Text 1: Biologist Park argues that all of life shares a single universal common ancestor, "LUCA" — the last universal common ancestor — from which bacteria, archaea, and eukaryotes all descend. The shared genetic code, ribosome structure, and core metabolic pathways are too unlikely to have evolved twice; LUCA is the explanation.
Text 2: Biologist Singh accepts shared ancestry but argues that "LUCA" suggests a single organism when the reality is messier. Early life likely consisted of populations exchanging genes laterally so promiscuously that no single ancestor existed; what we share are features that won the competition among many early lineages, not inheritance from one individual.
Based on the texts, how would Singh (Text 2) most likely respond to Park's argument?
- Acheck_circle
He would accept shared deep ancestry while resisting the framing of a single ancestral organism.
- B
He would agree that LUCA was a single individual organism.
- C
He would propose that life arose independently many times.
- D
He would deny that bacteria and archaea share any common features.
Explanation
Singh accepts shared ancestry but reframes it from a single organism to populations. B captures this. A, C, and D contradict him.