Answer:
Mayflies live a day, humans live a century, if we're lucky, but what is the oldest living organism on the planet? For scientists, accurately proving the age of any long-lived species is a hard task.
Under the boughs of a 300-year-old sweet chestnut tree in the Royal Botanic Gardens in Kew, Tony Kirkham, head of the arboretum, confirms that trees are capable of outliving animals.
Proving this can involve some traditional detective work, as he explains: "First of all we can look at previous records, to find out if a tree was growing there at a set date. Then we look at paintings and artwork, to look to see if that tree was present. And old Ordnance Survey maps quite clearly show ancient trees, especially important ones."
A well-known way of measuring the age of a tree is by counting the rings in its trunk: one ring per year of growth. It's a process known as dendrochronology and only works for certain types of tree that have an annual growth spurt.
