Complex sentence: It was originally formulated in 1922 by the British evolutionary biologist J. B. S. Haldane; since it appears to be usually but not universally true, it is described as a rule rather than a law.
Split into simpler sentences: It was originally formulated in 1922 by the British evolutionary biologist J. B. S. Haldane. Since it appears to be usually but not universally true, it is described as a rule rather than a law.