The size and shape of the vertebrate skull can reveal a great deal about an animal's lifestyle and evolutionary relationships. Consider your own skull. If you put your finger in your ear and move your jaw up and down, you can feel the space near the hinge of your jaw. Nestled in this space are the tiny bones that make your hearing possible: the malleus, incus, and stapes. All mammals have these three ear bones, but reptiles such as this T. rex don't. Where did ear bones come from? Researchers studied mice embryos as a model organism to determine whether the cells of the ear bones originated from the same embryonic cells as the cells that form the jaw in other vertebrates.
Why would the researchers use mice instead of humans?
Do the results from mice tell you something about your own ears? Why or why not?

Verified step by step guidance

1. Understand the context: The problem discusses the evolutionary origin of ear bones in mammals and the use of mice embryos to study this. It highlights the difference between mammals and reptiles in terms of ear bone presence.
2. Identify the reason for using mice: Mice are often used as model organisms in biological research due to their genetic, biological, and behavioral similarities to humans. They have a short reproductive cycle and are easy to maintain, making them ideal for studying developmental processes.
3. Consider the evolutionary perspective: Researchers might use mice to study the embryonic development of ear bones because mice, like humans, are mammals and share a common ancestor. This can provide insights into the evolutionary transition from jaw bones to ear bones.
4. Evaluate the relevance of the results: The results from mice can be extrapolated to humans due to the shared evolutionary lineage and similar developmental pathways. This means that findings in mice can often be indicative of similar processes in humans.
5. Reflect on the implications: Understanding the origin of ear bones in mammals can shed light on evolutionary biology and the adaptations that have occurred over time. It also helps in understanding the functional anatomy of hearing in different species.

Key Concepts

Evolutionary Homology

Evolutionary homology refers to the similarity in structures due to shared ancestry. In the context of ear bones, mammals have evolved three distinct bones (malleus, incus, and stapes) from jaw bones found in ancestral reptiles. Understanding homology helps explain how structures can change function over time while retaining a common origin.

Embryonic Development

Embryonic development is the process by which an embryo forms and develops, involving cell differentiation and organ formation. Researchers study embryonic development in model organisms like mice to trace the origin of specific structures, such as ear bones, to understand if they share developmental pathways with other structures like the jaw.

Model Organisms in Research

Model organisms, such as mice, are used in research due to their genetic and physiological similarities to humans, ease of manipulation, and rapid reproduction. Studying mice can provide insights into human biology because many developmental processes are conserved across species, allowing researchers to infer human biological functions from mouse models.