Which term expresses that species have descended from common ancestors with changes over time?

Which term expresses that species have descended from common ancestors with changes over time?

• A. Theory
• B. Fossil
• C. Descent with modification
• D. Fitness

Answer: (C)

Descent with modification is the idea that all living things are related by common ancestry and that lineages change over generations. This phrase encapsulates both parts: there is a shared origin for species, and the offspring accumulate heritable differences that lead to the diversity we see over time. It’s the way biologists describe evolution in a concise term—the lineage from a common ancestor may split and, through variation, natural selection, and other processes, accumulate changes that shape new forms. This term is the best fit because it directly names the pattern of relationships and change across time. The word theory refers to a broad framework for understanding natural phenomena, not the specific idea of ancestry with accumulated changes. A fossil is a piece of evidence about ancient life, not the concept describing how species are related. Fitness describes reproductive success, not the historical relationship among species. Descent with modification uniquely conveys both shared origins and the gradual changes that produce new species.

Descent with modification is the idea that all living things are related by common ancestry and that lineages change over generations. This phrase encapsulates both parts: there is a shared origin for species, and the offspring accumulate heritable differences that lead to the diversity we see over time. It’s the way biologists describe evolution in a concise term—the lineage from a common ancestor may split and, through variation, natural selection, and other processes, accumulate changes that shape new forms.

This term is the best fit because it directly names the pattern of relationships and change across time. The word theory refers to a broad framework for understanding natural phenomena, not the specific idea of ancestry with accumulated changes. A fossil is a piece of evidence about ancient life, not the concept describing how species are related. Fitness describes reproductive success, not the historical relationship among species. Descent with modification uniquely conveys both shared origins and the gradual changes that produce new species.