Why_RRQ do_VD0 human_JJ testicles_NN2 hang_VV0 like_II that_DD1 ?_? 
Earlier_RRR this_DD1 year_NNT1 ,_, I_PPIS1 wrote_VVD a_AT1 column_NN1 about_II evolutionary_JJ psychologist_NN1 Gordon_NP1 Gallup_NP1 's_GE "_" semen_NN1 displacement_NN1 hypothesis_NN1 ,_, "_" a_AT1 convincing_JJ hypothesis_NN1 presenting_VVG a_AT1 very_RG plausible_JJ ,_, empirically_RR supported_VVN account_NN1 of_IO the_AT evolution_NN1 of_IO the_AT peculiarly_RR shaped_JJ human_JJ penis_NN1 ._. 
In_RR21 short_RR22 ,_, Gallup_NP1 and_CC his_APPGE colleagues_NN2 argued_VVD that_CST our_APPGE species_NN '_GE distinctive_JJ phallus_NN1 ,_, with_IW its_APPGE bulbous_JJ glans_NN2 and_CC flared_VVD coronal_JJ ridge_NN1 ,_, was_VBDZ sculpted_VVN by_II natural_JJ selection_NN1 as_II a_AT1 foreign_JJ sperm-removal_JJ device_NN1 ._. 
As_II a_AT1 companion_NN1 piece_NN1 to_II that_DD1 work_NN1 on_II our_APPGE phallic_JJ origins_NN2 ,_, Gallup_NP1 ,_, along_II21 with_II22 Mary_NP1 Finn_NN1 and_CC Becky_NP1 Sammis_NP1 ,_, have_VH0 put_VVN forth_RR a_AT1 related_JJ hypothesis_NN1 in_II this_DD1 month_NNT1 's_GE issue_NN1 of_IO Evolutionary_JJ Psychology_NN1 ._. 
This_DD1 new_JJ hypothesis_NN1 ,_, which_DDQ the_AT authors_NN2 call_VV0 "_" the_AT activation_NN1 hypothesis_NN1 ,_, "_" sets_VVZ out_RP to_TO explain_VVI the_AT natural_JJ origins_NN2 of_IO the_AT only_JJ human_JJ body_NN1 part_NN1 arguably_RR less_RGR attractive_JJ than_CSN the_AT penis_NN1 --_NN1 the_AT testicles_NN2 ._. 
In_II many_DA2 respects_NN2 ,_, the_AT activation_NN1 hypothesis_NN1 serves_VVZ to_TO elaborate_VVI what_DDQ many_DA2 of_IO us_PPIO2 already_RR know_VV0 about_II descended_VVD scrotal_JJ testicles_NN2 :_: that_CST they_PPHS2 serve_VV0 as_II a_AT1 sort_NN1 of_IO "_" cold_JJ storage_NN1 "_" and_CC production_NN1 unit_NN1 for_IF sperm_NN ,_, which_DDQ keep_VV0 best_RRT at_II lower_JJR body_NN1 temperatures_NN2 ._. 
But_CCB it_PPH1 goes_VVZ much_RR further_RRR than_CSN this_DD1 fact_NN1 ,_, too_RR ._. 
It_PPH1 turns_VVZ out_RP that_DD1 human_JJ testicles_NN2 display_VV0 some_DD rather_RG elaborate_JJ yet_RR subtle_JJ temperature-regulating_JJ features_NN2 that_CST have_VH0 gone_VVN largely_RR unnoticed_JJ by_II doctors_NN2 ,_, researchers_NN2 and_CC laymen_NN2 alike_RR ._. 
The_AT main_JJ tenet_NN1 of_IO the_AT activation_NN1 hypothesis_NN1 is_VBZ that_CST the_AT heat_NN1 of_IO a_AT1 woman_NN1 's_GE vagina_NN1 radically_RR jumpstarts_VVZ sperm_NN that_CST have_VH0 been_VBN hibernating_VVG in_II the_AT cool_JJ ,_, airy_JJ scrotal_JJ sack_NN1 ._. 
Yet_RR it_PPH1 explains_VVZ many_DA2 other_JJ things_NN2 too_RR ,_, including_II why_RRQ one_MC1 testicle_NN1 is_VBZ usually_RR slightly_RR lower_JJR than_CSN the_AT other_JJ ,_, why_RRQ the_AT skin_NN1 of_IO the_AT scrotum_NN1 becomes_VVZ more_RGR taut_JJ and_CC the_AT testicles_NN2 retract_VV0 during_II sexual_JJ arousal_NN1 ,_, and_CC even_RR why_RRQ testicular_JJ injuries_NN2 --_NN1 compared_VVN to_II other_JJ types_NN2 of_IO bodily_JJ assault_NN1 --_NN1 are_VBR so_RG excruciatingly_RR painful_JJ to_II men_NN2 ._. 
After_CS you_PPY 've_VH0 finished_VVN exorcising_VVG that_DD1 unsettling_JJ image_NN1 from_II your_APPGE mind_NN1 ,_, consider_VV0 that_CST the_AT dangling_JJ gonads_NN2 of_IO many_DA2 male_JJ animals_NN2 (_( including_II humans_NN2 )_) are_VBR no_AT less_RGR puzzling_JJ ._. 
After_II all_DB ,_, why_RRQ in_II all_DB of_IO evolution_NN1 would_VM nature_NN1 have_VHI designed_VVN a_AT1 body_NN1 part_NN1 with_IW such_DA obviously_RR enormous_JJ reproductive_JJ importance_NN1 to_TO hang_VVI off_II the_AT body_NN1 so_RG defenseless_JJ and_CC vulnerable_JJ ?_? 
Although_CS we_PPIS2 tend_VV0 to_TO become_VVI accustomed_JJ to_II our_APPGE body_NN1 parts_NN2 and_CC it_PPH1 often_RR fails_VVZ to_TO occur_VVI to_II us_PPIO2 to_TO even_RR ask_VVI why_RRQ they_PPHS2 are_VBR the_AT way_NN1 they_PPHS2 are_VBR ,_, some_DD of_IO the_AT biggest_JJT evolutionary_JJ mysteries_NN2 are_VBR also_RR the_AT most_RGT mundane_JJ aspects_NN2 of_IO our_APPGE lives_NN2 ._. 
Thus_RR ,_, the_AT first_MD big_JJ question_NN1 is_VBZ why_RRQ so_RG many_DA2 mammalian_JJ species_NN evolved_VVD hanging_JJ scrotal_JJ testicles_NN2 to_TO begin_VVI with_IW ._. 
The_AT male_JJ gonads_NN2 in_II some_DD phylogenetic_JJ lineages_NN2 went_VVD in_RP completely_RR different_JJ directions_NN2 ,_, evolutionary_JJ speaking_NN1 ._. 
For_REX21 example_REX22 ,_, modern_JJ elephants_NN2 '_GE testicles_NN2 remain_VV0 undescended_JJ and_CC are_VBR deeply_RR embedded_VVN in_II the_AT body_NN1 cavity_NN1 ,_, whereas_CS other_JJ mammals_NN2 ,_, such_II21 as_II22 seals_NN2 ,_, have_VH0 descended_VVN testicles_NN2 but_CCB are_VBR ascrotal_JJ ,_, with_IW the_AT gonads_NN2 simply_RR being_VBG subcutaneous_JJ ._. 
Gallup_NP1 and_CC his_APPGE coauthors_NN2 jog_VV0 through_II several_DA2 possible_JJ theories_NN2 of_IO our_APPGE species_NN '_GE testicular_JJ evolution_NN1 by_II descent_NN1 ._. 
One_MC1 of_IO the_AT more_RGR fanciful_JJ accounts_NN2 --_NN1 and_CC one_PN1 ultimately_RR discarded_VVN by_II the_AT authors_NN2 --_NN1 is_VBZ that_DD1 scrotal_JJ testicles_NN2 evolved_VVN in_II the_AT same_DA spirit_NN1 as_CSA peacock_NN1 feathers_NN2 ._. 
That_REX41 is_REX42 to_REX43 say_REX44 ,_, given_VVN the_AT enormous_JJ disadvantage_NN1 of_IO having_VHG your_APPGE entire_JJ genetic_JJ potential_NN1 contained_VVN in_II a_AT1 thin_JJ satchel_NN1 of_IO unprotected_JJ ,_, delicate_JJ flesh_NN1 and_CC swinging_VVG several_DA2 millimeters_NN2 away_II21 from_II22 the_AT rest_NN1 of_IO your_APPGE body_NN1 ,_, perhaps_RR scrotal_JJ testicles_NN2 evolved_VVN as_II a_AT1 sort_NN1 of_IO ornamental_JJ display_NN1 communicating_VVG the_AT genetic_JJ quality_NN1 of_IO the_AT male_NN1 ._. 
In_II evolutionary_JJ biology_NN1 ,_, this_DD1 type_NN1 of_IO adaptationist_NN1 account_NN1 appeals_NN2 to_II the_AT "_" handicapping_JJ principle_NN1 ._. "_" 
The_AT theoretical_JJ gist_NN1 of_IO the_AT handicapping_JJ principle_NN1 is_VBZ that_CST if_CS the_AT organism_NN1 can_VM thrive_VVI and_CC survive_VVI while_CS still_RR being_VBG hobbled_VVN by_II such_DA a_AT1 costly_JJ ,_, maladaptive_JJ trait_NN1 such_DA as_CSA elaborate_JJ ,_, cumbersome_JJ plumage_NN1 or_CC vulnerably_RR drooping_JJ gonads_NN2 ,_, then_RT it_PPH1 must_VM have_VHI some_DD high_JJ quality_NN1 genes_NN2 and_CC be_VBI a_AT1 valuable_JJ mate_NN1 ._. 
Although_CS descended_VVN scrotal_JJ testicles_NN2 do_VD0 satisfy_VVI the_AT obvious_JJ criterion_NN1 of_IO being_VBG counterintuitively_RR costly_JJ ,_, the_AT authors_NN2 conclude_VV0 that_CST handicapping_JJ is_VBZ an_AT1 unlikely_JJ explanation_NN1 ._. 
If_CS it_PPH1 were_VBDR true_JJ ,_, we_PPIS2 would_VM expect_VVI to_TO see_VVI scrotal_JJ testicles_NN2 becoming_VVG increasingly_RR elaborate_JJ and_CC dangly_RR over_II the_AT course_NN1 of_IO evolution_NN1 ,_, not_XX to_TO mention_VVI women_NN2 should_VM display_VVI a_AT1 preference_NN1 for_IF males_NN2 toting_VVG around_II the_AT most_RGT ostentatious_JJ scrotal_JJ baggage_NN1 ._. 
I_PPIS1 'm_VBM not_XX aware_JJ of_IO any_DD studies_NN2 on_II intra-species_JJ individual_JJ variation_NN1 in_II scrotal_JJ design_NN1 ,_, but_CCB I_PPIS1 'm_VBM nonetheless_RR willing_JJ to_TO speculate_VVI that_CST most_DAT human_JJ males_NN2 have_VH0 rather_RG bland_JJ ,_, run-of-the-mill_JJ scrota_NN1 ._. 
Anything_PN1 deviating_VVG from_II this_DD1 --_NN1 particularly_RR a_AT1 set_NN1 of_IO unusually_RR pendulous_JJ testicles_NN2 suspended_VVN in_II knee-length_JJ scrota_NN1 --_NN1 is_VBZ probably_RR more_RGR likely_JJ to_TO have_VHI a_AT1 woman_NN1 dry-heaving_JJ ,_, screaming_VVG ,_, or_CC staring_VVG in_II confusion_NN1 than_CSN serving_VVG as_II an_AT1 aphrodisiac_NN1 ._. 
Sperm_NN ,_, it_PPH1 turns_VVZ out_RP ,_, are_VBR extraordinarily_RR sensitive_JJ to_TO even_RR minor_JJ fluctuations_NN2 in_II room_NN1 temperature_NN1 ._. 
When_CS the_AT ambient_JJ temperature_NN1 rises_VVZ to_II body_NN1 temperature_NN1 levels_NN2 ,_, there_EX is_VBZ a_AT1 temporary_JJ increase_NN1 in_II sperm_NN motility_NN1 ,_, but_CCB only_RR for_IF a_AT1 period_NN1 of_IO time_NNT1 before_II fizzing_VVG out_RP ._. 
To_TO be_VBI more_RGR exact_JJ ,_, sperm_NN thrive_VV0 at_II body_NN1 temperature_NN1 for_IF 50_MC minutes_NNT2 to_II four_MC hours_NNT2 ,_, the_AT average_JJ length_NN1 of_IO time_NNT1 it_PPH1 takes_VVZ for_IF them_PPHO2 to_TO journey_VVI through_II the_AT female_JJ reproductive_JJ tract_NN1 and_CC to_TO fertilize_VVI the_AT egg_NN1 ._. 
But_CCB once_RR the_AT spermatic_JJ temperature_NN1 rises_VVZ much_RR above_II 37_MC degrees_NN2 Celsius_NP1 ,_, the_AT chances_NN2 for_IF a_AT1 successful_JJ insemination_NN1 consequently_RR plummet_VV0 --_NN1 any_DD viable_JJ sperm_NN become_VV0 the_AT equivalent_NN1 of_IO burnt_JJ toast_NN1 ._. 
So_RR in_II other_JJ words_NN2 ,_, except_CS during_II sex_NN1 ,_, when_CS it_PPH1 's_VBZ adaptive_JJ for_IF sperm_NN to_TO be_VBI highly_RR mobile_JJ and_CC hyperactive_JJ ,_, sperm_NN are_VBR stored_VVN and_CC produced_VVN most_RGT efficiently_RR in_II the_AT cool_JJ ,_, breezy_JJ surroundings_NN2 of_IO the_AT relaxed_JJ scrotal_JJ sack_NN1 ._. 
One_PN1 does_VDZ n't_XX want_VVI their_APPGE scrotum_NN1 to_TO be_VBI too_RG cold_JJ ,_, however_RR ,_, since_CS nature_NN1 has_VHZ calibrated_VVN these_DD2 temperature_NN1 points_VVZ at_II precisely_RR defined_VVN optimal_JJ levels_NN2 ._. 
Fortunately_RR ,_, human_JJ scrota_NN1 do_VD0 n't_XX just_RR hang_VVI there_RL holding_VVG our_APPGE testicles_NN2 and_CC brewing_VVG our_APPGE sperm_NN ,_, they_PPHS2 also_RR "_" actively_RR "_" employ_VV0 some_DD interesting_JJ thermoregulatory_JJ tactics_NN2 to_TO protect_VVI and_CC promote_VVI males_NN2 '_GE genetic_JJ interests_NN2 ._. 
I_PPIS1 place_VV0 "_" actively_RR "_" in_II scare_NN1 quotes_NN2 ,_, of_RR21 course_RR22 ,_, because_CS although_CS it_PPH1 would_VM be_VBI rather_RG odd_JJ to_TO ascribe_VVI consciousness_NN1 to_II human_JJ scrota_NN1 ,_, testicles_NN2 do_VD0 respond_VVI unintentionally_RR to_II the_AT reflexive_NN1 actions_NN2 of_IO the_AT cremasteric_JJ muscle_NN1 ._. 
This_DD1 muscle_NN1 serves_VVZ to_TO retract_VVI the_AT testicles_NN2 so_CS they_PPHS2 are_VBR drawn_VVN up_RP closer_RRR to_II the_AT body_NN1 when_CS it_PPH1 gets_VVZ too_RG cold_JJ --_NN1 just_RR think_VV0 cold_JJ shower_NN1 --_NN1 and_CC also_RR to_TO relax_VVI them_PPHO2 when_CS it_PPH1 gets_VVZ too_RG hot_JJ ._. 
This_DD1 up-and-down_JJ action_NN1 happens_VVZ on_II a_AT1 moment-to-moment_JJ basis_NN1 ,_, thus_RR male_JJ bodies_NN2 continually_RR optimize_VV0 the_AT gonadal_JJ climate_NN1 for_IF spermatogenesis_NN1 and_CC sperm_NN storage_NN1 ._. 
It_PPH1 's_VBZ also_RR why_RRQ it_PPH1 's_VBZ generally_RR inadvisable_JJ for_IF men_NN2 to_TO wear_VVI tight-fitting_JJ jeans_NN2 or_CC especially_RR snug_JJ "_" tighty_JJ whities_NN2 "_" --_NN1 under_II these_DD2 restrictive_JJ conditions_NN2 the_AT testicles_NN2 are_VBR shoved_VVN up_RP against_II the_AT body_NN1 and_CC artificially_RR warmed_VVN so_CS21 that_CS22 the_AT cremasteric_JJ muscle_NN1 can_VM not_XX do_VDI its_APPGE job_NN1 properly_RR ._. 
Another_DD1 reason_NN1 not_XX to_TO wear_VVI these_DD2 things_NN2 is_VBZ that_CST it_PPH1 's_VBZ no_AT longer_JJR 1988_MC ._. 
Now_RT ,_, I_PPIS1 know_VV0 what_DDQ you_PPY 're_VBR thinking_VVG ._. 
In_II fact_NN1 ,_, the_AT temperature_NN1 regulating_VVG function_NN1 governed_VVN by_II the_AT cremasteric_JJ muscle_NN1 can_VM account_VVI even_RR for_IF the_AT most_RGT lopsided_JJ ,_, ,_, waffling_VVG asymmetries_NN2 in_II testes_NN2 positioning_VVG ._. 
According_II21 to_II22 a_AT1 2008_MC report_NN1 ,_, each_DD1 testicle_NN1 continuously_RR migrates_VVZ in_II its_APPGE own_DA orbit_NN1 as_II a_AT1 way_NN1 of_IO maximizing_VVG the_AT available_JJ scrotal_JJ surface_NN1 area_NN1 that_CST is_VBZ subjected_VVN to_TO heat_VVI dissipation_NN1 and_CC cooling_VVG ._. 
Like_II ambient_JJ heat_NN1 generated_VVN by_II individual_JJ solar_JJ panels_NN2 ,_, when_CS it_PPH1 comes_VVZ to_II spermatic_JJ temperatures_NN2 ,_, the_AT whole_NN1 is_VBZ greater_JJR than_CSN the_AT sum_NN1 of_IO its_APPGE parts_NN2 ._. 
With_IW a_AT1 keen_JJ enough_DD eye_NN1 ,_, presumably_RR one_PN1 could_VM master_VVI the_AT art_NN1 of_IO "_" reading_VVG "_" testicle_NN1 alignment_NN1 ,_, using_VVG the_AT scrotum_NN1 as_II a_AT1 makeshift_JJ room_NN1 thermometer_NN1 ._. 
But_CCB that_DD1 's_VBZ just_JJ me_PPIO1 speculating_VVG ._. 
From_II an_AT1 evolutionary_JJ perspective_NN1 --_NN1 in_II contrast_NN1 to_II my_APPGE own_DA personal_JJ perspective_NN1 --_NN1 the_AT design_NN1 of_IO male_JJ genitalia_NN1 only_RR makes_VVZ sense_NN1 to_II the_AT extent_NN1 that_CST it_PPH1 adaptively_RR complements_VVZ the_AT female_JJ anatomy_NN1 ._. 
In_II contrast_NN1 to_II males_NN2 ,_, unless_CS a_AT1 woman_NN1 is_VBZ doing_VDG something_PN1 unusual_JJ ,_, the_AT female_JJ reproductive_JJ tract_NN1 is_VBZ maintained_VVN continuously_RR at_II standard_JJ body_NN1 temperature_NN1 ._. 
This_DD1 is_VBZ the_AT crux_NN1 of_IO Gallup_NP1 's_GE "_" activation_NN1 hypothesis_NN1 "_" :_: The_AT rise_NN1 in_II temperature_NN1 surrounding_VVG sperm_NN as_CSA occasioned_VVN by_II ejaculation_NN1 into_II the_AT vagina_NN1 "_" activates_VVZ "_" sperm_NN ,_, temporarily_RR making_VVG them_PPHO2 frenetic_JJ and_CC therefore_RR enabling_VVG them_PPHO2 to_TO acquire_VVI the_AT necessary_JJ oomph_NN1 to_TO penetrate_VVI the_AT cervix_NN1 and_CC to_TO reach_VVI the_AT fallopian_JJ tubes_NN2 ._. 
One_MC1 of_IO the_AT things_NN2 you_PPY may_VM have_VHI noticed_VVN in_II your_APPGE own_DA genitalia_NN1 or_CC those_DD2 of_IO someone_PN1 you_PPY 're_VBR especially_RR close_JJ to_II is_VBZ that_CST ,_, in_II contrast_NN1 to_II the_AT slackened_JJ scrotal_JJ skin_NN1 accompanying_VVG flaccid_JJ ,_, non-aroused_JJ states_NN2 ,_, penile_JJ erections_NN2 are_VBR usually_RR accompanied_VVN by_II a_AT1 telltale_NN1 retraction_NN1 of_IO the_AT testicles_NN2 closer_RRR to_II the_AT body_NN1 ._. 
This_DD1 is_VBZ the_AT sort_NN1 of_IO thing_NN1 easiest_JJT to_TO demonstrate_VVI using_VVG visual_JJ illustrations--the_NN2 editors_NN2 at_II Scientific_JJ American_NN1 would_VM n't_XX let_VVI me_PPIO1 get_VVI away_RL with_IW it_PPH1 here_RL ,_, but_CCB a_AT1 quick_JJ Google_NN1 image_NN1 search_NN1 should_VM provide_VVI ample_JJ examples_NN2 ._. 
Just_RR choose_VV0 your_APPGE own_DA search_NN1 terms_NN2 and_CC disable_VV0 "_" safe_JJ search_NN1 "_" --_NN1 though_CS if_CS you_PPY 're_VBR at_II work_NN1 right_RR now_RT ,_, you_PPY may_VM want_VVI to_TO save_VVI this_DD1 as_CSA homework_NN1 for_IF later_JJR ._. 
According_II21 to_II22 Gallup_NP1 and_CC his_APPGE coauthors_NN2 ,_, this_DD1 is_VBZ another_DD1 smart_JJ scrotal_JJ adaptation_NN1 ._. 
Not_XX only_RR does_VDZ the_AT cremasteric_JJ reflex_NN1 serve_VV0 to_TO raise_VVI testicular_JJ temperature_NN1 ,_, thus_RR mobilizing_VVG sperm_NN for_IF pending_JJ ejaculation_NN1 into_II the_AT vagina_NN1 ,_, but_CCB it_PPH1 also_RR offers_VVZ protection_NN1 against_II possible_JJ damage_NN1 to_II too-loose_JJ testicles_NN2 resulting_VVG from_II vigorous_JJ thrusting_JJ during_II intercourse_NN1 ._. 
There_EX are_VBR many_DA2 other_JJ ancillary_JJ hypotheses_NN2 connected_VVN to_II the_AT activation_NN1 hypothesis_NN1 as_RR21 well_RR22 ._. 
For_REX21 example_REX22 ,_, the_AT authors_NN2 ponder_VV0 whether_CSW humans_NN2 '_GE well-documented_JJ preference_NN1 --_NN1 and_CC one_PN1 rather_RG unique_JJ in_II the_AT animal_NN1 kingdom_NN1 --_NN1 for_IF nighttime_NNT1 sex_NN1 can_VM be_VBI at_RR21 least_RR22 partially_RR explained_VVN by_II temperature-sensitive_JJ testicles_NN2 ._. 
Although_CS the_AT authors_NN2 note_VV0 the_AT many_DA2 benefits_NN2 of_IO nocturnal_JJ copulation_NN1 ,_, this_DD1 preference_NN1 may_VM also_RR reflect_VVI a_AT1 circadian_JJ adaptation_NN1 related_VVN to_II descended_VVD scrota_NN1 ._. 
Given_CS21 that_CS22 our_APPGE species_NN evolved_VVD originally_RR in_II equatorial_JJ regions_NN2 where_CS daytime_NNT1 temperatures_NN2 often_RR soared_VVD above_II body_NN1 temperature_NN1 ,_, optimal_JJ testicular_JJ adjustments_NN2 would_VM be_VBI difficult_JJ to_TO maintain_VVI in_II such_DA excessive_JJ heat_NN1 ._. 
In_II contrast_NN1 ,_, ambient_JJ temperatures_NN2 during_II the_AT evening_NNT1 and_CC at_II night_NNT1 fall_NN1 below_II body_NN1 temperature_NN1 ,_, returning_VVG to_II ideal_JJ thermoregulatory_JJ conditions_NN2 for_IF the_AT testes_NN2 ._. 
Additionally_RR ,_, after_II nighttime_NNT1 sex_NN1 the_AT woman_NN1 is_VBZ likely_JJ to_TO sleep_VVI ,_, thus_RR remaining_VVG in_II a_AT1 stationary_JJ ,_, often_RR supine_JJ position_NN1 that_CST also_RR maximizes_VVZ the_AT odds_NN2 of_IO fertilization_NN1 ._. 
Although_CS the_AT activation_NN1 hypothesis_NN1 helps_VVZ us_PPIO2 to_TO better_RRR understand_VVI the_AT functional_JJ ,_, if_CS quirky_JJ ,_, architecture_NN1 of_IO the_AT human_JJ male_JJ gonads_NN2 ,_, it_PPH1 may_VM still_RR seem_VVI odd_JJ to_II you_PPY that_DD1 nature_NN1 would_VM have_VHI invested_VVN so_RG heavily_RR in_II such_DA a_AT1 precipitously_RR placed_VVN genetic_JJ bank_NN1 ._. 
After_II all_DB ,_, we_PPIS2 're_VBR still_RR left_VVN with_IW the_AT curious_JJ fact_NN1 that_CST our_APPGE precious_JJ gametes_NN2 are_VBR literally_RR hanging_VVG in_II the_AT balance_NN1 in_II a_AT1 completely_RR unprotected_JJ vessel_NN1 ._. 
Enter_VV0 pain_NN1 ._. 
Not_XX just_RR any_DD pain_NN1 ,_, but_CCB the_AT unusually_RR acute_JJ ,_, excruciating_JJ pain_NN1 accompanying_VVG testicular_JJ injury_NN1 ._. 
Most_DAT males_NN2 have_VH0 some_DD horrific_JJ stories_NN2 to_TO tell_VVI on_II this_DD1 score_NN1 --_NN1 whether_CSW it_PPH1 be_VBI a_AT1 soccer_NN1 ball_NN1 to_II the_AT groin_NN1 or_CC the_AT flailing_JJ foot_NN1 of_IO a_AT1 sibling_NN1 --_NN1 but_CCB each_DD1 of_IO us_PPIO2 men_NN2 shares_VVZ something_PN1 in_RR21 common_RR22 :_: we_PPIS2 've_VH0 all_DB become_VV0 extraordinarily_RR hypervigilant_JJ against_II threats_NN2 to_II the_AT welfare_NN1 of_IO our_APPGE scrotal_JJ testicles_NN2 ._. 
The_AT fact_NN1 that_CST males_NN2 are_VBR so_RG squeamish_JJ and_CC sensitive_JJ to_II this_DD1 particular_JJ body_NN1 part_NN1 ,_, point_VV0 out_RP the_AT authors_NN2 ,_, can_VM again_RT be_VBI understood_VVN in_II the_AT context_NN1 of_IO evolutionary_JJ biology_NN1 ._. 
If_CS you_PPY 're_VBR male_JJ ,_, the_AT reason_NN1 that_CST you_PPY probably_RR wince_VV0 when_RRQ you_PPY hear_VV0 the_AT word_NN1 "_" squash_NN1 "_" or_CC "_" rupture_NN1 "_" paired_VVN with_IW "_" testicle_NN1 "_" but_CCB not_XX with_IW ,_, say_VV0 ,_, "_" arm_NN1 "_" or_CC "_" spleen_NN1 "_" is_VBZ because_CS testicles_NN2 are_VBR disproportionately_RR more_RGR vital_JJ to_II your_APPGE reproductive_JJ success_NN1 than_CSN these_DD2 other_JJ body_NN1 parts_NN2 are_VBR ._. 
I_PPIS1 ,_, for_IF one_PN1 ,_, had_VHD to_TO pause_VVI to_TO cover_VVI myself_PPX1 just_RR by_II typing_VVG those_DD2 former_DA words_NN2 together_RL ._. 
It_PPH1 's_VBZ not_XX that_CST those_DD2 other_JJ body_NN1 parts_NN2 are_VBR n't_XX adaptively_RR important_JJ ,_, but_CCB variation_NN1 in_II pain_NN1 sensitivity_NN1 across_II different_JJ bodily_JJ regions_NN2 ,_, according_II21 to_II22 this_DD1 view_NN1 ,_, reflects_VVZ the_AT vulnerability_NN1 and_CC importance_NN1 different_JJ adaptations_NN2 play_VV0 in_II your_APPGE reproductive_JJ success_NN1 ._. 
Male_JJ ancestors_NN2 who_PNQS learned_VVD to_TO protect_VVI their_APPGE gonads_NN2 would_VM have_VHI left_VVN more_DAR descendants_NN2 --_NN1 and_CC pain_NN1 is_VBZ a_AT1 pretty_RG good_JJ motivator_NN1 for_IF promoting_VVG preemptive_JJ defensive_JJ action_NN1 ._. 
Or_CC ,_, to_TO think_VVI about_II it_PPH1 another_DD1 way_NN1 ,_, any_DD male_NN1 in_II the_AT ancestral_JJ past_II that_DD1 was_VBDZ oblivious_JJ to_II or_CC ,_, gulp_VV0 ,_, enjoyed_VVD testicular_JJ insult_NN1 would_VM have_VHI been_VBN quickly_RR weeded_VVN out_II21 of_II22 the_AT gene_NN1 pool_NN1 ._. 
Additionally_RR ,_, argues_VVZ Gallup_NP1 ,_, the_AT cremasteric_JJ muscle_NN1 flexes_NN2 in_II31 response_II32 to_II33 threatening_VVG stimuli_NN2 ,_, in_II effect_NN1 pulling_VVG the_AT testicles_NN2 up_RP closer_RRR to_II the_AT body_NN1 and_CC out_II21 of_II22 harm_NN1 's_GE way_NN1 ._. 
In_II fact_NN1 ,_, the_AT authors_NN2 point_VV0 out_RP ,_, Japanese_JJ physicians_NN2 have_VH0 been_VBN known_VVN to_TO apply_VVI a_AT1 pin_NN1 prick_NN1 to_II the_AT inner_JJ thigh_NN1 of_IO male_JJ patients_NN2 as_II a_AT1 surgical_JJ prep_NN1 :_: if_CS the_AT patient_NN1 displays_VVZ no_AT cremasteric_JJ reflex_NN1 ,_, this_DD1 means_VVZ the_AT spinal_JJ anesthesia_NN1 has_VHZ kicked_VVN in_RP and_CC he_PPHS1 's_VBZ ready_JJ to_TO go_VVI under_II the_AT knife_NN1 ._. 
Other_JJ evidence_NN1 suggests_VVZ that_CST fear_VV0 and_CC the_AT threat_NN1 of_IO danger_NN1 trigger_NN1 the_AT cremasteric_JJ reflex_NN1 ._. 
I_PPIS1 suspect_VV0 there_EX are_VBR any_DD number_NN1 of_IO ways_NN2 to_TO test_VVI this_DD1 at_II home_NN1 ,_, if_CS you_PPY 're_VBR so_RG inclined_JJ ._. 
Just_RR make_VV0 sure_JJ the_AT owner_NN1 of_IO the_AT fearfully_RR reflexive_VV0 testicles_NN2 knows_VVZ what_DDQ you_PPY 're_VBR up_II21 to_II22 before_II frightening_VVG him_PPHO1 ._. 
So_RR ,_, there_RL you_PPY have_VH0 it_PPH1 ._. 
A_AT1 new_JJ ,_, evolutionarily_RR informed_VVN account_NN1 of_IO the_AT natural_JJ origins_NN2 of_IO descended_VVN scrotal_JJ testicles_NN2 in_II humans_NN2 ._. 
What_DDQ do_VD0 you_PPY think_VVI of_IO Gallup_NP1 's_GE seminal_JJ theory_NN1 ?_? 
Is_VBZ the_AT whole_JJ thing_NN1 nuts_NN2 ?_? 
Do_VD0 n't_XX leave_VVI me_PPIO1 hanging_VVG ,_, folks_NN2 ._. 
Ball_NN1 's_VBZ in_II your_APPGE court_NN1 ._. 
