Inevitable King Kong island giant story

As surely as night follows day, we have this story from CNN on the real island giant animals that evolved in a King-Kong-like fashion.

Animals sometimes follow exotic evolutionary trajectories on islands because of a lack of predators or competitors. That's the essential truth of the story. It certainly explains the killer mice:

On remote Gough Island in the South Atlantic, "monster mice" are eating albatross chicks alive, threatening rare bird species on the world's most important seabird colony.
The house mice -- believed to have made their way to Gough decades ago on sealing and whaling ships -- have evolved to about three times their normal size.

But you can't shoehorn these cases into a universal "islands breed giants and dwarfs" rule. Consider:

The huge Indian Ocean island of Madagascar -- the setting of another 2005 Hollywood blockbuster -- has also given rise to plenty of natural oddities.
These included massive elephant birds that stood over 9 feet 10 inches in height and lemurs that weighed 176 pounds and more.

Yes, and mouse lemurs, and dozens of species of every intermediate size. The point is that the island created opportunities that might have been filled by other animals in a larger landmass.

A reader sent me a reference to a 2001 PNAS paper by Gary Burness, Jared Diamond, and Timothy Flannery that examines the relation of land area to body size of top carnivores and herbivores. There's no mechanism in the paper to relate the two, but there does seem to be an empirical relationship between the areas of islands and continental landmasses of different sizes and the sizes of their largest animals.

Ectotherms in the empirical data get larger than endotherms, also. So taking everything together, there shouldn't be either dinosaurs or gigantogorillas on Skull Island, but if there were either, they should be dwarfish in size, and the dinosaurs should be plenty larger than the giant gorilla.

And of course, they shouldn't exist in populations of single individuals!

CNN has this part covered, also:

Seemingly the last of his kind, King Kong also reflects another phenomenon of islands -- their disturbingly high rate of extinction, especially when humans land on them.
Many island species have evolved in a predator-free environment -- producing things like flightlessness in birds -- which makes them easy prey for meat-eating intruders.
Such was the fate of Madagascar's elephant birds as well as the famed dodo of Mauritius.
According to the World Conservation Union, close to 800 species have become extinct since 1500, when accurate historical and scientific records began.
While the vast majority of extinctions since that time have occurred on islands, over the past 20 years continental extinctions have become as common.
Scientists say this is partly because continental habitats are being diced up by human activities -- a process that is creating what some biologists term "virtual islands."
King Kong's real-life relatives are marooned on one of these "islands" on East Africa's Virunga mountain range, home to the last of the world's roughly 700 mountain gorillas.

I think the most interesting aspect of Skull Island is the way it exaggerates the scale of the man-nature conflict. Clearly the fauna of the island could never exist. But to make a nature capable of thwarting humans, even for a short time, it takes predators of gigantic proportions. Even in 1933, the real gorillas wouldn't stand a chance.

It is notable that in later movies featuring giant animals, like Godzilla and Them, they are frequently products of human agency -- especially our abuse of poorly understood forces of nature like radioactivity.

As I write this, by the way, the television has "Speed Buggy" encountering a giant island gorilla named "King Zilla".


Burness GP, Diamond J, Flannery T. 2001. Dinosaurs, dragons, and dwarfs: the evolution of maximal body size. Proc Nat Acad Sci USA 98:14518-14523. Full text