After 40 years spent making a career from the completely different, Monty Python star Terry Jones has gone back to basics.
Terry Jones' numbers documentary takes in fossils and Pythagoras
The writer and historian, best known for his work with the surreal comedy troupe, presents The Story of 1, a one-off BBC One documentary on the history of numbers in which he merges slapstick, quirky humour and learning.
The history of counting is long, says Jones, 63.
"You can see marks on bones from 100000 BC but we don't know what they mean," he explains.
"But by 25000 BC you get the Ishango Bone where you know they were counting because it has notches in groups."
The Ishango Bone, from an ancient baboon, is reckoned to be the oldest counter and lunar calendar in history.
It was inevitable that Jones and his crew would end up in India, the birthplace of numeracy.
Jones travelled the world to explore the history of counting
"The numerals we use are from India. We think they are Arabic but they aren't," he says.
"We travelled miles to a temple to find the place where the first ever zero had been written on to a wall," he says. It was a Pythonesque quest.
"When we got there it was locked and the gatekeepers were on holiday," he explains.
"Anyway, we managed to get into the right room and looked at this inscription and it was early Hindi writing.
"But without a guide we had no idea what it said or which one was the nought."
West Europeans started using the zero in medieval times, says Jones.
"The Arabs got it from the Indians and we got it from the Arabs.
"But don't ask me when that was. I can't remember, I'm hopeless with dates. I'd never make an academic."
Jones has directed films including Life of Brian and Personal Services
For the record it is believed that an Indian astronomer Brahmagupta first put forward the idea of zero in about 620AD.
His treatise was then translated into Arabic.
Numerals had a huge impact on commerce, the arts, and learning, says Jones.
"Roman numerals may have held the Romans back. Their system was so cumbersome and they never produced any mathematicians, unlike the Greeks."
Humans are not alone when it comes to counting, says Terry.
"I did a lot of interviews with animal experts who can prove that animals count.
"They can count to three and possibly four.
"Lions listen for the sounds of other prides and if there is more than three in another pride they won't attack."
Jones has another project on the go, the forthcoming Barbarians for BBC Two, which proved bigger than he expected.
Medievalist Jones has presented several BBC TV history series
"You can't just do a TV series nowadays, you have to do the book as well so I'm writing and presenting both," he says.
"The first one is about the Celts and what I love about these things is you get a totally different view on history.
"They are only called 'barbarians' because the Romans called them that and this looks at their worlds from their point of view.
"The great thing about this is that there are so few texts. It takes about a morning to read the texts from that era."
Jones and the Pythons reunited at last year's Spamalot US premiere
One major source for Jones is the Roman historian Tacitus.
"Archaeology is now turning up stuff that is confirming Tacitus but you have to be careful of the classical texts.
"In one written by Caesar he describes elks to the Romans. He claims that elks don't have any knees and so can't kneel down.
"He claims they go to sleep leaning against the trees and people catch them by sawing through the trees, which is hilarious."
The Story of 1 is on BBC One on Wednesday at 2000 BST.