Genetically-modified (GM) foods and genetic engineering have become a hot topic of debate in recent years. Advances in biotechnology have made it possible for man to put a gene from a jellyfish into a monkey, or a gene from a bacterium into a maize plant.
This process is possible because a gene is simply a set of instructions that tells a cell how to manufacture a specific protein. That protein can then go on and alter an organism's functioning, to produce a desired result. For example, genes to produce human insulin have been inserted into bacteria, which then act as factories to produce insulin for diabetics.
Plants and animals use basically the same machinery to interpret genes, so genes can be transferred between plants and animals and made to work provided that the correct amino acid building blocks are present.
Genetic modification has gone on for centuries through selective breeding, to produce everything from sausage dogs to boerboels from a common wolf-like ancestor. Seed companies have been producing specific varieties of seeds that will withstand different climatic conditions for years.
Genetic engineering is now a more rapid way of producing crops and animals with desirable traits - only scientists can look further afield to find a characteristic that they want a particular organism to show. For example, a certain bacterium (Bacillus thuringiensis) produces crystal proteins that kill insect larvae. These bacterial genes have been inserted into maize plants, allowing the plant to produce its own pesticide (B.t toxin), which can reduce the amount of chemical insecticide added to a crop as it is growing.
Scientists are looking at many different ways of altering the food we eat - producing plants with pest resistance, herbicide tolerance, disease resistance, cold tolerance, drought tolerance, salinity tolerance. Scientists can also beef up the nutritional value of plants - work has been done on making rice that has added vitamin A, to help prevent blindness in those countries where rice is a staple food and blindness is a common problem.
Plants that have been genetically modified for agriculture include soya beans, maize, cotton, canola and potatoes. Soya beans and maize are among the most widely grown crops, and are usually genetically modified for herbicide and insect resistance.
Much of the work being done would help grow crops in what would previously have been marginal agricultural areas, and this could be of tremendous benefit to the third world, and help ease food shortages.
Those opposed to GM foods worry that the crops could become environmental hazards - already the maize with B.t. toxin has been implicated in harming monarch butterfly caterpillars in North America. Other concerns include insects becoming resistant to the plants that produce their own pesticide, and the transfer of genes to other plants, which might create "superweeds".
The transfer of genes can happen through pollen blowing from plants, and the Environmental Protection Agency in the United States has recently reported that engineered genes have been found in wild grasses over 20km away from a test plot of GM creeping bent grass.
Health concerns have also been raised - more and more children are developing food allergies, and for example taking a gene from a peanut and putting it into a soya bean may cause unexpected allergic reactions.
Genetic engineering, while faster than selective breeding, is very expensive. This means that although many genetically modified food crops would be good things for third world farmers to grow, those most in need of the seeds may be unable to afford them.
Governments around the world are grappling with legislative concerns about GM foods, and South Africa, along with other Southern African Development Community (SADC) countries, adopted guidelines for the regulation of GM organisms in May this year. South Africa is also in the process of amending the Act that governs the regulation and release of GMOs in the country.
Around the world almost 70 million hectares of GM crops are grown, with the amount increasing dramatically each year. The United States is a major grower of GM crops - in 2000, America grew almost 70 percent of the world's GM crops. Argentina also grows a substantial amount of GM crops.
It is estimated that South Africa grows about 220,000 hectares of genetically modified crops - mostly yellow and white maize and insect-resistant cotton.
By Melissa Wray