Population Density and Social Pathology

Population Densy ad Soca athoog  When a populatio of borory ras S allowed o crease   coned space, he rs evelop acely aoma paters o ehavior th ca eve lead o the exnto  he pouao b Jhn  n

I

 the ceebrated thesis o homas Maths, vice ad misery impose the timate atra imit o the growth o popatios. Stdets o the sbject have give most o their attetio to misery, that is, to predatio, disease ad food sppy as forces that operate to adjst the size o a popatio to its e vironmet. Bt what of vice? Settig side the mora brde of this word, what are the eects o the socia behavior o a species o popatio growthad o popatio desity o soci behavior Some years ago I attempted to sbmit this qestio to experimeta iqiry.  coed a popatio o wid Norway rats i a qarteracre ecosre. ith a abdace of food ad pacs to ive ad with predatio ad disease eimi ated or miimized, oy the aims behavior with respect to oe aother re maied as a actor that might aect the icrease i their mber. There cod be o escape rom the behaviora cose qeces o rising popatio desity. By the ed of 27 mths the popatio had become stabiized at 150 adts. Yet adt mortaity was so ow that 5,000 adts might have bee exected from the observed reprodctive rate. The rea so this arger popatio did ot mate riaize was that iat mortaity was ex tremey high. Eve with oy 150 adts i the ecosre, stress rom socia iteracti ed to such disrtio o atera behavior that ew youg srvived. With this backgrod i ind  tred to observatio o a domesticated abio strai of the Norway rat nder more cotroed circmstances doors. he data or the reset discssio come rom the histories o six diret popatios. Each was permittd to icrease to approximatey twice the mber that my experiece had idicated cod occpy the avaiabe spae with oy moderate stress rom socia iteractio. I ach

case my associates ad I maitied cose srveiace of the cooies or 6 moths i order to otai detaied records o the modictios o behavior idced by  opatio  opatio  desity he coseqeces o the behaviora pthoogy we observed were most apprt amog the mas. May were nbe to carry pregac to  term or to srvive deivery o their itters if they did. A eve greater mber, ater sc cssy givig birth, fe short i their mtera fnctios. Amog the maes the behavior distrbaces raged rom sexa deviatio to caibaism ad from reetic overactivity to a pathoogi ca withdrawa ro which idividas wod emerge to eat, drink ad move abot oy whe other members o the commity were asee. he socia or gnizatio of the aimas showed eqa disrptio. Each o the experimeta popatios divided itse ito severa grops, i each o which the sx ratios were drasticay modied. Oe grop might cosist o six or seve femaes ad oe mae, whereas aother wod have 20 maes ad ony 10 maes. he commo sorce o these distrb aces became most dramaticay appar et i the popatios o or rst series o thre exprimets, i which we ob srvd the deeopmet o what we caed a behaviora sink. he animas wod crowd together i greatest mbe i oe o the or itercoectig pes i which the cooy was maitaied. As ma as 60 o the 80 rats i each ex prieta popatio wod ssembe i oe e drig periods of feedig. Idi viua rats wod rarey at excpt i the comp o other rats. As a rest ex treme uatio desities deveoped i the e adopted or eatig, eaving the others with sparse popuatios. Eatig ad othr bioogica activities wr thereby trnsfored into soci ac

tivities i which the pricipa satisfac tio was iteractio with other rats. I the case of eatig, this trasormatio of behavior did ot keep the aimas rom secrig adeqate tritio. But the same pathoogica "togetheress eded to disrpt the ordered seqeces o activity ivoved i other vita modes of behavior sch as the cortig o sex parters, the bidig o ests ad the rsig d care o the yog. I the experimets i which the behviora sik deveoped, inat mortaity ra as high as 96 per cent amog the most disorieted grops i the popatio. ve i the absece o the behaviora sik, i the secod series o three experimets, iat mortaity reachd 80 per cet amog the correspodig members o the expri meta opatios e desig o the experimets was  reativey simpe. he three popa

tios o the rst series each bega with 2 rats; each popatio o the second series bega with 56 rats. I a cases the aimas were jst past weaig ad were evey divided betwee aes ad emaes. B the 12th moth a the popatios had mtipied ad each comprised 80 adts. hereafter remova of the iats that srvived birth ad wea ig hed the popatios stead. A thogh the destrctive eects o popatio desity icreased drig the corse of the experimets, ad the mortaity rate amog the femaes ad amog the yog was mch higher i the 16th moth tha it was earier, the nmber o yog that srvived to weaig was aways arge eogh to oset the eects o adt mortaity ad actay to icrase the popatio The evidece idicates, however, that i time aires o reprodctive c tio wod have cased the cooies to die ot. At the ed of the rst series o exerimets eight ratsthe or heathi

  © 1962 SCIENTIFIC AMERICAN, INC

EFFECT  PPLATON ENSITY n te bhir nd sci gniztin f ts s stdid b nning gs f 80 nims in  10·b·1·ft m diidd int  ns b n eetid fn A ns (nmbed   3 nd  cise m d}  mp ding ns Cnic bjs e d ps; trs it t bts  dinng t Ed b chd

b winding stics c d  nst bxs sn i pn 1  tp f b s bn md Rmps cnncd  pns bt 1 nd  Rts trf tndd t cncntt in pns  nd 3 De mnt f  "bi sin ic ft insd pp tin in n n is cted in pn  h th ts e ti simtns R ppchng mp i n 3 is n et fm

  © 1962 SCIENTIFIC AMERICAN, INC

iasd  hse hsica arre, he sies of the grops i eac  o have ee exected o rage from s fe as 13 o as a as 27. Wih the passae of ti, however, chages i ehavior teded o skew the distritio of e rats amog the es eve ore. Of the 100 distic sleeig gros coted i h 10th to 12h moth of each exeri , ol 37 fe withi he expected se rage. I 33 gros there were few er tha 13 ras, ad i 30 gros he o xceded 27 The sex ratio aproxi ated eqalit ol i hose grops tha fell wihi the exected sie rage.  he saller gros, geerall composed of ight adlts, her re seldo mor

ha wo males. I h lrger rop,  he other had, hre were ma mor males tha feales. As igh e x peced, h smaler grops esalished heselves i the ed pes, whras h larger grops were sall oservd o for i the iddle ps. The fa emers of th polaio disried heselves ao eqall i he for es, t he ale poplatio as co craed almos overwhelmig i the iddle pes. Oe major facor i the creaio of this sae of aairs was he rggle for sats hat oo plae aog th ales. Shorl afer ae ras reach marit a ao six moh of ae, h er io

 rod ri of ghs ha va xes heir ositio i he soil rr  or exerims sch g  a aog h ales i al he pes, o middle ad ed. I he ed es, ho ever, i ecame possile for a sige doia ae o ae over he area as his rrior. Drig he period whe th socia hierarh was i esaished, he sordiae males i  pes adoed the ai of arisig ear. his ead hem to ea d drik i pec. Sice ras geera ea i he corse f heir oral waderig, he sori ae rsids of he d pe er i  o feed i oe of  m s. Wh, after feedig, h ae o

OOD HOPPER used in rs series of eperimes is seen a e f i this drai Waer ra is a te ri Te opper overe ith ire grati ad o ad peles o food, made eain a hy ativiy dui h oe ra as likey  mee anoer

us i oserd e deveopme of a beaviora sik: e animas uld ea oy i te presene of oers, an e prefeed ne o e four oppers in te room o a e oers  im  per en f e animals rodd io e p ontaiig his opper o a

WATER ONTAN used i seond series o eperimens i s a he riht i his drain. ood oppe is a e ef Te founai as opad by essin a . Thus i made rikin a lthy tivity, assoiad it he pesee of ohers Bu i

did no rae a bhaviora sik Ahou e rats oud drik nl if or aimals e ps, hey eaed i is atiity in eir ome pes immedia aftr aakei. The foutai erefoe ad o podue a ev distributio of  puation

  © 1962 SCIENTIFIC AMERICAN, INC

oung ui nss fo h and rod h fo ha I an siuaion aos ha a oh onsird a dang o h us sh woud i h infans u on a a i and a h in h ouh o a sa a Nohing ou isa hr fo his as uni h ni i ha n ov Ha h inas o in h ood ns suviv h gnan as od aong h as in h i ns w no ow han hos od in h nd ns u a sa nag of hs gnancis inad in iv ihs In h son sis of xins 80  n o h infans o in h i

ahoog ha an  foun wii a go h gn of a havioa sink was fosd  h arangns a w ad o ing h anias In hs xins h ood consisd of sa ha s ha  k n a cicua ho od  wi sh In consqunc sasacion o hung r quid a oninuous o asing sva inus h hans ho w good ha hi on ra was aing aoh ou oin i a h ho As was niond ai as usa a in i houghou hi waking hous hnv h a hung an foo is vaia Sin h aangn o  ras  o as ino h id pns han ino h  os i as i

ns id fo aning I h rs sis 96  n ish fo his i h as i h i ns  no ss ac han h as  h ssus o ouaion dnsi In oh sis o xins h soia ahoog aong h as as high. In h s sis hov i was o aggva han i was in h son his inas in disuanc ong h n ouans of h s sis o xins was di ad o h dvon of h hnonon of h havioa snh ouo o an havioa oss ha os ani as ogh in unusua ga nus h unhah onnoaions of h  a no accina: a havioa sink dos ac o aggava a fs of

  FM � K    • 

 

 

   < : z < l

 f Z w u  w 

      

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



2



4

EAVIORAL SINK developed in the rst series of three experimets drain half the rats either into pen  or pen 3 o eah room to drin d sleep, ad even more ito that pe to eat Chrt





eribes the situation in the 13th mot of th experiment By then the poplation distributions ere fairl stae and many emales in the dese opuated pens hd died_ Oe mle i room

 





2

 

70

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� 5 z 



  Z w u  w 

    





2





4

OULATON DISTRIBTONS in the seond series of three experimnts, in whi no bevioral sin developd ere more eve than they ere in the rst series and the det rte mo



2





emles and infnts as loer hart shos the situatio i the 13th month hen oe male had established pens 3 and  of room  s is terrtory and nother s taing ovr pen  thus

  © 1962 SCIENTIFIC AMERICAN, INC

mn v u  su o sus a  wi u amon os a sisd a lau a dvod In  owdd mdd ns no on in dividul oud  o osion n is ia mann In v oup of 12 o mo mas on was  mos ssiv an mos on  vio in s Nvlss s  was odal ousd om s osiion A ula invals duin  ous o i wakin ous  oankn mals n ad n ffoas  umnad n  ns o dominan fom on ma o no. In wn s umuu ous anins o  uad aiv m pvaild.  ssv dominan animas w  mos noma mas i ou populaons  sdom od   fmals o  juvnils Y vn  xd oasiona sns of aol o oin sk aakin fmals juvnis and  lss aiv mals n sowin  aua pdilion wi as do no nomall disla

fo in o anmals o  il Blow  domnan mas o on  us sa and n i  of  vi w  omosxuasa ou as  dsd as ansxual s animas anl oud no dsmina wn aoa and naoa sx ans  mad sxual advans o mas juvnils and mas a w no in sus  mas in ludn  domans as wll as  os o  ansxuals' own ou usu al ad  anons  na vl o aivi o s anima as onl mod  w fqu a akd  i dominan assoas u  v a onndd fo saus wo o s o mal md o o wi ad sind ni om  sul fo domnan  w owv a xa opos ols as fa s i lvs of aiv w on nd  s w omll assiv and movd ou  ommun lk somnamuliss  inod al  o as of o sxs and a 

o as od m Evn n  mas w  sus s assi animas mad no advans o m And onl v al did o mals aak m o aoa m o an kind o a o  sual os  assiv anmals woud av aad o   ais and mos aai mms o h mmuni.  w a and slk and i fu sowd non o  aks and a sos    n in wi mals usual na Bu i soial disonaio was na l om

p a as  ss  all  s md amon  mals was  ou I av ald  s s anmas wi alwas ivd i  mdd ns ook no a a al in  saus sul Nvlss  w  mos av of al  mas in  ximna oulaons and  ssd in i aiv in s o aaks   domnan anmals In addiion o in paiv  ps w o

NORMAL MATERAL BEHAVOR among rats inludes buiding  , wellshped nest for the oung. The ding at the left sows suh a nes holding a reent orn itter. The drawing at te rigt shows ths ame nest out wo wees late. It has been

attened  the eght of the animals' odes t it sti oes mple poeon and wh n the emaining pups an ti rest omora In these expeimets ha he osping of o ma mothes survive infa nd were suesfu weaned.

ABORMAL MATERNAL EAVIOR shown b females ex· poe to he pessues o popuaton desi inludes aiure to id adequae nets. The dg a e et shows he reen on oung o  disturbed femle. She sted to mae  net but

ever ished t. Te dawing a he ig shows he oung about two wees lae. One pup has alead eft and anothe is eaving. Nehe an suvive one. In hese expeiments te moait rte among nfns of disubed mothers was as high  96 pe ent.

  © 1962 SCIENTIFIC AMERICAN, INC

A new science-techology suppors decisionmakng o a globa scale. How do you control

wol-wide focs wh cons ms b made i mnts or sconds, as o hge amonts of nforma tio, which  tur ms be tray pothscod? Dcson o ths scae ar mad posb by a w cnc cholog: sysems ha provde iformato procssig astance fo mtary ad govrnmntal lads. Sciits, Enginee d Computer Programmers at SC hav b on he grong dg of this

scic-choogy snce i began wh SAGE (the s sstm of hs yp) and SACCS (th scod systm) Toay Huma Facos Sciists, Opratons Rsarch Scntt Engnrs and Compu Programmrs a S ae ply ivolv  a umb of w sysms Workng n a cos ndscpnary man, th ae coibig o hs sysms i aras of systm analss sysm sythss, pogramming gan comps aig pesol i he use of h sysms, ad i sysm vauaon Th ar also carryng o search i fuue gatos o hese ssms Wha dos hs w cctchnoogy o you profssonaly? We inv  ou qiy o hs scoe if o ambons, bacgroud and curosiy rn you oward h ew d Addrss  H L. Bs a 2430 Cooao Avnu Saa Moica, Cafora Opengs ar  San Moca, ashg  .C aas, Nw Jrsy, ad Lxngton, aachsts "An ual opputy mpoyr'

D

yt Dvot Cootio

Systms ha h m mae csons and rce contro

DECISON·MKING   GB C

DYMAXION PROECTON B R. BKS FLL

l

4  © 1962 SCIENTIFIC AMERICAN, INC

LRI GRR Utilized Woldwide for Applications n: Nula Physics, Insulation Testng, Electon Micoscopy, Mneal Sepaation, Electostatic Pecipitation Povde High-Voltage Powe Suplies in a Wide Range of Moels ... Featuing: • ssentially pue • Voltages to

DC output

 KV, nnitely vaiabl

• Cuent to 14 ma • Medium or High Stability, to 01% hr

di • Easily adjustable, cloely regulated out

put voltages to 00%  Siplied mantenane, long lie • Exteme saety: Low output caatae,

Minial shotcicuit & oveloa cuet, Remote adjustment & sut own

W  l  g 100 vg  m   s s s

p 23 Bad  w 

4,

N 

P H P Current contractors to O.D and Industry for Integrated Maagement Inormation Systems Desgn and mplementation providig eective contro over Tme, Costs ad Performance

AOUE

962 MANGEMNT SEMNR & COU Basic PERT System Advanced PERT System PRT Analys's Course PRT Courses for Miliary Personnel Management Games Design or Reseach and Tainng Business Inelligence and Advanced lanning Progam Reliability Management Infomation Systems Special In·lant Courses for Militay and Industy For Natiowide Loations and Course Shedules, cal or write:

OPERATINS RARCH NCRPORATD System raining Centers

225 Santa Mona Boulevad Santa onca Caornia Phone 39·2763

I

865 Cameron Street Silver Spring Maryland Phone JU 868

8  © 1962 SCIENTIFIC AMERICAN, INC

hyersexu  hsexu a i tie ay f te beae anniba st They ere ys  the aert fr estrus fees If tere were e i their n es hey wu ie i wait fr g eris at the ts f te ras that gve  the brd es a eer dwn it the. They ways tured ad  e s s as the territria rt aught sight f the Eve if they i t age t ese uhurt they wud s retu t their vatage it. Te rbers duted their ursuit f estrus fees i  bra a er Mtig ag rats usuay invves  distit urtshi ritu I the rst hase f tis riu the e ursues the fee She thereu retires fr a whie it te bur d e e ies quiety  it utside siay king his head it the bur fr  ent but never eterig it ( I te id frs f te Nrwy rat ths hse usuy ivves a urtshi de n the un t te ut f te burw) The feae t st eerges fr the burrw d a ets the as ves Eve i te disrdered uity f the idde es this tte as bserved by a the es wh egaged i nra etersex u beavir ut the rbers wud nt terte eve a srt erid f waitig at the burrws i te es here aessi be feaes ived As s as  feae retired t a burrw  rber wud f w er iside On these exeditins the rbers fte fud ded yung ying i the ests s  resut they tended t ee aibaisti i te ter nths f a uatins istry

�

thugh the bevira sik did t eve i te se series f exeriets te thg exibited by te uatis i bth sets f exeri es ad in  es was severe Even i the brd es feaes u raise ny haf teir yug t weaing Nr des te dierene in it rtaity betwee the dde ens f te rst a sed series96 er et i the rst as sed t 80 er et in te sed rereset a bigiay sigiant irveet It is bvius tat the be· havira reertry wit whi the Nrway rt s eerge fr te trias  evuti ad estiati ust break dw uder te si ressures generated by uatin desity In tie reeet f exerieta reures and f the iterretatin f these studies ay advne ur understadig t the it where the y ntribute t the akig f vaue judgents abut anagus rbes frnting the hua sees

1,0 The mst siulng cae for sece in Amra tdy  n New York S.

H  M SIC BG BUI  NEW YORK TA

N rr d delpe et r goig up   prdd re. Currny   mr n 1,00 h r  wk   g, ,   p pd dp dd kd th f  d g  p   0 , t d d   n   rp th ' gr rn of rrh t d ' d  r   Yrk 17 g tn u Amr lrg r o youn scientss and nneers. Com bld

yur boy

eeah ct in th ivgrg enrmn. Hr 'l d he kd prl u d rg  d. The qpmn d r f u  hv r r, t Equ mprn  b n  r wh gd hl fr r hdr d xpl u d rrl ppr We wil ppae for you  o     dl v f ppe ln   t  ur d Ou u r qmt  ur bu etre nd d h  mer Kh S. Mug Dprmen of mr, Rm 3813,2 Stt Sree An 7 Ne York or

  © 1962 SCIENTIFIC AMERICAN, INC