文化進化のパターンとプロセス

Patterns and processes in cultural evolution:

Archaeology and cultural evolutionary studies

Hisashi Nakao

Nagoya [email protected]

http://www.hisashinakao.com

1

mailto:[email protected]

mailto:[email protected]

Self-introduction

2

+ 中尾央（Hisashi Nakao, Ph.D）・京都大学文学研究科科学哲学科学史選修・日本学術振興会特別研究員（PD, 名古屋大学情報科学研究科）・専門：科学哲学（生物学，心理学，神経科学，社会科学の　　　　哲学）．一番の関心は人間進化（と人間の進化的研究）

- 最近の仕事：　　・中尾・三中（編）2012. 『文化系統学への招待』勁草書房．　　・Nakao & Machery 2012. The evolution of punishment. Biology and Philosophy, 27(6): 833-850. ...etc.　　・その他に関しては：http://www.hisashinakao.comを．



Introduction

3

+ 中尾・三中（編）『文化系統学への招待』勁草書房．

- 文化系統学：文化進化研究の一端　→文化進化研究とは何ぞや？　→考古学の事例を使って文化進化研究の　　構造を紹介．　→文化の歴史研究と生物の歴史研究は　　意外に親和的で似た部分があり，　　両者は対象が異なるだけで，　　同じ“歴史科学”の一部である．

- 時間GIS研究会ですので，文化進化研究に　おける時間についても最後に少し．

Introduction

4

+ 進化研究の大枠：パターンとプロセス - パターン：歴史的・地理的パターン　→系統学の対象は歴史的パターン（先祖-子孫関係）　→文化系統学：文化の様々な対象に系統学的手法を適用 - プロセス：自然選択，遺伝的浮動，etc.　→進化生態学などで用いられる最適化モデルに基づいた　　道具の進化に関する考察

Outline

5

1. Inferring evolutionary patterns: Cultural phylogenetics

2. Inferring evolutionary processes (1): Optimality models in archaeology

3. Inferring evolutionary processes (2): Cognitive mechanisms behind the evolution of tools and technologies

6

+ Very rough scheme of phylogenetics:

Inferring evolutionary patterns

7

+ O’Brien et al. 2001.

- 11500～10000年前の南東アメリカで出土した矢じり - 左図：別の場所での炭素年代測定や層序学的分析からの外挿による推定（1）系統関係が分からない（2）SuwanneeなどはClovisより古い？


8

+ 系統推定...の前に分類

・一般的に用いられる8つの　特徴を選ぶ・この基準で621の標本を分類　→491のクラスに分けられる・4つ以上の標本を持つクラス　を選んで系統推定・結果的に17のクラスに関して　系統推定．

CharacterCharacter state


I. Location of maximum blade width 1. Proximal quarter 2. Secondmost proximal quarter 3. Secondmost distal quarter 4. Distal quarter

II. Base shape 1. Arc-shaped 2. Normal curve 3. Triangular 4. Folsomoid

III. Basal indentation ratio 1. No basal indentation 2. 0.90-0.99 (shallow) 3. 0.80-0.89 (deep)

IV. Constriction ratio 1. 1.00 2. 0.90-0.99 3. 0.80-0.89 4. 0.70-0.79 5. 0.60-0.69 6. 0.50-0.59

V. Outer tang angle 1. 93°-115° 2. 88°-92° 3. 81°-87° 4. 66°-88° 5. 51°-65° 6. <50°

VI. Tang-tip shape 1. Pointed 2. Round 3. Blunt

VII. Fluting 1. Absent 2. Present

VIII. Length/width ratio 1. 1.00-1.99 2. 2.00-2.99 3. 3.00-3.99 4. 4.00-4.99 5. 5.00-5.99 6. 6.00


9

E

E’

A A’

D

D’

B B’

F

C

C’

B B’

G

E

E’

C

C’

A A’

D

D’

F

G

H

Landmark Characters

A-A’ = maximum blade width

B-B’ = minimum blade width

C-C’ = height of maximum blade width

D-D’ = medial length

E-E’ = maximum length

F = outer tang angle

G = tang tip

H = flute

Base shapes

Arc-shaped

Normal curve

Triangular

Folsomoid



I. Location of maximum blade width 1. Proximal quarter 2. Secondmost proximal quarter 3. Secondmost distal quarter 4. Distal quarter

II. Base shape 1. Arc-shaped 2. Normal curve 3. Triangular 4. Folsomoid

III. Basal indentation ratio 1. No basal indentation 2. 0.90-0.99 (shallow) 3. 0.80-0.89 (deep)

IV. Constriction ratio 1. 1.00 2. 0.90-0.99 3. 0.80-0.89 4. 0.70-0.79 5. 0.60-0.69 6. 0.50-0.59

V. Outer tang angle 1. 93°-115° 2. 88°-92° 3. 81°-87° 4. 66°-88° 5. 51°-65° 6. <50°

VI. Tang-tip shape 1. Pointed 2. Round 3. Blunt

VII. Fluting 1. Absent 2. Present

VIII. Length/width ratio 1. 1.00-1.99 2. 2.00-2.99 3. 3.00-3.99 4. 4.00-4.99 5. 5.00-5.99 6. 6.00

+ 系統推定...の前に分類


10

・系統推定は外群（outgroup）との　比較から系統樹を推定　→外群：祖先形態を持つ対象・今回はKDRが外群　1. 祖先型と考えられるClovisを　　含んでいる　2. KDRを祖先と考えてseriationを　　行うと，Clovisなどより新しいと　　考えられるBQDが対極に来る

+ 系統推定...の前に外群の決定


11

+ ようやく系統推定

・PAUP*を使用．・最節約法による系統推定　→その結果が右図．


12

+ 他の例（Cochrane 2009a，2009b）


・フィジーで出土した2700～550年前の陶器に関する系統推定

13

+ 他の例（Cochrane 2009a，2009b）


・PAUP*による最節約系統樹．

14

+ Different results by different methodologies:

・NJ（近隣結合法）を用いると... ・MPと結果を比べてみると...


15


・Networkを書いてみると... ・MPと結果を比べてみると...


16


canoe design, they also borrowed, traded andexchanged both canoes (Rolett 2002) and canoebuilders (D’Arcy 2006). For example, the druacanoes built in the Lau Group of Fiji were con-structed by the Lemaki. The Lemaki were aTongan and Samoan clan of specialist canoe buildersrenowned for their extremely watertight method ofjoining wooden planks without numerous holes andlashings (D’Arcy 2006). While Polynesians readilyborrowed functional aspects of canoe design, thesymbolic aspects of canoe design might be more clo-sely tied to cultural identity and history. The prowsof Maori waka were typically carved in a regionalstyle (Hiroa 1949). This would explain why the sym-bolic traits fit the languages trees slightly better thanthe functional traits.

The canoe data reveal that, at least when itcomes to highly functional aspects of material cul-ture, the fabric of cultural evolution is ratherdifferent from the evolution of genes in vertebratespecies. Different aspects of culture can have quitedifferent evolutionary histories. One challenge forfuture research is to characterize the processes thatpromote the tight coupling of cultural lineages andthose that lead the different threads to followseparate paths.

5. CONCLUSIONIn this paper we have argued that we need to movebeyond dichotomous disputes about the validity of cul-tural phylogenetics. Instead, we have suggested thatthe debate is better conceptualized as involving pos-itions along continuous dimensions. The challengefor empirical research is to determine how tree-likeand how tightly coupled the evolution of particularaspects of culture are. Both critics and proponents ofcultural phylogenetics need to become ‘evidence-based’ in their claims about cultural evolution. Usingnew network methods derived from evolutionarybiology, we have outlined how such investigationscan reveal some surprising results—the far-flung Poly-nesian islands in the Pacific are a hotbed of horizontallexical and cultural evolution. Properly characterizingthe shape and fabric of human cultural history willno doubt require further methodological innovations.For example, it would be very useful to be able totest for significant differences in the degree of tree-like-ness. However, the most fundamental requirement forfurther progress is the collection of more high-qualitycomparative cultural data. The days when all a studyof cultural evolution required was a quick trawlthrough the Ethnographic Atlas (Murdock 1967) arerapidly drawing to an end. It is time for anthropolo-gists to roll their sleeves up and get serious aboutgathering comparative data again. We can only echothe sentiments expressed by Shennan (2008,

site-specific likelihood

freq

uenc

yfr

eque

ncy

freq

uenc

yfr

eque

ncy

0 –2 –4 –6 –8 –100

100

200

0

4

8

0

20

40

400

800

0

(a)

(b)

(c)

(d )

Figure 9. Histograms showing the distribution of likelihoodscores for (a) basic vocabulary, (b) functional aspects ofcanoe design, (c) symbolic aspects of canoe design and (d)randomization of the canoe data on the language tree. Like-lihood scores close to zero indicate a good fit. The basicvocabulary data fit the tree the best (mean ! 22.89,median ! 22.89, s.d. ! 2.31). Both the functional and sym-bolic aspects of canoe design are close to the randomdistribution (functional: mean ! 26.64, median ! 27.36,s.d. ! 1.28; symbolic: mean ! 26.13, median ! 26.34,s.d. ! 1.37; random: mean ! 26.30, median ! 26.92,s.d. ! 1.45).

Marquesan

Hawaiian

Societies

ManihikiTuamotuan

Fijian

Tongan

SamoanCooks Australs

New Zealand

Hawaiian

Societies

Cooks

Australs

Marquesan

ManihikiSamoan

TonganFijian

Tuamotuan

New Zealand

(a)

(b)

Figure 10. Split graphs showing the results of NeighborNetanalyses of the (a) functional and (b) the symbolic aspectsof canoe design. For functional traits, the average deltascore was 0.46 and the average Q-residual ! 0.03. For sym-bolic traits, the average delta score was 0.37 and the averageQ-residual ! 0.05. Scale bar, 0.01.

The shape and fabric of human history R. D. Gray et al. 3931

Phil. Trans. R. Soc. B (2010)

on August 18, 2012rstb.royalsocietypublishing.orgDownloaded from

canoe design, they also borrowed, traded andexchanged both canoes (Rolett 2002) and canoebuilders (D’Arcy 2006). For example, the druacanoes built in the Lau Group of Fiji were con-structed by the Lemaki. The Lemaki were aTongan and Samoan clan of specialist canoe buildersrenowned for their extremely watertight method ofjoining wooden planks without numerous holes andlashings (D’Arcy 2006). While Polynesians readilyborrowed functional aspects of canoe design, thesymbolic aspects of canoe design might be more clo-sely tied to cultural identity and history. The prowsof Maori waka were typically carved in a regionalstyle (Hiroa 1949). This would explain why the sym-bolic traits fit the languages trees slightly better thanthe functional traits.

The canoe data reveal that, at least when itcomes to highly functional aspects of material cul-ture, the fabric of cultural evolution is ratherdifferent from the evolution of genes in vertebratespecies. Different aspects of culture can have quitedifferent evolutionary histories. One challenge forfuture research is to characterize the processes thatpromote the tight coupling of cultural lineages andthose that lead the different threads to followseparate paths.

5. CONCLUSIONIn this paper we have argued that we need to movebeyond dichotomous disputes about the validity of cul-tural phylogenetics. Instead, we have suggested thatthe debate is better conceptualized as involving pos-itions along continuous dimensions. The challengefor empirical research is to determine how tree-likeand how tightly coupled the evolution of particularaspects of culture are. Both critics and proponents ofcultural phylogenetics need to become ‘evidence-based’ in their claims about cultural evolution. Usingnew network methods derived from evolutionarybiology, we have outlined how such investigationscan reveal some surprising results—the far-flung Poly-nesian islands in the Pacific are a hotbed of horizontallexical and cultural evolution. Properly characterizingthe shape and fabric of human cultural history willno doubt require further methodological innovations.For example, it would be very useful to be able totest for significant differences in the degree of tree-like-ness. However, the most fundamental requirement forfurther progress is the collection of more high-qualitycomparative cultural data. The days when all a studyof cultural evolution required was a quick trawlthrough the Ethnographic Atlas (Murdock 1967) arerapidly drawing to an end. It is time for anthropolo-gists to roll their sleeves up and get serious aboutgathering comparative data again. We can only echothe sentiments expressed by Shennan (2008,

site-specific likelihood

freq

uenc

yfr

eque

ncy

freq

uenc

yfr

eque

ncy

0 –2 –4 –6 –8 –100

100

200

0

4

8

0

20

40

400

800

0

(a)

(b)

(c)

(d )

Figure 9. Histograms showing the distribution of likelihoodscores for (a) basic vocabulary, (b) functional aspects ofcanoe design, (c) symbolic aspects of canoe design and (d)randomization of the canoe data on the language tree. Like-lihood scores close to zero indicate a good fit. The basicvocabulary data fit the tree the best (mean ! 22.89,median ! 22.89, s.d. ! 2.31). Both the functional and sym-bolic aspects of canoe design are close to the randomdistribution (functional: mean ! 26.64, median ! 27.36,s.d. ! 1.28; symbolic: mean ! 26.13, median ! 26.34,s.d. ! 1.37; random: mean ! 26.30, median ! 26.92,s.d. ! 1.45).

Marquesan

Hawaiian

Societies

ManihikiTuamotuan

Fijian

Tongan

SamoanCooks Australs

New Zealand

Hawaiian

Societies

Cooks

Australs

Marquesan

ManihikiSamoan

TonganFijian

Tuamotuan

New Zealand

(a)

(b)

Figure 10. Split graphs showing the results of NeighborNetanalyses of the (a) functional and (b) the symbolic aspectsof canoe design. For functional traits, the average deltascore was 0.46 and the average Q-residual ! 0.03. For sym-bolic traits, the average delta score was 0.37 and the averageQ-residual ! 0.05. Scale bar, 0.01.

The shape and fabric of human history R. D. Gray et al. 3931

Phil. Trans. R. Soc. B (2010)

on August 18, 2012rstb.royalsocietypublishing.orgDownloaded from

- Networks for functional and symbolic aspects of canoe (Gray et al. 2010)


17

+ まとめておくと：・系統学の手法は生物限定ではなく，文化にも上手く使えるもの・ただし，アルゴリズムによって結果が違ったりもするので，　今後どのアルゴリズムが使用されるべきなのか，などといった　点について議論が必要．・言語系統樹の場合，言語変化に関するモデルに基づいた　最尤法／ベイズ法などの使用が主流になりつつある（私信）．　→考古学で最尤法／ベイズ法に使えるようなモデルが想定できる　　だろうか？ etc.


Outline

18




19

+ Optimality models and archaeology (Bright et al. 2002)

- The historical changes in diets, tools, and technologies were adaptive

R =E

T + S

R: return rate (kcal/hr)E: average energy (kcal)T: average handling time (hr)S: average search time (hr)

ET + S

1

1 1

ET + S

2

2 2

>E1, T1, S1: for plants seedsE2, T2, S2: for large games If plants seeds are much more available, R1 will be larger than R2.

+ Investment in tools and technology included: T would decline while extra time for tools would be needed.

Inferring evolutionary processes (1)

20


21


22


23


24

+ Bifaces are more technologically demanding than core-flake tools and more useful for larger games.


25

+ Prediction from the optimality model:

The reduced emphasis on large and medium game after AD 1300 should be accompanied by a shift from higher-cost bifacial tools in favor of more expedient core/flake technology (176).

+ Results:

Bifaces core/flake tech

AD 700-1300 96.8% 3.2%

After AD 1300 85.1% 14.9%

→The prediction was successfully confirmed.


Outline

26





27

+ Bettinger and Eerkens 1999:

・研究の背景はちょっと複雑なので省略・中央ネバダ・東カリフォルニアで　出土した矢じり（3150BP～650BP）を　比較→basal widthとweightの相関に差異

28

+ Bettinger and Eerkens 1999:

・中央ネバダ：幅と重さに強い正の相関・東カリフォリニア：相関がほぼない　→中央ネバダでは何らかのモデルを模倣したからこそこうした　　相関が見られ，他方東カリフォリニアは各自が試行錯誤で　　作成したせいで，相関がみられなくなったのではないか


29

+ Bril et al. 2012:


30

+ Bril et al. 2012:

・nut割りだとチンパンジーと6歳くらいの子は同じような感じで　石を叩き付ける．


31

+ Bril et al. 2012:・しかし剥片作成の際，専門家・練習　した素人・完全な素人では加える力　が明らかに違ってくる　→nut割りと剥片作成では必要と　される技術の程度が異なる・もしかするとこうした複雑な技術は　社会的（i.e., 観察）／試行錯誤学習　だけでは不十分なのかもしれない？・composite tools作成に必要な接着剤の　作成など（Wadley 2010; Sterelny 2012）


32

+ The natural pedagogy (NP) hypothesis by Csibra & Gergely:

“[W]e hypothesize that the "birth of [natural] pedagogy" was necessitated by extensive tool use by early hominid groups...In fact, proliferation of tool use, and the emergence of rich artefact culture, would have probably been impossible without an efficient social learning mechanism [i.e., natural pedagogy] that enabled transmission of not just observable behaviours but also unobservable knowledge” (Csibra & Gergely 2006, 253).

+ NP is a set of human unique and innate cognitive adaptations “to transfer knowledge to, and receive knowledge from, conspecifics through teaching” (Csibra & Gergely 2006, 252).


33

[Natural pedagogy] makes it possible to efficiently convey knowledge with opaque content to others in a single act of demonstration not only because the recipient is prepared to recognize such actions as communicative demonstrations, but also because the addressee has the default expectation that the content of the demonstration represents shared cultural knowledge and is generalizable along some relevant dimension to other objects, other occasions or other individuals (Csibra & Gergely, 2011, 1150, emphasis added).


(1) NP includes a set of human unique and innate cognitive traits, (2) enables novice learners to gain generalizable or shared and relevant knowledge more efficiently,(3) especially in opaque contexts, across different domains from a single demonstration that is marked with OSs.

34

+ NP is effective especially in an opaque context (Gergely et al. 2002). - Children do not imitate in a transparent context even with OSs

Here we show that if an adult demon-strates a new way to execute a task to agroup of infants aged 14 months, the

children will use this action to achieve thesame goal only if they consider it to be the most rational alternative. Our resultsindicate that imitation of goal-directedaction by preverbal infants is a selective,interpretative process, rather than a simplere-enactment of the means used by ademonstrator, as was previously thought1–3.

In Meltzoff ’s seminal study1, a group of14-month-old subjects watched a demon-strator illuminate a light-box by leaning forwards and touching its top with her fore-head1,2. One week later, two-thirds of themre-enacted this head action to achieve thesame outcome, although none of the controlgroup used it spontaneously. This was takenas evidence that infants separate the goalfrom the means, automatically imitating themeans as demonstrated2. Such imitativelearning is thought to be specific to humans,as primates do not imitate new strategies toachieve goals, relying instead on motoractions already in their repertoire (emula-tion)3. If this were also the case in infants,they would be expected to touch the boxwith their hands, rather than imitating theunfamiliar head action. (Meltzoff, however,did not report such hand actions1,2.)

The readiness of infants to re-enact thehead action is surprising, given that 1-year-old babies can evaluate the rationality of themeans in relation to the goal and the con-straints of the situation4,5. When constraintschange, these infants are able to work out themost effective action that the demonstratorshould use to achieve the goal (the principleof rational action6,7). Infants would thereforebe expected to re-enact an action only if itseemed to them to be the most effectivemeans to achieve the goal (see also ref. 8).

So why did Meltzoff ’s subjects re-enactthe head action, when they could just havetouched the box with their hands? If infantsnoticed that the demonstrator declined touse her hands despite the fact that they werefree, they may have inferred that the headaction must offer some advantage in turningon the light. They therefore used the sameaction themselves in the same situation.

To test this idea, we replicated Meltzoff ’sstudy1 with one modification: in one condi-tion, the subjects could see that the demon-strator’s hands were occupied while sheexecuted the head action (pretending to becold, she had wrapped a blanket around herself which she held onto with both hands;‘hands occupied’, Fig. 1a). After witnessingthe same head action when the adult’s hands

were free (Fig. 1b), 69% of infants re-enactedthe head action, replicating Meltzoff ’sresults1. However, after watching the adultturn on the light with her head when herhands were occupied, the number of chil-dren who imitated the head action droppedsignificantly to only 21% (P!0.02; Fig. 1c).It must therefore have seemed sensible to theinfants that the demonstrator should use thehead action when her hands were occupied— nevertheless, 79% of them chose not toimitate her because their own hands werefree, presumably concluding that the headaction was not the most rational.

Whether they re-enacted the head actionor not, all infants who watched the adultperform under both conditions still used thehand action. This suggests that 14-month-old infants are still subject to an automatic,emulation-like process whereby the memoryof the effect (illumination by touch) acti-vates the response that is most strongly associated with establishing contact (handaction). But the re-enactment of the headaction, when inferred to be rational by the

infant, indicates that imitation by 14-month-olds goes beyond emulation. Weconclude that the early imitation of goal-directed actions is a selective, inferentialprocess that involves evaluation of the rationality of the means in relation to theconstraints of the situation. György Gergely*, Harold Bekkering†‡,Ildikó Király**Institute for Psychology, Hungarian Academy ofSciences, 1132 Budapest, Hungarye-mail: [email protected]†Max Planck Institute for Psychological Research,Amalienstrasse 33, 80799 Munich, Germany‡Present address: Department of Experimental andWork Psychology, University of Groningen, 9712 TS Groningen, The Netherlands

1. Meltzoff, A. N. Dev. Psychol. 24, 470–476 (1988).2. Meltzoff, A. N. J. Exp. Child Psychol. 59, 497–515 (1995).3. Tomasello, M. The Cultural Origins of Human Cognition

(Harvard Univ. Press, Cambridge, Massachusetts, 1999).4. Gergely, G. et al. Cognition 56, 165–193 (1995).5. Csibra, G. et al. Cognition 72, 237–267 (1999).6. Gergely, G. & Csibra, G. Cognition 63, 227–233 (1997).7. Csibra, G. & Gergely, G. Dev. Sci. 1, 255–259 (1998).8. Bekkering, H., Wohlschlager, A. & Gattis, M.

Q. J. Exp. Psychol. Human Exp. Psych. 53A, 153–164 (2000).

brief communications

NATURE | VOL 415 | 14 FEBRUARY 2002 | www.nature.com 755

Rational imitation in preverbal infantsB a b ie s m ay o pt for a sim p ler w ay to turn o n a lig ht a ft er w atc h in g a n a d u lt d o it.

Figure 1 Comparison of the methods used by 14-month-old infants to switch on a light-box 1 week after watching how an adult executedthe same task under two different conditions. a, b, Adult switching on the light by touching the lamp with her forehead in the hands-occupiedcondition (a, n"14) or the hands-free condition (b, n"13). c, Methods used by infants to switch on the light-box after watching the headaction used by the demonstrator under these two conditions (left bar, adult had hands occupied; right bar, adult had hands free), recordedover a 20-s period. Blue, head action was re-enacted; green, only manual touch was used. Further details are available from the authors.

0 %

20 %

40 %

60 %

80 %

100 %

H andsoccupied

H andsfree

a b c

Evolutionary biology

Performance constraintsin decathletes

Physical performance by vertebrates isthought to be constrained by trade-offs between antagonistic pairs of

ecologically relevant traits and betweenconflicting specialist and generalist pheno-types1,2, but there is surprisingly little evidence to support this reasoning3–5. Herewe analyse the performance of world-classathletes in standardized decathlon eventsand find that it is subject to both types oftrade-off, after correction has been made

for differences between athletes in generalability across all 10 events. These trade-offsmay have imposed important constraintson the evolution of physical performance inhumans and other vertebrates.

Decathletes compete in 10 differenttrack and field events over two consecutivedays. We constructed a data set of the performance of 600 world-class decathletesacross all events from sources available onthe Internet (see Fig. 1 legend). Individualperformance for any pair of disciplines waspositively correlated for the entire data set.This was unexpected, as physiological andbiomechanical theory predicts that thereshould be trade-offs between certain pairs

© 2002 Macmillan Magazines Ltd

a: hands occupied, transparent b: hands free, opaque blue: head action imitated green: hand touch imitated


+ OSs allow children to get generalizable object valence?

35

- Gergely et al. 2007

- Two experimenters: A & B - Subjects: 14-months-old children - A: ostensive positive expressions to O1 but negative expressions to O2. - B: ostensive negative expressions to O1 but positive expressions to O2.

- Asymmetric trials: One of the two experimenters appears three times more often than the other (e.g., A appears 15 times and B 5 times)

O1 O2

B A

positive

negative

15 times5 times


Human pedagogy 143

© 2007 The Authors. Journal compilation © 2007 Blackwell Publishing Ltd.

and one

‘attitude-inconsistent’ object-choice

(relative totheir object-specific emotional attitude manifestedduring familiarization). The order of test events wascounterbalanced across subjects.

Procedure

Infants sat on their parent’s lap, 80 cm from a 21

!

mon-itor. They were presented with the familiarization eventsin one block followed by the four test events. Their visualbehaviour was recorded by a video-camera hidden abovethe monitor. An experimenter watched their lookingbehaviour on a monitor in an adjacent room and regis-tered through a computer program the length of theirvisual fixations to each test event by pressing a key on akeyboard. Each test event lasted until the infant lookedaway for more than 2 seconds. A sound cue oriented theinfant’s attention back to the display before the nextevent started.

Results

We used the looking times during test trials as the soledependent measure. A second experimenter re-codedoff-line 25% of the video-records measuring subjects’looking times for the test events. The two coders’measurements showed significantly high correlation(Pearson:

r

= .99), indicating the reliability of the look-ing time data.

Figure 1 depicts the mean looking times to the differ-ent types of object-choices during test events for the

Symmetric vs. Asymmetric conditions. To analyze thelooking times, first we performed a repeated measuresmixed ANOVA with Object (A vs. B) and Attitude-Consistency (Consistent vs. Inconsistent object-choice)as within-subject factors, and Condition (Symmetric vs.Asymmetric) as the between-subjects factor. This analysisyielded a significant main effect of Condition (

F

(1, 62) =7.243,

p

< .01), which reflects the longer overall lookingtimes for the test trials in the Asymmetric condition(Figure 1). We found a tendential main effect of Object(

F

(1, 62) = 3.514,

p

< .07) and a nearly significant Object

"

Condition interaction (

F

(1, 62) = 3.685,

p

= .06). Theanalysis also yielded a significant Attitude-Consistency

"

Condition interaction (

F

(1, 62) = 4.30,

p

< .05). Notethat no main effect of Attitude-Consistency (

p

= .555)was present.

To resolve the interactions, we ran separate repeatedmeasures ANOVAs for the two conditions. In the Sym-metric condition neither the effect of Object (

p

= .971)nor that of Attitude-Consistency (

p

= .315) approachedsignificance and there was no Object

"

Attitude-Consistencyinteraction (

p

= .935) either. In contrast, a similar ANOVAfor the Asymmetric condition yielded a significant maineffect of Object (

F

(1, 31) = 5.903,

p

= .021). The maineffect of Consistency did not reach significance (

F

(1, 31)= 3.751,

p

< .07), and the direction of difference wasactually opposite (longer looking at the consistent events,Figure 1) to what the mindreading account would havepredicted. We found no interaction between Object andAttitude-Consistency (

p

= .521). A non-parametric Signtest also confirmed the Object valence effect for theAsymmetric condition yielding a close to significant result(

z

=

#

1.945,

p

= .052).Finally, we checked for any effect of (a) Person

(Demonstrator 1 vs. 2) or (b) Order of test trials separ-ately for the two conditions. While there was no Personeffect in either the Symmetric (

p

= .935) or Asymmetric(

p

= .521) condition, the Symmetric condition yielded asignificant Order effect (

F

(3, 93) = 10.432,

p

< .001),showing a continuous decrease in looking times fromthe first to the last test event (1st: 17.89 sec; 2nd: 12.14sec; 3rd: 11.80 sec; 4th: 10.33 sec). No Order effect waspresent in the Asymmetric condition (

F

(3, 93) = 1.978,

p

= .123).

Discussion

First, as Figure 1 shows, the main prediction of themindreading account that attitude-inconsistent object-choices, which violate infants’ person-specific attitude-based expectations, should result in longer looking timesin both conditions is clearly not supported by the results.

Figure 1 Mean looking times to ‘attitude-consistent’ vs. ‘attitude-inconsistent’ object-choices and to choosing Object A vs. B in the Symmetric and Asymmetric familiarization conditions.

36

- The children were not surprised when watching B choosing O1

though she had appeared to like O2.- Rather, they were surprised when watching B choosing O2.

- This should be due to the fact that the children understand shared valence of objects (not subjective preferences of the A & B).

+ OSs allows children to get generalizable object valence?


37

Conclusion

・考古学と生物学，心理学などが連携しながら文化進化研究が　色々進められつつある．・進化生物学の研究枠組み・観点・手法が文化の歴史的変遷を考察　していくにあたって結構有用である・導入でも述べたように，文化／生物と対象は異なるが，両者は　同じ“歴史科学”の分岐した枝．　→とかいう話を先日地球惑星物理学者と古生物学者と西洋史家を　　集めた研究会でも少ししていました．

+ まとめておくと：

38

Conclusion

・生物進化と文化進化のスピードが違う，という指摘・道具・技術進化などで設定される時間枠は長くて数千年　生物進化などでは数万とか数十万とか．下手すれば数億とか．　→でも，だからどうした　→スピードが違っても十分方法論は使える　　＋認知の進化などは生物形質の進化（当たり前だが）・以上ふまえると，もちろん文化／生物進化の時間スピードは　異なるのだが，それが両者を分け隔てる要素にはなりえない

+ 最後は「時間」について：

文化進化のパターンとプロセス

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