There have been few issues related to modern agriculture that have been quite so contentious as that of Genetic Modification and with the media portraying dramatic images of "frankenstein foods", it has been little wonder that opinion has been so polarised. And yet on the whole subject there is widespread ignorance; in a recent survey over half of all respondents thought that genes were only contained in genetically modified material. We consider the origins of genetic modification and the biotechnology revolution.
Ever
since the start of farming over 10,000 years ago, man has sought to
find ways of making his crops and livestock more productive. Innovations
in mechanisation and farming systems have been combined with the deliberate
selection of crops or livestock for "improved" characteristics.
The
result of this selection can be seen in the obvious differences between
a primitive sheep breed, pictured above, and its modern successor alongside.
The improved chartacteristics of the modern sheep include: its willingness
to be flocked and driven, its docile nature, higher lambing output and
the production of more meat and wool.
The
selection that has resulted in the modern sheep may have arisen either
by accident or through design. A farmer may have noticed a particular
charcteristic in some of his of sheep that was desirable and therefore
retained these animals. Alternatively he may have actively crossed sheep
of very different charcteristics to see if an improved charcteristic
would result.
In
much the same way that sheep breeds have been improved through selection,
so the same has occurred with crop varieties. Crops that suffer less
from disease, which are more drought resistant or which produce grain
of a higher quality are constantly preferred. In being preferred, they
remain in use for both production and future breeding.
The
characteristics that we define in crops or livestock (for example disease
resistance or wool quality) are often known as traits and these are
conferred by something known as genes. Genes
either act singly or collectively to confer a trait. Some traits will
persist in a population for a long time, for example wool quality whereas
some may disappear quickly - disease resistance in crops can be lost
as fungi find new ways of attacking the plant.
Genes
are found on chromosones that exist within
every cell of every living organism. Each organism contains a selection
of unique genes that confers it with sufficient differences to make
it recognisable as a species, for example a cow or a sheep, whereas
the arrangement and charcteristics of a number of other genes confers
differences between members of the same species.
During
the process of reproduction, a copy of the genes from each parent are
passed down to the offspring. In this process the genes get mixed up
before being laid out on the offspring's chromosones. The new mix of
genes determines the specific or distinguishing characteristics of the
offspring.
Within
the last decade advances in biotechnology have allowed mankind to identify
the specific genes that cause specific traits. The technology has further
provided man with the ability to artificially transfer genes from one
chromosone to another, even if this is across the species barrier. Thus,
a gene from a plant that is resistant to insect attack can be transferred
to a different species of plant that would normally be susceptible.
This is the process of genetic modification and the new crop will be
known as a transgenic crop.
Whilst the transfer of genes across species has been condemned by some religious communities, most species already share a very significant amount of common genetic material. In the case of man and the chimpanzee, 99.4% of this is common.
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