MacArthur and Wilson’s Radical Theory wasn’t actually radical (even great ideas in ecology go unnoticed)

Most ecologists know about the Theory of Island Biogeography; the theory that diversity patterns on islands are the consequence of dispersal from a mainland source. Robert MacArthur and E.O. Wilson presented this theory first as a research paper in 1963 and then as a monograph in 1967. The rest, as they say, is history.

The Theory of Island Biogeography is remarkable because it suggests that patterns of species co-existence are the consequence of chance, history and random dispersal. Before its publication, community ecologists generally assumed that species co-existence was due to deterministic niche-assembly, where the number and relative abundance of species were a result of ecological niches and the functional roles of each species.

The theory placed randomness at the forefront to community ecology. It also paved the way for Stephen Hubbell’s Unified Neutral Theory of Biodiversity and Biogeography; one of the most influential ecological theories in 21st century. In fact, the introductory chapter of Hubbell’s monograph (like this blog post) was titled “MacArthur and Wilson’s Radical Theory” in reverence to their path-breaking work.

Like the theory itself, MacArthur and Wilson have also reached cult-like status. Perhaps a most telling way of illustrating this fact is not by listing the prizes awarded to these two men (and there were many), but rather by listing the academic prizes named after them! The Ecological Society of America, for instance, awards the ‘Robert H. MacArthur Award‘ to eminent mid-career ecologists and the American Society of Naturalists grants the ‘Edward O. Wilson Naturalist Award‘ to mid-career researchers who make significant contributions to a particular ecosystem of group of organisms. Similarly, the International Biogeography Society has the ‘MacArthur & Wilson Award‘ for notable contributions to the field of biogeography.  Needless to say, MacArthur and Wilson are very influential and well-respected by contemporary ecologists (well, in most cases…).

The funny thing is that their paradigm shifting idea was actually proposed two decades earlier, by the less well-known lepidopterist Eugene Munroe.

Don’t believe me? Here’s an excerpt from Munroe’s PhD thesis published in 1948:

A correlation of this kind [between number of species and logarithm of area of island] is as interesting as it is unexpected, for it suggests the existence of an equilibrium value for the number of species in a given island, a value which acts as a limit to the size of the fauna. The processes which determine the equilibrium value for an island of given size must be, on the one hand, the extinction of species, and, on the other hand, the formation of new species within the island, and the immigration of new species from outside it.”

MacArthur and Wilson came up with their theory independently, so I am not suggesting anything sinister. However, we cannot ignore the fact that they will forever be associated with this idea, while the original discoverer has faded into obscurity.

Perhaps even more surprising is that Munroe’s role in the Theory of Island Biogeography was already clarified in 1989 by James Brown and Mark Lomolino, the founding-fathers of modern macroecology. They wrote a great commentary for Ecology on the similarity between Munroe’s work and that of MacArthur and Wilson (mathematical formulations included!). Yet, 25 years later, Munroe’s contributions are still under-appreciated, despite this endorsement by two eminent ecologists.

The frightening thing is not just that ground-breaking ideas can go unnoticed, but also that it might be more common than we realise. In fact, I suspect that this phenomenon may even be increasing! At a smaller scale, it happens every time a referee points out a missing article during peer review (even when you already cited more than 100 other studies!) and you can’t help wondering how you missed that one.

More and more papers are being published every year, so the odds of missing that one important snippet of information are also continually increasing. For example, a quick search on Web of Science showed that 63 studies with the keywords “Island biogeography” (both words together) were published last year alone and 765 were published in last decade. Essentially, anyone reading less than one new article on island biogeography each week is missing out on some relevant research (and this is only just a tiny corner of the wider ecology research landscape).

This leads to my first observation: the likelihood of missing important information because you didn’t read an article increases as more articles are published.

Sadly, if Eugene Munroe’s part in the Theory of Island Biogeography teaches us anything, it’s that ecologists don’t have a great track record of foreseeing the future significance of research.  However, not every new piece of research is ground-breaking; most just confirm well-established theories. So one could argue, and I do, that the likelihood of one major scientific breakthrough increases as more articles are published. By chance alone, 1000 random papers are more likely to contain brilliant and significant insights than 100 random papers.

This leads to my second observation: the likelihood of a major scientific breakthrough increases as more studies are published.

These two observations can be combined, just as immigration and extinction rates were famously combined in the Theory of Island Biogeography, to formulate an Equilibrium Theory of Scientific Progress (yes, I realise that this sounds incredibly pretentious; please just bear with me).


This theory suggests an optimal number of publications to ensure the most scientific progress. If fewer articles are published, then it is less likely that there is a hidden gem among them. If more articles are published, then it is also likely that the great research will be lost among the mountains of new manuscripts.

Of course, all of this is just me thinking aloud; there is no real evidence either way. Nevertheless, it is something I’ll definitely consider next time I am confronted by a very prestigious journal that prides itself on its high rejection rate or an indiscriminate open access journal that chooses to publish anything that is scientifically sound.

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