By Dylan Cleaver and Chris Knox
Here's one for the rugby anoraks: What links Scotland forward Bill Maclagan and the prince of centres Philippe Sella?
Too easy, right?
Of course, they were international rugby's most capped players (respectively) at the turn of the 20th and 21st centuries.
The only difference between them – apart from nationality, age, position, food preferences, modes of transport and, oh everything apart from footy – was that one of them led the charts on the first day of 1900 with just 29 tests, the other had accrued 111 by January 1, 2000.
There might be other ways of demonstrating how the volume of international rugby has changed over the years but that is stark. Maclagan had enjoyed a 13-year international career to achieve his 29 tests; Sella sashayed across 13 Frankish years to post 111.
The current chip leader, one Richard Hugh McCaw played one year more for his 148 tests.
It is tempting to think international rugby has plateaued in terms of volume, so there would be no more great leaps forward in terms of winning caps for your country, but don't discount it.
While it is difficult to think of any technological advances that would shrink the world at a rate that would allow for much more than the 10.5 tests per year that McCaw averaged over his career, the next big jump could come from medical science.
In Yuval Noah Harari's contemplative of the future, "Homo Deus", he wrote that man's next great challenge was to conquer mortality.
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While that concept still reads like a sci-fi plot shtick, it is not beyond the realms of probability that our understanding of the human body and what best fuels it will increase to the point where athletes find the keys to playing longer.
Tom Brady just quarterbacked a team to a Super Bowl victory at age 41; using that as a rough guide, Beauden Barrett could have four more World Cups and end with 300 test caps.
OK, for any number of reasons that will not happen with Barrett.
But someone, someday, will find a way to play test rugby for 20 years.
Another big indicator of how the rugby landscape has recently altered so dramatically is the fact 2011 was the first year in which the top-15 capped players all had more than 100 tests to their name.
On January 1, 2010, John Hayes (99), Raphael Ibanez (98), Chris Paterson (98) and Colin Charvis (96) occupied places 12-15 on the list. Twelve months later Hayes was up to seventh on the list with 106 caps and Ibanez, Paterson and Charvis had been replaced by Ronan O'Gara, George Smith and Martyn Williams, with David Campese slipping to 15th on 101 caps.
As we stand now, you must have 118 caps – Kieran Read and Fabien Pelous – to crack the top 15. In 1900, the wonderfully named and exquisitely mustachioed Temple Gurdon, a Cambridge University graduate, England forward and future chairman of the RFU, sat in 15th spot with a mere 16 caps.
The bar chart also illustrates how international rugby was an overwhelmingly northern phenomenon in its early history. The first player from outside the Home Nations to make the top 15 at year-start was Frenchman Aime Cassayet-Armagnac in 1927. By 1966, four of the top five places and eight out of 15 were occupied by Frenchman.
Two years later, New Zealand would have its first entry, the indomitable Colin Pinetree Meads, who would peak at the end of 1971 in fourth with 55 caps. It would be a quarter of a century before Sean Fitzpatrick, who would also peak at fourth, would become the second New Zealander to make an appearance on the chart.
It was 2012 before McCaw cracked the top 15, when 103 caps were enough to rocket him to 13th on the all-time list. He would quickly climb the ranks and on January 1, 2016, after a triumphant farewell at the World Cup, he would be top of the tree with 148.
He sits there still, represented here by a black bar. It leads for now but it won't last.
Check back in on January 1, 2100, and if McCaw is even in the top 15 I'll buy you a beer.