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Why can scientific classifications change when new genetic evidence is discovered?

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A herd of African elephants stands at the edge of the Chobe River in Botswana, drinking water with a backdrop of dry hills and scattered green trees. — life A herd of African elephants (*Loxodonta africana*) drinking from the Chobe River, Botswana.

Scientific classifications change when new genetic evidence is discovered because modern taxonomy is based on phylogeny—the study of evolutionary relationships by descent from common ancestors.12

Historically, organisms were grouped primarily by apparent physical similarities or morphology. However, physical traits can be misleading; for example, some similarities are analogies (traits that evolved independently due to similar environments) rather than homologies (traits inherited from a common ancestor).3

The advent of molecular genetics has provided a more objective tool for constructing evolutionary trees. By measuring differences in DNA sequences or protein structures, scientists can more accurately estimate the degree of evolutionary divergence between species. As these molecular data often provide a clearer picture of true ancestral relationships than physical appearance alone, classifications are updated to reflect this deeper understanding of the tree of life.321