Is it even possible for a human to run a marathon in under two hours?

Wilson Kipsang set a new world record this past weekend at the Berlin Marathon, finishing the race in 2:03:23. The above graphic looks at the world records created in the last 10 years (recognized by the International Association of Athletics Federations as a world best).

It's interesting to note that most of the records in the last decade were made at the Berlin Marathon. It's known for being flat. But if you run in the states, chances are you won't set a record.

Many folks in our Boston newsroom were wondering why the Boston Marathon, or even New York Marathon didn't make the list. Well, the International Association of Athletics Federations does not consider the records made at the Boston Marathon legitimate on grounds of a "downhill point-to-point course" while some of the records created at the New York Marathon have been disputed on grounds of a short course.

In case you are wondering what are the specifications of a marathon course to be considered by IAAF, here is the list:

•  26 miles 385 yards (42.195 kilometers)  and measured in a defined manner using the calibrated bicycle method and meet other criteria that rule out "artificially fast times" produced on courses aided by downhill slope or tailwind.

• The start and finish points of a course, measured along a theoretical straight line between them, shall not be further apart than 50 percent of the race distance.

• The decrease in elevation between the start and finish shall not exceed an average of one in a thousand, i.e. 1m per km.

The role of technology is another thing to consider in the breaking and creating of new records. Over years, equipments used by athletes to compete and authorites to measure records have become more sophisticated allowing for more accurate and calibrated results.

But Michael Joyner says that is not the whole story.

Joyner works at the Mayo Clinic in Minnesota. He studies the physiological limits of the human body. He says there are many factors that make East African runners great at marathons. They grow up at high altitude–8,000 to 9,000 feet. They are tiny and lightweight.

Think 120lbs.

And they are super efficient at running. So they are able to convert a whole bunch of speed without much oxygen. But Joyner adds there is also something else that is certainly pushing the athletes to the extreme: money.

Wilson Kipsang took home an additional $68,000 for breaking the world record. Joyner says that's way more money than an average Kenyan could dream of making in a lifetime. And that promise of a huge payday has attracted plenty of East Africans to the sport. 

And as these runner's push the sport to faster times, it is making the dream of a running a marathon in under two hours a possibility. Joyner thinks the racers will gradually push the time down to 2:02:15. 

"And then the fun will start," he says. 

That's because lowering the time will become infinately harder. Each additional second and minute could feel like a lifetime to the runners. 

"It's a little like what Nelson Mandela said about being in prison," he says. "'The days seemed like years and the years seemed like days.' So sometimes a minute or two in a marathon can be the longest minute or two you will experience."