National Geographic : 1984 Dec
When a strawberrycreatesa new plant with a runner, left, the offspring's genetic blueprintis unchanged since it carriesidenticalchromosomes from the top of the triangle. This is asexual reproduction.Calves from a cow and bull mating inheritvaried characteristics. This is sexual reproduction. LONG BEFORE the genetic basis of heredity was understood,farmers bred animals and plants to enhance desirabletraits.In a sense the first genetic engineers, they recognized that selecting superior parentsproduced improved offspring. Since domestication,cattle have been bredfor strength at the plow, for fighting spirit,and, as early as 1700, for more milk or beef (below). Unlike asexual reproduction, in which an entire organism grows to the genetic blueprint of a sole parent,sexual mating is nature'sway of varying the geneticpattern by combining elements from two blueprints. As DNA within the ovary \ and testis cells replicates, WILD AUROCH, 8000-5000 B.C . ZEBU, 3000 B.C. LONGHORN, 1493-1890 DRAFT, MEAT, MILK HIDES, MEAT Nature's variety improves the breed DRAFT OX, 3000 B.C .