They can do it many ways:
carbon dating
Age, weight, blood tests.
They see the height of growth of tge tree From Mr Hogge
fossill
Go into space and look at the amount of circles (just like what you do to a tree)
At age sixteen he started as a scientist.
he became a scientist at the age of 16
no
albert became a scientist at the age of 2yrs old
he became a scientist at the age of 16
Probably Lucy, the hominid, or Sue, the T-Rex.
A geochronologist is a scientist who researches the age of rocks. Geochronology is a specialised form of geology.