A recent article posted in the BBC News provided a good explanation of why scientists commonly study these organisms as models for human diseases and conditions. Model organisms are chosen because their physiology is similar to other animals, including humans, in addition to other reasons:
Visit the BBC News to see why researchers most often use flies, fish, mice and worms to understand the mechanisms of disease and health.
Did you know that ~70% of the genes in a fruit fly are homologous to human genes? Zebrafish have genes that are homologous to those involved in ~75% of genetic-related human diseases.
Top Image: EMBL, Explore Model Organisms