Glossary
Allometry.
Direct answer
Allometry describes how measurable traits of an organism change with body size. Heart weight, metabolic rate and breathing volume do not follow body mass proportionally; they follow a power relationship. Comparing species of different size therefore requires this scaling to be taken into account rather than assumed away.
The classic error is simple proportion: a horse weighs many times a human, so every quantity should be that many times larger. It is not. Energy turnover per kilogram falls as body mass rises, so a large animal consumes less oxygen per kilogram than a small animal of similar build does.
In pharmacokinetics, allometry is used to move from one species to another. That transfer is a starting point, not an answer: differences in enzyme equipment, binding to blood proteins and excretion can put the estimate well off target. In the horse, a large fermenting hindgut adds a further particularity.
The evidence letter
Once a month: new syntheses, checked studies, and what has changed in the state of the evidence.