The genome of the honeybee Apis mellifera has been sequenced, revealing unique characteristics that provide insights into its social behavior and ecology. Compared to other insect genomes, the A. mellifera genome has high A+T and CpG contents, lacks major transposon families, and evolves more slowly. It is more similar to vertebrates in genes related to circadian rhythm, RNA interference, and DNA methylation. The genome shows fewer genes for innate immunity, detoxification enzymes, and gustatory receptors, but more genes for odorant receptors and novel genes for nectar and pollen utilization, consistent with its social organization. Compared to Drosophila, genes in early developmental pathways differ in Apis, while similarities exist for functions like sex determination, brain function, and behavior. Population genetics suggest a novel African origin for A. mellifera and insights into the spread of Africanized bees. The honeybee is a eusocial insect with a complex social structure, including queens and workers. Queens have a longer lifespan and lay more eggs than workers. Workers have a smaller brain but display sophisticated cognitive abilities. They communicate through 'dance language' and can learn abstract concepts. Africanized bees, introduced to Brazil, are known for their aggressive behavior and have spread throughout the New World. The honeybee genome has unique features, including high A+T content, greater spatial heterogeneity of A+T content, high CpG content, and an absence of most major transposon families. It shows greater similarities to vertebrate genomes than Drosophila and Anopheles for genes involved in circadian rhythms, RNA interference, and DNA methylation. The genome has fewer genes for innate immunity, detoxification enzymes, cuticle-forming proteins, and gustatory receptors, but more genes for odorant receptors and novel genes for nectar and pollen utilization. Genes involved in queen and brood nursing exemplify genes gaining new functions during the evolution of sociality. Novel microRNAs were detected and shown to have caste- and stage-specific expression, suggesting a role in social diversification. Key elements in early developmental pathways differ between Apis and Drosophila, indicating that these evolved after the lineages separated. The honeybee shows similarities to Drosophila for functions that differ markedly, such as sex determination, brain function, and behavior. Population genetic analyses support a hypothesis involving an African origin for A. mellifera and provide new insights into the spread of Africanized bees. The honeybee genome was sequenced using DNA from multiple drones derived from a single queen. The genome was assembled using Atlas software and a microsatellite marker linkage map. The genome size and coverage were determined, and the genome was compared to other insect genomes. The honeybee genome has a unique structure, with a high A+T content and a lack of major transposon families. The genome shows greater similarities to vertebrate genomes than DrosophilaThe genome of the honeybee Apis mellifera has been sequenced, revealing unique characteristics that provide insights into its social behavior and ecology. Compared to other insect genomes, the A. mellifera genome has high A+T and CpG contents, lacks major transposon families, and evolves more slowly. It is more similar to vertebrates in genes related to circadian rhythm, RNA interference, and DNA methylation. The genome shows fewer genes for innate immunity, detoxification enzymes, and gustatory receptors, but more genes for odorant receptors and novel genes for nectar and pollen utilization, consistent with its social organization. Compared to Drosophila, genes in early developmental pathways differ in Apis, while similarities exist for functions like sex determination, brain function, and behavior. Population genetics suggest a novel African origin for A. mellifera and insights into the spread of Africanized bees. The honeybee is a eusocial insect with a complex social structure, including queens and workers. Queens have a longer lifespan and lay more eggs than workers. Workers have a smaller brain but display sophisticated cognitive abilities. They communicate through 'dance language' and can learn abstract concepts. Africanized bees, introduced to Brazil, are known for their aggressive behavior and have spread throughout the New World. The honeybee genome has unique features, including high A+T content, greater spatial heterogeneity of A+T content, high CpG content, and an absence of most major transposon families. It shows greater similarities to vertebrate genomes than Drosophila and Anopheles for genes involved in circadian rhythms, RNA interference, and DNA methylation. The genome has fewer genes for innate immunity, detoxification enzymes, cuticle-forming proteins, and gustatory receptors, but more genes for odorant receptors and novel genes for nectar and pollen utilization. Genes involved in queen and brood nursing exemplify genes gaining new functions during the evolution of sociality. Novel microRNAs were detected and shown to have caste- and stage-specific expression, suggesting a role in social diversification. Key elements in early developmental pathways differ between Apis and Drosophila, indicating that these evolved after the lineages separated. The honeybee shows similarities to Drosophila for functions that differ markedly, such as sex determination, brain function, and behavior. Population genetic analyses support a hypothesis involving an African origin for A. mellifera and provide new insights into the spread of Africanized bees. The honeybee genome was sequenced using DNA from multiple drones derived from a single queen. The genome was assembled using Atlas software and a microsatellite marker linkage map. The genome size and coverage were determined, and the genome was compared to other insect genomes. The honeybee genome has a unique structure, with a high A+T content and a lack of major transposon families. The genome shows greater similarities to vertebrate genomes than Drosophila