Life History & Reproductie Strategies

Life History & Reproductie Strategies - Life...

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Unformatted text preview: 1/15/12 Life Histor & Reproductie Strategies LIFE HISTORY & REPRODUCTIVE STRATEGIES While logic a ell a ob e a ion ell ha pop la ion gene all achie e a balance b n. bi h & dea h , and h b n. e o ce ppl and demand, he don' ell ho hi i achie ed Mal h gge ed ha , beca e he "fle h i inc ea e han fe ili ed c ion eak," balance i achie ed mo e of en ia mo ali O he (e p. an h opologi ) ha e a g ed ha c l al eg la ion of pop la ion h o gh fe ili con ol i dominan mean (b he e idence fo hi in p e-mode n pop la ion i p e eak) I an o foc on a hi d ie , ing heo of ep od c i e ecolog ( ee al o he a igned eading b Bobbi Lo ) a egie de eloped in e ol iona Adaptation and Population Regulation A e ha e een, a ke i occ e fo ecological adap a ion i le el a hich adap i e de ign i likel o One a g men hold ha ince e ceeding ca ing capaci h ea en he pe i ence of he pop la ion (o e en eco em), ep od c i e e ain (i.e., limi ing ep od c i e a e belo ha i c en l ppo able) e ol e o p e en f e o e pop la ion Af e all, hi a g men goe , if o e - ep od c ion lead o e en al e o ce deple ion, hen a ome poin he e ill be fe e e o ce in f e fo one' de cendan ; hence i follo ha le ep od c ion o ld ac all inc ea e n mbe of i ing de cendan , and p o ide an e ol iona ad an age o fe ili limi a ion Thi ie , hich a pop la among biologi n il mid-1960' (e.g., W nne-Ed a d 1965), and emain pop la i h ome ocial cien i oda , o nd in i i el pla ible B i ffe f om o e io eakne e: 1) i confla e ha ' adap i e fo he collec i i ( he pop la ion) i h ha ' adap i e fo each membe of he collec i i (indi id al, ei he a pa en o a off p ing) 2) i foc e on he e long- e m o come, hich i no elec ion o deci ion-making o k all he a ei he na al The ke i e i h 1) i ha he adap i e benefi of inc ea ing ep od c i e cce (n mbe of i ing off p ing) go o ho e ho do o, hile co (o e pop la ion, e o ce deple ion) a e di ided among all N membe of pop la ion -- a cla ic "p blic good " p oblem ( ee "Concep of Adap a ion" lec e no e , ec ion on "Le el of elec ion," fo f he di c ion) Wi h ega d o 2), i ' e ha a ep od c i el p olific a eg onl "pa " (ha a elec i e ad an age) n il he e o ce ba e i deple ed, and a ha poin e e one ill be o e off in e m of pe capi a e o ce o ep od c i e cce han if he had a oided pop la ion g o h courses.washington.edu/anth457/repstrat.htm 1/9 1/15/12 Life Histor & Reproductie Strategies T , , ' ( ) T , (W ( ); ) ( " -E I ), " ( . ., , ) E , ( ); , , , i hi n- I , ; ( ?) Op imal Reprod c i e Ra e A , ; , i ndi i d al S (RS), O ( T (1) L' L ' ( ( ) ), (2) , (L L ) D 1968) B ( L ( ) , , .) , I , ; courses.washington.edu/anth457/repstrat.htm RS , 2/9 1/15/12 Life Histor & Reproductie Strategies [see diagram of Lack Clutch-Si e Model] It basically comes down to a trade-off between quantity and quality: more offspring & smaller investment in each one, vs. fewer offspring & larger investment in each The optimal point on this tradeoff will vary bet een species as a function of basic reproductive biology and behavior of each species, while the optimum ithin a species (e.g., different human populations), or even among individual parents, will vary as a function of local ecological and social constraints !Kung Birth Spacing These points are well illustrated in the case of ! Kung San reproductive strategy ! Kung San (also known as Ju/'hoansi) are hunter-gatherers in Kalahari desert of southern Africa (Botswana & Namibia) studied by Richard Lee (1979), Nancy Howell (1979), and others They have been characterized as an "affluent society" w/ plenty of food, leisure time, and healthy lives that last into old age (though all of these generalizations have been questioned, as we will see in the readings for our next class) One of the remarkable things about the ! Kung is that they have very wide inter-birth intervals (IBIs) in comparison to other "natural fertility" (non-contracepting) populations Lee & Howell calculated that mean IBI was about 4 yrs for ! Kung women living a traditional foraging lifestyle (vs. 2 yrs among those settled at Bantu cattle posts and subsisting more on agropastoral products) One explanation for this wide birth-spacing is that it is a way to control population so it doesn't exceed K or Cc), but this unlikely for several reasons, including: 1. millions of mongongo nuts (staple plant food) rot on the ground every year 2. the ! Kung harvest less than 1% of large herbivore biomass annually in their area, vs. the sustainable yield of 10-20% [Hill 1993:196ff] Lee's explanation (Lee 1979, 1980) is that ! Kung mothers carry their kids until they are 4 yrs old, and walk 1500 km/yr, so carrying more than one child is just too much work (as ! Kung say, "Woman who gives birth to too many children has a permanent backache! ") Plausible argument; but then why not go for 6 yr intervals? or 8 or 10 yrs? Or (to really minimize workload) have no kids at all? Since the observed IBI leads to a population growth rate just barely above replacement rate, longer IBIs would apparently lead to demise of ! Kung; but Lee's "backache" explanation doesn't predict any particular IBI, or why it would be at or above replacement level (which is also determined by offspring mortality rates, not just IBIs) Furthermore, ! Kung women readily express a desire for more children, and did not practice any courses.washington.edu/anth457/repstrat.htm 3/9 1/15/12 Life Histor & Reproductie Strategies L N B J ' (1986, 1987) , : " - "= ( . ., RS) T ( !K , ); , , , ( A " B "C ) J ) N H ' (IBI , R = ) [see !K ng IBI Graph] IBI (48 T , IBI ( ) IBI : , L , ' S B 1) not J ' - IBI : ( ) 2) ( IBI, ) T IBI !K ( ); P , IBI ! K , - , , !K ; m a xi m i i n g , , !K ( decreased ; , ), 1. G : ( & - ; ) 2. K ' ) [B T ' , , courses.washington.edu/anth457/repstrat.htm J ( . 1994 , 1994 ] !K 4/9 1/15/12 Life Histor & Reproductie Strategies , A - H Demog aphic T an i ion !K , , H - , " " ; RS? O - W " " (DT) = DT , : 2 ( ), & ( ) T , -- D ( - - d T , ) 2 I F : : ( , ), - (. , ) W I DT, 1) H E ( , 2) K ( W ) & ) ) ( T 3) I , ) H : ; ' ( T DT E =W : DT , courses.washington.edu/anth457/repstrat.htm ( 2 1 ) . ( , ) - & 5/9 1/15/12 Life Histor & Reproductie Strategies eadi g a gh e ih e N e ha h e i di id a di ec i g hei e e gie ce & ed ca i h achie e a d ca ee (a Thi i he " ie fi e -de e i achie i g high a i a i iii Thi ade- ff b a e (gi e c Th I i e ce i i d ia cie ge e a d ed hei fa i ie , f e a e) d : ? e" -- e achie e i e i ie , c ai cce a d e d c i i e ecia b i g f a ia cha di i i f ab ) b ac ifice ha i g id f , e e ai e , , e c. ef e ,b i c ea i g f e ehd a e ch fi e ac ifice ha e a be e cha ce f a ai i g ii f i e ce (ge i g a MD JD MBA, ge i g e e, bec i g a e ec i e, e c.) , i e i ca ee c e de ( g ad de eii a ha e be e cha ce f bec i g i f e ia , e i g a , e -e e e ee , ia a edi a) Thi ea he ha e di i a e cce i a cce f he , a d he e a e ca " a " c i a i ia a e a a ii Th , beha i ha ed ce e h gh a a e ec i c i i g he a e ha ade he e i g a e ha igh be ead d ci i de ad a ce ca ee ca a( ge e ic! ) a ia i ead i he ai Thi e a e, i f c ec , h hc ae i ca di e ge f bi gica e i ,a d ac a e i ead f ai ha ed ce he RS f hei bea e (a di c ed i ea i e ec e c ae i) Thi ch 1. c 2. c eie ha e if (a i a a ia i a i f e ce c hi ca e): ed a e a i ed f ae (Ne e e a . 2007) e e di ec i h e d c i (B d & Riche 2005:169ff) Ecolog and Mating S stems E h g a hic e ide ce e ea a e c a , hich ai e a b i ei eg a e e a i & ai e i d ? Oe c di i A ie h he i i ha diffe e a ie fh a a i g & fa i : Wh ha e e e de e ed a e a e ada ed he i ha ce ai c aae e i gi e e ae he e e ada i e, b ead f If e b h ie ec gica /ec We ca a ha g he ea a e c ec , e h d be ab e a ch ic i a i , a d/ 2) c a adi i ach hi i courses.washington.edu/anth457/repstrat.htm eb i g a e a ch f 3 diffe e ai f ha e e f fa i f ec e c diffe e gica a ec ic a i g a d fa i e 1) ecific a i age 6/9 1/15/12 Life Histor & Reproductie Strategies Monogam 2 1. W : , ( . ., , - ) 2. W ( . ., E A ); E ( , , , . P ol g n (E hnog aphic A la ) ( 716 ) 863 = 83%), , P , T ( , , , ( .), ) E E A ; ' ; " , " S " ," ; 2) 3 L -- ' , 2 ( - ' : 1) , - " " ) S , - , ( . ., A Y , L .) p o l an d r : 1 W 80% (E hnog aphic A la /2 , = 0.5%) 4/863 E f a e nal ( ( - = ) T , ( , , ), RS ); , , B courses.washington.edu/anth457/repstrat.htm =T [ D 1991 7/9 1/15/12 S Life Histor & Reproductie Strategies 1998] T , & : , - , - ( . ., ) ,3 T , O ( " "; - ) -- T & I , RS - N ) , ( 2-3 B 4 5 - ) [L , ( ' ,T (S , &S ; , 1997] , , , 2 , ) S , O , : I , ( . ., N L ' < ) [L H L , ) S. A T I &S 1997] ( T ,I , S S. A , & - ( , .) Refe ence courses.washington.edu/anth457/repstrat.htm 8/9 1/15/12 Life Histor & Reproductie Strategies B J e , Nic h a G. (1986) B Soc iob iolog 7: 91-105. h a bi h ac i g: a e f B J e , Nic h a G. (1987) B Soc iob iolog 8: 183-203. h a bi h i a i e bi h i e a . Etholog and ac i g: di ec e f ei e edic i . Etholog and B J e , Nic h a , K i e Ha e , a d Pa ic ia D a e (1994) Diffe e c e be ee Had a a d !K g c hi d e ' : Aff e c e ac ic a ea ? I Ke is s ues in hunter-gatherer res earc h, ed. E e S. B c h, J . a d Li da J. E a a, . 189-215. O f d/P ide c e: Be g. B J e , Nic h a , K i e Ha e , a d Pa ic ia D a e (1994) F agi g e h did ' !K g c hi d e f age? J . of Anthropologic al Res earc h 50:217-248. B d, R be a d Pe e J. Ric he Chic ag : U i e i f Chic ag P e D ha , W i ia g ad a d c hi d e : (2005) Not b Genes alone: How c ulture trans formed human evolution. . H. (1991) Coevolution: genes , c ulture, and human divers it . S a f d: S a f d U i e i Hi , Ki (1983) Ma e S b i e c e S a egie a d Ti e A c a i A c i i ie a Pa ag a . Ph. D. Di e a i , De . f A h g , U i . f U ah. H f !K e , Na c W . (1979) Demograph of the Dob e !Kung. Ne Y Lac , Da id (1968) Ec ologic al Adaptations for Breeding in Birds . L g he Ac he H : Ac ade ic P e d Pe . e -Ga he e . : Me h e . Lee, Ric ha d B. (1979) The !Kung San: Men, W omen and W ork in a Foraging Soc iet . Ca b idge, Ne Y Ca b idge U i e i P e . : Lee, Ric ha d B. (1980) Lac a i , a i , i fa ic ide, a d e' :a d f h e -ga he e ai eg a i . I Bios oc ial Mec hanis ms of Population Regulation, ed. M.N. C he , R.S. Ma a , a d H.G. K ei , 321-348. Ne Ha e : Ya e U i e i P e . Le i e, Na c E. a d J a B. Si (1997) W h Current Anthropolog 38:375-398. ad Ne e, Le e , e a . (2007) I f e c e c Evolution and Human Behavior 28(3):199-210. S i h, E ic A. (1998) I Tibe a 9:225-261. W ad ic a i ada i e? Me h d e-Ed a d , V.C. (1965) Se f- eg a i g courses.washington.edu/anth457/repstrat.htm fai : e i ce ab fi e abi i d ci gic a a d ai f i : he c ad ae e a he e ic a c i i . a iage . i f fe i i . e . Human Nature f a i a . Sc ienc e 147: 1543-48. 9/9 ...
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