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Human Evolution 101

A short introduction of scientific theories that deal in the evolution of human beings 



In brief

1.    Out of Africa
2.    Out of Asia
3.    Multiregional Hypothesis

The earliest migrations of pre-modern and modern human, according to the Out of Africa theory, began two million years ago with the migration of Homo erectus out of Africa. The journey of other pre-modern humans including H. heidelbergensis, the closest ancestor of both modern humans and Neanderthals followed soon afterwards. Finally, Homo sapiens moved out of Africa around 200,000 years ago, spread across Asia from 75,000 years ago.

Informally known as the out of Africa (OOA) theory, palaeontologists call it by different names such as:
•    Recent African origin of modern humans
•    Recent single-origin hypothesis (RSOH)
•    Replacement hypothesis
•    Recent African origin model (RAO)


However, some scientists view that it should be Asia rather than Africa. This could be a great news for the Manipur-based cultural group, Universal Friendship Organisation (Satjal), which preaches that human beings originated from the Koubru mountain, the Meitei’s birthplace. Though the Out of Asia theory has fewer takers now, until the mid 20th century, more anthropologists used to believe that human beings were first born in Asia. Currently, Africa has more votes than Asia.

As an alternative to OOA, some other scientists have come up with the scientific model of the multiregional hypothesis, which is also known as the multiregional evolution (MRE) or the polycentric theory. According to the proponents of this hypothesis, human beings were born two million years ago and evolved within a distinct, continuous human species. Out of the three theories on the evolution of human, the multiregional hypothesis has the least support.


Main proponents

Out of Africa     Charles Darwin, Thomas Huxley, Carleton Coon, Chris Stringer

Out of Asia     Ernst Haeckel, Eugene Dubois, Henry Fairfield Osborn, Roy Chapman Andrews, Johan Gunnar Andersson, Otto Zdansky, Walter W. Granger, Von Koenigswald

Multiregional Hypothesis     Milford Wolpoff, Alan Thorne, Xinzhi Wu


A graph detailing the Multiregional Hypothesis of human evolution.
Image: Fred the Oyster/Wikimedia Commons


Watch


•    Dawn of Humanity      A 2015 documentary film: Deep in a South African cave, an astounding discovery reveals clues to what made us human   


•    Becoming Human A three-part series on evolution, with computer-simulated rendition of our predecessors, based on interviews with paleoanthropologists and archaeologists as they explain the scientific processes of evolution, excavation and investigation

•    Walking with Cavemen A film that provides a cinema-graphic, thought-provoking introduction to human development, while presenting stimulating and investigative vignettes to follow the build-up of the traits that make modern humans what they are today  

Image: DEIDATVM/Wikimedia Commons

•    Ape to Man A show on historical perspective on human origins research through interviews with an evolutionary biologist and a paleoanthropologist, beginning with the first discovery of early human remains and chronicling some of the most important advancements and events in the field

•    The Journey of Man This “Story of the Human Species" focuses on the genetic proof for an African origin of Homo sapiens and explains both the heterogeneity and homogeneity that the human species demonstrates today

•    Evolution “A Journey Into Where We’re From and Where We’re Going,” it is a seven-part series that presents a concise, but all-inclusive review of the most important topics in evolutionary hypothesis


The structure of evolutionary biology. The history and causes of evolution (centre) are subject to various subdisciplines of evolutionary biology. The areas of segments give an impression of the contributions of subdisciplines to the literature of evolutionary biology.
Image: Conquistador/Wikimedia Commons


Vocabulary

ABIOGENESIS             The natural process of life arising from non-living matter, such as simple organic compounds; considered to have occurred on Earth between 3.8 and 4 billion years ago

ANATOMICALLY MODERN HUMANS (AMH) OR ANATOMICALLY MODERN HOMO SAPIENS (AMHS)         Individual members of Homo sapiens with an appearance consistent with the range of phenotypes in modern humans

BIOLOGICAL DETERMINISM         A term used in literature to describe the belief that human behaviour is controlled solely by an individual’s genes or some component of physiology

CEPHALOMETRY            The measurement of the head, usually the human head, especially by medical imaging such as radiograph

CREATION–EVOLUTION CONTROVERSY         A frequent cultural, political and theological debate about the origins of the Earth

CREATIONISM         The religious belief that the Universe and life originated from specific acts of divine creation

ETHNOLOGY         A branch of anthropology that compares and analyses the characteristics of different peoples and the relationship between them

EUGENICS         A set of beliefs and practices which aims at improving the genetic quality of the human population

EVOLUTION         The change in the heritable traits of biological populations over successive generations

The numbers represent thousand years before present. The blue line represents area covered in ice or tundra during the last great ice age. The letters are the mitochondrial DNA haplogroups (pure motherly lineages)
Image: Chronus/Wikimedia Commons


MITOCHONDRIAL EVE         In human genetics, Mitochondrial Eve is the matrilineal most recent common ancestor (MRCA), in a direct, unbroken, maternal line, of all currently living humans, who is estimated to have lived approximately 100,000–200,000 years ago

MODERN EVOLUTIONARY SYNTHESIS         A twentieth-century synthesis of ideas from several fields of biology that provides an account of evolution which is widely accepted (Also known as the new synthesis, the modern synthesis, the evolutionary synthesis, millennium synthesis or the neo-Darwinian synthesis)

MONOGENISM        A theory of human origins which posits a common descent for all human races, opposite to polygenism

Through random drift or selection lineage will trace back to a single person. In this example over five generations, the colours represent extinct matrilineal lines and black the matrilineal line descended from the MRCA.
Image: ChrisTi/Wikimedia Commons

NATURE–CULTURE DIVIDE         A theoretical foundation of contemporary anthropology on whether nature and culture function separately from one another, or if they have a continuous biotic relationship with each other

THE ORIGIN OF SPECIES             A work of scientific literature by Charles Darwin which is considered to be the foundation of evolutionary biology; first published in November 1859, its original title was On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life. In later edition, ‘On’ was omitted, so the title becomes The Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life, or simply The Origin of Species.

PALEOANTHROPOLOGY         The study of the formation and the development of the specific characteristics of humans and the reconstruction of evolutionary kinship lines in the family Hominidae, by means of the study of fossils, such as petrified skeletal remains, bones fragments, footprints and associated evidence, stone tools, artefacts and settlement localities
tadpole
PHRENOLOGY        A pseudoscience primarily focused on measurements of the human skull, based on the concept that the brain is the organ of the mind, and that certain brain areas have localised, specific functions or modules

PHYLETIC GRADUALISM         A model of evolution which theorises that most speciation (the evolutionary process by which new biological species arise) is slow, uniform and gradual.

POLYGENISM         A theory of human origins positing that the human races are of different origins (polygenesis); opposite to monogenism, which posits a single origin of humanity

RACIAL HYGIENE         A set of early twentieth century state sanctioned policies by which certain groups of individuals were allowed to procreate and others not, with the expressed purpose of promoting certain characteristics deemed to be particularly desirable (E.g. the Nazis’ onslaught)

SCIENTIFIC RACISM         The use of scientific techniques and hypotheses to support or justify the belief in racism, racial inferiority, or racial superiority, or alternatively the practice of classifying individuals of different phenotypes into discrete races

Y-CHROMOSOMAL ADAM         In human genetics, Y-chromosomal most recent common ancestor (Y-MRCA); the most recent common ancestor (MRCA) from whom all currently living people are descended patrilineally



- Concluded.


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