Blood and semen
Common DNA
DNA (Deoxyribonucleic acid) is the genetic material because it contains the code for the entire organism. It's sort like an equation from which an entire organism with all it's unique differences can be created.
The most common DNA helix is B-DNA.
Similarities in DNA sequences, anatomical structures, and developmental pathways provide evidence of a common ancestry among organisms. Additionally, the study of fossils and transitional forms help support the idea of evolution and common ancestry.
DNA evidence is much more reliable an identifier of an individual than eyewitness accounts.
Simularities in DNA sequence
The three types of evidence that suggest organisms are related through common descent are anatomical evidence (similarities in body structures), molecular evidence (similarities in DNA sequences), and fossil evidence (transitional forms showing evolutionary changes over time).
The DNA genetic code provides the best evidence of the common ancestry of life. Science has shown that there are many similarities between DNA sequences.
Simularities in DNA sequence
DNA evidence can take on many forms, but commonly is either hair, skin, saliva, blood, or semen. Find a non-violent way to collect one of these in a decent amount, and there you go.
I believe there is only one form of DNA. There are numerous forms of RNA. The least common RNA molecule is tRNA as it is stimulated by the protein synthesis cycle and is only produced at certain times.
Fossil record: Shows a gradual change in species over time, supporting the idea of common ancestry and evolution. Genetic evidence: Similarities in DNA sequences between different species indicate shared ancestry and evolutionary relationships. Comparative anatomy: Homologous structures among different species suggest a common origin and evolution from a common ancestor.