SETON^ — EVOLUTIONARY FORCE OF A WIDE RANGE 
167 
THE EVOLUTIONARY FORCE OF A WIDE RANGE 
By Ernest Thompson Seton 
(It is with considerable hesitation that I offer this paper on a subject that is 
somewhat out of my usual line. I do so on the advice of my friend, Dr. Joseph 
Grinnell, of Berkeley, California, as he assures me it will be found new and 
important, and that I should certainly put it on record.) 
In 1892, I corresponded with a Russian naturalist, Baron Max von 
Sivers, of Roemershof, Riga, Livonia, who represented a group that 
intended to introduce the wild turkey into Livonia. Though in sym- 
pathy with their purpose, I took a pessimistic view of its feasibility, 
and, in a brief paper, pointed out a principle involved that seems nearly 
self-evident when one arrays the available facts. 
This principle I have often referred to in my writings since, and elab- 
orated in my lectures, but have not hitherto offered for record in formal 
scientific print. Therefore I now reproduce that paper. 
The theory is briefly this: Other things equal, a species evohed in a 
large area, is stronger than one evolved in a small area. Obviously, the 
chances of superior variants appearing are greater in a large popula- 
tion than in a small one. And further, a race that can adapt itself 
to the many vicissitudes of a large range is stronger than one that is 
fitted to the less vicissitudes of a more limited space. Evidently a 
big fire is hotter in the middle than a little fire. 
The largest existing land-area, for a species that can freely traverse 
mountains and rivers, is Eurasia. Therefore, if my theory be right, 
a Eurasian species will speedily overcome an American species, or an 
Australian species. Witness the triumphant march of the house- 
sparrow, the starling, the brown rat, the house-mouse, the mongoose, 
the fruitbat, the carp, the brown trout, the browntail and the gypy- 
moths, etc., many weeds and even trees. 
These, being Eurasian, have been specialized in so many ways, and^ 
hardened in so many more fires and forces than our own kindred species, 
that they are stronger, hardier, more adaptive, less subject to disease, 
more resistant, more aggressive, more frugal, more prolific. And they 
march ever on, possessing and destroying, even as the white man him- 
self has done. Significant illustration is seen in the facts that the Asi- 
atic chestnut is immune to the blight that is destroying the American, 
and the Caucasian pine is proof against the blister-rust that is filling 
American foresters with dismay. 
