More than 30 years after the development and testing of transgenic techniques that mimicked the horizontal transfer of genes that is widespread in nature,these techniques were being used to produce a wide variety of medicines,virtually all beer and cheese consumed in the world,and were planted (in 2013) by approximately 18 million farmers on 175 million hectares in 27 countries. Hundreds of millions of people and billions of farm animals have been consuming these plants and products derived from them for nearly 20 years without a single verified case of harm encountered anywhere.Against this background,it is difficult to understand the resistance to cultivating such crops that persists in some regions.Concerning the relationship between GM crops and biodiversity,one may first note that agriculture itself is a major enemy of biodiversity,having spread to occupy about a third of the world’s land surface over the past 12 000 years as the human population has grown from an initial 1 million people to more than 7.2 billion at present.The more efficiently agriculture is carried out on cultivated lands and the more productive and sustainable it is there,the less harm to biodiversity generally.Naturally-occurring hybridization between related species is a prominent feature of plant evolution,and has resulted in the genetic enrichment of crops as human beings have selected them for improved characteristics.It has also affected the genetic characteristics of the wild and weedy relatives of many crops,and in a few cases increased their weediness.These phenomena are neither enhanced nor retarded when transgenes are involved,but should be studied and dealt with agronomically on a case-by-case basis.