Animal Behavior: An Evolutionary Approach

505 Pages·2001·65.12 MB·English

by  John Alcock

SEVENTH EDITION

AN EVOLUTIONARY APPROACH

A

ARIZONA STATE UNIVERSITY

SINAUER ASSOCIATES, INC.

SUNDERLAND, MASSACHUSETTS

TM C_
A ~ itIk ('OIlwy1' ~ informatioo. about .... fiP1~uponry 10 ri,'~
INln. ~aphby Ilruc'l' lyan.

1M FrontiJPi«~
1lw lhrNt d;,.pa.y of tIw l-WnadJyas Nboon noion many qun"'- for
n 'olutionary ~ ~aph by C K. 1.oftnz-

Animal ~hovior.An Evolutionary Approach,~nfh Edifion

C Copyright 2001 bySiN..... AS6Oriare.. lee.

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This book may"''' be ...prod lK't'd in who'" <>f ill pan I.... any purp..... whal"'·....
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Akod, John, IQ.l2-
Anim.a\ bfoty"ior / John Akork.-7lh <"d.
r·mI.
Indudor.. bobl"w'aphiuoI ...-ft,,,,, la'S.

1S8~ 0-8",,3-011-6
I. An,m.a\ behoo\'ior-E..olutioo.. I. Titl<-

QL751 .A5Il 2001
591.5-.k21

lO'l H7 65 43 21

To Tht Naturt COl1st rvancy

Contents in Brief

1
An Evolutionary Approach To Anima/Behavior
J

2
Proximate and Ultimate Causes ofBehavior:How and Why BirdsSing 22

3
The DevelopmentofBehavior: A Focus on Heredity
50

4
The DevelopmentofBehavior:AFocus on the Environment 76

5
The Control ofBehavior; Neural Mechanisms
1/4

6
The Organization ofBehavior: Neurons and Hormones
154

7
Adaptationand Antipredator Behavior /82

8
The EvolutionofFeeding Behavior 214

9
Choosing Where to Live 248

10
The Evolution ofCommunication 280

11
The Evolution of Reproductive Behavior J 1f>

12
The Evolution ofMating Systems 300

13
The Evolution of Parental Care 394

14
The EvolutionofSocialBehavior 420

15
The Evolution ofHuman Behavior 456

Contents

1 I An Evolutionary Approach To Animal Behavior 1

Qul'Stions about Behavinr 2

II.,U' Qurs/ions nh",t Proximatf QWSfS 3
Wh!f Qut'ShOlls nwut U/h"",tr (nuSt'S 3

Ans",·..ring Pru~ima t<' and Ulhm.ote Qut.."tiOll5 abo",

Bt'h.wior :;
8tn..:Jll'rS n..J H""""1l Btftn.ivr 5

Gulls and Egphrl/ R,."mt",1 9

Da rw iniolfl Theory and Ulti mate Hypoth......" 11

v..n.t,jnWtl Logic and 1MStudyof &Nwim 13
TM Probkm ""tlr Group sn~f;"" 14

T....ling AltemahH' Hypot~ 16

(Lm,i"'y,,,,1i $rim« 18

2 I Proximate and UltimateCauses of Behavior: How andWhy BirdsSing 22

D1ffnmt Songs: Proxim.oloPQ..-; 2.-

s..o.d Uprnrna"'" Softg Dr,..Iop".", 26
nr AlIi.Pl Soflg C",,'rol S~..... 28
nr DtwIopmtntof''''' Sortg Conlrol 5~..... JI

Sorr,~ Drffrrmcrs Bt1,.......,,,, So-uo Jl
Awiding" MisunJm;tlllldill!i 34

Oifftonont Song$.: UltiINIe c.ll'O.'S J.I

1JIrAd<Ipt4t...."" ApyI_1I J5
I'.'lryDoOnly ,"",In: SINg ~ 39
N/ltrmlJ S<-I«tiorl.Pl4 o..I«ts 42
Proximal.. and L%m.tle c.~ Are

Complementory
45

3
The DevelopmenrofBehavior:A Focus on Heredity 50

TIw Go.onetic5 of Beh.....io! 52

Gmt1i(" Dilfrrrnas Imd H......." Bt/Ion"", 55
Goorr.1ic Diffrrmcn ",,<I IQ f),~ 57
H_ Mmy Cmdic DIjfrrrncn A" NtrdftI to Pralwcr

• &lwt.....aJ CJiffrrma~ S9

1l\I' h olulion 01Bt>h.villf 65
Difrermt SelKtion ",""UlYt'. Diffnnlt Centos.

Diffnnll8eh.lvion 67

4 I The Development of Behavior:A Focuson the Environment 76

T1w InIWKti\'e' T1wofy of Dr\-eklpment: IiorrtIorll'!o

.lind fltoh.o,ior 78

W/ItIl tol!«tIrIIt'.I FCItIl~ irt • HoNy 8ft' Colony so
W/ItIl to~. Tm'itor¥/ ~ 82

E"~.nd Bt-hil"iof.1 Dr\'elnpmmt ll..f

u rly Expt'Tietlc~ ,m4 ~Ilioll of RtlatilYS 85
I.tIIrm"8 as Bthal'wnll Ott",I"!'me"t 90

holution and fltoh.o,ior.ll Dr\-dopment 92
Thr ~ino V.t..,.o/ Dt(lflopll..~t"" f/nibility 94
Sn Dljfrre't1a5 ;rt S,..tWllNtrtillK AkJity 98
Thr EroIuhorr ofIwocioftit", u..mirtK 99
Thr Erolu/ioll of Ott",I",, """'t~t H~ts15i5 10j
Thr Ada/'tit'" Value vf Dn>t1"P.......t,,1 Homro>lll$i$ 106

5 I The Control of Behavior: Neural Mechanisms "4

How Sn1n:Jm Cootrol BeN\v 116

StnMW)'~.,....rIJ 5..rrm./ J19

~Ilg ..w ~illg '" Stn50ry /I'pIIl U6
UIIt" P.t"", GmmIIon US
TIlt s..tg ofIW Mid.<Jfipllwll fM 131
TIlt Pron""," &s;" of 5ti","II~ fillm"g J31

$ttttIoJ... FiI/niJIg '" A"",1ory RlaJoton 132
5Ii","11I5 fil"""g i" titt' Tctil.- M<oit JJ4

A<Upti\~ Prlninwte"~ of 80"'••1\_ 137

AMptiPrMtdlm...... of,...."uitwl 141
All OIji1ctory Map 145

6 I The Organization ofBehavior; Neurons and Hormones 1S4

How N..ural Command C..ntM'! OrganiZt'

Ikha\';ur 156

CW MtduIllisms.lId 8rlrtlIOt>NI5drt>iwks 159
H_ DI10 Circ:adillll MKIloIllislllS WorA:? 161
w..g·TmnCydncfBml..... 165

T~ Ph!f.'iC/2/ EIII"rollmt'IJl llIfl"fflCf'i; LoIIg-TmII
Cydl:S 167
Changing Prioritit-s in Changing Sucial
Erwironl1>l"Tlb 170

TIlt Effrr:ts of u,n.l.litwI iii Iitt' C...... Anok 171

H~tklp~i:.tSocMlBoIMI'"
17J

71Adaptation andAntipredator Behavior 182

T1w MNlning of Adapl.llioo 184
T1w Comp.uati\·" Method for T..,;ting Adapl.lliooist

Hypotlll"Sol."S 187
~ Impvrlana of Dit\'rgffll ft\liw'iQII 189
TIlt Imp"',an.:t uf CoIl""":<l'tIl EPOiw,ioll 190

The Di....rsity of Antipl't'darn. Ada ptations 192
~ Va/wt ".f Body "Dtroralioll.'· 194

TItt V.I....ofW/lTIi'lig ~ 197

H<JW To51",.. Pun..". 200
TItt V.llIt ".f Vrgi"'lIO' 202
Tht Dillllioll E/ftclalld lilt StIfi..oJr Hmi 1Q.1
fightlllg Back 207
A Tactic of Lasl RI:S<,.,? 209

8
The Evolution ofFeeding Behavior 214

Incolhng Food 216

Tht 0rig11UofPr-ty-l..oal'"g MtdMfoisllts 117
Cortt,,,, Htlpfrom e-,..."'" 119
Tht History of~ &r DrlIIIaS 111
Tht A40tptin' Va.... afHonty &r £l,m,;r.o 225
Tht I~ U111" HypotltniJ 117
L«/JI'"g Prry I1y Dtmt 219
Sel«ting " 'hal lOEar 231

H_ '" Cltoost"" Opf.......a.r... 23J
H_ '" Cltoost"" Opti-t MIIUd lJ4
Cnti<"is>m ofOpti-t,ty 17wvry 136
TIttEroIllhoft '"Al/mW11A" OW/!; 136
Conwming "'hal You SeI«t lOEat 238
H_ to CJI;1tIt. Wlwlk 240
Why DI10 HII""'IU eoo..l1..... Akohol. 5Fn.
Il1ld Dirt? 141

9 I Choosing Where to Live 248

H..bitat Selection 250

HiIblwt P'r,Ii"'iUS "'" Ttrntorilfl Sj;wlr5 ill
Dr<prningfrom Onr P/lIa '" Anotlorr m

M,gration 259
T1u' Cosl. ofMigralion 260
TIlt 1k'Nfit5 uf Migralitm 262

MigNfi<ln iIO .. QmdiliolW TiKti.:" 2U
TemtorWity 266
TrrTiiorilllity ..ptJ c.lorits 269
TrrTilorUzl Puuks 271
Why Do Tf'Trill1'Y Ho/dm AI..."", Alw"y' Win? 272

10
The Evolution ofCommunication 280

The Origin. and Adaptive Value l>f a Sign<ll 282

C~...~lIIlit.. SrlKfitm 4P1d Mllllirk awngt5 283
TIlt AJoortiR' VoIlwuj hit o...ng<'< 284
Cllnmf AJoortItY V.w 286

11>0' History of .. Sign.al-Rf'mving M..dwusm 2'l7
n", History of1n"d Wing. 289
s"n.<lry hpl<litltiun of Signal Receiv,,"
by SigNlet's 292
x-y Ptrft',Joa'f ~ ~ flw £llCII~"'" of..
SigfwI 293

n", Panda P"n,ipk 297
The Ad"pta~tAppl'OlCh to CommWlK..tion

~m
Yo1ry Oct &by Bmls&x SoN<tislJjIfor Food~ JOO

Ukg'/I_ I~ Rt'l:tn",.s 30S
Adapli,,,, Sig>1al Rt'Ui ,~n)( J07
Ricrivtrs Mily RI'1j~il'tH"IUS/ Sigrwls JOIj
Why ~ lktJ'Iio>r O<nor~ JJI

11
The Evolution ofReproductive Behavior 316

"Jh!o holution CIt Dillt iE ....fl if! 5el< R'*'" 3111

Tnh"g IIw£llCIIIII'""""Y 11II't>fyujSn Di/frrmtYo ill
s,,'ual 5ell"Clioo and Competition for Malt'S 3rl

SOCUZ/ Do...i""nct' and Millt FillUSs .HI
Altl"l"lllllivr Milling TiKtics 332
A e-'i~ Siraltfl/ll'ifil AllnnaliR' Molti,,!
TiICficJ J.U

J1rI'tl' DrsIi>od Stnrtrgin, J1rI'tl'MoItlflg r.-t'" liS
SavM smrtio>r I/ptJ 5"...... Coo'Ipt1" .... JJ7
Malt CWlrdin)( JJ8
s", u..l s"lt'ction ..nd Mat.. Choice 341

f~ .MIlt Chc>ict' ,,"11101<1 M11lmo1l &nqi15 J.I6
Ttstirrg IIwHnIlflry .MII~. Good Gnrn. ..>04 R~""""Y
~~J5J
Sex......l Conflict l;oen.·een !\.tales ..nd Fem.l~ 353

12 j The Evolution of Mating Systems 360

Is Monogamy Ad..pti,·..? 362
M.mllllamy III .MI......../. J64
M"nllllamy i" Bird. J66
ulrl/-Pai, C"P"iIIfio>r.: n",.MIk Prrsp«fi.". 369
£xItI-Pllir CDJ'IUIIfiorr£ TJw FtrItIIh P....ptdit'" 370

Poly.andry without Pol)·gyny m
Pol)·gyny J77

f"""/t [)o/nst Polygyny: Tht f"""lt Prnp«tiror 379

Rt50wIlY Dtfr- PolygyrIy J80
RrsouIlY [)%tst Polygyny, n", f(mak
Prnp«riw JSl

Saamlrlt Cc>mprlilion 1'oIYSY"JI JS2
Uk PoI!fSY'IY J85
Yo1ry Oct,\.Wts Aggrtpft;.. Ltb' J86
Why Oct MIIny F~ M111~ ll'illl flw Sa..... /o.Wks 1/1

Ub? JS9
I

X
T. l>I~ 01Ce>nlent.

~ ,13)
The Evolution ofParental Care 394
,

Why Is Parenl,ll Care More Often Maternal than
Paternal? 396

EXCl7'tion~ to tlw Ruit 397

Wh .~ Do Mille Wattr Bugs Do All tlw Work? 400

Discriminating Parental Cart' 402

Offip"ng Rt>:ognition; C"",,,,,rati,,,, St udi<'s 403

Why Adopt Gmetic Strangtrs~ 404
TIlt History ofIntersptfi/ic Brood Parasitism 406
Why Accept a Parasite's Egg~ 408
Can Adoption &neftt fostl'l' Parmt.? 410

The Evolution of Pan'lltal Favoritism 411

• 14
The Evolurion ofSocial Behavior 420

The Bent'fits and Costs of Social Life 422
1be E\'olulion of Helpful Behavior 427
R«iprocal Altruism ar Pl'I'sonal GIlin? 429
Altrl/ism and Indim:t Sd«tim, 433
TIwAlarm Cail of Belding's Ground Squirrel 434
The Concept of Inclusive Filness 435

Inclu,iPf Fitn,,, and Helpers at tilt Nest 437

Insect Helpers al tilt Nest 442

1be Evolution of Eusocial Behavior 445
Testing tilt Haplodiploid Hypotht<;,s 447
Vrry Clll:'( Relattdnr5S I., Not E"-<tntial for Eusociality

to [ 001,,,, 449

TIlt Ecology of[usocwlity 451

15
The Evolution ofHuman Behavior 456

1be Adaptalinnis! App roach 10 HUllliIn Beh.,"ior 4';8
TI,e SociobWlogyCo"t""",rsy 459
[1'lJlulum and the Diversity ofHuman Cult,,,,,, 462
Sociobiology versus Arbitrary Culture Theory 464
Adaptive Mating Oed sions 466
Adapli"" Mate Choice by Women 466

Glossary 489

Bibliography 495

lIIustrarion Credits 529

Index 53'

Adapti!'" Mate Choice byMe" 471
Conflicl btfw«tl the Sexes 474
Coerci,,,,Sex 477
Adaptive Parental Care 4IlO

Hel,'ing Chl/d,..n Marry 481

Preface

A n"th~r f"ur y~" rs or so have passed ' in<:e the f'r<'viou" <.>dition 01 Animal
Beha,,;")]" dppe.>n'd. Purin!\ thi, time, much thai L, d"Preso;ing hils occurn.'<l on
II><' polilk<l1 and """;ronm.",,,,1 fronts_L..1 us IlOI dwell on the;e ""<'I1l>;, but
i""tt'ad ronsider the pooitive side of the It'dl;t"f,which includes the many exce]-
\tonI P"J""T" on animal ochdvior that have been w ritt<>J1 over Ill<' last I<.>W years.
1ndt>e<I, the rMeat which impurt.,nt discowries about behaVK"-aTt' bt-inKmad"
has st('..dily inc",.sed thn"'K"''''I Irn, Iit.,'lime of my textbook. Just pid ' up a

n'O.",t ropy of any ;0"",,,1 in the dis<.~pli"" and compare the " ....arch reports
tlw", with tlu _
in the ""'" journal 15 or 2Q years p,,,v;ou,ly_Thu•• in 1982.

t.....journal A"i"",r Bmwwur publisht-d 1264f"' ges oI ...ports; in 20ClJ the t,,"'1
was 2180 raK'''>, a fig"... thaI unde""brnalt"!' the actual inc",. ... bi>cau,<, the
iuunt/ll substantially enlarged its p.lge siu in l'l'lll . \1o"-,<,,,('r, the quality of
tho> work, d" well as it, qU.Jnlity, to,.ch.l.nf:"d. The a,-.,tage """"'I paper on

~nimal bet"",ior i. mo", "'Phi,Ii.;",tt-d ~nd inl<'''-'Sting than tho> ~ver ~ge paP"'"
wriU,'n in It", 1'1805. SCi......lists ....~ lly do build ,m what olh~", haH' acrom-
plisl-...d, whi.;h ""tl; lho.' b.lr hi~l><'r and higl><'r ~Mh y~a,.

A. ,,-'S<'a,,-'he.. haw ""'" the chal\e.-l~,' of ~xp., nding our al"-"'dy 'ub.t.mtial

""',,,,ledg.' ,,j animal b<'ruvior, theyhaw gt"Ot"'al<'tI an ~mNrra"""""'t of riches
for a texlb""k " 'ril<'1". As I han> ",viS<'<! my bo"k ag~in, my m~in difficully has
N"-'" whalto I"",v~ "u!. nol who,t 10 put in. Although there ha ,'~ alway. M 'fl

m~ny mo.... ~ood pa!"," than spaC<'a"ailablc fur my .ummari.... Ihis time
anlUnd lho.· pn>bk'm holS se<1ll00especially aeun-. ~vt"J1 the numbo'.. of ..xcel-
1...,1 ......arrh "'P',rts c"'-'pl''tI wilh my desire to limil th., I""gtb of my boo k,
D<->pite <'Iforts in th., p"'1 10 k,,,-,p th~ number of pa~,.. of texl und~, " mImi.
my book had grown bigger over the y""rs. nu. lime Jhav~ m.u..g,>d 10",verse
the lnend, which should make the book '. conn-nls mo", dig,'Stibl", although
it d,,,.. m..an that "'''"Cgood ,tori,.. w......omitted. Read~ 1'!l "f my book can,

ho"'~\'('r, ,'xplo", any b<'1""'ioral tOPKoj Iht-ir choice by turning 10 tho> origi-
nallitetatu",. In this ""Hant onE" tool-the Web of Science (htlp: //www,w..oo/-
5Ciel\C<'.com)-il; lrt'm('lldo usly valuabl.. because il proviJ... such ~n ~~sy and
quirk ",ay 10 Irack down lhe wurk of particular "-'SC'an:h<o'" and 10folk'w the
trail of p"p.,rs that rit,' a "-""'arch "'f'Ort of inu,resl. I ram">t """",mrn''fld this
...arch me<:hani'm 100 sln>ngly.

In addition 10 b , in~ng Ih~ boo k up 10 dat.. and """uclng ils I""gth ,,>rn,~
whal, Jhow" bc\>n abl.. to Inrorrx-"'dl~ ....,1'" illustration. ltiroul':h<-.ul tho> text,
Ihanks 10 Ih~ willingn..," of mv publi.her, Sinau~r A''''lC;at...., to m~ k.. th..
mow f,om hlMk and ",hitt, to full rolor.This change not only add, 10Ih<' a,..-
thelK val"" of tho.' book, bUIshuuld .1"" ht-lp ,....d...,. gr.,-;.p tl><' poinl of graphs

xu
P,e/ace

more quic kly and easHy. The photograph. may also help .tudents
why

so many bclt",ioral biologi.l.low .lI.ldyinlll'l'al anilT4lls in ,..,al''1wiroror nts.

The many dI<Inl<;'" thaI I have made '" !hi,.."""th edition of my bo,l<,k ha,'e

all bteoen ft\dde with one primary goa l in mind; 10hel p my reade......... how
........ rche... have been able 10 reach .., tisfaclory =Iu.ion. aboul how and
why animal. do tht' things theydo. I hope thaI it>;"""mple. 01tht' wonderfully
inte""ting ........reh d,me on animal beh.vior will ft\dke the point th.t sci",,·
tiflC logic offers a powerful means to gain an underst.wding of nalure,

Acknowledgments

The author of.ny texlbook depends on cooperalion from a surpri.ingly lal')\"
number of pe",p l" . A, I have rewriU"" lhe bo,l<,k again, I haw, been very for-
tun. le in having many generous colle. g ue. willing 10 give me th..ir lime,
advice, pho togr aphs, and other form. of hdp, Mike Maxwell was especially
helpful in providing informalion on m;c"
ldlile analy" ",. All the cha pten<

of th e boo k have incorporated chang
uggested 10 me by Ihe following

revi"we....: Alex IMsolo, Eliot Brenowilz, Ken Cat.nia, Robin Dunbar, Bruce
Lyon, Jim Marden, Bob Montgom..rie. Randy Nd"m, Gabrielle Nevill. Don
Owings, Steve '\Iowkki, Ko:m JU.e, .." G:n<' Robin""', Tom Seek>y, Nancy Segal,
David ""'''''!neat, and leanne Zeh. Special thanks to Bob Montgomerie for read·
ing tht' entire manu"':Tipt and for offering "x!remely helpful .uggestions about
how 10do thin"" better.

A host of other colleagu... have provided m" wit h f""rmission to use iIIu<--

tration. that originally apf""a""" in their papers. and some have given me
the iIIuslrations !h<'m...i"..... I wanl to singk- out Bruce l yon for speciallhanl<s;
his sup>:rbphotog raph. ap!"'ar in many pta"" throughout the text as well
a. on the cover of the boo k, I have ackno wledged all supplie... of pholographs
in the !<>xl allhe appropriate figul'l'S.Acknowledgments 10the pu bli.hers who
ha"e also g''Jl,,,ously granted f""nnissi,m to use their copyri l<;hted material
.ppe.ron p.a~ located between the Bibliography .nd the Index.

~fy editor al Sin.""r A.sociates, Pete Farley, has done the hard and often

unglamourous work of keeping the project mov ing ahead. I am wry grateful
to him as well a. to all the other Sina uerian•. especially CheL.... Holabird, J"an
Gemme, Chris Small, David Mcintyre, and Mara Sil"er, Norma Roche, who
copyedl ted this edition as well as many othe.... ,..,ally know~ how to fix mis-
takes. Readers of my boo k are luc ky thallh<'}' get to read lhe copyedited ver·
sion rather than the original dr.ft,

Although dI<Ipter " ·vi,,,,'e..., photographe...., editorial.talf, and presidenl.

of lhe United Slates often change from ed ilion to edition. some Ihings slay lhe
"" me, which p"wid.... a certain reassuring stability t" my life. My wife Sue
continues 10 cope with my many idiosyncra.i..., .Iillli.tening thoughtfully
whenever I vigorously del\OUJ\('(-' the likes of, say, Henry Kissing..r or Antonin
Scalia, sliUwilling 10live in a cramped ~amp',rvan for month. at a lime w hom
we are in W...tern Australia for .nother round of bee research. My younger
son !\;ick is .till in town rr..mpe, Arizona), and he takes time olf from help-
ing lho6<' acruse<! of driving under the influence 10help u. eat dim"" and play
ping-pong, A. in the pa.t, he lets me win onee in a while so that I can retain
som.. small measure of S<-'11.... t<'<'m, thaI most important of mod..", com-
modities, My older son loe is dose .'nough (Albuquerque, !\lew Mexico) thaI
he ra n join uS 00 occasion, helping me ma in lain the iUusion of being .ur-
rounded by family, In addition, I .m happy to report that none of my friends
at Ariwna SI.lte (among lhem OO"e Brown, Sl,'v.. Carroll, Jim Colli,,", Stuart
Fi.her. Dave Pearson, and Ron RUlowski) has yet go"e IIIhis reward, which
means tha I we can aU g<>I tog<'lher at lunch and sometim... on Friday aft"r-

....... iDrt-.. juot ~ _
t..,...toowl. doing iDrdoocada AdmitWly.1Iwamount
cl ........ INI _
(OMUmi" Iwo ~ . dIOWb,& from tt... pildwr P""" pn"iOn
cl tt... good old d.I~ 10. sJ-or two rurTmtly. WI tt-e \I<lf"O undford.........
....... (Ihr nWJWltlUO dN<h-,",,~ cl grttinp; oldo.-f MIdIhr trout>Ift o..-d by
dri<rti,·.. <:<>IIoIo~) t..,.............lrloI"d IIw ........... INnk goo<tr-. TCI my f...,-
i1y .and fnend,. INro. y"".

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Pf><J'''9raph by Ma,l; Mofftrr

An Evolutionary
Approach to Animal
Behavior

or hundreds of thousands of years, humans

observed animals because their lives depended on a
knowledge of animal behavior. Even today, the sub-

ject still has great practical significance. Information on the

reprod uctive behavior of insect pests, for example, may

ultimately lead 10 their control, while knowledge of the
migratory routes of an endangered whale or shorebird may

enable conservanonlsts to design adequate reserves to save

the animal from extinction. Moreover, an understanding of

the evolutionary basis of our own behavior might help us

identify why we so often damage our environmen ts, per-

haps enabling us to reduce ou r destructive tendencies

(1251). But even if the only beneficiaries of studies of ani-

mal behavior were the persons who conducted the

research, 1suspect that work in this field would continue.

Learning how and why animals behave is an intrinsically

fascina ting business. Perhaps you can imagine what it

would be like to be the first person to discover that male

damselflies actually use their penis as a scrub brush to
remove the sperm of rival males from their mates [11 771; or

maybe you can put yourself in the shoes of the person who

first showed that female Seychelles warblers could control