( ( ( The biochemistry ) ( of ( the cell ) ) ) ( ( ( ( evolved ( ( 3.5 ( Billion years ) ) ago ) ) and ) ( was ( fixed ( ( ( ( at least ) 1 ) ( Billion years ) ) ago ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN biochemistry)) (PP (IN of) (NP (DT the) (NN cell)))) (VP (VP (VBD evolved) (ADVP (NP (CD 3.5) (JJ Billion) (NNS years)) (RB ago))) (CC and) (VP (VBD was) (VP (VBN fixed) (ADVP (NP (QP (IN at) (JJS least) (CD 1)) (JJ Billion) (NNS years)) (RB ago))))) (. .)))
The biochemistry of the cell evolved 3.5 Billion years ago and was fixed at least 1 Billion years ago.
(ROOT (S (NP (DT The) (JJ first) (VBG living) (NNS cells)) (VP (MD may) (VP (VB have) (VP (VBN evolved) (ADVP (NP (QP (RB around) (CD 4) (CD billion)) (NNS years)) (RB ago))))) (. .)))