Of Women and Toads

John Steinbeck made an animal connection for mens behaviours in 'Of Mice and Men', so the question is 'What do the Cane toads of Australia and the women pioneer settlers of the old Canadian and American frontiers have in common?'

I'll bet you haven't guessed, so I'll tell you its the fertility (or fecundity) of each wave of settlers ... yes apparently scientists and researchers have managed to link these two apparently disparate topics, with some detailed analysis of the well kept marriage and birth records of the French settlers of Canada (which go back to the 17th century), to show that women who were first to settle in a new land had more children and grandchildren than those who followed later.


French Candian Settlers with high birth rates

Now why this is a surprise to anyone beats me, anyone in Europe watching immigrants arrive in the last 35 yrs will have noted that they have larger families than the natives, and similarly in the US, the Latino immigrants into the USA have larger families than the natives, but in most cases their children have smaller families as each generation reproduces until they reach the norm for that area.

The main difference between this casual observation, and the research findings, is that they managed to show that woman who arrived as part of the first wave of immigration into an area had 15% more children than those who arrived a generation later ..... apparently pioneering woman married younger and benefited from scooping up the best local resources, and their daughters inherited their mother's higher rate of fertility. They then showed that women who came with the later immigration wave that arrived 30 years afterwards, did not exhibit the same fertility rates as the first wave and their offspring.

The Hatfields were a fertile pioneer settler clan in the Tug valley.
Who famously clashed with the similar McCoy clan.

So how have they managed to link this analysis, with the menace of the outback (I have posted on these creatures on more than one occasion), the cane toad, and thus allowed me to also link this post with them?

Well apparently, scientists have observed that the cane toads at the edge of their range have bigger front legs and stronger back legs; making it easier for them to invade new areas. Then when these pioneer cane toads at the frontiers breed, their offspring also inherit these bigger and stronger limbs. However, other cane toads who migrate into these areas after the first wave, don't exhibit these physical attributes.


Fertile Cane Toads - doing what they do best

Apparently this effect was not unexpected, but no one until now had been able to show this phenomenon operating in human populations .... the point of all this research (if there is one) is that families at the front of the wave of migration contributed more to the contemporary gene pool, than those that were slower to arrive and this explains why pockets of certain rare genetic diseases carried by the first settlers still exhibit in some areas to this day (so now you know!).