1 Iodine Sources

Our model second application relates to the probabilistic influence of another environmental chemical element (its cycle and its sources) in the biological hominisation processes and particularly in the encephalisation. Just like calcium, iodine contained in the earth's crust and the oceans can be regarded as a stimulus to which the organisms react.

Let us point out below the iodine quantities that contains our sphere (Bernard 1939):

In the grounds, iodine is retained by clay but especially by the organic matter. The iodine content increases with the organic matter rate (Jean Duval 1991). Iodine follows a cycle to the sphere surface which we cannot better specify than by quoting some lines extracted the L.M. Bernard work: " atmospheric iodine and telluric iodine, fixed by the plants, are assimilated by the organized beings. These beings final decomposition releases then the metalloid. Pulled by streaming waters, it is rejected towards the seas. The sea plants absorb it and concentrate it in their cells. From sea plants, iodine goes into the fishes and shellfishes organisms. By to their disappearance and to their precipitation at the sea-bed, all and sundry form the sedimentary grounds of which high content in iodine.....a highlighted by K Scharrer ".

We summarized, in the following table, the iodine contents, g %, of various rocks, waters, air, organized beings, etc... according to several authors, with the rough average.

One notes that the sources resulting from the the earth's crust interior (mineral waters and hot water sources, oil reservoirs salted water, peats and coals), have the largest iodine contents. Then come, on average, by descending order, the seas and oceans (2,3 10-4 g %), the sedimentary rocks (10-4 to 10-5 g %), the eruptive rocks (10-5 g %), then the rainwater (10-6 g %). The marine air (1,5 10-5 g/m3) contains 12 to 13 times more iodine than the continental air (1,1 10-6 g/m3). In the same way, in the organized beings, animals and plants, the iodine contents are more or less significant, according to their marine or terrestrial origin, algae (10-3 g %), marine fishes (10-3 to 10-4 g %), meats (10-5 to 10-6 g %), terrestrial plants, bread, vegetables, etc... (2 10-6 g %).

The seas and oceans middle salinity, about 3,4 to 3,5 g % (Ivanoff 1972), (Guilcher 1965), which can reach 20 g % in the Dead Sea, is weaker in the lakes, of 1 g to 1,3 g %, with exceptions such as the Lake Karabogaz, in draining process, with 20 g %. It is weaker in the rivers, lower than 0,06 g %, content in Bear River which feeds the Large Salted Lake. The Jordan has an exceptional salinity, in Jericho, about 0,77 g %. The iodine, which contributes, with the traces state, at salinity, thus has, proportionally, a decreasing concentration in the seas and oceans, then the lakes then the rivers (Dittmar law on the various salts relative proportion constancy) (Ivanoff 1972). One can thus estimate, with probability, the middle contents iodine some, roughly, about 2,3 10-4 g % in the seas and oceans, 7 10-5 g % in the lakes and 4 10-6 g % in the rivers. Iodine, absent from the glaciers water (Pascal 1960), exists in a free state volcanic and magmatic activity in the gas or solid products which introduce it by scrubbing into the iodine cycle such as it is described above.

2 Iodine and organisms

The morphological and physiological iodine role in the organisms is significant. Iodine influence on the caudal or cerebral tissues development or regression is well-known: brain hypertrophy at the frog tadpole by iodine injection, metamorphose tailless and Urodela Amphibia under the iodine dependence (Roth 1946), Axolotl transformation under thyroid feeding, etc... The thyroid hormone acts about on all tissues but with more effectiveness on bone and nervous tissues. The thyroxine effects depend on its dilution. Its effectiveness, in the tadpoles complete experimental metamorphosis, would act with a dilution between 1 per 100 million and 1 per 100 billion. According to dilution, one can cause the posterior legs push without atrophying the tail. Brain development claims higher amounts. In the thyroid private animals, the brain is more or less atrophied. In the young toad larvae, the thyroid ablation removes the tail regression (Rostand 1941). If, on the other hand, with a frog tadpole, for example, one grafts additional thyroid, its brain hypertrophies so much so that the cranium can sometimes burst (Rey 1948). It is interesting to note that, at Hominoids, the brain development is concomitant with the caudal appendix disappearance. The iodine influence in the cerebral tissue development at the man was highlighted by many searchs (Pharoah, Ellis, Williams 1976). At the man, the adult organism contains from 15 to 20 mg iodine of which 70 % to 80 % is in the thyroid one (Underwood 1989). The iodine influence on the brain development is well-known: high mountainous valleys congenital myxoedeme, which produces a physically dwarf and an intellectually idiot (Delange, Ermans 1976), because the iodine water poverty, iodine deprives acting directly on the brain development (Pharoah, Ellis, Williams 1976) or thyroid insufficiency related to a thyroid development lack (Dumont, Ermans, Bastenie 1963). Many studies showed that deficiency iodine some in the feeding is harmful with the brain growth. The iodine deficiency involves a thyroid hormones insufficient production essential to the brain growth and development. A article published in the Newspaper of Medicine of New England (Mars 1996) highlights that the thyroxine which crosses the mother placenta towards the foetus is necessary to the foetus brain development. In the past, other studies also showed that thyroxine low levels are present in the mentally delayed children. Experts health estimate that 100.000 cretins are born each year in the world because of iodine deficiency (A.B.C. News 1998). The stupidity (Iodine Deficiency Disorder) results from a severe iodine deficiency during the grossesse beginning. Iodine deprivation is the backwardness most frequent cause in the world. One estimates, that in 1997, 54 million Indians suffer from goitre, 6,6 million backwardnesses and 2,2 million stupidity, due to iodine deficiency (O.M.S. 1998).

3 Hominisation scenarii

Hominisation scenarii, i.e. a Primate line evolution, in the species Homo sapiens or the subspecies Homo sapiens sapiens (Stoczkowski 1992) are very numerous. They are based on a certain number of characters, the most frequently called upon are: tools, the bipedy and the free hand, the brain volume and various cultural activities (language, social life, labour division, mental faculties, etc...). The tools (Goodall 1971), just as the language (Linden 1979) are not the Homo only prerogative. The bipedy, which is an established fact for the Australopithecus, could go up to 5-6 million years, time when the oldest Hominids line diverged from that of Panids (Lovejoy 1981). Moreover, the bipedy also exists in other animals groups, like the Birds. The cerebralisation, i.e. the development and enrichment in brain convolutions (25 % in the chimpanzee for 65 % at the man) (Leakey, Lewin 1985), can seem the hominisation fundamental criterion with the brain/weight body ratio (1/40). Compared with the same ratio for whale 1/10.000, elephant 1/600, but only 1/12 for the marmoset and lower than that of the man for the sagouin, the porpoise and even the arboricole shrew (Leakey, Lewin 1985). The Heinz cerebralisation coefficient is not more convincing (Camps 1982).

One could consider that the hominisation is the whole of these characters resultant evolution and try to establish between them a Pearson correlation coefficient. The company seems difficult and artificial. The IQ and the Spearman G factor (Jensen 1979) seem very reducing and hardly convincing.

We will not take into account, in our search, in accordance with the probabilistic model, that of a parameter, the increase in brain volume and its complexification, in the hominisation process. We will not infer, by this step, that the only brain evolution in the Primates, Hominoids, Hominids then Homos is the exclusive hominisation parameter. Our methodology approaches the cladist analysis, according to which the search for a monophyletic group rests primarily on the morphological characters resemblance (Hennig 1966). Our search relates simply the brain evolution at Hominids and Homos. The increase in the brain volume at Hominids, during million years, involved cranium shape concomitant morphological modifications, face, mandibles, teeth, posture (bipedy). The neuronal connections multiplication and complexification generated by the increase in the brain volume and its convolutions were not without fundamental consequences on the behaviors (feeding, tools, cerebral faculties, socialization, language, culture, etc...). So, 50 % of the human cortex consists of surfaces devoted to the visual processes implied in linguistic functions. The brain auditive surfaces also intervene in the language development. This last seems to have appeared between 50.000 and 100.000 years (Martin I Sereno 1990). These modifications were translated, at Hominids, by a genera and species evolution which goes, in the current knowledge state, of Artipithecus ramidus (4,4 M.Y.) (White and all. 1994 - Wood 1994) in Homo sapiens sapiens standard Cro-Magnon (current).

Our probabilistic interaction model between a environment stimulus, iodine, and a group of animals, Hominids, appearing primarily by the increase in the brain volume, incidentally by the caudal appendix disappearance, leads us to seek if a probabilistic correlation can be established between the iodine sources and diffusion on the sphere surface and this encephalisation, simply characterized by the increase in the brain volume and its convolutions, their complexification, and the Hominids evolution. Our search will concern, on the one hand, the geological and prehistoric periods, on the other hand, at the present time, the Homo sapiens sapiens subspecies localization and settlement intensity. Our Hominids correlation model iode/encephalisation is not presented like a reducing model and a univocal explanation with the hominisation processes but like a probabilistic factor, i.e. prevalent, among the plurality of the possible causal factors.

4 The hominisation and the brain volume evolution

The classification of the organisms varies more or less according to authors. In the Mammals class, which " explode " with the Cenozoic one, the brain is remarkable by the cerebral hemispheres and the cerebellum great proportions. Among the 18 Mammals orders, the Primates order would comprise 13 families (Simpson - Walker 1945) but of many divergent classifications were born. At all events, of the primitive Primates to the evolved Primates, one notes an exceptional cerebral development. The oldest known Primate would be Pergatorius ceratops gone back to approximately 70 M.Y. One generally classifies the Primates in two sub-orders, Strepsirrhinia (Prosimii) and Happlorhinia (Anthropoids). The latter have larger brains and divide, with Oligocene, between New-World Monkeys (Platyrrhinia) and Old World Monkeys (Catarrhinia). The latter have a brain larger than Platyrrhinia. Catarrhinia divide, in their turn, into 2 Superfamilies: Cercopithecoids and Hominoids. Whereas Cercopithecoids have long tails, Hominoids do not have any more. The monkeys brain without tail is higher than that of the other monkeys by its dimensions and its convolutions, while remaining lower than that of Hominids, one of the Primates latest branches which develops in Pliocene (Leakey, Hay 1979), (Pilbeam 1992). First Hominoids nomenclature , gone back to approximately 23/25 M.Y. dubious and is discussed. One often classifies Hominoids in three families: Pongids, whose three genera survived (chimpanzees, gorillas and orangs-outangs), Hylobatids (gibbons) and Hominids. Hylobatids are sometimes regarded as a Pongids subfamily. Other phylogenetic relations are also proposed. Among Hominids, one distinguishes two genera, Australopithecus and Homos and, more recently, Ardipithecus. As search develops, the discovered species are increasingly numerous. Among the last arrivals, one can quote Australopithecus garhi (Adis-Abeba, approximately 2,5 M.Y.) and Homo antecessor (approximately 780.000 years, 1994-1996 Gran Dolina, Spain, Bermudez de Castro), Orrorin tugenensis (Tugen, Kenya, Brigitte Senut and Martin Pickford, 6 M.Y., 2001), Kenyanthropus platyops (Lomekwi, Turkana, Meave Leakey, 3,5 M.Y. 2001). The Hominids evolution is not linear but rather seems a bushy tree with branches finishing in deadlock (like Australopithecus robustus or perhaps Homo habilis and Homo neanderthalensis).

In the table which follows, we listed the major Hominids part to date known, in their chronological order appearance as well as their brain volume. It is obvious that of this data table are rough data, since the dates and volumes sometimes strongly fluctuate according to sources (Tim Mooney and Alan F Benjamin 1995; Ember and Ember 1996; Robert J Huskey 1998; Donald Johanson and Blake Edgar 1996; Aaron Valenzuela and Mary Reed 1999; Jim Foley 1999). In addition, the brain volume in the species is a rough data which must be appreciated with a corrective formula according to the body dimensions. Thus, oldest Australopithecus, anamensis and afarensis, have a volume comparable with that of the chimpanzee (approximately 400 cc), for a lower size (approximately 1m, 20), whereas the gorillas have a high middle (500 cc) but for a size much larger (approximately 2m). Genetically, the chimpanzees are the closest organisms to Homos (genetic variation from approximately 1 %, King, Wilson 1975).

One can, after reading this grid, to make the following general remarks, at first approximation:

1) At Australopithecus, one notes a parallel progression between the least seniority of the appearance of the species and the increase in brain volume (except for Australopithecus aethiopicus). Thus, by 4.4 M.Y. with 1 M.Y., i.e. in about 3,5 M.Y., the brain volume increases by 50 % (360 to 550/600 cc).

2) The same parallelism is observed at Homos (except for Homo neanderthalensis) with an increase in the brain volume rhythm stressing which doubles in approximately 2,5 M.Y. (from approximately 650 cc for Homo habilis to 1350 cc for Homo sapiens sapiens).

Ultimately, at Hominids, the brain volume will have almost quadrupled since the first Hominids appearance there are approximately 4,5 M.Y.

This progressive evolution is corroborated by the increase in recent Homo erectus brain, Homo erectus pekinensis, which lived in the site N° 1 of Zhoukoudian between 0,46 and 0,23 M.Y. before our era. The cranial capacities go from 915 cc for the oldest cranium to 1075 cc for more recent craniums and 1140 cc for most recent (Rukang, Shenglong 1992). This progressive increase in the Hominids cranial capacity arises with obviousness cranial capacities frequencies distribution of the Australopithecus africanus and Homos habilis of East Africa and oldest Homos erectus and most recent (Wolpoff 1991). First Homos sapiens (Archaic Homo sapiens) seem resulting from an alive Homo heidelbergensis subpopulation in Africa between 500.000 and 130.000 years, modern Homos sapiens (Cro-magnon type) going back to approximately 40.000 years.

Let us summarize the current state of knowledge on the encephalisation evolution in the hominisation processes. We will not take party in the many and fertile controversies on the lines filiation. We will only retain the different Hominoids and Hominids succession (and often coexistence) during Miocene, Pliocene, Pleistocene and the Holocene one.

Proconsul, considered as Protohominid (23-20 M.Y.), has a brain from approximately 167 cc with a encephalisation, weight brain/weight body ratio, higher than that of the current monkeys (Coppens 1983), (Beard, Teaford, Walker 1986). He does not have any more a tail. Hominoids, of which closest to Hominids are the Chimpanzees, diversify between 15 M.Y. and 6 M.Y. and perhaps, according to molecular phylogeny data, 4 to 5 M.Y. (Adoutte 1992). First true Hominids currently known appear towards 4-5 M.Y. in the African East (Ardipithecus ramidus, Australopithecus anamensis and afarensis) then in Chad (Australopithecus bahrelghazeli) (Leakey, Walker 1997) and in South Africa (Australopithecus africanus). According to species, the Australopithecins brain volume evolves between 400 cc (anamensis) and nearly 550/600 cc (robustus). First african Homininins appear in Eastern Africa towards 2,5-2,2 M.Y. with a much bulkier brain, Homo habilis (~ 650 cc), then Homo rudolfensis(750 cc) and Homo ergaster (> 850 cc). Homo erectus (900 to 1200 cc) (1,3 - 0,15 M.Y.) precede Homo antecessor and Homo heidelbergensis. Homo sapiens would be known almost since approximately 0.2 M.Y. Apparear finally Homo sapiens, known almost everywhere in the world, since approximately 0,150 M.Y. (Vandermeersch 1995) with a 1350 cc middle brain volume (being able to go from 1000 to 2000 cc). At present, the relations between Homo erectus, antecessor, heideldenbergensis and neanderthalensis are far from being clear. The Neandertalians traditional species or subspecies, with a 1500 cc middle brain volume (80000-27000 A.) seem to be a dead end. Approximately 4,5 M.Y. separate the Ardipithecus ramidus species from the Homo sapiens sapiens subspecies.

There is 1,9-2 M.Y., a migratory wave " Out of Africa " occurs starting from Eastern Africa and is spread in 100.000 years in the Old World (Western Europe, India, Java, China). Later, in Europe, Homo erectus is replaced by Homo sapiens neanderthalensis or Homo neanderthalensis (Hublin 1998) (80.000-27.000 Y.) and its ante and preneandertalians precursors (400.000-500.000 Y.), then by the modern man Homo sapiens sapiens (type Cro-Magnon) whose origin does not seem former to 40.000 Y. The man occupies all planet, invades the american continent, by the Behring strait, and Australia. Prehistoric and historical civilizations develop then starting from some hearths civilizations to lead to current settlement of the globe.

In short, the Hominids evolution, during approximately 5 M.Y., is characterized by an undeniable progressive encephalisation, carrying the taxa brain volume from 360 cc to 1350 cc. The cycle and the iodine sources, as we have already pointed out, encourage us to seek if, following the calcium example, iodine can be regarded as a stimulus environment to which react, in a probabilistic way, the living organisms and particularly Hominids.

5 The probabilistic correlation between the iodine sources and the hominisation

We have see, in the chapter 1 (Iodine sources), that the iodine mineral dissemination on surface of the sphere (Ivanoff 1972) is the scrubbing earth's crust fact but that this scrubbing be insufficient to explain the ocean iodine current middle content (2,3 10-4 g %). During geological era, the iodine earth's crust and asthenosphere have been carried within the globe with its surface by the magma and the lava and thus, primarily, by the volcanicity, continental or oceanic (Bardintzeff 1992) and the fissural faults emissions. The asthenosphere iodine is spread in the biosphere by the volcanic activity gas and solid products (Pascal 1960). The volcanoes emit gases during the eruptions and when they are not in eruption, gases escape through the cracks from the ground. In fact the fumerolles can last hundreds of thousands of years after the the eruptions end. Theses gas are, usually, water vapor (90 %), carbon dioxide, sulphur dioxide, hydrogen sulphide, hydrogen, argon, etc... and others composed with the traces state (iodine). These gases can be diffused by the wind with their source tens of kilometers (Miller 1989; Hoblitt and all. 1987; Wright and Pierson 1992; Myers and Brantley 1995). The various products are washed and iodine is introduced into the volcanic areas food chain or located in the vicinity. The volcanic influence can also extend relatively far from the volcanoes by the dissemination from ashes (ashes of the Eifel volcanoes to Berlin, Geneva and Zurich lakes, etc...) (Kraft, de la Rouziere 1991). The faults and the plio-pleistocene volcanicity characteristic of the " pliocene revolution " (Furon 1959) affect most of Europe (the Western and Eastern Mediterranean, Greece, Italy, Massif Central, Kaiserstuhl, Rhenish Schistous Massif, Czechoslovakia, etc...) but also America (United States Western, Patagonie, etc...) and Africa (East Africa Rift Valley, South Africa Great Dyke).Also exist at this time significant compression zones (Zagros chain overlappings). In Asia, in Java and in China, pleistocene volcanicity and the quaternary cracks are also intense. During million years, the asthenosphere iodine diffuses on the continents, primarily by the local volcanicity and the fissural emissions means, to succeed, by the earth's crust scrubbing, to the oceans current content of iodine.

We noted (Chapter 2: Iodine and organisms) that iodine plays a significant role, at the living organisms, in the brain morphology and physiology and the caudal appendix. Just like calcium seemed a fundamental stimulus in the construction of the exoskeletons and endoskeletons of the organisms, we propose a probabilistic role, i.e. dominating, stimulus iodine, in the hominisation process, considered primarily in its morphogenic character of increase brain volume and complexification. With the iodine stimulus in the environment, the organism response is the brain volume increase and its convolutions complexification. With weaker amounts, this stimulus atrophies or makes the caudal appendix disappear. If iodine is really a brain development probabilistic stimulus at Hominids, we must be able to establish a correlation of probabilistic order between the iodine sources during geological times (volcanic and fissural) and the hominisation process such as we considered it higher. This correlation between the iodine food chain and the brain evolution being of probabilistic order, must have 1) a necessary character but nonsufficient 2) a character statistically dominating but nonexclusive (relatively significant secondary factors can intervene in the Hominids evolution and dwelling sites such climates, glaciations, drynesses, etc., favorable or unfavourable, vegetation, relief, ecological niches, geographical insulation, migrations - to see higher -, psychological elements, etc...).