes the formation of a considerably larger protein, a preprohormone called proopiomelanocortin (POMC), which is the precursor of ACTH and several other peptides, including MSH, beta-lipotropin, beta-endorphin and few others. Under normal condition, most of these hormones are not secreted in enough quantity by the pituitary. But when the rate of secretion of ACTH is high, some of the POMC derived hormones may also be increased. The POMC gene is actively transcribed in several tissues, like cells of dermis and lymphoid tissue. In melanocytes, located abundantly between the dermis and epidermis of the skin, MSH stimulates formation of black pigment melanin and disperses into the epidermis. On the other hand within minutes the entire sequence leads to large quantities of cortisol in blood. It circulates through blood to reach skin cells. It slows down the skin cells and make cells take long time to get to the surface and peel off. Therefore, the dead skin cells enhance, resulting lifeless and looks of the skin. Along with that overstress situation moves the blood away from the skin, and a little amount of blood moves around, which turns again insufficient supply of oxygen through the skin. In this process, the skin doesn’t get the required nourishment, which results in pale and dull skin.
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References
- ↑ Sturm R, Box N, Ramsay M. Human pigmentation genetics: the difference is only skin deep. doi:10.1002/(SICI)1521-1878(199809)20.
- ↑ Mitra J, editor, (1st ed.). Sasilekha Sanskrit Commentary by Indu on Astanga Samgrah of Vriddha Vagbhata, Sharir Sthana; Putrakamiyo Adhyaya: Chapter 1, Verse 61. Varanasi: Chowkhamba Sanskrit Series Office, 2016; 273.
- ↑ Dominguez-Salas P, Moore SE, Baker MS, Bergen AW, Cox SE, Dyer RA, Fulford AJ, Guan Y, Laritsky E, Silver MJ, Swan GE, Zeisel SH, Innis SM, Waterland RA, Prentice AM, Hennig BJ. Maternal nutrition at conception modulates DNA methylation of human metastable epialleles. Nat Commun. 2014 Apr 29;5:3746. doi: 10.1038/ncomms4746. PMID: 24781383; PMCID: PMC4015319.
- ↑ Pavan WJ, Sturm RA. The Genetics of Human Skin and Hair Pigmentation. Annu Rev Genomics Hum Genet. 2019 Aug 31;20:41-72. doi: 10.1146/annurev-genom-083118-015230. Epub 2019 May 17. PMID: 31100995.
- ↑ Sturm RA. Molecular genetics of human pigmentation diversity. Hum Mol Genet. 2009 Apr 15;18(R1):R9-17. doi: 10.1093/hmg/ddp003. PMID: 19297406.
- ↑ 6.0 6.1 Li M, Zhang L, Zhang Z, Wang S, Dong N, Wang G, Xie M. Isolated Severe Right Ventricular Hypertrophic Cardiomyopathy. Ann Thorac Surg. 2019 Jan;107(1):e23-e25. doi: 10.1016/j.athoracsur.2018.05.061. Epub 2018 Jun 23. PMID: 29944878.
- ↑ 7.0 7.1 McClain SE, Mayo KB, Shada AL, Smolkin ME, Patterson JW, Slingluff CL Jr. Amelanotic melanomas presenting as red skin lesions: a diagnostic challenge with potentially lethal consequences. Int J Dermatol. 2012 Apr;51(4):420-6. doi: 10.1111/j.1365-4632.2011.05066.x. PMID: 22435430; PMCID: PMC4465919.
- ↑ 8.0 8.1 Jablonski, Nina (2012). Living Color. Berkeley, Los Angeles, London: University of California Press. ISBN 978-0-520-25153-3.
- ↑ 9.0 9.1 Sturm, R. A. (2006). "A golden age of human pigmentation genetics". Trends in Genetics. 22 (9): 464–469. doi:10.1016/j.tig.2006.06.010. PMID 16857289
- ↑ 10.0 10.1 Sturm, R. A.; Teasdale, R. D.; Box, N. F. (2001). "Human pigmentation genes: Identification, structure and consequences of polymorphic variation". Gene. 277 (1–2): 49–62. doi:10.1016/s0378-1119(01)00694-1. PMID 11602344
- ↑ 11.0 11.1 Jablonski, Nina (2012). Living Color. Berkeley, Los Angeles, London: University of California Press. ISBN 978-0-520-25153-3.
- ↑ 12.0 12.1 Schneider, Patricia (2003). "The Genetics and Evolution of Skin Color: The Case of Desiree's Baby". RACE—The Power of an Illusion. Public Broadcasting Service. Archived from the original on 6 May 2015. Retrieved 14 April 2015.
- ↑ Jablonski NG, Chaplin G. The evolution of human skin coloration. J Hum Evol. 2000 Jul;39(1):57-106. doi: 10.1006/jhev.2000.0403. PMID: 10896812.
- ↑ Sonam, Meena KS, (2019). Cosmetic Approach of Varna in Ayurveda. International Journal of Research in Medical Sciences and Technology Vol. No. 8, Jul-Dec e-ISSN: 2455-5134, p-ISSN: 2455-9059 555.
- ↑ Bhaurao, D.S. (2017). Understanding the Concept of Varnotpatti in Ayurveda. International Journal of Innovative Research in Medical Science, 2(09), 1341 to 1345. https://doi.org/10.23958/ijirms/vol02-i09/20
- ↑ Brahma S, Sharma MK (2018). The Concept of Varna An Ayurvedic Prospective. World Journal of Pharmaceutical Research, Volume 7, Issue 18, 450-460. ISSN 2277–7105.