Ayurveda

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https://en.wikipedia.org/wiki/Ayurveda 

Ayurveda (/ˌɑːjʊərˈveɪdə, -ˈviː-/) is an alternative medicine system with historical roots in the Indian subcontinent. The theory and practice of Ayurveda is pseudoscientific. The Indian Medical Association (IMA) characterises the practice of modern medicine by Ayurvedic practitioners as quackery.

The main classical Ayurveda texts begin with accounts of the transmission of medical knowledge from the gods to sages, and then to human physicians. In Sushruta Samhita (Sushruta's Compendium), Sushruta wrote that Dhanvantari, Hindu god of Ayurveda, incarnated himself as a king of Varanasi and taught medicine to a group of physicians, including Sushruta. Ayurveda therapies have varied and evolved over more than two millennia. Therapies are typically based on complex herbal compounds, minerals and metal substances (perhaps under the influence of early Indian alchemy or rasa shastra). Ancient Ayurveda texts also taught surgical techniques, including rhinoplasty, kidney stone extractions, sutures, and the extraction of foreign objects. Ayurveda has been adapted for Western consumption, notably by Baba Hari Dass in the 1970s and Maharishi Ayurveda in the 1980s.

Some scholars assert that Ayurveda originated in prehistoric times, and that some of the concepts of Ayurveda have existed from the time of the Indus Valley Civilization or even earlier. Ayurveda developed significantly during the Vedic period and later some of the non-Vedic systems such as Buddhism and Jainism also developed medical concepts and practices that appear in the classical Ayurveda texts. Doṣa balance is emphasized, and suppressing natural urges is considered unhealthy and claimed to lead to illness. Ayurveda treatises describe three elemental doṣas viz. vāta, pitta and kapha, and state that balance (Skt. sāmyatva) of the doṣas results in health, while imbalance (viṣamatva) results in disease. Ayurveda treatises divide medicine into eight canonical components. Ayurveda practitioners had developed various medicinal preparations and surgical procedures from at least the beginning of the common era.

There is no good evidence that Ayurveda is effective for treating any disease. Ayurvedic preparations have been found to contain lead, mercury, and arsenic, substances known to be harmful to humans. In a 2008 study, close to 21% of U.S. and Indian-manufactured patent Ayurvedic medicines sold through the Internet were found to contain toxic levels of heavy metals, specifically lead, mercury, and arsenic. The public health implications of such metallic contaminants in India are unknown.

Eight components

The earliest classical Sanskrit works on Ayurveda describe medicine as being divided into eight components (Skt. aṅga). This characterization of the physicians' art, "the medicine that has eight components" (Skt. cikitsāyām aṣṭāṅgāyāṃ चिकित्सायामष्टाङ्गायाम्), is first found in the Sanskrit epic the Mahābhārata, c. 4th century BCE. The components are:

• Kāyachikitsā: general medicine, medicine of the body
• Kaumāra-bhṛtya (Pediatrics): Discussions about prenatal and postnatal care of baby and mother, methods of conception; choosing the child's gender, intelligence, and constitution; and childhood diseases and midwifery.
• Śalyatantra: surgical techniques and the extraction of foreign objects
• Śhālākyatantra: treatment of ailments affecting ears, eyes, nose, mouth, etc. ("ENT")
• Bhūtavidyā: pacification of possessing spirits, and the people whose minds are affected by such possession
• Agadatantra/Vishagara-vairodh Tantra (Toxicology): It includes subjects about epidemics, toxins in animals, vegetables and minerals. It as well contain keys for recognizing those anomalies and their antidotes.
• Rasāyantantra: rejuvenation and tonics for increasing lifespan, intellect and strength
• Vājīkaraṇatantra: aphrodisiacs and treatments for increasing the volume and viability of semen and sexual pleasure. It also deals with infertility problems (for those hoping to conceive) and spiritual development (transmutation of sexual energy into spiritual energy).

Principles and terminology

Shown in the image is Nagarjuna, known chiefly for his doctrine of the Madhyamaka (middle path). He wrote the medical works The Hundred Prescriptions and The Precious Collection, among others.

 

The three doṣhas and the five elements from which they are composed.

The word "ayurveda" is Sanskrit: आयुर्वेद, Āyurveda, meaning knowledge of life and longevity.

The central theoretical ideas of Ayurveda developed in the mid-first millennium BCE, and show parallels with Sāṅkhya and Vaiśeṣika philosophies, as well as with Buddhism and Jainism. Balance is emphasized, and suppressing natural urges is considered unhealthy and claimed to lead to illness. For example, to suppress sneezing is said to potentially give rise to shoulder pain. However, people are also cautioned to stay within the limits of reasonable balance and measure when following nature's urges. For example, emphasis is placed on moderation of food intake, sleep, and sexual intercourse.

According to ayurveda, the human body is composed of tissues (dhatus), waste (malas), and biomaterials (doshas). The seven dhatus are plasma (rasa), blood (rakta), muscles (māmsa), fat (meda), bone (asthi), marrow (majja), and semen (shukra). Like the medicine of classical antiquity, Ayurveda has historically divided bodily substances into five classical elements, (Sanskrit) panchamahabhuta, viz. earth, water, fire, air and ether. There are also twenty gunas (qualities or characteristics) which are considered to be inherent in all matter. These are organized in ten pairs: heavy/light, cold/hot, unctuous/dry, dull/sharp, stable/mobile, soft/hard, non-slimy/slimy, smooth/coarse, minute/gross, and viscous/liquid.

The three elemental bodily humors, the doshas or tridosha, are vata (space or air, equated with the nervous system), pitta (fire, equated with enzymes), and kapha (earth and water, equated with mucus). A parallel set of mental doshas termed satogun, rajogun, and tamogun control psychology. Each dosha has particular attributes and roles within the body and mind; the natural predominance of one or more doshas thus explains a person's physical constitution (prakriti) and personality. Ayurvedic tradition holds that imbalance among the bodily and mental doshas is a major etiologic component of disease. One Ayurvedic view is that the doshas are balanced when they are equal to each other, while another view is that each human possesses a unique combination of the doshas which define this person's temperament and characteristics. In either case, it says that each person should modulate their behavior or environment to increase or decrease the doshas and maintain their natural state. Practitioners of Ayurveda must determine an individual's bodily and mental dosha makeup, as certain prakriti are said to predispose one to particular diseases. For example, a person who is thin, shy, excitable, has a pronounced Adam's apple, and enjoys of esoteric knowledge is likely vata prakriti and therefore more susceptible to conditions such as flatulence, stuttering, and rheumatism. Deranged vata is also associated with certain mental disorders due to excited or excess vayu (gas), although the Ayurvedic text Charaka Samhita also attributes "insanity" (unmada) to cold food and possession by the ghost of a sinful Brahman (brahmarakshasa).

Ama (a Sanskrit word meaning "uncooked" or "undigested" ) is used to refer to the concept of anything that exists in a state of incomplete transformation. With regards to oral hygiene, it is claimed to be a toxic byproduct generated by improper or incomplete digestion. The concept has no equivalent in standard medicine.

In medieval taxonomies of the Sanskrit knowledge systems, Ayurveda is assigned a place as a subsidiary Veda (upaveda). Some medicinal plant names from the Atharvaveda and other Vedas can be found in subsequent Ayurveda literature. The earliest recorded theoretical statements about the canonical models of disease in Ayurveda occur in the earliest Buddhist Canon.

Practice

Ayurvedic practitioners regard physical existence, mental existence, and personality as their own unique units, with each element being able to influence the others. This is a holistic approach used during diagnosis and therapy, and is a fundamental aspect of Ayurveda. Another part of Ayurvedic treatment says that there are channels (srotas) which transport fluids, and that the channels can be opened up by massage treatment using oils and Swedana (fomentation). Unhealthy, or blocked, channels are thought to cause disease.

Diagnosis

Ayurveda has eight ways to diagnose illness, called Nadi (pulse), Mootra (urine), Mala (stool), Jihva (tongue), Shabda (speech), Sparsha (touch), Druk (vision), and Aakruti (appearance). Ayurvedic practitioners approach diagnosis by using the five senses. For example, hearing is used to observe the condition of breathing and speech. The study of the lethal points or marman marma is of special importance.

An Ayurvedic practitioner applying oils using head massage

Treatment and prevention

Two of the eight branches of classical Ayurveda deal with surgery (Śalya-cikitsā and Śālākya-tantra), but contemporary Ayurveda tends to stress attaining vitality by building a healthy metabolic system and maintaining good digestion and excretion. Ayurveda also focuses on exercise, yoga, and meditation. One type of prescription is a Sattvic diet.

Ayurveda follows the concept of Dinacharya, which says that natural cycles (waking, sleeping, working, meditation etc.) are important for health. Hygiene, including regular bathing, cleaning of teeth, oil pulling, tongue scraping, skin care, and eye washing, is also a central practice.

Substances used

Plant-based treatments in Ayurveda may be derived from roots, leaves, fruits, bark, or seeds such as cardamom and cinnamon. In the 19th century, William Dymock and co-authors summarized hundreds of plant-derived medicines along with the uses, microscopic structure, chemical composition, toxicology, prevalent myths and stories, and relation to commerce in British India. Animal products used in Ayurveda include milk, bones, and gallstones. In addition, fats are prescribed both for consumption and for external use. Consumption of minerals, including sulphur, arsenic, lead, copper sulfate and gold, are also prescribed. The addition of minerals to herbal medicine is called rasa shastra.

Ayurveda uses alcoholic beverages called Madya, which are said to adjust the doshas by increasing Pitta and reducing Vatta and Kapha. Madya are classified by the raw material and fermentation process, and the categories include: sugar-based, fruit-based, cereal-based, cereal-based with herbs, fermentated with vinegar, and tonic wines. The intended outcomes can include causing purgation, improving digestion or taste, creating dryness, or loosening joints. Ayurvedic texts describe Madya as non-viscid and fast-acting, and say that it enters and cleans minute pores in the body.

Purified opium is used in eight Ayurvedic preparations and is said to balance the Vata and Kapha doshas and increase the Pitta dosha. It is prescribed for diarrhea and dysentery, for increasing the sexual and muscular ability, and for affecting the brain. The sedative and pain-relieving properties of opium are considered in Ayurveda. The use of opium is found in the ancient Ayurvedic texts, and is first mentioned in the Sarngadhara Samhita (1300-1400 CE), a book on pharmacy used in Rajasthan in Western India, as an ingredient of an aphrodisiac to delay male ejaculation. It is possible that opium was brought to India along with or before Muslim conquests. The book Yoga Ratnakara (1700-1800 CE, unknown author), which is popular in Maharashtra, uses opium in a herbal-mineral composition prescribed for diarrhea. In the Bhaisajya Ratnavali, opium and camphor are used for acute gastroenteritis. In this drug, the respiratory depressant action of opium is counteracted by the respiratory stimulant property of Camphor. Later books have included the narcotic property for use as analgesic pain reliever.

Cannabis indica is also mentioned in the ancient Ayurveda books, and is first mentioned in the Sarngadhara Samhita as a treatment for diarrhea. In the Bhaisajya Ratnavali it is named as an ingredient in an aphrodisiac.

Ayurveda says that both oil and tar can be used to stop bleeding, and that traumatic bleeding can be stopped by four different methods: ligation of the blood vessel, cauterisation by heat, use of preparations to facilitate clotting, and use of preparations to constrict the blood vessels. Oils are also used in a number of ways, including regular consumption, anointing, smearing, head massage, application to affected areas, and oil pulling. Liquids may also be poured on the patient's forehead, a technique called shirodhara.

Cataract in human eye – magnified view seen on examination with a slit lamp. Cataract surgery is mentioned in the Sushruta Samhita, as a procedure to be performed with a jabamukhi salaka, a curved needle used to loosen the obstructing phlegm and push it out of the field of vision. The eye would later be soaked with warm butter and then bandaged.

Panchakarma

According to Ayurveda, panchakarma are techniques to eliminate toxic elements from the body.

Current status

A typical Ayurvedic pharmacy, Rishikesh

India

Tulsi-flower (holy basil), an Ayurvedic herb

According to some sources, up to 80 percent of people in India use Ayurveda exclusively or combined with conventional Western medicine.

In 1970, the Indian Medical Central Council Act which aimed to standardise qualifications for Ayurveda practitioners and provide accredited institutions for its study and research was passed by the Parliament of India. In 1971, the Central Council of Indian Medicine (CCIM) was established under the Department of Ayurveda, Yoga and Naturopathy, Unani, Siddha medicine and Homoeopathy (AYUSH), Ministry of Health and Family Welfare, to monitor higher education in Ayurveda in India. The Indian government supports research and teaching in Ayurveda through many channels at both the national and state levels, and helps institutionalise traditional medicine so that it can be studied in major towns and cities. The state-sponsored Central Council for Research in Ayurvedic Sciences (CCRAS) is designed to do research on Ayurveda. Many clinics in urban and rural areas are run by professionals who qualify from these institutes. As of 2013, India has over 180 training centers offer degrees in traditional Ayurvedic medicine.

To fight biopiracy and unethical patents, in 2001 the government of India set up the Traditional Knowledge Digital Library as a repository for formulations of various systems of Indian medicine, such as Ayurveda, Unani and Siddha. The formulations come from over 100 traditional Ayurveda books. An Indian Academy of Sciences document quoting a 2003-04 report states that India had 432,625 registered medical practitioners, 13,925 dispensaries, 2,253 hospitals and a bed strength of 43,803. 209 under-graduate teaching institutions and 16 post-graduate institutions. Insurance companies cover expenses for Ayurvedic treatments in case of conditions such as spinal cord disorders, bone disorder, arthritis and cancer. Such claims constitute 5-10 percent of the country's health insurance claims.

Maharashtra Andhashraddha Nirmoolan Samiti, an organisation dedicated to fighting superstition in India, considers Ayurveda to be pseudoscience.

On 9 November 2014, India formed the Ministry of AYUSH. National Ayurveda Day is also observed in India on the birth of Dhanvantari that is Dhanteras.

Other countries on the Indian subcontinent

About 75%-80% of the population of Nepal use Ayurveda, and it is the most practiced form of medicine in the country.

Ayurveda spas are common in Sri Lanka, and some function as home-based income generating activity.

The Sri Lankan tradition of Ayurveda is similar to the Indian tradition. Practitioners of Ayurveda in Sri Lanka refer to Sanskrit texts which are common to both countries. However, they do differ in some aspects, particularly in the herbs used.

In 1980, the Sri Lankan government established a Ministry of Indigenous Medicine to revive and regulate Ayurveda. The Institute of Indigenous Medicine (affiliated to the University of Colombo) offers undergraduate, postgraduate, and MD degrees in Ayurveda Medicine and Surgery, and similar degrees in unani medicine. In the public system, there are currently 62 Ayurvedic hospitals and 208 central dispensaries, which served about 3 million people (about 11% of Sri Lanka's population) in 2010. In total, there are about 20,000 registered practitioners of Ayurveda in the country.

According to the Mahavamsa, an ancient chronicle of Sinhalese royalty from the sixth century C.E., King Pandukabhaya of Sri Lanka (reigned 437 BCE to 367 BCE) had lying-in-homes and Ayurvedic hospitals (Sivikasotthi-Sala) built in various parts of the country. This is the earliest documented evidence available of institutions dedicated specifically to the care of the sick anywhere in the world. Mihintale Hospital is the oldest in the world.

Outside the Indian subcontinent

Ayurveda is a system of traditional medicine developed during antiquity and the medieval period, and as such is comparable to pre-modern Chinese and European systems of medicine. However, beginning in the 1960s, Ayurveda has been advertised as alternative medicine in the Western world. Due to different laws and medical regulations in the rest of the world, the unregulated practice and commercialisation of Ayurveda have raised ethical and legal issues. In some instances, Ayurvedic practices or terminology have also been adapted specifically for Western consumption, notably in the case of "Maharishi Ayurveda" in the 1980s. In some cases, this involved active fraud on the part of proponents of Ayurveda in an attempt to falsely represent the system as equal to the standards of modern medical research.

Baba Hari Dass was an early proponent who helped bring Ayurveda to the US in the early 1970s. He taught classes derived from the Suśrutha Saṃhitā and the Charaka Saṃhitha, leading to the establishment of the Mount Madonna Institute, College of Ayurveda, Ayurveda World, and Ayurvedic pharmacy. He invited several notable Ayurvedic teachers, including Vasant Lad, Sarita Shrestha, and Ram Harsh Singh. The Ayurvedic practitioner Michael Tierra wrote that "[t]he history of Ayurveda in North America will always owe a debt to the selfless contributions of Baba Hari Dass."

In the United States, the practice of Ayurveda is not licensed or regulated by any state. The National Center for Complementary and Integrative Health says that "Few well-designed clinical trials and systematic research reviews suggest that Ayurvedic approaches are effective", warns against the issue of heavy metal poisoning, and emphasises the use of conventional health providers first.

Classification and efficacy

Although laboratory experiments suggest it is possible that some substances in Ayurveda might be developed into effective treatments, there is no evidence that any are effective in themselves. Cancer Research UK states that there is no evidence that ayurvedic medicine helps treat cancer in people, and some Ayurvedic drugs contain toxic substances or interact with legitimate cancer drugs in a harmful way.

Ayurvedic medicine is considered pseudoscientific because it confuses reality and metaphysical concepts, and because its premises are not based on science. Ethnologist Johannes Quack writes than although the rationalist movement Maharashtra Andhashraddha Nirmoolan Samiti officially labels Ayurveda – like astrology – a pseudoscience, these practices are in fact embraced by many of the movement's members.

A review of the use of Ayurveda for cardiovascular disease concluded that the evidence is not convincing for the use of any Ayurvedic herbal treatment for heart disease or hypertension, but that many herbs used by Ayurvedic practitioners could be appropriate for further research.

Research into ayurveda has been characterized as pseudoscience. Both the lack of scientific soundness in the theoretical foundations of ayurveda and the quality of research have been criticized.

Research

In India, research in Ayurveda is undertaken by the Ministry of AYUSH, an abbreviation for the Department of Ayurveda, Yoga and Naturopathy, Unani, Siddha and Homoeopathy, through a national network of research institutes.

In Nepal, the National Ayurvedic Training and Research Centre (NATRC) researches medicinal herbs in the country.

In Sri Lanka, the Ministry of Health, Nutrition and Indigenous Medicine looks after the research in Ayurveda through various national research institutes.

Use of toxic metals

Rasa shastra, the practice of adding metals, minerals or gems to herbal preparations, may include toxic heavy metals such as lead, mercury and arsenic. The public health implications of metals in rasa shastra in India is unknown. Adverse reactions to herbs are described in traditional Ayurvedic texts, but practitioners are reluctant to admit that herbs could be toxic and that reliable information on herbal toxicity is not readily available. There is a communication gap between practitioners of modern medicine and Ayurveda.

Some traditional Indian herbal medicinal products contain harmful levels of heavy metals, including lead. For example, ghasard, a product commonly given to infants for digestive issues, has been found to have up to 1.6% lead concentration by weight, leading to lead encephalopathy. A 1990 study on Ayurvedic medicines in India found that 41% of the products tested contained arsenic, and that 64% contained lead and mercury. A 2004 study found toxic levels of heavy metals in 20% of Ayurvedic preparations made in South Asia and sold in the Boston area, and concluded that Ayurvedic products posed serious health risks and should be tested for heavy-metal contamination. A 2008 study of more than 230 products found that approximately 20% of remedies (and 40% of rasa shastra medicines) purchased over the Internet from U.S. and Indian suppliers contained lead, mercury or arsenic. A 2015 study of users in the United States found elevated blood lead levels in 40% of those tested, leading physician and former U.S. Air Force flight surgeon Harriet Hall to say that "Ayurveda is basically superstition mixed with a soupçon of practical health advice. And it can be dangerous."

Heavy metals are thought of as active ingredients by advocates of Indian herbal medicinal products. According to ancient Ayurvedic texts, certain physico-chemical purification processes such as samskaras or shodhanas (for metals) 'detoxify' the heavy metals in it. These are similar to the Chinese pao zhi, although the Ayurvedic techniques are more complex and may involve physical pharmacy techniques as well as mantras. However, these products have nonetheless caused severe lead poisoning and other toxic effects. Between 1978 and 2008, "more than 80 cases of lead poisoning associated with Ayurvedic medicine use [were] reported worldwide". In 2012, the U.S. Centers for Disease Control and Prevention (CDC) linked Ayurvedic drugs to lead poisoning, based on cases where toxic materials were found in the blood of pregnant women who had taken Ayurvedic drugs.

Ayurvedic practitioners argue that the toxicity of bhasmas (ash products) comes from improper manufacturing processes, contaminants, improper use of Ayurvedic medicine, quality of raw materials and that the end products and improper procedures are used by charlatans.

In India, the government ruled that Ayurvedic products must be labelled with their metallic content. However, in Current Science, a publication of the Indian Academy of Sciences, M. S. Valiathan said that "the absence of post-market surveillance and the paucity of test laboratory facilities [in India] make the quality control of Ayurvedic medicines exceedingly difficult at this time". In the United States, most Ayurvedic products are marketed without having been reviewed or approved by the FDA. Since 2007, the FDA has placed an import alert on some Ayurvedic products in order to prevent them from entering the United States. A 2012 toxicological review of mercury-based traditional herbo-metallic preparations concluded that the long-term pharmacotherapeutic and in-depth toxicity studies of these preparations are lacking.

History

According to modern Ayurvedic sources, the origins of Ayurveda have been traced to around 6,000 BCE when they originated as an oral tradition. Some of the concepts of Ayurveda have existed since the times of Indus Valley Civilization. The first recorded forms of Ayurveda as medical texts evolved from the Vedas. Ayurveda is a discipline of the upaveda or "auxiliary knowledge" in Vedic tradition. The origins of Ayurveda are also found in Atharvaveda, which contains 114 hymns and incantations described as magical cures for disease. There are various legendary accounts of the origin of Ayurveda, e.g. that it was received by Dhanvantari (or Divodasa) from Brahma. Tradition also holds that the writings of Ayurveda were influenced by a lost text by the sage Agnivesa.

Ayurveda is one of the few systems of medicine developed in ancient times that is still widely practiced in modern times. As such, it is open to the criticism that its conceptual basis is obsolete and that its contemporary practitioners have not taken account of the developments of modern medicine. Responses to this situation led to an impassioned debate in India during the early decades of the twentieth century, between proponents of unchanging tradition (śuddha "pure" ayurveda) and those who thought ayurveda should modernise and syncretize (aśuddha "impure, tainted" ayurveda). The political debate about the place of ayurveda in contemporary India has continued to the present (2015), both in the public arena and in government. Debate about the place of Ayurvedic medicine in the contemporary internationalized world also continues today (2015).

Charaka

Main texts

There are three principal early texts on Ayurveda, the Charaka Samhita, the Sushruta Samhita and the Bhela Samhita. The dating of these works is historically complicated since they each internally present themselves as composite works compiled by several editors. All past scholarship on their dating has been evaluated by Meulenbeld in volumes IA and IB of his History of Indian Medical Literature. After considering the evidence and arguments concerning the Suśrutasaṃhitā, Meulenbeld states (IA, 348), "The Suśrutasaṃhitā is most probably the work of an unknown author who drew much of the material he incorporated in his treatise from a multiplicity of earlier sources from various periods. This may explain that many scholars yield to the temptation to recognize a number of distinct layers and, consequently, try to identify elements belonging to them. As we have seen, the identification of features thought to belong to a particular stratum is in many cases determined by preconceived ideas on the age of the strata and their supposed authors." The dating of this work to 600 BC was first proposed by Hoernle over a century ago, but has long since been overturned by subsequent historical research. The current consensus amongst medical historians of South Asia is that the Suśrutasaṃhitā was compiled over a period of time starting with a kernel of medical ideas from the century or two BCE and then being revised by several hands into its present form by about 500 CE. The view that the text was updated by the Buddhist scholar Nagarjuna in the 2nd century CE has been disproved, although the last chapter of the work, the Uttaratantra, was added by an unknown later author before 500 CE.

Similar arguments apply to the Charaka Samhita, written by Charaka, and the Bhela Samhita, attributed to Atreya Punarvasu, that are also dated to the 6th century BCE by non-specialist scholars but are in fact, in their present form, datable to a period between the second and fifth centuries CE. The Charaka Samhita was also updated by Dridhabala during the early centuries of the Common Era.

The Bower Manuscript (dated to the Gupta era, between the 4th and the 6th century CE) includes of excerpts from the Bheda Samhita and its description of concepts in Central Asian Buddhism. In 1987, A. F. R. Hoernle identified the scribe of the medical portions of the manuscript to be a native of India using a northern variant of the Gupta script, who had migrated and become a Buddhist monk in a monastery in Kucha. The Chinese pilgrim Fa Hsien (c. 337–422 AD) wrote about the healthcare system of the Gupta empire (320–550) and described the institutional approach of Indian medicine. This is also visible in the works of Charaka, who describes hospitals and how they should be equipped.

Other early texts are the Agnivesha Samhita, Kasyapa Samhita and Harita Samhita. The original edition of the Agnivesha Samhita, by Agnivesa, is dated to 1500 BCE, and it was later modified by Charaka. Kasyapa Samhita includes the treatise of Jivaka Kumar Bhaccha and is dated to the 6th century BCE. While Harita Samhita is dated to an earlier period, it is attributed to Harita, who was a disciple of Punarvasu Atreya. Some later texts are Astanga nighantu (8th Century) by Vagbhata, Paryaya ratnamala (9th century) by Madhava, Siddhasara nighantu (9th century) by Ravi Gupta, Dravyavali (10th Century), and Dravyaguna sangraha (11th century) by Chakrapani Datta, among others.

Illnesses portrayed

Underwood and Rhodes state that the early forms of traditional Indian medicine identified fever, cough, consumption, diarrhea, dropsy, abscesses, seizures, tumours, and leprosy, and that treatments included plastic surgery, lithotomy, tonsillectomy, couching (a form of cataract surgery), puncturing to release fluids in the abdomen, extraction of foreign bodies, treatment of anal fistulas, treating fractures, amputations, cesarean sections, and stitching of wounds. The use of herbs and surgical instruments became widespread. During this period, treatments were also prescribed for complex ailments, including angina pectoris, diabetes, hypertension, and stones.

Further development and spread

Ayurveda flourished throughout the Indian Middle Ages. Dalhana (fl. 1200), Sarngadhara (fl. 1300) and Bhavamisra (fl. 1500) compiled works on Indian medicine. The medical works of both Sushruta and Charaka were also translated into the Chinese language in the 5th century, and during the 8th century, they were translated into the Arabic and Persian language. The 9th-century Persian physician Muhammad ibn Zakariya al-Razi was familiar with the text. The Arabic works derived from the Ayurvedic texts eventually also reached Europe by the 12th century. In Renaissance Italy, the Branca family of Sicily and Gaspare Tagliacozzi (Bologna) were influenced by the Arabic reception of the Sushruta's surgical techniques.

British physicians traveled to India to observe rhinoplasty being performed using Indian methods, and reports on their rhinoplasty methods were published in the Gentleman's Magazine in 1794. Instruments described in the Sushruta Samhita were further modified in Europe. Joseph Constantine Carpue studied plastic surgery methods in India for 20 years and, in 1815, was able to perform the first major rhinoplasty surgery in the western world, using the "Indian" method of nose reconstruction. In 1840 Brett published an article about this technique.

During the period of British colonial rule in India, the practice of Ayurveda was not adopted by the British Indian Government, which was in favor of modern medicine. After Indian independence, there was more focus on Ayurveda and other traditional medical systems. Ayurveda became a part of the Indian National health care system, with state hospitals for Ayurveda established across the country. However, the treatments of traditional medicines were not always integrated with others.

Lamarckism

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Lamarckism 

Lamarckism, also known as Lamarckian inheritance or neo-Lamarckism, is the notion that an organism can pass on to its offspring physical characteristics that the parent organism acquired through use or disuse during its lifetime. It is also called the inheritance of acquired characteristics or more recently soft inheritance. The idea is named after the French zoologist Jean-Baptiste Lamarck (1744–1829), who incorporated the classical era theory of soft inheritance into his theory of evolution as a supplement to his concept of orthogenesis, a drive towards complexity.

Introductory textbooks contrast Lamarckism with Charles Darwin's theory of evolution by natural selection. Darwin's book On the Origin of Species however supported the Lamarckian idea of use and disuse inheritance, and his own concept of pangenesis implied a Lamarckian soft inheritance.

Many researchers from the 1860s onwards attempted to find evidence for Lamarckian inheritance, but these have all been explained away, either by other mechanisms such as genetic contamination or as fraud. August Weismann's experiment, considered definitive in its time, is now considered to have failed to disprove Lamarckism, as it did not address use and disuse. Later, Mendelian genetics supplanted the notion of inheritance of acquired traits, eventually leading to the development of the modern synthesis, and the general abandonment of Lamarckism in biology. Despite this, interest in Lamarckism has continued.

Studies in the fields of epigenetics, genetics, and somatic hypermutation have highlighted the possible inheritance of traits acquired by the previous generation. The characterization of these findings as Lamarckism has been disputed. The inheritance of the hologenome, consisting of the genomes of all an organism's symbiotic microbes as well as its own genome, is also somewhat Lamarckian in effect, though entirely Darwinian in its mechanisms.

Early history

Origins

Jean-Baptiste Lamarck repeated the ancient folk wisdom of the inheritance of acquired characteristics.

The inheritance of acquired characteristics was proposed in ancient times, and remained a current idea for many centuries. The historian of science Conway Zirkle wrote in 1935 that:

Lamarck was neither the first nor the most distinguished biologist to believe in the inheritance of acquired characters. He merely endorsed a belief which had been generally accepted for at least 2,200 years before his time and used it to explain how evolution could have taken place. The inheritance of acquired characters had been accepted previously by Hippocrates, Aristotle, Galen, Roger Bacon, Jerome Cardan, Levinus Lemnius, John Ray, Michael Adanson, Jo. Fried. Blumenbach and Erasmus Darwin among others.

Zirkle noted that Hippocrates described pangenesis, the theory that what is inherited derives from the whole body of the parent, whereas Aristotle thought it impossible; but that all the same, Aristotle implicitly agreed to the inheritance of acquired characteristics, giving the example of the inheritance of a scar, or of blindness, though noting that children do not always resemble their parents. Zirkle recorded that Pliny the Elder thought much the same. Zirkle also pointed out that stories involving the idea of inheritance of acquired characteristics appear numerous times in ancient mythology and the Bible, and persisted through to Rudyard Kipling's Just So Stories. Erasmus Darwin's Zoonomia (c. 1795) suggested that warm-blooded animals develop from "one living filament... with the power of acquiring new parts" in response to stimuli, with each round of "improvements" being inherited by successive generations.

Darwin's pangenesis

Charles Darwin's pangenesis theory. Every part of the body emits tiny gemmules which migrate to the gonads and contribute to the next generation via the fertilised egg. Changes to the body during an organism's life would be inherited, as in Lamarckism.

Charles Darwin's On the Origin of Species proposed natural selection as the main mechanism for development of species, but did not rule out a variant of Lamarckism as a supplementary mechanism. Darwin called this pangenesis, and explained it in the final chapter of his book The Variation of Animals and Plants Under Domestication (1868), after describing numerous examples to demonstrate what he considered to be the inheritance of acquired characteristics. Pangenesis, which he emphasised was a hypothesis, was based on the idea that somatic cells would, in response to environmental stimulation (use and disuse), throw off 'gemmules' or 'pangenes' which travelled around the body, though not necessarily in the bloodstream. These pangenes were microscopic particles that supposedly contained information about the characteristics of their parent cell, and Darwin believed that they eventually accumulated in the germ cells where they could pass on to the next generation the newly acquired characteristics of the parents.

Darwin's half-cousin, Francis Galton, carried out experiments on rabbits, with Darwin's cooperation, in which he transfused the blood of one variety of rabbit into another variety in the expectation that its offspring would show some characteristics of the first. They did not, and Galton declared that he had disproved Darwin's hypothesis of pangenesis, but Darwin objected, in a letter to the scientific journal Nature, that he had done nothing of the sort, since he had never mentioned blood in his writings. He pointed out that he regarded pangenesis as occurring in protozoa and plants, which have no blood, as well as in animals.

Lamarck's evolutionary framework

Lamarck's two-factor theory involves 1) a complexifying force that drives animal body plans towards higher levels (orthogenesis) creating a ladder of phyla, and 2) an adaptive force that causes animals with a given body plan to adapt to circumstances (use and disuse, inheritance of acquired characteristics), creating a diversity of species and genera. Lamarckism is the name now widely used for the adaptive force.

Between 1800 and 1830, Lamarck proposed a systematic theoretical framework for understanding evolution. He saw evolution as comprising four laws:

1. "Life by its own force, tends to increase the volume of all organs which possess the force of life, and the force of life extends the dimensions of those parts up to an extent that those parts bring to themselves;"
2. "The production of a new organ in an animal body, results from a new requirement arising. and which continues to make itself felt, and a new movement which that requirement gives birth to, and its upkeep/maintenance;"
3. "The development of the organs, and their ability, are constantly a result of the use of those organs."
4. "All that has been acquired, traced, or changed, in the physiology of individuals, during their life, is conserved through the genesis, reproduction, and transmitted to new individuals who are related to those who have undergone those changes."

Lamarck's discussion of heredity

In 1830, in an aside from his evolutionary framework, Lamarck briefly mentioned two traditional ideas in his discussion of heredity, in his day considered to be generally true. The first was the idea of use versus disuse; he theorized that individuals lose characteristics they do not require, or use, and develop characteristics that are useful. The second was to argue that the acquired traits were heritable. He gave as an imagined illustration the idea that when giraffes stretch their necks to reach leaves high in trees, they would strengthen and gradually lengthen their necks. These giraffes would then have offspring with slightly longer necks. In the same way, he argued, a blacksmith, through his work, strengthens the muscles in his arms, and thus his sons would have similar muscular development when they mature. Lamarck stated the following two laws:

1. Première Loi: Dans tout animal qui n' a point dépassé le terme de ses développemens, l' emploi plus fréquent et soutenu d' un organe quelconque, fortifie peu à peu cet organe, le développe, l' agrandit, et lui donne une puissance proportionnée à la durée de cet emploi; tandis que le défaut constant d' usage de tel organe, l'affoiblit insensiblement, le détériore, diminue progressivement ses facultés, et finit par le faire disparoître.
2. Deuxième Loi: Tout ce que la nature a fait acquérir ou perdre aux individus par l' influence des circonstances où leur race se trouve depuis long-temps exposée, et, par conséquent, par l' influence de l' emploi prédominant de tel organe, ou par celle d' un défaut constant d' usage de telle partie; elle le conserve par la génération aux nouveaux individus qui en proviennent, pourvu que les changemens acquis soient communs aux deux sexes, ou à ceux qui ont produit ces nouveaux individus.

English translation:

1. First Law [Use and Disuse]: In every animal which has not passed the limit of its development, a more frequent and continuous use of any organ gradually strengthens, develops and enlarges that organ, and gives it a power proportional to the length of time it has been so used; while the permanent disuse of any organ imperceptibly weakens and deteriorates it, and progressively diminishes its functional capacity, until it finally disappears.
2. Second Law [Soft Inheritance]: All the acquisitions or losses wrought by nature on individuals, through the influence of the environment in which their race has long been placed, and hence through the influence of the predominant use or permanent disuse of any organ; all these are preserved by reproduction to the new individuals which arise, provided that the acquired modifications are common to both sexes, or at least to the individuals which produce the young.

In essence, a change in the environment brings about change in "needs" (besoins), resulting in change in behaviour, causing change in organ usage and development, bringing change in form over time—and thus the gradual transmutation of the species. The evolutionary biologists and historians of science Conway Zirkle, Michael Ghiselin, and Stephen Jay Gould have pointed out, these ideas were not original to Lamarck.

Weismann's experiment

August Weismann's germ plasm theory. The hereditary material, the germ plasm, is confined to the gonads and the gametes. Somatic cells (of the body) develop afresh in each generation from the germ plasm, creating an invisible "Weismann barrier" to Lamarckian influence from the soma to the next generation.

August Weismann's germ plasm theory held that germline cells in the gonads contain information that passes from one generation to the next, unaffected by experience, and independent of the somatic (body) cells. This implied what came to be known as the Weismann barrier, as it would make Lamarckian inheritance from changes to the body difficult or impossible.

Weismann conducted the experiment of removing the tails of 68 white mice, and those of their offspring over five generations, and reporting that no mice were born in consequence without a tail or even with a shorter tail. In 1889, he stated that "901 young were produced by five generations of artificially mutilated parents, and yet there was not a single example of a rudimentary tail or of any other abnormality in this organ." The experiment, and the theory behind it, were thought at the time to be a refutation of Lamarckism.

The experiment's effectiveness in refuting Lamarck's hypothesis is doubtful, as it did not address the use and disuse of characteristics in response to the environment. The biologist Peter Gauthier noted in 1990 that:

Can Weismann's experiment be considered a case of disuse? Lamarck proposed that when an organ was not used, it slowly, and very gradually atrophied. In time, over the course of many generations, it would gradually disappear as it was inherited in its modified form in each successive generation. Cutting the tails off mice does not seem to meet the qualifications of disuse, but rather falls in a category of accidental misuse... Lamarck's hypothesis has never been proven experimentally and there is no known mechanism to support the idea that somatic change, however acquired, can in some way induce a change in the germplasm. On the other hand it is difficult to disprove Lamarck's idea experimentally, and it seems that Weismann's experiment fails to provide the evidence to deny the Lamarckian hypothesis, since it lacks a key factor, namely the willful exertion of the animal in overcoming environmental obstacles.

Ghiselin also considered the Weismann tail-chopping experiment to have no bearing on the Lamarckian hypothesis, writing in 1994 that:

The acquired characteristics that figured in Lamarck's thinking were changes that resulted from an individual's own drives and actions, not from the actions of external agents. Lamarck was not concerned with wounds, injuries or mutilations, and nothing that Lamarck had set forth was tested or "disproven" by the Weismann tail-chopping experiment.

The historian of science Rasmus Winther stated that Weismann had nuanced views about the role of the environment on the germ plasm. Indeed, like Darwin, he consistently insisted that a variable environment was necessary to cause variation in the hereditary material.

Textbook Lamarckism

The long neck of the giraffe is often used as an example in popular explanations of Lamarckism. However, this was only a small part of his theory of evolution towards "perfection"; it was a hypothetical illustration; and he used it to discuss his theory of heredity, not evolution.

The identification of Lamarckism with the inheritance of acquired characteristics is regarded by evolutionary biologists including Ghiselin as a falsified artifact of the subsequent history of evolutionary thought, repeated in textbooks without analysis, and wrongly contrasted with a falsified picture of Darwin's thinking. Ghiselin notes that "Darwin accepted the inheritance of acquired characteristics, just as Lamarck did, and Darwin even thought that there was some experimental evidence to support it." Gould wrote that in the late 19th century, evolutionists "re-read Lamarck, cast aside the guts of it ... and elevated one aspect of the mechanics—inheritance of acquired characters—to a central focus it never had for Lamarck himself." He argued that "the restriction of 'Lamarckism' to this relatively small and non-distinctive corner of Lamarck's thought must be labelled as more than a misnomer, and truly a discredit to the memory of a man and his much more comprehensive system."

Neo-Lamarckism

Context

Edward Drinker Cope

The period of the history of evolutionary thought between Darwin's death in the 1880s, and the foundation of population genetics in the 1920s and the beginnings of the modern evolutionary synthesis in the 1930s, is called the eclipse of Darwinism by some historians of science. During that time many scientists and philosophers accepted the reality of evolution but doubted whether natural selection was the main evolutionary mechanism.

Among the most popular alternatives were theories involving the inheritance of characteristics acquired during an organism's lifetime. Scientists who felt that such Lamarckian mechanisms were the key to evolution were called neo-Lamarckians. They included the British botanist George Henslow (1835–1925), who studied the effects of environmental stress on the growth of plants, in the belief that such environmentally-induced variation might explain much of plant evolution, and the American entomologist Alpheus Spring Packard, Jr., who studied blind animals living in caves and wrote a book in 1901 about Lamarck and his work. Also included were paleontologists like Edward Drinker Cope and Alpheus Hyatt, who observed that the fossil record showed orderly, almost linear, patterns of development that they felt were better explained by Lamarckian mechanisms than by natural selection. Some people, including Cope and the Darwin critic Samuel Butler, felt that inheritance of acquired characteristics would let organisms shape their own evolution, since organisms that acquired new habits would change the use patterns of their organs, which would kick-start Lamarckian evolution. They considered this philosophically superior to Darwin's mechanism of random variation acted on by selective pressures. Lamarckism also appealed to those, like the philosopher Herbert Spencer and the German anatomist Ernst Haeckel, who saw evolution as an inherently progressive process. The German zoologist Theodor Eimer combined Larmarckism with ideas about orthogenesis, the idea that evolution is directed towards a goal.

With the development of the modern synthesis of the theory of evolution, and a lack of evidence for a mechanism for acquiring and passing on new characteristics, or even their heritability, Lamarckism largely fell from favour. Unlike neo-Darwinism, neo-Lamarckism is a loose grouping of largely heterodox theories and mechanisms that emerged after Lamarck's time, rather than a coherent body of theoretical work.

19th century

Charles-Édouard Brown-Séquard tried to demonstrate Lamarckism by mutilating guinea pigs.

Neo-Lamarckian versions of evolution were widespread in the late 19th century. The idea that living things could to some degree choose the characteristics that would be inherited allowed them to be in charge of their own destiny as opposed to the Darwinian view, which placed them at the mercy of the environment. Such ideas were more popular than natural selection in the late 19th century as it made it possible for biological evolution to fit into a framework of a divine or naturally willed plan, thus the neo-Lamarckian view of evolution was often advocated by proponents of orthogenesis. According to the historian of science Peter J. Bowler, writing in 2003:

One of the most emotionally compelling arguments used by the neo-Lamarckians of the late nineteenth century was the claim that Darwinism was a mechanistic theory which reduced living things to puppets driven by heredity. The selection theory made life into a game of Russian roulette, where life or death was predetermined by the genes one inherited. The individual could do nothing to mitigate bad heredity. Lamarckism, in contrast, allowed the individual to choose a new habit when faced with an environmental challenge and shape the whole future course of evolution.

Scientists from the 1860s onwards conducted numerous experiments that purported to show Lamarckian inheritance. Some examples are described in the table.

19th century experiments attempting to demonstrate Lamarckian inheritance

Scientist	Date	Experiment	Claimed result	Rebuttal
Charles-Édouard Brown-Séquard	1869 to 1891	Cut sciatic nerve and dorsal spinal cord of guinea pigs, causing abnormal nervous condition resembling epilepsy	Epileptic offspring	Not Lamarckism, as no use and disuse in response to environment; results could not be replicated; cause possibly a transmitted disease
Gaston Bonnier	1884, 1886	Transplant plants at different altitudes in Alps, Pyrenees	Acquired adaptations	Not controlled from weeds; likely cause genetic contamination
Joseph Thomas Cunningham	1891, 1893, 1895	Shine light on underside of flatfish	Inherited production of pigment	Disputed cause
Max Standfuss	1892 to 1917	Raise butterflies at low temperature	Variations in offspring even without low temperature	Richard Goldschmidt agreed; Ernst Mayr "difficult to interpret".

Early 20th century

Paul Kammerer claimed in the 1920s to have found evidence for Lamarckian inheritance in midwife toads, in a case celebrated by the journalist Arthur Koestler, but the results are thought to be either fraudulent or at best misinterpreted.

A century after Lamarck, scientists and philosophers continued to seek mechanisms and evidence for the inheritance of acquired characteristics. Experiments were sometimes reported as successful, but from the beginning these were either criticised on scientific grounds or shown to be fakes. For instance, in 1906, the philosopher Eugenio Rignano argued for a version that he called "centro-epigenesis", but it was rejected by most scientists. Some of the experimental approaches are described in the table.

Early 20th century experiments attempting to demonstrate Lamarckian inheritance

Scientist	Date	Experiment	Claimed result	Rebuttal
William Lawrence Tower	1907 to 1910	Colorado potato beetles in extreme humidity, temperature	Heritable changes in size, colour	Criticised by William Bateson; Tower claimed all results lost in fire; William E. Castle visited laboratory, found fire suspicious, doubted claim that steam leak had killed all beetles, concluded faked data.
Gustav Tornier	1907 to 1918	Goldfish, embryos of frogs, newts	Abnormalities inherited	Disputed; possibly an osmotic effect
Charles Rupert Stockard	1910	Repeated alcohol intoxication of pregnant guinea pigs	Inherited malformations	Raymond Pearl unable to reproduce findings in chickens; Darwinian explanation
Francis Bertody Sumner	1921	Reared mice at different temperatures, humidities	Inherited longer bodies, tails, hind feet	Inconsistent results
Michael F. Guyer, Elizabeth A. Smith	1918 to 1924	Injected fowl serum antibodies for rabbit lens-protein into pregnant rabbits	Eye defects inherited for 8 generations	Disputed, results not replicated
Paul Kammerer	1920s	Midwife toad	Black foot-pads inherited	Fraud, ink injected; or, results misinterpreted; case celebrated by Arthur Koestler arguing that opposition was political
William McDougall	1920s	Rats solving mazes	Offspring learnt mazes quicker (20 vs 165 trials)	Poor experimental controls
John William Heslop-Harrison	1920s	Peppered moths exposed to soot	Inherited mutations caused by soot	Failure to replicate results; implausible mutation rate
Ivan Pavlov	1926	Conditioned reflex in mice to food and bell	Offspring easier to condition	Pavlov retracted claim; results not replicable
Coleman Griffith, John Detlefson	1920 to 1925	Reared rats on rotating table for 3 months	Inherited balance disorder	Results not replicable; likely cause ear infection
Victor Jollos [pl]	1930s	Heat treatment in Drosophila melanogaster	Directed mutagenesis, a form of orthogenesis	Results not replicable

Late 20th century

The British anthropologist Frederic Wood Jones and the South African paleontologist Robert Broom supported a neo-Lamarckian view of human evolution. The German anthropologist Hermann Klaatsch relied on a neo-Lamarckian model of evolution to try and explain the origin of bipedalism. Neo-Lamarckism remained influential in biology until the 1940s when the role of natural selection was reasserted in evolution as part of the modern evolutionary synthesis. Herbert Graham Cannon, a British zoologist, defended Lamarckism in his 1959 book Lamarck and Modern Genetics. In the 1960s, "biochemical Lamarckism" was advocated by the embryologist Paul Wintrebert.

Neo-Lamarckism was dominant in French biology for more than a century. French scientists who supported neo-Lamarckism included Edmond Perrier (1844–1921), Alfred Giard (1846–1908), Gaston Bonnier (1853–1922) and Pierre-Paul Grassé (1895–1985). They followed two traditions, one mechanistic, one vitalistic after Henri Bergson's philosophy of evolution.

In 1987, Ryuichi Matsuda coined the term "pan-environmentalism" for his evolutionary theory which he saw as a fusion of Darwinism with neo-Lamarckism. He held that heterochrony is a main mechanism for evolutionary change and that novelty in evolution can be generated by genetic assimilation. His views were criticized by Arthur M. Shapiro for providing no solid evidence for his theory. Shapiro noted that "Matsuda himself accepts too much at face value and is prone to wish-fulfilling interpretation."

Ideological neo-Lamarckism

Trofim Lysenko promoted an ideological form of neo-Lamarckism which adversely influenced Soviet agricultural policy in the 1930s.

A form of Lamarckism was revived in the Soviet Union of the 1930s when Trofim Lysenko promoted the ideologically-driven research programme, Lysenkoism; this suited the ideological opposition of Joseph Stalin to genetics. Lysenkoism influenced Soviet agricultural policy which in turn was later blamed for crop failures.

Critique

George Gaylord Simpson in his book Tempo and Mode in Evolution (1944) claimed that experiments in heredity have failed to corroborate any Lamarckian process. Simpson noted that neo-Lamarckism "stresses a factor that Lamarck rejected: inheritance of direct effects of the environment" and neo-Lamarckism is closer to Darwin's pangenesis than Lamarck's views. Simpson wrote, "the inheritance of acquired characters, failed to meet the tests of observation and has been almost universally discarded by biologists."

Botanist Conway Zirkle pointed out that Lamarck did not originate the hypothesis that acquired characteristics could be inherited, so it is incorrect to refer to it as Lamarckism:

What Lamarck really did was to accept the hypothesis that acquired characters were heritable, a notion which had been held almost universally for well over two thousand years and which his contemporaries accepted as a matter of course, and to assume that the results of such inheritance were cumulative from generation to generation, thus producing, in time, new species. His individual contribution to biological theory consisted in his application to the problem of the origin of species of the view that acquired characters were inherited and in showing that evolution could be inferred logically from the accepted biological hypotheses. He would doubtless have been greatly astonished to learn that a belief in the inheritance of acquired characters is now labeled "Lamarckian," although he would almost certainly have felt flattered if evolution itself had been so designated.

Peter Medawar wrote regarding Lamarckism, "very few professional biologists believe that anything of the kind occurs—or can occur—but the notion persists for a variety of nonscientific reasons." Medawar stated there is no known mechanism by which an adaptation acquired in an individual's lifetime can be imprinted on the genome and Lamarckian inheritance is not valid unless it excludes the possibility of natural selection but this has not been demonstrated in any experiment.

Martin Gardner wrote in his book Fads and Fallacies in the Name of Science (1957):

A host of experiments have been designed to test Lamarckianism. All that have been verified have proved negative. On the other hand, tens of thousands of experiments— reported in the journals and carefully checked and rechecked by geneticists throughout the world— have established the correctness of the gene-mutation theory beyond all reasonable doubt... In spite of the rapidly increasing evidence for natural selection, Lamarck has never ceased to have loyal followers.... There is indeed a strong emotional appeal in the thought that every little effort an animal puts forth is somehow transmitted to his progeny.

According to Ernst Mayr, any Lamarckian theory involving the inheritance of acquired characters has been refuted as "DNA does not directly participate in the making of the phenotype and that the phenotype, in turn, does not control the composition of the DNA." Peter J. Bowler has written that although many early scientists took Lamarckism seriously, it was discredited by genetics in the early twentieth century.

Mechanisms resembling Lamarckism

Studies in the field of epigenetics, genetics and somatic hypermutation have highlighted the possible inheritance of traits acquired by the previous generation. However, the characterization of these findings as Lamarckism has been disputed.

Transgenerational epigenetic inheritance

DNA molecule with epigenetic marks, created by methylation, enabling a neo-Lamarckian pattern of inheritance for some generations.

Epigenetic inheritance has been argued by scientists including Eva Jablonka and Marion J. Lamb to be Lamarckian. Epigenetics is based on hereditary elements other than genes that pass into the germ cells. These include methylation patterns in DNA and chromatin marks on histone proteins, both involved in gene regulation. These marks are responsive to environmental stimuli, differentially affect gene expression, and are adaptive, with phenotypic effects that persist for some generations. The mechanism may also enable the inheritance of behavioral traits, for example in chickens rats and human populations that have experienced starvation, DNA methylation resulting in altered gene function in both the starved population and their offspring. Methylation similarly mediates epigenetic inheritance in plants such as rice. Small RNA molecules, too, may mediate inherited resistance to infection. Handel and Romagopalan commented that "epigenetics allows the peaceful co-existence of Darwinian and Lamarckian evolution."

Joseph Springer and Dennis Holley commented in 2013 that:

Lamarck and his ideas were ridiculed and discredited. In a strange twist of fate, Lamarck may have the last laugh. Epigenetics, an emerging field of genetics, has shown that Lamarck may have been at least partially correct all along. It seems that reversible and heritable changes can occur without a change in DNA sequence (genotype) and that such changes may be induced spontaneously or in response to environmental factors—Lamarck's "acquired traits." Determining which observed phenotypes are genetically inherited and which are environmentally induced remains an important and ongoing part of the study of genetics, developmental biology, and medicine.

The prokaryotic CRISPR system and Piwi-interacting RNA could be classified as Lamarckian, within a Darwinian framework. However, the significance of epigenetics in evolution is uncertain. Critics such as the evolutionary biologist Jerry Coyne point out that epigenetic inheritance lasts for only a few generations, so it is not a stable basis for evolutionary change.

The evolutionary biologist T. Ryan Gregory contends that epigenetic inheritance should not be considered Lamarckian. According to Gregory, Lamarck did not claim that the environment directly affected living things. Instead, Lamarck "argued that the environment created needs to which organisms responded by using some features more and others less, that this resulted in those features being accentuated or attenuated, and that this difference was then inherited by offspring." Gregory has stated that Lamarckian evolution in epigenetics is more like Darwin's point of view than Lamarck's.

In 2007, David Haig wrote that research into epigenetic processes does allow a Lamarckian element in evolution but the processes do not challenge the main tenets of the modern evolutionary synthesis as modern Lamarckians have claimed. Haig argued for the primacy of DNA and evolution of epigenetic switches by natural selection. Haig has written that there is a "visceral attraction" to Lamarckian evolution from the public and some scientists, as it posits the world with a meaning, in which organisms can shape their own evolutionary destiny.

Thomas Dickens and Qazi Rahman (2012) have argued that epigenetic mechanisms such as DNA methylation and histone modification are genetically inherited under the control of natural selection and do not challenge the modern synthesis. They dispute the claims of Jablonka and Lamb on Lamarckian epigenetic processes.

Edward J. Steele's disputed Neo-Lamarckian mechanism involves somatic hypermutation and reverse transcription by a retrovirus to breach the Weismann barrier to germline DNA.

In 2015, Khursheed Iqbal and colleagues discovered that although "endocrine disruptors exert direct epigenetic effects in the exposed fetal germ cells, these are corrected by reprogramming events in the next generation." Also in 2015, Adam Weiss argued that bringing back Lamarck in the context of epigenetics is misleading, commenting, "We should remember [Lamarck] for the good he contributed to science, not for things that resemble his theory only superficially. Indeed, thinking of CRISPR and other phenomena as Lamarckian only obscures the simple and elegant way evolution really works."

Somatic hypermutation and reverse transcription to germline

In the 1970s, the Australian immunologist Edward J. Steele developed a neo-Lamarckian theory of somatic hypermutation within the immune system and coupled it to the reverse transcription of RNA derived from body cells to the DNA of germline cells. This reverse transcription process supposedly enabled characteristics or bodily changes acquired during a lifetime to be written back into the DNA and passed on to subsequent generations.

The mechanism was meant to explain why homologous DNA sequences from the VDJ gene regions of parent mice were found in their germ cells and seemed to persist in the offspring for a few generations. The mechanism involved the somatic selection and clonal amplification of newly acquired antibody gene sequences generated via somatic hypermutation in B-cells. The messenger RNA products of these somatically novel genes were captured by retroviruses endogenous to the B-cells and were then transported through the bloodstream where they could breach the Weismann or soma-germ barrier and reverse transcribe the newly acquired genes into the cells of the germ line, in the manner of Darwin's pangenes.

Neo-Lamarckian inheritance of hologenome

The historian of biology Peter J. Bowler noted in 1989 that other scientists had been unable to reproduce his results, and described the scientific consensus at the time:

There is no feedback of information from the proteins to the DNA, and hence no route by which characteristics acquired in the body can be passed on through the genes. The work of Ted Steele (1979) provoked a flurry of interest in the possibility that there might, after all, be ways in which this reverse flow of information could take place. ... [His] mechanism did not, in fact, violate the principles of molecular biology, but most biologists were suspicious of Steele's claims, and attempts to reproduce his results have failed.

Bowler commented that "[Steele's] work was bitterly criticized at the time by biologists who doubted his experimental results and rejected his hypothetical mechanism as implausible."

Hologenome theory of evolution

The hologenome theory of evolution, while Darwinian, has Lamarckian aspects. An individual animal or plant lives in symbiosis with many microorganisms, and together they have a "hologenome" consisting of all their genomes. The hologenome can vary like any other genome by mutation, sexual recombination, and chromosome rearrangement, but in addition it can vary when populations of microorganisms increase or decrease (resembling Lamarckian use and disuse), and when it gains new kinds of microorganism (resembling Lamarckian inheritance of acquired characteristics). These changes are then passed on to offspring. The mechanism is largely uncontroversial, and natural selection does sometimes occur at whole system (hologenome) level, but it is not clear that this is always the case.

Lamarckian use and disuse compared to Darwinian evolution, the Baldwin effect, and Waddington's genetic assimilation. All the theories offer explanations of how organisms respond to a changed environment with adaptive inherited change.

Baldwin effect

The Baldwin effect, named after the psychologist James Mark Baldwin by George Gaylord Simpson in 1953, proposes that the ability to learn new behaviours can improve an animal's reproductive success, and hence the course of natural selection on its genetic makeup. Simpson stated that the mechanism was "not inconsistent with the modern synthesis" of evolutionary theory, though he doubted that it occurred very often, or could be proven to occur. He noted that the Baldwin effect provide a reconciliation between the neo-Darwinian and neo-Lamarckian approaches, something that the modern synthesis had seemed to render unnecessary. In particular, the effect allows animals to adapt to a new stress in the environment through behavioural changes, followed by genetic change. This somewhat resembles Lamarckism but without requiring animals to inherit characteristics acquired by their parents. The Baldwin effect is broadly accepted by Darwinists.

In sociocultural evolution

Within the field of cultural evolution, Lamarckism has been applied as a mechanism for dual inheritance theory. Gould viewed culture as a Lamarckian process whereby older generations transmitted adaptive information to offspring via the concept of learning. In the history of technology, components of Lamarckism have been used to link cultural development to human evolution by considering technology as extensions of human anatomy.