Why do some of our organs come in pairs, but we only have one heart?

17 May 2023

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Why do some of our organs come in pairs, such as kidneys, whereas we only have one heart, one liver etc?

Richard SwifteDarmstadt, Germany

Unlike rocket engineers, who design in "redundancy" (spare parts for use if key components fail), evolution doesn't waste energy producing spare body parts unless they have a definite survival value, either for the individual or the species. Most creatures in the wild have their work cut out finding enough food to survive, let alone growing unused parts. So it is fair to expect that having two organs fulfils a definite need.

For example: two ears …

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