Wednesday, December 28, 2022

Terrace Cultivation

Photo by Maksym Kaharlytskyi on Unsplash

Terrace cultivation is an agricultural practice that suggests rearranging farmlands or turning hills into farmlands by constructing specific ridge platforms. These platforms are called terraces. The essential and distinguishing feature of terrace agriculture is excavating and moving topsoil to form farmed areas on ridges. The trick is that water flows down to lower platforms when the upper platforms are full. Thus, the amount of water is distributed more or less evenly. 

Farmed areas in agricultural terracing are either level or tilted, depending on the soil infiltration properties. If soil infiltration is sufficient, they are made level. The most popular terrace types in farming are: broad base, narrow base, and grassed back-slope; depending on how steep the hill is. 

  • Broad-base terrace farming method is suitable for the gentlest hills, and terrace farming includes all the slopes.
  • Grassed back-slope terrace farming is an example of perennial terracing, as the back slope cover is perennial grass. 
  • Narrow-base terrace farming is another example of perennial terracing, but in this case, permanent vegetation covers both, the front and back sides. 
This technique of cultivation is credited to the Incas, who developed the farming method of terracing in the Andes. Today, terracing is typical for mountainous rice paddies in Asia. There are various benefits in this method,
  • increases land productivity of sloped fields,
  • contributes to water conservation; slows down and reduces water runoffs, improves rainwater harvesting,
  • prevents soil erosion by decreasing rill formation,
  • boosts soil conservation,
  • reduces sedimentation and water pollution,
  • increases food production by adjusting hilly land for farming,
  • adds to ecosystem diversity.
There are some challenges too,
  • specific types of machinery required,
  • high labor and cost input
  • land disturbances that often require additional treatment
  • trained people needed to arrange terraces
  • preliminary soil testing is required,
Prevention or reduction of soil erosion, as well as soil conservation by terracing, allows using the terraced farmlands in the long run. It attests to the essential role of terracing in sustainable agriculture.

Reference: collected from various sources

Shifting Cultivation

Shifting cultivation is an agricultural system which has been in practice since the Neolithic period. In this system, plots of land are cultivated temporarily, and then abandoned and allowed to revert to their natural vegetation. The period of cultivation is terminated when the soil shows signs of exhaustion, or more commonly when the field is overrun by weeds. The length of time that a field is cultivated is usually shorter than the period over which the land is allowed to regenerate by lying fallow. The duration of the fallow period also depends upon the availability of land with forest vegetation and the size of the group practicing it. 

Shifting cultivation is also known as swidden/slash-and-burn/dry cultivation. The process in brief is as follows:
  1. The land is rain-fed and the natural vegetation is slashed, dried, and then burnt. The clear land is known as 'swidden'. The basic technology of shifting cultivation, also known as dry cultivation, is to grow crops without the help of irrigation or external input of fertilizers. 
  2. The topsoil is then mixed with the layer of ash that provides the necessary compounds to act as fertilizers. 
    Photo by Maksym Ivashchenko on Unsplash

  3. Cultivation of the land after clearing is usually accomplished by hoe and a digging stick and not by a plough. 
  4. After the field is cultivated, it is left to fallow till there is sufficient growth of vegetation after the soil regains its fertility - to commence another cycle of cultivation. The fallow period has to be very long, 10-15 years, for the system to be reasonably productive, therefore it is also known as extensive cultivation. 
This technique is adopted by different tribal communities in many parts of the Indian subcontinent. It is known by different names in tribal regions. 
  • Jhum - NorthEast India
  • Podu / Koman / Bringa - Orissa
  • Deppa - Bastar
  • Kumari - Western Ghats
  • Penda - SouthEast Rajasthan 
  • Bewar - Madhya Pradesh
It is also prevalent in other parts of the World.
  • Milpa - Central America and Mexico
  • Ladang - Indonesia and Malaysia
etc.

An important feature of this agricultural system is that it can be productive even in poor soil conditions, for example on mountains; as it makes its own top soil and doesn't go deep in the earth. However, this method is not suitable in a community with high population density.

Reference: collected from various sources

Monday, December 26, 2022

Rituals of Liminality

This concept was introduced by Arnold van Gennep (1873-1957) and elaborated by Victor Turner (1920-1983) and Edmund Leach (1910-1989). 

A 'liminal period' is -- "a betwixt and between" period; where normal life and time stand still or is reversed. Arnold van Gennep analysed the role of life cycle rituals such as birth, puberty, marriage and death, mark stages of transition in an individual's life, where a person makes a transition from one status to another. 

According to him, every ritual has 3 stages:

  1. A stage of separation - the time period when the individual is removed from normal life, often giving up normal daily activities, surrounded by taboos and often enters a ritual status of sacredness. (e.g. during marriage)
  2. Liminal period - the time period when a person is kept away from society, sometimes physically hidden away, therefore, they are in the society but not a part of it. This is the "betwixt and between" situation when one is suspended as it were in social space and time. (e.g. bride does not leave the house before marriage and does not take part in usual daily activities)
  3. A final stage of incorporation - after the transition is made, the individual comes out of the liminal period and back to normal life. (e.g. new bride asked to cook a dish at her in-law's house)
Edmund Leach used the concept of liminality to describe what he calls - the marking of structural time/intervals; where important social events mark the oscillations of time, from one period to another. (e.g. Harvest rituals mark the interval between one agricultural cycle and another. The sowing-reaping-sowing cycle is marked at each phase my a ritual.) Leach called this oscillating time as against the concepts of lineal time. There is a sense of reversal, where ordinary life is reversed/stopped. (e.g. during a festival in India called Holi, social norms get reversed. Normal social distances get abandoned; young people take over, hostilities and inequalities are ignored and also in some cases, injustice suffered in regular life acted in reverse, women beat husbands with brooms.)

Functional study of Rituals

Emile Durkheim (1858-1917)

In his book, 'Elementary forms of religious life' (1912), set the stage for functional analysis from the earlier emphasis on evolution. Durkheim showed how the Totemic rituals establish within the participants;

  • sense of oneness
  • sense of solidarity
  • sense of commitment
  • sense of morality
He also showed how the Totemic rituals led to a harmonious relationship between nature and humans. Every time the Totemic rituals were performed, all the values become reemphasized and reaffirmed. The repetitive nature of rituals was to recreate the collective sentiments of the people - a process necessary for survival. 

A. R. Radcliffe Brown (1881-1955)

Followed Durkheim to give a structural-functional analysis of collective rituals. He introduced the terms 'ritual value' and 'ritual status' to describe the symbolic significance of collective rituals. He showed the significance of taboos/prescriptions and prohibitions in creating a ritual status and thereby giving a ritual value to an object. (Ritual values are social values necessary for maintaining necessary sentiments essential for social reproduction and solidarity.) 
His hypothesis - rituals, by their restrictions on action, create anxiety that is just right to make a person realize the importance of a relationship. In this analysis, importance is given to the function of rituals for social structure.

Bronislaw Malinowski (1884-1942)

His hypothesis - explains rituals as relieving anxiety rather than creating anxiety. In this analysis, importance is given to the function of rituals for individuals.

All human beings have certain amount of rational knowledge about the tasks we do. In spite, a certain degree of uncertainty prevails. The role of rituals is to take care of this 'grey area' which no amount of skill or knowledge can cover. The more dangerous the result of failure, greater the anxiety, more elaborate the rituals. For example, in his study of the Trobrianders, a seafaring community of Pacific Islands, Malinowski showed that when they are fishing in backwaters or otherwise safe zones, the fishermen perform little rituals, but they always perform elaborate rituals when they are venturing out in the deep sea or any long distance voyage where the risk factor is high.
The performance of rituals can be rationalized by the positive mindset/confidence it builds in an individual, who feels satisfied at having done all that could be, including those that are beyond human control and only the supernatural can take care of. 
In his book, 'The Coral gardens and their Magic' (1935), he showed how rituals performed by magicians help to regulate agricultural work and imposes rational time schedule that actually helps in scientific management of productive activities. Once activities are projected as a sacred duty, there is greater compliance and less chance of people defaulting. 

Reference: IGNOU Study Materials

A note on Rituals

A performance, to be socially meaningful, must have a public content. 

Even if, a person is performing a ritual individually, he/she follows a pattern that is publicly recognized and followed. For example, a Hindu woman blowing a conch shell and lighting a lamp under the Tulsi tree in the evening. Every culture prescribes a format for the performance of rituals that must be followed by everyone, whether or not the ritual is actually performed publicly. 

Photo by Naveen Kumar on Unsplash

Friday, December 23, 2022

Religion and Anthropology

The anthropological approach of studying human societies as integrated wholes consider religion as a part of culture. Anthropologists try to find out the relevance of religion in human societies, whether primitive or technologically advanced, and the significance of religion in human societies. Notable is the fact that there is no society known so far without any religious idea, it is a cultural universal. They made attempts to search for earlier forms of religion and religious thoughts and the courses of change therein. Some intellectuals thought that religion will have no place where science and technology flourish - but the reality is to the contrary. 

Anthropologists defined religion in different ways, but none of them adequately cover all aspects of religion practised by all human societies

Edward Burnett Tylor : "Belief in spiritual things"

Emile Durkheim : …"a unified system of beliefs and practices relative to sacred things, that is to say, things set apart and forbidden -- beliefs and practices which unite into one single moral community called a Church all those who adhere to them."

Clifford Geertz : "A religion is a system of symbols which acts to establish powerful, pervasive, and long-lasting moods in men by formulating conceptions of a general order of existence and clothing those conceptions with such an aura of factuality that the moods and motivations seem uniquely realistic."

for more - Various Definitions of Religion

Typical dictionary definition of religion : "belief in, or the worship of, God or Gods."

References: IGNOU Study Materials

Monday, September 26, 2022

Extinction

Extinction refers to the disappearance of an animal group (e.g. a species), from the evolutionary period. It is not an unusual event, but rather a natural phenomenon. It is estimated that 99.9% of all species that ever lived on earth are now extinct. 

Extinction appears to be the ultimate fate of all species. The rate of extinction spikes in occasional mass extinction events. The 2 ways in which species may become extinct are:

  • negative role of environmental selection in evolution (species develops a way of life such that a change in environment would prevent its persistence). 
  • a species may become extinct as it is transformed into another. 
Major Extinction events:
  1. Permian-Triassic extinction - Though it is less known, it was the most severe and approximately 96% of species were driven to extinction. 
  2. Cretaceous-Tertiary extinction - The non-avian dinosaurs went extinct.
  3. Holocene extinction - Ongoing mass extinction associated with humanity's expansion across the globe over the past few thousand years. Present-day extinction rates: 10-1000 times greater than the background rate. 

Saturday, September 17, 2022

Application of Physical Anthropology in Sports

The cultural aspect of sports is undeniable, but the biological aspect is considerably responsible for performance in any sport, i.e. factors like body size, proportions, physique, and nutrition. Many of the required traits are acquired through heredity, but they are also influenced by the environment to a large extent. Psychological factors like motivation, training, etc. play a role in moulding sportive behaviour.

Hence, cultural, biological, environmental and psychological aspects must be understood to understand sports and performance. Thus, laying the foundation for the anthropological role in this field. 

Kinanthropometry is a specialized branch of physical anthropology that evaluates an individual's physical structure. It focuses on selecting the fit genotypes which is suitable for a particular sport, to attain its full potential, because -

training and other external influences can change a person's morphological status only within narrow limits set by genotype. It is impossible to alter the capacity of the genotype.

hence, Kinanthropometry enabled anthropologists to classify humans into different somatotypes and suggest the right sport for them.

Physical anthropometry also plays a constructive role in designing sports equipment using anthropometric techniques.

Reference: IGNOU Study Materials

Saturday, July 30, 2022

Theories of Social Anthropology/ Sociology

  1. Evolutionism/ Classical Evolutionism
      • Baron de Montesquieu (1689-1755)
      • Henry Summer Maine (1822-1888)
      • Johann Jacob Bachofen (1815-1887)
      • John F. McLennan (1827-1881)
      • James George Frazer (1854-1941)
      • Herbert Spencer (1820-1903) 
      • Lewis Henry Morgan (1818-1881)
      • Edward Burnett Tylor (1832-1917) unilineal evolutionism
  2. Diffusionism (late 19th C. - early 20th C.)
    • German Diffusionism
      • Friedrich Ratzel (1844-1904) criterion of form
      • Wilhelm Schmidt (1868-1954) 
      • Leo Frobenius (1873-1938) criterion of quantity
      • Frtiz Graebner (1877-1934) 
    • American diffusionism
      • Franz Boas (1858-1942) historical particularism
      • Clark Wissler (1870-1947) age-area hypothesis
      • Albert L. Kroeber (1876-1960) configurations of cultural growth
    • British Diffusionism
      • Grafton Elliot Smith (1871-1937)
      • W.H.R. Rivers (1864-1922)
      • William James Perry (1887-1949)
  3. Historical Particularism
      • Franz Boas (1858-1942)
  4. Neo - Evolutionism
      • V. Gordon Childe (1892-1957) universal evolutionism
      • Leslie White (1900-1975) 
      • Julian Steward (1902-1972) multilineal evolutionism 
      • Marshal Sahlins (1930-2021) 
  5. Functionalism
      • Emile Durkheim (1858-1917) positivism
      • Bronislaw Malinowski (1884-1942) functionalism
      • Alfred Radcliffe-Brown (1881-1955) structural functionalism
      • Talcott Parsons (1902-1979)
      • Robert K. Merton (1910-2003)
  6. Dynamic theories of structure
  7. Culture and Personality School
      • Sigmund Freud (1856-1939)
      • Ruth Benedict (1887-1948) configuration of culture
      • Margaret Mead (1901-1978) 
  8. Neo - Functionalism
      • Niklas Luhmann (1927-1998)
      • Jurgen Habermas (1929-)
      • Jeffrey Alexander (1947-)
      • Paul Colomy
  9. Marxism/ Marxist Anthropology
      • Karl Marx (1818-1883)
  10. Cultural Ecology
  11. Cultural materialism
  12. Structuralism
  13. Feminism/ Feminist Anthropology
  14. Post modernism
  15. Post colonialism
  16. Ethnoscience
  17. Symbolic Anthropology
*a brief list with the names of the main proponents, may not include all. 

source - History and Theory in Anthropology, Alan Barnard


Evolution and History of Man in Time

*under construction

------------------------------------66MYA: beginning of the Cenozoic era-----------------------------------

---Age of Mammals---

The start of the Cenozoic Era came after the mass extinction of the dinosaurs occurred. This is known as the K-Pg event, which stands for Cretaceous-Paleogene extinction event. Some also refer to this as the KT event, which stands for Cretaceous-Tertiary extinction event.

-------------------------------------66MYA: beginning of Tertiary period------------------------------------
(also referred to in terms of Paleogene Period and Neogene Period)

---Rise of Mammals---

Paleogene Period

66-56MYA: Paleocene epoch
probable emergence of the primates 

56-33.9MYA: Eocene epoch

33.9-23.03MYA: Oligocene epoch 

Neogene Period

23.03-5.333MYA: Miocene epoch 
probable emergence of Hominoidea and Homininae

14-10MYA: genus Ramapithecus

6MYA: Bipedalism - The upright, bipedal (two-footed) gait was the first hallmark feature of our hominin ancestors. (Larsen)

5.5MYA: Nonhoning Chewing - Humans’ nonhoning chewing complex lacks large, projecting canines in the upper jaw and a diastema, or gap, between the lower canine and the third premolar. The chewing complex of apes such as gorillas has large, projecting upper canines and a diastema in the lower jaw to accommodate them. (Larsen)

5.333-2.58MYA: Pliocene epoch
multiple genera of Homininae, emergence of genus Homo 

4.4-1.4MYA: various species of the genus Australopithecus (Plio-Pleistocene)

3.3MYA: Material Culture and Tools - Humans’ production and use of stone tools is one example of complex material culture. The tools of our closest living relatives, the chimpanzees, do not approach the complexity and diversity of modern and ancestral humans’ tools. (Larsen)

2.5MYA: Speech - In the entire animal kingdom, only humans can speak and, through speech, express complex thoughts and ideas. The shape of the hyoid bone is unique to hominins and reflects their ability to speak. Speech is part of the overall package in the human lineage of increased cognition, intelligence, and brain-size expansion. (Larsen)

2.5*MYA: first stone tools (first artifacts)

----------------------------------2.58MYA: beginning of Quaternary period----------------------------------

---Rise of Man---

2.58MYA-0.0117MYA/11.7KYA: Pleistocene epoch
many species of humans

1.8MYA-150KYA: Homo erectus, first to demonstrate cultural adaptation (Middle Pleistocene)

1MYA: Hunting - Humans’ relatively large brains require lots of energy to develop and function. Animal protein is an ideal source of that energy, and humans obtained it for most of their evolution by eating animals they hunted. To increase their chances of success in hunting, humans employed tools they made and cooperative strategies. (Larsen)

75-35KYA: Homo neanderthalensis, extinct species of genus Homo (Middle to Upper Pleistocene)

0.0117MYA/11.7KYA-present: Holocene epoch
Homo Sapiens dominates

11KYA: Domesticated Food - In recent evolution, humans domesticated a wide variety of plants and animals, controlling their life cycles and using them for food and other products, such as clothing and shelter. (Larsen)

6KYA: earliest writing systems



References: 
"International Commission On Stratigraphy". Stratigraphy.Org, 2022, https://stratigraphy.org/chart
Spencer, John J, and Joseph B Aceves. Instructor's Manual To Accompany Introduction To Anthropology, Joseph B. Aceves And H. Gill King. General Learning Press, 1979.
Larsen, Clark Spencer. Essentials of Biological Anthropology. W.W. Norton & Company, 2022. 
IGNOU MA Anthropology (MAAN) Books

Tuesday, July 19, 2022

Theories of Evolution

Theory

Proponents

Brief note

(Greek and Roman Thinkers)

6th Century BC

Anaximander of Miletus

(Greek)

Proposed that the first animals lived in water, during a wet phase of the Earth's past, and that the first land-dwelling ancestors of mankind must have been born in water, and only spent part of their life on land. He also argued that the first human of the form known today must have been the child of a different type of animal (probably a fish), because man needs prolonged nursing to live. Man evolved/originated from fish.

Theory of spontaneous generation/

creation or Abiogenesis

Aristotle, Thales, Plato, Von Helmont, Empedocles Democritus

The theory of spontaneous generation is as old as human thought. It is well known that life arises only from pre-existing life (principles of bio-genesis) and assumes that life originated from inert, inorganic matter as a result of a series of physico-chemical conditions which must have existed at a given moment during the evolution of earth. The theory contends that life had originated repeatedly from inanimate materials or non-living things in a spontaneous manner. Aristotle thought that fireflies originated from morning dew and mice from the moist soil spontaneously.

(Medieval & others)

Creationism/ Theory of special creation/ Theory of Divine creation

17th and 18th century

 

Father Suarez

(1548-1671)

A Spanish Monk

Proposed this theory. It was based on the Biblical book of Genesis. According to Genesis, of Old Testament of Bible, the world was created by the supernatural power (God) in six natural days. Since all species were made individually by god, the theory does not accept the idea of origin of new species from ancestral forms. The created organisms exist unchanged from the day of their creation.

James Ussher (1581-1656) Archbishop of Northern Ireland

Fixed the date of creation at October 23, 4004 B.C.

Dr. Charles Lightfoot(1889-1961)

Added the exact time of creation, i.e., 9 a.m. on October 23, 4004 B.C.

mid 18th century

Carl Linnaeus (1707-1778)

Swedish Botanist

Designated each living organism two Latin names (binary nomenclature), one for Genus and the other for Species. Thus, from the days of Linnaeus, Man has been scientifically known as Homo Sapien.his immortal work “The Systema Nature

Late in the 18th century

Comte de Buffon

(1707-1778)

French scientist

 

Suggested strongly that life forms are not fixed.He strongly believed that this could be the influence of the environment on living organisms. He explained this in his voluminous work, “Historic Naturelle. He had more clear ideas on the physical features of man than Linnaeus. He explained them in his book “Varieties Humanies”. He argued that although catastrophic events do occur, they are rare and so “have no place in the ordinary course of nature.” Instead, the earth’s history is mainly explained by “operations uniformly repeated, motions which succeed one another without interruption”. Thus, much of the earth’s geological history could be explained by normal, everyday, uniform processes—the things taking place before our eyes, such as erosion and deposition of sediments in water. For such processes to account for all the changes recorded in the earth’s strata, however, the earth would have to be older than 6,000 years. Buffon also published Les Epoques de la Nature (1788) where he openly suggested that the planet was much older than the 6,000 years proclaimed by the church, and discussed concepts very similar to Charles Lyell's "uniformitarianism" which were formulated 40 years later.

18th Century

Erasmus Darwin (1731-1802)

Suggested through his work the evolutionary aspects of animals and strongly contended that the earth and life on it must have been evolving for millions of years and the history of mankind is the latest.

Lamarckism

Jean Baptiste Lamarck(1744 – 1829)

Was the first evolutionist who confidently put forward his ideas about the process leading to biological change in the organism.

Catastrophism/ Theory of Catachysm

 

17th Century/ 18th Century

 

 

 

Nicholas Steno (1638-1686)

 

Steno and Hooke, still believed in a biblical chronology. To Steno, the water-deposited layers of the stratigraphic sequences represented two events—the original water-covered earth on which God created land and plants and animals (Genesis 1) and the waters of Noah’s flood (Genesis 6-8). The geological record, however, shows a vast amount of change, and the Bible provides only 6,000 years of the earth’s history. So much change in such a short time, thought Steno and Hooke, required the presence of global catastrophic events such as earthquakes and volcanoes. Steno and Hooke and others who subscribed to this explanation are often referred to as catastrophists.

Robert Hooke (1635-1703)

 

George Cuvier (1769-1832)

French scientist

Objected to Lamarck strongly. This is the extension of the theory of special creation. This theory assumes that life is originated by the creation and it is followed by catastrophe due to geographical disturbances. Each catastrophe destroyed the life completely whereas each creation forms life different from the previous one. His observation was based on the fossil remains of varied organisms. According to him, the earth had to face severe natural calamities at different times for which many animal species have been destroyed. But each time when the earth settled after a great Catastrophe, relatively higher forms of animals appeared to replace the situation. Cuvier did not believe in continuous evolution. To him the species never evolved by modification and re-modification; a series of Catastrophes were responsible behind changes where previous sets of living creatures get replaced by new creatures of complex structure.

Theory of Uniformitarianism

 

19th Century

 

Charles Lyell (1797-1875)

English lawyer and geologist

Disproved Cuvier’s Catastrophism. Lyell, in his three volume book on ‘Principles of Geology’ (1830-1833), documented the fact that the earth must be considerably old; and natural processes through time, like, erosions, earthquakes, glacial movements and volcanoes have changed the shape of the earth and its living units. He provided conclusive evidence for the theory of uniformitarianism. He explained this saying that the present would be the key for understanding the past. He argued that the natural changes were the same in the past and the present. This theory on one hand discarded the “theory of Catastrophism” and on the other hand nullified the “theory of divine Creation”.

Through the work of Hooke, Steno, Hutton, Smith, and Lyell—and many others—the study of the earth shifted from the supernatural to the natural. Scientists sought data about earth’s history from the earth itself, not from the presuppositions of belief systems. As a result, by the early nineteenth century, our world was viewed through the interacting perspectives of constant change brought about by observable processes over vast amounts of time. Lyell put these ideas down in his three-volume Principles of Geology, first published between 1830 and 1833. Among those weighing Lyell’s ideas was a young British naturalist, Charles Darwin, who took the first volume of Lyell’s book with him as he embarked, in 1831, on a round-the- world voyage of scientific exploration.

Theory of Eternity of Present Conditions

 

19th Century

Preyer (1880)

This is an orthodox theory. It believes that some organisms were there from the very beginning of the Universe. Those organisms still exist and will be continued in future in addition to some new forms. According to this theory, the original forms are eternal, and they have been preserved automatically.This theory assumes that life had no beginning or end. It believes that life has ever been in existence and it will continue to be so ever. It further believes that there is no question of origin of life as it has no beginning or end. The theory is also known as steady state theory.

Theory of Cosmic Origin of life

 

19th Century

 

Richter (1865)

Richter developed this theory and he was supported by Thomson, Helmholtz (1884), Von Tieghem (1891) and others. This theory advocated that the first life seed had been transported through the cosmic particles from other planet. According to them the meteorites that travelled through the earth’s atmosphere, contained embryos and spores in them; those gradually grew and evolved into different types of organisms. 

(organic evolution)

Organic Evolution :

The theory that more recent types of plants and animals have their origins in other pre-existing forms and that the distinguishable differences between ancestors and descendents are due to modifications in successive generations.

Lamarckism/ Theory of Inheritance of acquired characters 

18th /19th Century

Jean Baptiste Lamarck(1744 – 1829)

French naturalist/biologist

He opined that the structure of a living being is dependent on its function. He used the example of Giraffe, saying that it got long-neck structure for its constant use of reaching to higher foliage. Based on this observation, he propounded two theories, namely: i) use and disuse of characters and ii) the acquired characters are inherited. He presented a complete theory of evolution in his book ‘Philosophie Zoologique’, published in 1809.

Neo-Lamarckism

McDougall, Spencer, Cope, Packard, Kammere, Sumner, etc.

A group of evolutionary biologists further studied and modified the Lamarckism. They carried out experiments to find evidences for the inheritance of acquired characteristics. This modified version came to be known as Neo-Lamarckism.

Darwinism/ Theory of Natural Selection & the Origin of Species

19th Century

Charles Darwin

(1809-1882) English naturalist, geologist and biologist

The start of new era for understanding biological evolution through genetic mechanisms. His book ‘The Origin of Species’ was published  in the year 1859. He proposed the term ‘Organic Evolution’ which signifies ‘descent with modification’, the hypothesis that all organisms on Earth are connected by bonds of genealogy and have changed through time.

Neo-Darwinism

 

(Also- Modern theory of origin of species/ developed into Modern Synthetic Theory)

Weismann, Earnest Heckle, Lyell, Huxley, Wallace and Simposon.

Supported the natural selection.

R.A Fisher, Sewall Wright, and J.B.S Haldane.

Explained natural selection by modern synthesis.

Natural selection is differential reproduction, plus the complex interplay in such phenomena as heredity, genetic variation, and all other factors that affect selection and determine its results.

Mendelism/ Laws of inheritance

 19th Century

 

 

Gregor Mendel (1822-1884)


Mendelism is used to refer to the theoretical principles of heredity of the single-gene trait, which is derived from the principle put forward by Gregor Mendel, known as Mendel’s laws. Mendel’s laws came to be known as Laws of inheritance, which are as follows: Law of Dominance, Law of Segregation, Law of Independent Assortment.

Mutationism

19th Century

Hugo de Vries(1840 – 1935) Dutch Botanist

The theory states that evolution is a jerky process where new varieties and species are formed by mutations (discontinuous variations) that function as raw material of evolution.

Synthetic Theory/ Modern Synthesis

20th Century


Present understanding of the process of evolution. With more complete understanding of mechanism of inheritance, the biological sciences now generally define evolution as- The sum total of the genetically inherited change in the individuals who are the members of the gene pool of a population.

Neo-Mutationism

20th Century

Masatoshi Nei(1931-)

The contemporary view corresponding to Mutationism. A main feature of this theory is how single mutations can have significant effects to influence evolution.