The Lifetime Cardiac-Cycle Invariant in Endothermic Vertebrates: A 230-Species Comparative Dataset, Statistical Validation, and Explicit Falsifiability Criteria

Abstract

A pygmy shrew (\textit{Suncus etruscus}, $\approx 2$\,g) sustains a resting heart rate near $1,000$\,beats\,min${}^{-1}$ and dies within two years; an African elephant ($\approx 4,000$\,kg) beats at $28$\,beats\,min${}^{-1}$ and lives seven decades. Their chronological lifespans differ by a factor of 35, yet each accumulates close to $10^9$ cardiac cycles before death -- a near-constancy first noted by Rubner~(1908) and quantified by Lindstedt and Calder~(1981)~\cite{lindstedt1981}, but never subjected to multi-clade statistical testing, phylogenetic correction, or explicit falsifiability criteria with a large modern dataset. We address this gap with a curated 230-species vertebrate dataset spanning non-primate placentals ($n=43$), primates ($n=18$), marsupials and monotremes ($n=19$), duty-cycle-corrected bats ($n=31$), dive-corrected cetaceans ($n=12$), birds ($n=78$), and Arrhenius-corrected ectotherms ($n=26$), and subject the log-invariant $\ell ={\log }_{10}(N^{\star })$ -- where $N^{\star }=f_{H}L\times 525,960$ cardiac cycles -- to four independent tests.

27 pages