Related by context. Frequent words. (Click for all words.) 38 humans 28 mysteries 28 discovered 25 evolutionary 21 clues 21 believed 21 mystery 21 say 20 realize 20 actually 20 theoretically 20 pinpoint 20 wonders 19 theories 19 naturally 19 perceive 19 myth 19 puzzle 18 probably 18 myths 18 acknowledge 18 figured 18 thought 17 speculated 17 suggests 17 argue 17 guessed 17 suspect 17 hypothesis 17 wonder 17 ponder 17 seem 16 reckon 16 fear 16 believe 16 notion 16 feared 16 puzzling 16 clue 15 puzzled 15 presumed 15 apparently 14 worry 14 suspicions 14 understand 14 predict 14 contend 14 insist 14 fearful 14 theory 14 suppose 14 believing 14 fret 14 curious 14 speculating 14 know 14 presume 13 think 13 guess 13 speculate 12 predicted 12 assert 12 attribute 12 wondered 12 determine 12 baffled 12 suggest 11 tell 11 pretend 11 guessing 11 wondering 10 conclude 10 induced 10 tease 10 warn 9 complain 9 convinced 9 unclear 9 assumed 9 cite 9 worried 8 argued 8 expressed concern 8 explain 8 talk 8 argues 7 arguing 7 suggesting 7 opined 7 suggested 7 unsure 7 allege 6 contends 6 explains 6 claim 5 assume 5 doubted 5 explained 3 contended 3 reasoned -2 argument