The evolutionary importance of internal body clocks

Circadian clocks may provide adaptive advantages to organisms by synchronizing their processes with environmental cycles.

• Circadian clocks are found in a wide range of organisms, from bacteria to mammals.
• Functional circadian clocks have been observed in organisms living in constant environments, indicating potential intrinsic adaptive value.
• Organisms may experience a fitness advantage in periodic environments that align with their internal rhythms.
• Evidence from wild organisms and selection studies suggests that circadian clocks may also confer extrinsic adaptive value.
• Several hypotheses have been proposed regarding the emergence of circadian clocks based on empirical studies.

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