(N/A) Evidences that the evolution of life forms has indeed taken place on Earth have come from many sources.
$1$. Paleontological evidences: Paleontology is the study of fossils,which are the remains of hard parts of life forms found in rocks.
- Rocks form sediments,and a cross-section of the Earth's crust depicts the arrangement of these sediments one over the other during the long history of the Earth.
- Sediments of different aged rocks contain fossils of different life forms that lived and died during the formation of a particular segment.
- Some of these appear similar to modern organisms,while others represent extinct organisms like dinosaurs.
- The study of fossils in different sedimentary layers indicates the geological period in which they existed.
- It shows that life forms varied over time and that certain life forms are restricted to specific geological time scales.
- Hence,new forms of life have evolved at different times in the history of the Earth.
$2$. Comparative anatomy and morphology: These provide evidence for evolution by comparing the structural similarities and differences among organisms.
- Homologous organs: Organs that have the same structural origin and developmental pattern but perform different functions (e.g.,the forelimbs of whales,bats,cheetahs,and humans). This indicates common ancestry (divergent evolution).
- Analogous organs: Organs that perform similar functions but have different structural origins (e.g.,the wings of a butterfly and a bird). This indicates convergent evolution,where different organisms adapt to similar environmental conditions.