Said Excoffier: "We knew that the migration of species into new areas promoted the spread of rare mutations through a phenomenon known as 'gene surfing', but now we find that selection at the wave front can make this surfing much more efficient. There is thus a long-term evolutionary success of people living on the edge."
The research team leaders support this by pointing out that women on the wave front had a selective advantage in terms of reproductive success. They generally married about one year earlier than women in the following "range core" and had about 15% more children overall and 20% more children who married and had children. This correlated with greater resource availability and thus less competition among individuals to access those resources. "People could indeed marry younger as more farm land was available on the wave front than in the core, where good lands were mostly already occupied", said Excoffier.
The study also implies the possibility that other human traits that may have been causal to the force for human exploration, population expansion and migration, such as curiosity or the drive to improve one's situation, may have been favored in the vanguards or pioneers of population range expansion and then passed on to their descendants as a part of the human evolutionary process. Said Hélène Vézina, the BALSAC database manager: "It is exciting to see how a study on a regional population of Quebec can bring insights on human processes that have been going on for thousands of years."
Most human populations on the Earth today are the result of range expansions that occurred since early modern humans left Africa about 50,000 or more years ago to colonize the rest of the world.
The researchers caution that the study only represents a short period of human evolution of a specific farmer population within a limited geographical region, and so general inference to population dynamics and human evolution should be considered somewhat tentative, pending results from future studies in other parts of the world. This is a natural consideration in the course of scientific inquiry.
The results of their study are published in the prestigious journal Science, a publication of the American Association for the Advancement of Science.
Cover photo, top left: The Pioneer’s Cabin, Lawrence & Houseworth – Publisher, Wikimedia Commons http://popular-archaeology.com/issue/september-2011/article/first-wave-pioneer-settlers-in-quebec-may-hold-keys-to-understanding-human-evolution-study-suggests