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What is heredity?We are all aware of family resemblances. The Hapsburg lip & jaw and the presence a sixth finger or toe, polydactyly, red hair and diseases such as hemophilia and sickle cell anemia, are among many traits that occur in families. These traits are inherited. People have had a rough understanding of the "rules" heredity for thousands of years, and have used this knowledge to generate the amazing diversity of domesticated plants and animals. |
They selected specific traits – bred organisms with those traits, and selected offspring with the desired traits for future breeding. Over tens to hundreds of generations, diverse types of organisms were derived. For example, all breeds of dog (Canis familiaris) appear to be derived from an ancestral species through the process of artificial selection. |
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A cousin of Charles Darwin, Francis Galton (1822-1911) believed that it was possible to measure a wide range of characteristic, including moral characteristics. Others believed, that traits such as a tendency to commit murder, are reflected in the shape of the skull (phrenology) and other physical characteristics. |
All of the organisms of a specific type or species have the same set of characters. The forms these characters take, however, can vary. It is these differences that are referred to as traits. For example, all carnations have flowers (the character), but different plants can have flowers of different colors, size, shape and position on the plant (the trait). |
Occasionally, it is possible to determine the exact origin of a new trait. Consider the short-legged Ancon sheep. |
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25-Jul-2009
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