Ultraviolet Radiation, Vitamin D and Rickets
orWhere did fair haired people come from ?
The hereditary factors of the early human being in Africa were formed by the
African life conditions, among other things by the hot African sun
Our African ancestors left in early times the shadow jungle and settled in the
more food rich Savanna.They had to adapt to the hot, shadeless Savanna
and lost in a process of evolution their animal' hair dress.
( Not provablen, but could be)
An advantage: The naked sweating skin improved its ability for cooling, a
needed for long distance hunting.
A Marathon race in midsummer Australia (TV) Desert, blue sky. A man can
do it, if he drinks sufficient water. A dog can´t stand the whole distance .Its
coat is the limit. It can evaporate primarily water only on the tongue.The price:The hairless skin is suspended in the Savanna directly to a deadly
sun radiation. To survive, a black skin is necessary. By storage of a black
coloring material (Melanin) the skin was protected. This black Melanin
absorbs about 85 % of the ultraviolet (UV) radiation and prevents thereby an
otherwise deadly sun burn. An obviously necessary and effective protection,
for a white-skinned naked Irish will probably not survive for a longer time.
Later the African early human left its southern homeland and migrated in a
course of thousands o f years gradually northward, step by step The sun
became weaker and weaker and the skin color changed.
The African BLACK changed toward s a Mediterranean BROWN. In the
high north. Within the ´isolated´ western area of the Baltic Sea, the immigra-
ting post glacial Magdalénean reindeer hunter became a pale Scandi-
navian WHITE.
This change in skin color was enforced by a typical ´nordic´ illness, caused
by a lack of vitamin D. The Rickets.
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Vitamin D is a steroid hormone that is produced in the skin by the action of
sunlight's ultraviolet rays .Vitamin D plays an important role in the metabo-
lism of calcium. In its absence, the deposition in the bones does not proceed
normally, and the softened bones become curved and stunted.
A narrowed chest and pelvis may be responsible later in life for increased
susceptibility to lung diseases and difficulties in childbearing.
Vitamin D supplement, usually with milk,has been important in preventing
the incidence of rickets in the northern and temperate climates . In 1924 it
was demonstrated that curative effects of ultraviolet light resulted from the
formation of vitamin D by such irradiation. Pure vitamin D 2 was first iso-
latedn 1930-31 in England and in Germany.
dunkle Oberhaut = dark skin,
Unterhaut-Fettgewebe= hypodermic fatty tissue
Knochen= bone
Ostsee= Baltic Sea
A dark skin may absorb up to 85 % of the ultraviolet radiation.The quantity of
vitamin D synthesized in the region of the hypodermic fatty tissue may remain
stable as long as radiation and skin coloring changed n the same way,
approximately according to the functionAmount of Vit.D = function of [UV-radiation / skin color]
If so, then vitamin D becomes -even in the North- sufficiently synthetized and
the necessary daily amount of calcium can be absorbed in the intestine and
be deposited over the bloodstream in the bone. The bone can harden. If not,
then an imperfect calcificatiom, softening and distortion of the bones may
result (Typically bowed legs)
Darwin´s Theory *Adapt or Perish*
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According to Darwin´s Theory there are two functions, which enforce genetic
adaptation of the hereditary characteristics of an organism to the environ-
ment. It is the interaction between mutation and selection
Mutation (change) Life originated in the form of primordial organisms that
were very simple and very small. All living things have evolved from these
lowly beginnings. At present there are more than 2,000,000 known species,
which are widel y diverse in size, shape, and way of life, as well as in the
DNA sequences that contain their genetic information.
The information encoded in the nucleotide sequence of DNA is, as a rule,
faithfully reproduced during replication, so that each replication results in two
DNA molecules that are identical to each other and to the parent molecule.
But heredity is not a perfectly conservative process; otherwise, evolution
could not have take n place. Occasionally "mistakes,"or mutations, occur in
the DNA molecule during replication, so that daughter cells may differ from
the parent cells in the sequence or in the amount of DNA. Mutation first
appears on a single cell of an organism, but it is passed on to all cells des-
scended from the first. (Encyclo. Brittannia)Selection What has produced genetic variation within natural populations
and the genetic differences among species? There mus be some evolutio-
nary means by which existing DNA sequences are changed and new
sequences are incorporated into the gene pools of species.
For instance a decrease of number and size of cells producing the black
Melanin in the skin.
In case of skin complexion the effect of selection is obvious. Increased
Melanin pigmentation is advantageous to inhabitants of tropica Africa,where
dark skin protects them from the sun's ultraviolet radiation; but is not ben-
eficial in Scandinavia, where the intensity of sunlight is low and light skin is
needed to support the synthesis of vitamin D.
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How dangerous had been the Rickets in northern Europe?
In pratice. Assumed the average value of the skin colouring in the gene pool
of a population amounts to 100 +/- 1. Supposed furthermore that - due to
mutation- two sisters differ genetically slightly in their skin coloring. One has
a somewhat darker skin coloring factor of 101 and the other one is somewhat
brighter with a factor of 99. These small ´accidental´ differences in skin color
can hardly be recognized by a viewer, but this difference is the biological tool
of selection.An example.
Less UV- radiation penetrates the skin of the sister with a somewhat darker
skin of 101. Consequently less calcium is stored in her bones and her pelvic
cavity might be restricted by rickety deformation of her pelvic bones. In its
worth case, she can´t give birth to a child. She dies under the birth In the
North her ´dangerously ´colored skin factor of 101 is not transmitted , is
´deselectet´.
In the course of thousands of years the origenally more Mediterrean colored
gene pool of the immigrating and than isolated post-Magdalénian becomes
typical. After Tacitus:" All are blue-eyed and fair-haired"..
Even to day our babies in northern Europe are further endangered by
Rickets. Therefore they generally receive vitamin D tablets during the first
18 months..Each day one, in order to exclude the danger of rickets.
(I remember with ' horror ' a weekly spoon with sweetend cod-liver oil)
How much UV-radiation do we need? Between November and February in
northern latitudes hardly vitamin D is synthesized in the skin. Mothers are in
particular endangered.They need a sunshine exposition of 30 min on a clear
summer day against noon in a moderate climate.
During the quiet time mothers may lose additional calcium by insufficient
nutrition, because the milk gland extracts the necessary calcium for the baby,
about 400 mg per day from the mother without ' consideration'. The danger
of a bone softening threatens, particularly in the process of several preg-
nancies. Grandmother´s experience: Each pregnancy one tooth ! Her best
´therapy´: Drinking MILK with its surplus of calcium.
1 kg of contains mg calcium
beef 110
bread 300
full milk 1200
cheese 12000
Thereby it could be that hunters as ´beef-eaters´ get not enough Ca,
while milk as the main food of cattle/dairy farmer provides a surplus of
calcium.( Is the large body size of Tacitus´s Northerners due to lifelong
milk drinking?)
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Objections
Blond hair and blue eyes don´t synthezise vitamin D
Correct.Generally the main objection)
But the trias of skin-hair-eyes develops in the outermost of the ectodermal
germlayer with masses of cells, which appeare early in the development of
an animal embryo.
In vertebrates the ectoderm subsequently gives rise to hair, skin, and the
lens of the eye. Thereby conceivable that the Ectoderm as a whole becomes
darkened or depigmentated with more or less Melanin
Inui live in the polar region.They have little sun, long winters , a brown skin,
black hair and dark eyes however no Rickets, but their food offers a surplus
of vitamin D (among other things cod-liver oil)
Albinos develop not by selection and mutation but by a gene defect. The
synthesis of ectodermal coloring material is genetically imperfect. A too large
pathological jump in the normal mutation rate.
Black hair and blue eyes. The gene combination of black hair with blue
eyes results by crossing, not by selection.The procedure of a crossing needs
a relatively short time, may be a matter of moments. The effect of selection
needs thousands of years.
Wrong nutrition. Nothing is known about the level of vitamin D in the food
of northern Post-Madalénean reindeer hunter, but i t stands firmly that even to
day in the North the population can´t completely compensate a deficit of
vitamin D with today´s nutrition.
Facit:
Selection by
1.) Rickets
2.) genetic isolation
3.) along millennia
enforced white skin, blue eyes , fair hair in the North
Branda, R. and J. Eatoil "Skin Color and Photolysis: An Evolutionary Hypo-
thesis,"Science, 201 1978
Neer, R. M. "The Evolutionary Significance of Vitamin D, Skin Pigment,
and Ultraviolet Light," American Journal of Physical Anthropology, 43. 1975
1-rickets 20.06.04 update
Next Cattle and forest-pasture
Cattle may root a wood and thereby help Magdalénian to survive in the North
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