THE HOMINIZATION PROCESS OF HOMO SAPIENS

European Anthropological Association
, 2007, Prague, Czech Republic
EAA Summer School eBook 1: 43-46
THE HOMINIZATION PROCESS OF HOMO SAPIENS
Ajeet Jaiswal
University of Delhi, Delhi, India
The Hominization process consists of evolutionary transformation of hominoids into Hominids. It is a process that has occurred in the hominoid-line since its divergence from the last common hominoid ancestor shared with any living ape. Initially the term has a restricted meaning and implied emergence of modern man, different from all other forms. Currently, however, the term is broadened and includes all those aspects of structural and behavioral changes that occurred in the Hominid line finally leading to man.
All such changes can be broadly grouped into following heads.
1. Bipedalism
2. Hand manipulation and tool use (manual dexterity)
3. Modification of jaw and teeth.
4. Enlargement of brain
5. Changes in vocal tracts, language and speech
Bipedalism
Analysis of postcranial elements of A. africanus, A. afarensis, A. ramidus (Tim et al. 1994) and A. anamensis (Leakey et al. 1995) clearly establishes bipedalism to be one of the oldest of all hominid characteristics. The age of most primitive australopithecines. A. ramidus is estimated to be 4.4 mya, perhaps one million years after separation of ancestral lines leading to great apes and man. The branch point between ape and human accestors is estimated to be 5-6 mya. According to Stanford (1995). A. ramidus was a biped, its lower body was clearly adapted for walking on the ground, though they may have continued to use trees for gathering fruits and for shelter at night. Postcranial elements of A. afarensis is well documented. The kind of limb and pelvis show many bipedal adaptations. illiac blades were short and broad, ischium was short, anatomy of hand and ankle joints were favourable, big toe was parallel. In all such features afarensis was more human like than ape like.
In addition to post cranial elements, the Laetoli (Tanzania) foot prints of A.afarensis, austratopithecine to have existed around 3.77 mya, is another proof of bipedalism. It shows a convergent big toe, heel strikes, arches etc similar to humans in many aspects.
There are, however, certain features possessed by afarensis such as shorter hind limbs, longer foot, longer toes etc. which suggest that australopithecine blpedalism was different from, and costlier than human blpedalism.
Such differences in the locomotor behaviour can be explained due to the habitat supposed to have existed in eastern Africa-woodland, bushland and dry savannah with patches of forest along rivers and lakes. Thus they had to live somewhat less on the tree and more on the ground.
Hand anatomy and tool use
The earliest evidences of hand manipulations different from apes and sufficiently similar to Homo can be found in A. afarensis approximately to human proportions but differ from those of humans in having fingers more curved suggesting greater power grip. A precision grip greater than chimpanzee but lesser that the Homo is suggested. A. afarensis was spending more time on the land than on the trees hence hand-anatomy had started foreshadowing the characteristics of hands of Homo and different from those of apes. Hominids with their manipulative hands, precision grip and contemplating brains, had been able to expand their ecological niche so far beyond the physical capabilities inherent in their makeup, one that no other animal has ever had the potential to achieve.
The classical view of anthropologists has been that the use of tools led to the distinction between human and ape-that the split between the pongidae and the hominidae resulted from the acquisition of tool-use by one of the ancestral hominoid populations. Others now feel that environmental influence and adaptation to nonarboreal ecological niches were more important for early hominid evolution. However these divergent views are ultimately resolved, it is interesting to learn how far back human technology and culture can be traced.
43
TENSIVE COURSE IN BIOLOGICAL ANTHROPOLOGY
1st Summer School of the European Anthropological Association
16–30 June, 2007, Prague, Czech Republic
Recent paleoanthropological findings is that the use of tools, antedates the origin of the big-brained Homo sapiens by at least a million and a half year. There is now indisputable evidence of the occurrence of modifies stone tools 2 million years old found in association with the bones of Homo habilis. In other words, tool-use and tool-making developed before hominid brain capacity had undergone remarkable increase. The old idea that a large brain and associated high intelligence were prerequisites for tool use is no longer tenable. The use of tools by primitive hominids may, in fact, have been a major factor in the evolution of the cerebral cortex and higher intelligence, for once the use and making of tools began to favour survival, there would be high selection pressure for neural mechanism promoting improved crafting and use of tools. The elaborate brain of Homo sapiens may be a consequence of culture as much as its cause. Hominization process, with respect to cultural attainments, had set in much before the modern man appeared on the earth. Oldwan industry of earliest Homo habilis clearly proves the point.
Homo erectus had not only perfected stone tools considerably but had also learned how to control and use fire, as revealed by radioisotope dated hearths in caves, With fire humans could cook their food they could keep themselves warm in cold weather; they could ward off predators and they could light up the dark to see. The hearth no doubt promoted the development of social organization and allowed an opportunity for the beginning of communication through spoken language.
Neanderthal people practiced ritual burial in Europe and the Near East at least 60,000 years ago, suggesting that religious beliefs had developed by that time. By 40,000 years ago or a little later, Cro-Magnon people began constructing their own dwellings and were living in communities. The domestication of animals and plants, development of agriculture and the dawn of civilization followed in relatively quicker that characterize modern humans. The cultural attainments in terms of tool making and tool use that characterizes modern humans had thus set in at least 2 mya for which there exist sufficient proof in archaeology since the time of Homo habilis.
Modification of jaws and teeth
Apes are characterized by larger, thick enameled teeth large jaw and jaw muscles, large canines, high cuspid molars and a higher ratio of cheek teeth area to body weight of Australopithecines, Paranthropines and habilines differed from apes in some features. A. ramidus had teeth which resembled those of Homo in some features. They were smaller with thin enamel and canine were smaller. The dentition in general resembled to those of Chimpanzee in some aspects. Similarly, A. afarensis dentition had some ape like and some Homo features. The incisors were chimpanzee like but canines were low crowned and incisors like A. africanus had dentition similar to those to afrensis except that the cheek teeth were slightly bigger. In Paranthropus, front teeth were smaller than those of afarensis and africanus but cheek teeth, jaw and jaw muscles were more massive in them. In Homo habilis, teeth were more or less similar to those of A. afarensis.
Dental variation among these hominids are peculiar. There is gradual reduction in the sizes of the front teeth, where as there is gradual increase in the sizes of cheek teeth in case of Paranthropus.
Such variation in hominid dentition is explained by the climatic changes that occured around 2.5 mya, opening up more and more savanna. It is hypothesized that species composition of both plants and animals changed and Paranthropus had to survive on low quality food which required prolonged mastication. Larger teeth, jaw and jaw muscles in Paranthropus developed due to such responses.
Around 2 to 2.5 mya, originated H. habilis which is clearly associated with tools. These forms, however, do not show enlarged cheek teeth, jaw and jas muscles. It is supposed that habilines ‘prepared” their food outside mouth, hence larger cheek teeth, heavy jaw is absent in them. The enamel is also not as thick as in the Paranthropines.
To conclude, Paranthropines, while displaying a hominid pattern in general, have larger cheek teeth because of ecological reasons. With the advent of tools, the teeth were put to different selection pressure and hence H. habilis has smaller cheek teeth in comparison to Paranthropines. Gradually there is reduction in the cusp height of the teeth, a prominent feature of the apes. The ratio between cheek teeth area to body weight was high in Paranthropine where as it is constant for later hominids. Hominization process in dental morphology thus consisted of reduction in sizes of teeth, jaw and jaw muscles, reduction in cusp height of teeth, and constant cheek teeth area. These features are seen to begin with in australopithecines and H. habilis.
44
TENSIVE COURSE IN BIOLOGICAL ANTHROPOLOGY
1st Summer School of the European Anthropological Association
16–30 June, 2007, Prague, Czech Republic
Enlargement of Brain
Earlier Palaeoanthropologists believed that evolution of human brain occurred after bipedalism and changes in the dentition were complete. Recent endocranial cast or endocast studies indicate that encephalisation process progressed along with other changes that characterize Hominids. In the latter stages of hominid evolution, the brain evolution consisted more of relative growth of brain and body size i.e. allometric growth rather than simple reorganization
Endocast studies of Homo habilis clearly indicate that its brain volume is significantly greater that those of australopithecines. Body weight of these hominids have been estimated from fossils and the encephalisation quotient determined by computing brain sizes relative to their body sizes. These data show that absolute and relative brain sizes increased during hominid evolution. Furthermore, the increase is not gradual. The period between 4 to 2 mya show insignificant change in brain volume as afarensis and africanus showed a brain volume below 450cc whereas those of H. habilis between 2 to 1.5 mya in the range of 650-700cc. The Hominization process that involved evolution of hominid brain can be said to have resulted during this period, between 2 to 1.5mya.
Speech and Language
Speech. The speech apparatus of humans consists of two physiological components: the subglottal system that includes lungs and associated muscles which provide the power for speech production, the larynx which communicates the subglottal system to upper supralaryngeal tracts itself which modulates acoustic energy generated by first two system.
The human supralaryngeal airways differs from that of other primates. In human beings the palate has moved backward and larynx downward to achieve unique constructions of supralaryngeal airway different from other primates. Moreover, the round human tongue moving in space defined by the palate and spinal column can generate frequency patterns that define vowels and consonants.
The area of brain specialized for language and speech are in the region surrounding the sylvian fissure of left hemisphere. This area contains the cortical centres for auditory perception and motor control of face, mouth and larynx for speech production. These motor area for speech and areas for sound perception are closely located to the language areas, the Broca’s area (immediately in front of motor area) and Wernicke’s area (immediately behind and to the side of the auditory area).
The structures and neural control mechanism necessary for the complex patterns of human speech seem to have evolved during the last 1.8 mya. The comparative anatomy of the living primates and hominid fossils suggest that evolution of supralaryngeal vocal tract probably started in early African populations of H. erectus (Liebeman, 1992). However the hominization process took sometime to complete. There is definite proof that hominids from the Israeli sites of Skhul and Quafzeh had definite human supralaryngeal airways, Neardertals, the non hominid supralaryngeal airways. Endocast studies of such forms indicate that their neural mechanisms had not appropriately developed, whereas those of from Skhul and Quafzeh were capable of producing human speech.
Language. Language is an adaptation unique to humans but its biological basis is very difficult to define. The American linguist Noam Chomsky has proposed that a unique “language organ” or language acquisition device (LDC) evolved within the human brain. Although there is no anatomical evidence for a new “organ” it is clear that there exist certain areas such as Broca’s area and Wernicke’s area for language.
Since language leaves no fossil record, the evidences for its origin are circumstantial. Comparative linguistics was used to estimate a date for a single common language. The recent approaches however have used anatomical and archaeological information to suggest a date of origin for language.
Anthropologists differ in the exact time of origin of languages. One group argues for a relatively recent origin and correlates it with the appearance of modern Homo sapiens with modern sized brains and fully descended vocal tracts. The tools and artistic culture that flourished in late Paleolithic coincides with development of language and communication. Another group traces origin of language to Homo habilis when first appearance of tools and beginning of enlargement of brain took place.
The two conditions have different consequences for the nature of mind. If origin of language is considered late linguistic changes in brain become secondary to the non linguistics changes, allowing only little to the languages to influences the structure of brain, if its origin is considered early, it is logical to think that it passed through multitude of forms and had major language on evolution of brain and vocal tract. The diverse language adaptation and its deep integration in human nature point to its ancient origin and it has been suggested that earliest language were singing, accompanied with gestures.
45
TENSIVE COURSE IN BIOLOGICAL ANTHROPOLOGY
1st Summer School of the European Anthropological Association
16–30 June, 2007, Prague, Czech Republic
Acknowledgment
I would like to thank the following people and institution for their advice and support. The University of Delhi gave us permission to carry out this research and logistical support. We thank to the Head of the department and staff of the Department of Anthropology, University of Delhi, India: Prof. A.K. Kapoor, Prof, Satwanti Kapoor, Department of Anthropology, University of Delhi, Delhi, India. Without their help, this work would never have been completed. On this occasion, we would be like to deliver our gratitude to all the experts who have been playing an important role in the evaluation phase .Thank you very much.
References
Britanica 2005 – Software
Britanica 2006 – Software
Craig B. Stanford (1996),The Hunting Ecology of Wild Chimpanzees: Implications for the Evolutionary Ecology of Pliocene Hominids, American Anthropologist, Vol. 98, No. 1, 96-113
Leakey, M.G., Feibel, C.S., McDougall, I. & Walker, A. (1995). New four-million-year-old hominid species from Kanapoi and Allia Bay, Kenya. Nature 376, 565-571.
Lieberman, D. E. (1995) Curr. Anthropol. 36, 159-197.
Lieberman, Hampton, Littlefield & Hallead (1992) Race in Biology and Anthropology: A Study of College Texts and Professors,Journal of Research in Science Teaching 29,301-321.
White, T.D., Suwa, G & Asfaw, B. (1994). Australopithecus ramidus, a new species of early hominid from Aramis, Ethiopia. Nature 371, 306-312
www. Evolution.com
www.googles.com
www.hominization.co.in
Mailing address: Ajeet Jaiswal
University of Delhi
110007 Delhi, India
epgajeet@redifmail.com
46

Human Evolution

In the simplest sense ,evolution means the slow process of change from a simple to a more complex structure. Evolution assumes that all living things are inter-related. Humans are supposed to have developed from some simpler forms. Most of the scientists today accept the basic principle of evolution but they have varying views regarding how evolution has taken place or how far it has gone.

The evolution of life began in the oceans. About four hundred million years ago the first land based creatures emerged. Some of these gradually evolved into the large reptiles who were later displaced by mammals. Mammals are warm-blooded creatures having greater capacity to learn from experience than other animals and this capacity has reached its highest development in the human species.

Our closest relatives are chimpanzee, gorilla and oranguatan. Though similarities between man and other animal forms were discovered by Linnaeus who grouped men ,the great ape and monkeys in a single order, primates, the three main theories are Lamarckism, Darwinism and Synthetic theory.

Lamarck is chiefly remembered for his belief in the inheritability of acquired character which is disputed. But he is credited in the history of evolutionary thought for recognizing and stating for the first time that evolution is a general fact covering all forms of life and it is a gradual process.

The scientific establishment of the theory of evolution was mainly the work of Charles Darwin. In his book 'The Origin of Species'1859 he showed that human evolution has occurred through the process of natural selection. The main points of this theory are:

• Struggle for existence
• Variation
• Survival of the fittest
• Natural selection

Darwin's natural selection serves as the corner-stone of the modern synthesis, but the mutation theory,Mendelian genetics and the statistics of population dynamics are also very important components of its foundation.

The basic postulate of the synthetic theory is that evolution proceeds principally as a result of the interaction between five indispensable processes-

• Mutation
• Genetic recombination
• Changes in the chromosome number and structure
• Natural selection
• Reproductive isolation

This is also called Neo-Darwinism.

Stages in Human Evolution

During the Miocene epoch the family Hominoidea diverged into two sub-families the Pongidae (apes) and the Hominidae(humans).The exact point of divergence between the ape line and the human line is debatable. In general Dryopithecus is considered to be ancestor of both apes and humans.

Dryopithecus: This genus lived in Africa,China,India and Europe. The genetic title dryopithecus means oak wood apes because it is believed that the environmental conditions were such at that time with densely forested tropical lowlands and the members might have been predominantly herbivorous.

Ramapithecus: The first remains of Ramapithecus were discovered from Shivalik hills in Punjab and later discovered in Africa and SaudiArabia.The region where Ramapithecines lived was not merely forest but open grassland. A hominid status for them is claimed on two grounds: Fossil evidence indicating adaptation including robust jaws, thickened tooth enamel and shorter canines. Extrapolation regarding upright posture and the use of hands for food and defense.

Australopithecus: This genus is the immediate forerunner of the genus Homo.The first Australopithecine find was made in 1924 at Taung a limestone quarry site in South Africa by Raymond Dart. They walked erect, lived on the ground and probably used stones as weapons to hunt small animals. They weighed 60 to 90 pounds and were about 4 feet tall.

Home Erectus: The first evidence of the Homo species was discovered in Java by Eugene Dubois in 1891.He named his find as pithecanthropus erectus meaning the erect ape man. It is said to be the missing link. Another find was made in China ,south-west of Peking called Peking man. These had larger cranial capacity then Australopithecus lived in communal existence and used fire. The cranial capacity of Homo erectus which include Java man and Peking man varied from about 775 to nearly 1300 CC.The Acheulean tool tradition is associated with the Homo Erectus way of life. The stone tools were largely made of quartz. Bone tools and wooden tools like wooden spears have also been discovered. There is evidence of big game hunting which indicates that there must have been collective cooperative hunting. The Homo Erectus seem to be cave-dwellers. An important advancement is that there is evidence of the use of fire.

Homo Sapiens Neanderthalensis : The Home erectus gradually evolved into the Homo Sapiens. In this transitional event two sub-species of the Homo sapiens have been identified. One the primitive man who has been labeled Homo sapien Neanderthal and two the modern man who is called Homo sapiens sapiens. Most of the evidences about the primitive man that have been unearthed are 75,000 years old. The first fossil that was found of the Neanderthal type was a skull cap found in Germany. The cranial capacity of Neanderthal exceeded that of the modern man.It ranged from 1200 to 1610 c.c.Their culture has come to known as Mousterian culture. A few small hand axes are also found. For the first time pointed stone flakes which seem certainly to be spearheads have also been found. There caves were made more comfortable for winter dwelling by placing a fire work with holes at the entrance of the cave and by covering it with stretched hide. The Neanderthals were capable of big game hunting, including elephants, rhino etc.

Homo Sapiens Sapiens: The first skeletal remains of Homo sapiens sapiens were found in Europe and were named Cro-Magnon. In the Homo sapiens sapiens there is final reduction of the jaws, the appearance of modern man's chin and of the rounded skull.Mean cranial capacity was about 1350 c.c.Modern man is very closely related to Cro-magnon.Their culture which dates back to 35,000 years is also called upper Paleolithic culture. Hunting and gathering seem to have been the primary methods of food gathering. The first appearance of art was during this time. The drawings on cave walls were mainly of animal figures.

ABO blood group system

ABO blood group antigens present on red blood cells and IgM antibodies present in the serum

The ABO blood group system is the most important blood type system (or blood group system) in human blood transfusion. The associated anti-A antibodies and anti-B antibodies are usually IgM antibodies, which are usually produced in the first years of life by sensitization to environmental substances such as food, bacteria and viruses. ABO blood types are also present in some animals, for example cows and sheep, and apes such as chimpanzees, bonobos, and gorillas.

Contents 1 ABO antigens 2 History of discoveries 3 Serology 4 ABO hemolytic disease of the newborn 5 Inheritance 6 Distribution and evolutionary history 7 Association with von Willebrand factor 8 Subgroups 8.1 A1 and A2 9 Bombay phenotype 10 Nomenclature in Europe and former USSR 11 Examples of ABO and Rhesus D slide testing method 12 Universal blood created from other types, and artificial blood 13 Myths 14 References 15 Further reading 16 External links

 ABO antigens

The A antigen and the B antigen are derived from a common precursor known as the H antigen (or H substance). The H antigen is a carbohydrate sequence with carbohydrates linked mainly to protein (with a minor fraction attached to ceramide moiety). The majority of the ABO determinants are expressed on the ends of long polylactosamine chains attached mainly to Band 3 protein , the anion exchange protein of the red cell membrane, and a minority of the epitopes are expressed on neutral glycosphingolipids . In blood group O, the H antigen remains unchanged and consists of a chain of beta-D-galactose, beta-D-N-acetylglucosamine, beta-D-galactose, and 2-linked, alpha-L-fucose, the chain being attached to the protein or ceramide. H antigens can be changed into A or B antigens by enzymes coded by the blood group A or B genes, which are sugar (glycosyl) tranferases. Type A has an extra alpha-N-acetyl-D-galactosamine bonded to the D-galactose at the end, while type B has an extra alpha-D-galactose bonded to the D-galactose at the end.

• Individuals with type A blood can receive blood from donors of type A and type O blood.
• Individuals with type B blood can receive blood from donors of type B and type O blood.
• Individuals with type AB blood can receive blood from donors of type A, type B, type AB, or type O blood. Type AB blood is referred to as the universal recipient.
• Individuals with of O blood can receive blood from donors of only type O.
• Individuals of type A, B, AB and O blood can receive blood from donors of type O blood. Type O blood is called the universal donor.

One caveat to this axiom of 'universal donor' is that this applies to packed RBC's and not to whole blood products. Using the first table, type O carries anti-A and anti-B antibodies in the serum. To transfuse a type A, B, or AB recipient with type O whole blood would produce a hemolytic transfusion reaction due to the antibodies found in the serum of whole blood.

recipient	donor
A	A or O
B	B or O
AB	A, B, AB, or O
O	O

Antibodies are not formed against the H antigen, except by those with the Bombay phenotype.

In ABH secretors, ABH antigens are secreted by most mucus-producing cells of the body interfacing with the environment, including lung, skin, liver, pancreas, stomach, intestines, ovaries and prostate.

 History of discoveries

The ABO blood group system is widely credited to have been discovered by the Austrian scientist Karl Landsteiner, who found three different blood types in 1900;[3] he was awarded the Nobel Prize in Physiology or Medicine in 1930 for his work. Due to inadequate communication at the time it was subsequently found that Czech serologist Jan Janský had independently pioneered the classification of human blood into four groups,  but Landsteiner's independent discovery had been accepted by the scientific world while Janský remained in relative obscurity. Janský's classification is however still used in Russia and states of former USSR (see below). In America, Moss published his own (very similar) work in 1910.

 Landsteiner described A, B, and O; Decastrello and Sturli discovered the fourth type, AB, in 1902. Ludwik Hirszfeld and E. von Dungern discovered the heritability of ABO blood groups in 1910–11, with Felix Bernstein demonstrating the correct blood group inheritance pattern of multiple alleles at one locus in 1924.. Watkins and Morgan, in England, discovered that the ABO epitopes were conferred by sugars, specifically N-acetylgalactosamine for the A-type and galactose for the B-type (Morgan, W. T. J. & Watkins, W. M. Br. Med. Bull. 25, 30–34 (1969), Watkins, W. M. in: Advances in Human Genetics Vol. 10 (eds Harris, H. & Hirschhorn, K.) 1–136 (Plenum, New York, 1980), Watkins, W. M. & Morgan, W. T. J. Vox Sang. 4, 97−119 (1959). After much published literature claiming that the ABH substances were all attached to glycosphingolipids, Laine's group (1988) found that the band 3 protein expressed a long polylactosamine chain (Jarnefelt, Rush, Li, Laine, J. Biol. Chem. 253: 8006–8009(1978)) which contained the major portion of the ABH substances attached (Laine and Rush in Molecular Immunology of Complex Carbohydrates (A. Wu, E. Kabat, Eds.) Plenum Publishing Corporation, N.Y. NY (1988)). Later, Yamamoto's group (Yamamoto, et al., Nature 345, 229–233 (1990)), showed the precise glycosyl transferase set that confers the A, B and O epitopes.

 Serology

Anti-A and anti-B antibodies, which are not present in the newborn, appear in the first years of life. It is possible that food and environmental antigens (bacterial, viral or plant antigens) are similar enough to A and B glycoprotein antigens that antibodies created against the environmental antigens in the first years of life can cross react with ABO-incompatible red blood cells. Anti-A and anti-B antibodies are usually IgM, which are not able to pass through the placenta to the fetal blood circulation. O-type individuals can produce IgG-type ABO antibodies.

The "Light in the Dark theory" (DelNagro, 1998) suggests that when budding viruses take with them host cell membranes from one human patient (in particular from the lung and mucosal epithelium where they are highly expressed) they also take along ABO blood antigens from those membranes, and may carry them into secondary recipients where these antigens can elicit a host immune response against these non-self foreign blood antigens. These viral-carried human blood antigens may be responsible for priming newborns into producing neutralizing antibodies against foreign blood antigens. Support for this theory has come to light in recent experiments with HIV. HIV can be neutralized in "in-vitro" experiments using antibodies against blood group antigens specifically expressed on the HIV producing cell lines.

The "Light in the Dark theory" suggests a new novel evolutionary hypothesis that there is true communal immunity, which has developed to reduce the inter-transmissibility of viruses within a population. It suggests that individuals in a population supply and make a diversity of unique antigenic moieties so as to keep the population as a whole more resistant to infection. A system set up ideally to work with variable recessive alleles.

 ABO hemolytic disease of the newborn

Main article: Hemolytic disease of the newborn (ABO)

ABO blood group incompatibilities between the mother and child does not usually cause hemolytic disease of the newborn (HDN) because antibodies to the ABO blood groups are usually of the IgM type, which do not cross the placenta; however, in an O-type mother, IgG ABO antibodies are produced and the baby can develop ABO hemolytic disease of the newborn.

Blood groups are inherited from both parents. The ABO blood type is controlled by a single gene with three alleles: i, IA, and IB. The gene encodes a glycosyltransferase—that is, an enzyme that modifies the carbohydrate content of the red blood cell antigens. The gene is located on the long arm of the ninth chromosome (9q34).

The IA allele gives type A, IB gives type B, and i gives type O. As both IA and IB are dominant over i, only ii people have type O blood. Individuals with IAIA or IAi have type A blood, and individuals with IBIB or IBi have type B. IAIB people have both phenotypes, because A and B express a special dominance relationship: codominance, which means that type A and B parents can have an AB child. A type A and a type B couple can also have a type O child if they are both heterozygous (IBi,IAi) Therefore, an O child is not a direct proof of illegitimacy, just as a child with blond hair could be born from parents who both had brown hair. The cis-AB phenotype has a single enzyme that creates both A and B antigens. The resulting red blood cells do not usually express A or B antigen at the same level that would be expected on common group A1 or B red blood cells, which can help solve the problem of an apparently genetically impossible blood group.

Distribution and evolutionary history

The distribution of the blood groups A, B, O and AB varies across the world according to the population. There are also variations in blood type distribution within human subpopulations.

In the UK, the distribution of blood type frequencies through the population still shows some correlation to the distribution of placenames and to the successive invasions and migrations including Vikings, Danes, Saxons, Celts, and Normans who contributed the morphemes to the placenames and the genes to the population.

There are six common alleles of the ABO gene that produce one's blood type:[12][13]

A A101 (A1) A201 (A1)

B B101 (B1)

O O01 (O1) O02 (O1v) O03 (O2)

Many rare variants of these alleles have been found in human populations around the world.

Some evolutionary biologists theorize that the IA allele evolved earliest, followed by O (by the deletion of a single nucleotide, shifting the reading frame) and then IB.[citation needed] This chronology accounts for the percentage of people worldwide with each blood type. It is consistent with the accepted patterns of early population movements and varying prevalent blood types in different parts of the world: for instance, B is very common in populations of Asian descent, but rare in ones of Western European descent.) Another theory states that there are four main lineages of the ABO gene and that mutations creating type O have occurred at least three times in humans. From oldest to youngest, these lineages comprise the following alleles: A101/A201/O09, B101, O02 and O01. The continued presence of the O alleles is hypothesized to be the result of balancing selection. Both theories, contradict the previously-held theory that type O blood evolved earliest, supported by the fact that all human beings can receive it[citation needed]. The British National Blood Transfusion Service states this to be the case (see the web-link under External Links below) and says that originally all human beings were type O.

 Association with von Willebrand factor

The ABO antigen is also expressed on the von Willebrand factor (vWF) glycoprotein,[15] which participates in hemostasis (control of bleeding). In fact, having type O blood predisposes to bleeding, as 30% of the total genetic variation observed in plasma vWF is explained by the effect of the ABO blood group, and individuals with group O blood normally have significantly lower plasma levels of vWF (and Factor VIII) than do non-O individuals. In addition, vWF is degraded more rapidly due to the higher prevalence of blood group O with the Cys1584 variant of vWF (an amino acid polymorphism in VWF):[20] the gene for ADAMTS13 (vWF-cleaving protease) maps to the ninth chromosome (9q34), the same locus as ABO blood type. Higher levels of vWF are more common amongst people who have had ischaemic stroke (from blood clotting) for the first time.[21] The results of this study found that the occurrence was not affected by ADAMTS13 polymorphism, and the only significant genetic factor was the person's blood group.

Subgroups

This section is incomplete - please help to expand it.

 A1 and A2

The A Blood Type contains about twenty subgroups, of which A1 and A2 are the most common (over 99%). A1 makes up about 80% of all A-type blood, with A2 making up the rest. These two subgroups are interchangeable as far as transfusion is concerned, however complications can sometimes arise in rare cases when typing the blood.

 Bombay phenotype

Main article: Hh antigen system

Individuals with the rare Bombay phenotype (hh) do not express substance H on their red blood cells, and therefore do not bind A or B antigens. Instead, they produce antibodies to substance H (which is present on all red cells except those of hh genotype) as well as to both A and B antigens, and can therefore receive blood only from other hh donors (although they can donate as though they were type O).

 Nomenclature in Europe and former USSR

In parts of Europe the "O" in ABO blood type is substituted with "0" (zero), signifying the lack of A or B antigen. In the former USSR blood types are referenced using numbers and Roman numerals instead of letters. This is Janský's original classification of blood types. It designates the blood types of humans as I, II, III, and IV, which are elsewhere designated, respectively, as O, A, B, and AB. The designation A and B with reference to blood groups was proposed by Ludwik Hirszfeld.

 Examples of ABO and Rhesus D slide testing method

Blood group O positive: neither anti-A nor anti-B have agglutinated, but anti-Rh has

Result: Blood group B negative: anti-A and anti-Rh have not agglutinated but anti-B has

In the slide testing method shown above, three drops of blood are placed on a glass slide with liquid reagents. Agglutination indicates the presence of blood group antigens in the blood.

 Universal blood created from other types, and artificial blood

In April 2007 an international team of researchers announced in the journal Nature Biotechnology an inexpensive and efficient way to convert types A, B and AB blood into type O. This is done by using glycosidase enzymes from specific bacteria to strip the blood group antigens from red blood cells. The removal of A and B antigens still does not address the problem of the Rhesus blood group antigen on the blood cells of Rhesus positive individuals, and so blood from Rhesus negative donors must be used. Patient trials will be conducted before the method can be relied on in live situations.

Another approach to the blood antigen problem is the creation of artificial blood which could act as a substitute in emergencies. BBC.

 Myths

There are numerous popular myths surrounding ABO blood groups. These beliefs have existed since the ABO blood groups were identified and can be found in different cultures throughout the world. For example, during the 1930s, connecting blood groups to personality types became popular in Japan and other areas of the world.

The popularity of Peter J. D'Adamo's book, Eat Right For Your Blood Type suggests that these myths persist. This book claims that ABO blood groups can be used to determine diet as well as to predict diseases.

Additional myths include the idea that Group A causes severe hangovers, group O is associated with perfect teeth, and those with blood group A2 have the highest IQs. Scientific evidence in support of these concepts is scant or nonexistent.