"THE JOURNAL IS UNDER CONSTRUCTION: This page last revised 12-17-1999
Copyright (c) 1997 "The Vitamin C Foundation "
|Coming in the next issue: THE EVOLUTION OF MAN||
OUR ANCESTRAL PRIMATE
If we come forward to a time some 55 to 65
million years ago we will find that the warm-blooded vertebrates
are the dominant animals, and they are getting ready to evolve
into forms that are familiar to us. Life has come a long way since
it discovered how to make ascorbic acid. In the warmer areas the
vegetation is dense and the ancestors of our present-day primates
-- the monkeys,apes, and man -- shared the forests and treetops
with the innumerable birds.
At about this time something very serious happened
to a common ancestor of ours, the animal who would be a progenitor
of some of the present primates. This animal suffered a mutation
that eliminated an important enzyme from its biochemical makeup.
The lack of this enzyme could have proved deadly to the species
and we would not be here to read about it except for a fortuitous
combination of circumstances.
Perhaps we should digress here and review some
facts of mammalian biochemistry as related to this potentially
lethal genetic accident. It will not be difficult, and it will
help in understanding the thesis of this book.
All familiar animals are built from billions
of cells. Masses of cells form the different tissues, the tissues
form organs, and the whole animal is a collection of organs. The
cell is the ultimate unit of life. Each cell has a cell membrane,
which separates it from neighboring cells and encloses a jellylike
mass of living stuff. Floating in this living matter is the nucleus,
which is something like another, smaller cell within the cell.
This nucleus contains the reproducing macromolecule called desoxyribonucleic
acid (DNA). DNA is the biochemical basis of heredity and determines
whether the growing cells will develop into an oak tree, a fish,
a man or whatever. This molecule is a long, thin, double-stranded
spiral containing linear sequences of four different basic unit
molecules. The sequence of the four unit molecules as they are
arranged on this spiral is the code that forms the hereditary
blueprint of the organism. When a cell divides, this double-stranded
molecule separates into two single strands and each daughter cell
receives one. in the daughter cell, the single strand reproduces
an exact copy of itself to again form the double strand and in
this way each cell contains a copy of the hereditary pattern of
These long threadlike molecules are coiled
and form bodies in the nucleus that were called chromosomes by
early microscopists because they avidly absorbed dyes and stains
and thus became readily visible in preparations viewed microscopically.
These microscopitst suspected that these bodies were in some way
connected with the process of inheritance but did not know the
Certain limited sections of these long, spiral
molecules, which direct or control a single property such as the
synthesis of a single enzyme, are called genes. A chromosome may
be made up of thousands of genes. The exact order of the four
different unit molecules in a gene determines, say, the protein
structure of an enzyme. If only one of these unit molecules is
out of place or transposed among the thousands in a gene sequence,
the protein structure of the enzyme will be modified and its enzymatic
activity may be changed or destroyed. Such a change in the sequence
of a DNA molecule is called a mutation.
These mutations can be produced experimentally
by means of various chemicals and by radiations such as X rays,
ultraviolet rays, or gamma rays. Cosmic rays, in nature, are not
doubt a factor in inducing mutations. It is on these mutations
that Nature has depended to produce changes in evolving organisms.
If the mutation is favorable and gives the plant or animal an
advantage in survival, it is transmitted to its descendants. If
it is unfavorable and produces death before reproduction takes
place, the mutation dies out with the mutated individual and is
regarded as a lethal mutation. Some unfavorable mutations which
are serious enough to be lethal, but which the mutated animal
survives, are called conditional lethal mutations. This type of
mutation struck a primitive monkey that was the ancestor of man
and some of our present-day primates.
In nearly all the mammals, ascorbic acid is
manufactured in the liver from the blood sugar, glucose. The conversion
proceeds stepwise, each step being controlled by a different enzyme.
The mutation that occurred in our ancestral monkey destroyed his
ability to manufacture the last enzyme in this series -- L-gulonolactone
oxidase. This prevented his liver from converting L-gulonolactone
into ascorbic acid, which was needed to carry out the various
biochemical processes of life. The lack of this enzyme made this
animal susceptible to the deadly disease, scurvy. To this day,
millions of years later, all the descendants of this mutated animal,
including man, have the intermediate enzymes but lack the last
one. And that is why man cannot make ascorbic acid in his liver.
This was a serious mutation because organisms
without ascorbic acid do not last very long. However, by a fortuitous
combination of circumstances, the animal survived. First of all,
the mutated animal was living in a tropical or semitropical environment
where fresh vegetation, insects, and small animals were available
the year round as a food supply. All these are good dietary sources
of ascorbic acid. Secondly, the amount of ascorbic acid needed
for mere survival is low and could be met from these available
sources of food. This is not to say that this animal was getting
as much ascorbic acid from its food as it would have produced
in its own body if it had not mutated. While the amount may not
have been optimal, it was sufficient to ward off death from scurvy.
Under these ideal conditions the mutation was not serious enough
to have too adverse an effect on survival. It was only later when
this animal's descendants moved from these ideal surroundings,
this Garden of Eden, and became "civilized" that they
-- we -- ran into trouble.
This defective gene has been transmitted for
millions of years right up to the present-day primates. This makes
man and a few other primates unique among the present-day mammals.
Nearly all other mammals manufacture ascorbic acid in their livers
in amounts sufficient to satisfy their physiological requirements.
This had great survival value for these mammals, who, when subjected
to stress, were able to produce much larger amounts of ascorbic
acid to counteract adverse biochemical effects. And there was
plenty of stress for an animal living in the wild, competing for
scarce food, and trying to avoid becoming a choice morsel for
some other predator.
To the best of our knowledge, only two other
non-primate mammals have suffered a similar mutation and have
survived. How many others may have similarly mutated and died
off, we shall never know. The guinea pig survived in the warm
lush forests of New Guinea where vegetation rich in fresh ascorbic
acid was readily available. The other mammal is a fruit-eating
bat (Pteropus medius) from India. The only other vertebrates
that are known to harbor this defective gene are certain passeriforme
Because of this missing or defective gene,
man, some of the other primates, the guinea pig, and a bat will
develop and die of scurvy if deprived of an outside source of
ascorbic acid. A guinea pig, for example, will die a horrible
death within two weeks if totally deprived of ascorbic acid in