In the classic book series, Little House on the Prairie, Pa's wanderlust repeatedly drives the Ingalls family westward past the edges of civilization. That craving for open space is probably what drove Homo sapiens to leave Africa in the first place and spread across the globe. According to new research, the desire to expand into new territory may have provided an evolutionary advantage to those who had it over those who lacked it. 

The study, published November 4 in Science, analyzed the genealogies of settlers in Canada's Charlevoix Saguenay Lac-Saint-Jean region, northeast of Quebec City. Since the colony's initiation in 1608, it underwent several waves of geographic expansion. The researchers, led by population geneticist Laurent Excoffier of the University of Montreal, looked at the colony's marriage and birth records between 1686 and 1960. The analysis found that families living on the edges of the expansions had 20 percent more children than families living at the settlement's core. They also married one year earlier, on average, and contributed up to four times more genes to the region's current population. 

"This is a lovely paper," said Henry Harpending, an anthropologist at University of Utah, who did not participate in the study. Although the researchers could only include births registered in church records, which most likely excluded illegitimate births, Harpending said the researchers "did a thorough job, and analyzed lots of data."

Of course, these lands weren't unpopulated when the French Canadians settled them. They just overwhelmed the Indians.

Benjamin Franklin more or less pointed this out in 1754 in calling for immigration restriction in Observations Concerning the Increase of Mankind. (By the way, somebody should post a more readable version with modern spelling and without Franklin's surfeit of capitalization — this is one of the key documents in intellectual history, Franklin->Malthus->Darwin, but it's hard for 21st Century people to read in the original.)

After the outbreak of the French & Indian War in 1756, Franklin progressively lost interest in immigration restriction as the opportunity for his people to break out of their narrow coastal strip and violently conquer the great Mississippi watershed increased. (Now, in the Pinkerian imagination, immigration restrictionism is equated with war, while the Enlightenment is equated with peace and immigration, but in the mind of Franklin, one of the great geopolitical strategists of the Enlightenment, immigration restriction and war were alternatives. War against the French and Indians would obviate the need for immigration restriction by allowing the English to conquer vast new lands.After the war, the British government thought to give Canada back to the French in return for a sugar island, but Franklin managed to convince them not to do that: he recognized that the St. Lawrence watershed was key to controlling the Mississippi watershed, which he lusted after for his people.

Then, when the British government tried to restrict the colonists from expanding over the Appalachians, Franklin slowly turned toward war with Mother England to free up the center of the continent for Anglo-American settlement.

In the 21st Century, we witness the same kind of fertility explosions among illegal immigrants to the U.S.

You'll notice that there aren't a lot of Amerindians around these days.