Humans have evolved as a migratory species with the highest fertility shown by those who move first into unoccupied habitats, a new study suggests.
Women among the first "wave front" of migrants into a new area marry earlier and have more children than women who settle in the central "core" of a region that already has an established population, the study found.
Scientists believe the findings demonstrate the importance of being in the first migratory wave of people who move to new, unoccupied regions.
They believe it sheds important light on how humans have evolved since they first began to move out of Africa about 50,000 years ago.
"We find that families who are at the forefront of a range expansion into new territories had greater reproductive success. They had more children and more children who also had children," said Damian Labuda of the University of Montreal. "As a result, these families made a higher genetic contribution to the contemporary population than those who remained behind."
The study analysed parish records in the region of Charlevoix-Saguenay Lac St-Jean dating from 1686, when the first Europeans began to colonise Quebec, to 1960. Analysing the extended genealogies of hundreds of families, involving more than 1 million people, allowed the scientists to determine which of the pioneering families left the greatest number of descendants.
The scientists found that women on the front of the migratory expansion into the virgin territories of Quebec married on average a year earlier than women who lived in the core population. They also had up to 20 per cent more children.
The scientists said the study, published in the journal Science, focuses on a farming community and may not be directly relevant to the hunter-gatherer societies that dominated much of the evolutionary history of humans.