Evidence for Evolution

Charles Darwin proposed the theory of evolution, stating that all species have evolved from simple life forms over millions of years.
Evolution occurs via a process known as Natural Selection: only the fittest organisms survive to pass on their genes.
Evidence supporting the theory of evolution is derived from different scientific disciplines such as palaeontology, comparative anatomy, molecular biology, and genetics.
Fossil records provide a chronology of past life forms, showing gradual changes within species over time. They often display transitional forms – species that have traits of both their ancestors and their descendants.
The study of embryos, known as embryology, shows that many different animals share common development processes, implying a common ancestor.
Comparative anatomy studies physical characteristics across species. Similar structures known as homologous structures (like the bones in human arms, cat paws, whale fins and bird wings) suggest common ancestry.
On the other hand, analogous structures - similar features serving the same function in different species but not due to common ancestry - point towards convergent evolution (separate species independently evolving similar traits).
Vestigial structures (parts that seem to be leftovers from ancestors, like the human appendix), help to trace lineage and ancestral environments.
Molecular biology (the analysis of proteins and DNA) shows genetic similarities across species— another clue to shared ancestry. Particularly, DNA sequence comparisons reveal degrees of relationship between species.
Microevolution is evidence that evolution is currently taking place. Examples include antibiotic resistant bacteria, and moths changing colour during the industrial revolution (industrial melanism).

Remember: It is important to distinguish between a scientific theory (well-substantiated explanation based on a body of evidence) and the colloquial use of the word ‘theory’ that implies lack of certainty. In scientific terms, the theory of evolution is widely accepted.