The homeobox genes that define the basic body plan of mice and fruit flies are illustrated in this graphic. The accompanying article describes how these genes act as "molecular architects" in all animal species.
The discovery of homeobox genes, their role in controlling body shape, and their astonishing similarity across widely different species has yielded new insights into both how embryos grow and how life evolved from a common ancestor. Homeobox genes evidently duplicated twice during the evolution of vertebrates from invertebrates; mammals have 4 clusters of about 10 genes each, while the fruit fly has only 1 group of 10.
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