Introduction to Evolution
Imagine the whole world as one big, exciting game of change! Evolution is the process where living things slowly change over time, making over 8.7 million species on Earth.
Evolution
How it Works
- Genetic Variation: Differences in genes create new traits. Mutations (tiny changes in DNA) and gene mixing during reproduction introduce these traits.
- Natural Selection: Traits that help organisms survive and reproduce get passed on, while others disappear. This phenomenon is called Natural Selection!
Fun Facts
A long, long time ago, life on Earth began with simple RNA strands that evolved into cells, small organisms, fish, then reptiles, and finally into mammals like us!
How We Study Evolution
Scientists can study evolution in many ways, whether that’s looking at animal embryos, tracing the past, or analyzing genes. Let’s explore some of these methods!
Comparative Embryology
By looking at embryos of different animals, scientists see that all vertebrates (like us) had gill slits and tails at some point, showing we share a common ancestor with fish.
Comparative Anatomy
By studying body parts, scientists find:
- Homologous Structures: Similar features in different animals from a common ancestor, like human arms and bat wings.
- Analogous Structures: Different structures with similar functions, like bird wings and butterfly wings.
Fossils
Fossils are like time capsules, showing us what ancient creatures looked like and where they lived. Paleontologists study these to learn about the history of life.
Molecular Biology
All living things share DNA. By comparing the sequences of nucleotides (the building block of DNA), scientists can figure out how closely related different organisms are.
Conclusion
Evolution shows us how diverse and fascinating life on Earth truly is!
Challenge
Scientists have recently discovered three new species. Here are snippits of their DNA. Your mission is to identify sequence similarities to discover which two organisms are most closely related. Organism A: TCAGAAGGA Organism B: TCAACAGGC Organism C: AGGGCGAAA Can you complete the mission?
Answer
Organism A and B share the most simmilarities in the nucleotide sequence. Their shared DNA leads us to conclude that the organisms are closely related!