Just when you thought it was safe to assume that we now know all we are ever likely to know about the past, someone digs another hole and unearths (literally or figuratively) some ancient  one day it is a fragile scroll, found in a cave near the Dead Sea, that turns out to be pre-Biblical; the next day it is an entire terracotta army of Chinese  the next it is a skull, excavated from the Olduvai Gorge, that compels anthropologists (once again) to revise their guesses about the earliest stages of Homo sapiens sapiens vs hominids.
( ( ( ( ( Just ( when ( you ( thought ( it ( was ( safe ( to ( assume ( that ( we ( now ( know ( all ( we ( ( are ever ) ( likely ( to ( know ( ( about ( ( ( ( ( the past ) , ) ( ( someone digs ) ( another hole ) ) ) and ) ( unearths ( -LRB- ( ( ( literally or ) figuratively ) -RRB- ) ) ) ) ) ( some ( ancient ( one day ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ( it ( is ( ( ( ( ( a ( fragile scroll ) ) , ) ( found ( in ( ( a cave ) ( near ( the ( Dead Sea ) ) ) ) ) ) ) , ) ( that ( ( turns out ) ( to ( be pre-Biblical ) ) ) ) ) ) ) ) ; ) ( ( the ( next day ) ) ( it ( is ( ( ( an ( entire ( terracotta army ) ) ) ( of ( ( Chinese the ) next ) ) ) ( it ( is ( ( ( ( ( a skull ) , ) ( excavated ( from ( the ( Olduvai Gorge ) ) ) ) ) , ) ( that ( compels ( ( anthropologists ( -LRB- ( ( once again ) -RRB- ) ) ) ( to ( ( revise ( their guesses ) ) ( about ( ( the ( earliest stages ) ) ( of ( Homo ( sapiens ( sapiens ( vs hominids ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) . )
(ROOT (S (S (SBAR (RB Just) (WHADVP (WRB when)) (S (NP (PRP you)) (VP (VBD thought) (SBAR (S (NP (PRP it)) (VP (VBD was) (ADJP (JJ safe) (S (VP (TO to) (VP (VB assume) (SBAR (IN that) (S (NP (PRP we)) (ADVP (RB now)) (VP (VBP know) (NP (NP (DT all)) (SBAR (S (NP (PRP we)) (VP (VBP are) (ADVP (RB ever)) (ADJP (JJ likely) (S (VP (TO to) (VP (VB know) (PP (IN about) (NP (NP (DT the) (NN past)) (, ,) (NP (NP (NN someone) (NNS digs)) (NP (DT another) (NN hole))) (CC and) (NP (NP (NNS unearths)) (PRN (-LRB- -LRB-) (ADVP (RB literally) (CC or) (RB figuratively)) (-RRB- -RRB-)))) (NP (DT some) (JJ ancient) (CD one) (NN day)))))))))))))))))))))))) (NP (PRP it)) (VP (VBZ is) (NP (NP (DT a) (JJ fragile) (NN scroll)) (, ,) (VP (VBN found) (PP (IN in) (NP (NP (DT a) (NN cave)) (PP (IN near) (NP (DT the) (NNP Dead) (NNP Sea)))))) (, ,) (SBAR (WHNP (WDT that)) (S (VP (VBZ turns) (PRT (RP out)) (S (VP (TO to) (VP (VB be) (NP (NN pre-Biblical))))))))))) (: ;) (S (NP (DT the) (JJ next) (NN day)) (NP (PRP it)) (VP (VBZ is) (NP (NP (DT an) (JJ entire) (NN terracotta) (NN army)) (PP (IN of) (NP (NNP Chinese) (DT the) (JJ next))) (SBAR (S (NP (PRP it)) (VP (VBZ is) (NP (NP (DT a) (NN skull)) (, ,) (ADJP (VBN excavated) (PP (IN from) (NP (DT the) (NNP Olduvai) (NNP Gorge)))) (, ,) (SBAR (IN that) (S (NP (NNS compels)) (VP (VBZ anthropologists) (PRN (-LRB- -LRB-) (ADVP (RB once) (RB again)) (-RRB- -RRB-)) (S (VP (TO to) (VP (VB revise) (NP (PRP$ their) (NNS guesses)) (PP (IN about) (NP (NP (DT the) (JJS earliest) (NNS stages)) (PP (IN of) (NP (CD Homo) (JJ sapiens) (JJ sapiens) (NN vs) (NNS hominids)))))))))))))))))) (. .)))
We already know everything there is to know about our past, nothing can ever change that. 
( ( We ( already ( know ( everything ( there ( is ( to ( know ( about ( our past ) ) ) ) ) ) ) ) ) ) ( , ( nothing ( ( ( can ever ) ( change that ) ) . ) ) ) )
(ROOT (S (S (NP (PRP We)) (ADVP (RB already)) (VP (VBP know) (NP (NP (NN everything)) (SBAR (S (NP (EX there)) (VP (VBZ is) (S (VP (TO to) (VP (VB know) (PP (IN about) (NP (PRP$ our) (NN past)))))))))))) (, ,) (NP (NN nothing)) (VP (MD can) (ADVP (RB ever)) (VP (VB change) (NP (DT that)))) (. .)))