ANATOMY

Detailed explanation-1: -Species may share similar physical features because the feature was present in a common ancestor (homologous structures). Molecular biology. DNA and the genetic code reflect the shared ancestry of life. DNA comparisons can show how related species are.

Detailed explanation-2: -More than 150 years ago, Charles Darwin proposed the theory of universal common ancestry (UCA), linking all forms of life by a shared genetic heritage from single-celled microorganisms to humans.

Detailed explanation-3: -Similar anatomy found in different species may be homologous (shared due to ancestry) or analogous (shared due to similar selective pressures). Molecular similarities provide evidence for the shared ancestry of life. DNA sequence comparisons can show how different species are related.

Detailed explanation-4: -Scientists can compare the DNA of two organisms; the more similar the DNA, the more closely related the organisms. This method can also help when looks are deceptive. One example of looks being deceptive is: The bat and the crow both have wings, and the squirrel does not.

Detailed explanation-5: -Universal common ancestry (UCA) is a central pillar of modern evolutionary theory. As first suggested by Darwin, the theory of UCA posits that all extant terrestrial organisms share a common genetic heritage, each being the genealogical descendant of a single species from the distant past.