Book Chapter 1 Mention
On Being the Right Size
J.B.S. Haldane•2017
Carl A. Price
Top 1% · 99th Percentile
72 citations · History and Philosophy of Science

TLDR

Animals and plants work best at certain sizes. Getting bigger changes how their bodies are built, rather than simply making them more complicated.

Summary

1 Study Aim

The authors aim to explain why body size is a major difference among living things and why each kind has an optimum size (the size that works best). They argue that zoology (the study of animals) has overlooked size and that greater complexity often results from being larger. The study asks how size shapes the way living things are built and function.

2 Study Design

The work presents a conceptual argument rather than an experiment. The authors use comparisons among animals and plants, including eagles and sparrows, hippopotamuses and hares, mice and whales, and simple algae (small plant-like organisms). They discuss how size relates to body complexity and eye size, noting that whales and elephants have eyes only slightly larger than human eyes. No sample, measurements, or statistical analysis are reported. The authors use examples from nature to explain how size affects living bodies.

3 Findings

The authors argue that higher animals are not larger because they are more complicated; instead, their greater size allows or requires greater complexity. They extend this reasoning to plants, noting that some simple plants consist of single round cells. The study also reports that large animals need relatively small eyes compared with their body size, while each kind of animal has a size that suits it best. These observations support treating body size as a central feature in biological research. Living things are shaped by their size, and each kind works best within a suitable size range.

Abstract

The most obvious differences between different animals are differences of size, but for some reason the zoologists have paid singularly little attention to them. In a large textbook of zoology author find no indication that the eagle is larger than the sparrow or the hippopotamus bigger than the hare, though some grudging admissions are made in the case of the mouse and the whale. The higher animals are not larger than the lower because they are more complicated. They are more complicated because they are larger. Just the same is true of plants. The simplest plants, such as the green algae growing in stagnant water or on the bark of trees, are mere round cells. Large animals on the other hand only require relatively small eyes, and those of the whale and elephant are little larger than our own. Such are a very few of the considerations which show that for every type of animal there is an optimum size.

Referenced In