Final answer:
The thorough mapping of the Drosophila genome using three-point crosses was feasible due to the fly's simpler genome and the lack of ethical concerns in breeding them, while human genome mapping faced ethical dilemmas and required more advanced techniques.
Step-by-step explanation:
The Drosophila genome was thoroughly mapped using three-point crosses primarily because of its simplicity compared to the human genome and because there are no ethical concerns associated with breeding fruit flies for genetic studies.
Conversely, mapping the human genome through breeding programs for the purpose of three-point crosses would raise serious ethical issues, including concerns about eugenics, consent, and potential harm to subjects. Additionally, humans have much longer generation times and more complex genomes, rendering this method impractical.
As a result, human genome mapping required different techniques. It involved a combination of biochemical methods, such as sequencing, and computer tools to analyze and assemble the vast amount of data. This shift in methodology underscores the unique challenges associated with human genome mapping, such as ethical concerns and the need for advanced mapping techniques that are both fast and accurate.
These ethical and technological needs have also driven the pursuit of questions about the ethics of genetic information use, the effort poured into genome mapping applications, and research into whether there is common DNA among different species to enhance our understanding of genetics and improve medical technologies.