最適採食戦略・語彙集

（出典は口蔵（2000）に準拠し、一部改変した）

最適採食理論：optimal foraging theory

進化生態学：behavioral ecology

進化生態学：evolutionary ecology

社会生態学：socioecology

社会生物学：sociobiology

表現型：phenotype

遺伝子型：genotype

生態人類学：ecological anthropology

環境決定論：environmental determinism

環境可能論：environmental possibilism

文化生態学：cultural ecology

生態系生態人類学：ecosystem ecological anthropology

新機能主義：neofunctionalism

プロセス生態人類学：processual ecological anthropology

意思決定：decision-making

身体努力：somatic effort

生殖努力：reproductive effort

配偶努力：mating effort

親としての努力：parental effort

採食者：forager

採食：foraging

食餌幅：diet breadth

餌選択：prey choice

パッチ選択（パッチ＝微小生息環境）：patch choice

時間配分：time allocation

時間配分モデル：time allocation model

採食活動集団サイズ：group size

居住地選択：settlement choice

兼ね合い・トレードオフ：trade-off

戦略：strategy

最適戦略：optimal strategy

最適化：optimization

進化的安定戦略：Evolutionarily Stable Strategy, ESS

戦略目標：strategic goal

利用可能な選択肢：alternative

コストベネフィットを測る通貨：currency

制約：constraint

決定：decision

効用：utilization

至近通貨：proximate currency

純エネルギー収益率：net energy return rate

仮説ー演繹法：hypothetico-deductive method

均質環境・きめ細かな環境：fine-grained environment

採食収益率：foraging return rate

探索：searching

処理：handling

処置：processing

現場処置：field processing

密度・遭遇率：encounter rate

機会費用：opportunity cost

一般化された食餌：generalized diet

管理されたパッチ：managed patch

豊かな菜食者：affluent forager

移動時間：travelling time

パッチ・タイム（パッチ滞在時間）：patch time

速度：rate

利得関数：gain function：パッチ滞在時間と獲得エネルギー量の関係

効用関数：utility funcition

単一最良パッチ：single best patch

限界値定理：marginal value theorem

パッチ間隙採食パターン：interstice foraging pattern

パッチごとの採食パターン：patch-to-patch foraging pattern

自由裁量の狩猟：discretionary game

埋め込まれた狩猟：embedded game

私利：self-interest

中心点採食：Central Place Foraging, CPF

一個の荷物運びモデル：Single-Prey Loader, SPL

複数個の荷物運びモデル：Multiple-Prey Loader, MPL

最大運搬距離：Maximum Transport Distance, MTD：獲得エネルギー量から消費可能な運搬距離

完全な情報：complete information

全知：omniscient

サンプリング・調査行動：sampling

おおざっぱなやり方・アバウトな方法：rule of thumb

決定論モデル：deterministic model

確率論モデル：stochastic model

不確実性：uncertainly

リスク：risk

リスク回避的：risk averse

リスク選好的：risk-prone

最少収益閾値：minimal return threshold, see starvation threshold

飢餓閾値：starvation threshold, see minimal return threshold

線形計画法：linear programming

無差別曲線：indifference curve

無差別曲線図：indifference map

栄養相補モデル：nutrient complementary model

投入：input

効用：output

最小問題：minimization problem

最大問題：maximization problem

食餌問題：diet problem

移動性：mobility

追跡：pursuit

日和見主義・機会主義：opportunism

財：utility

商品空間：commodity space

引用から

「最適化分析は,理論ではなくて方法であり,生物の構造と機能についての仮説を生み出す体系的な手段を提供することである。換言すれば, 「生物学における最適化理論の役割は生物が最適化することを示すのではなく,生命(活)の多様性を理解することである」(Maynard　Smith　 1978:52)。行動生態学にとって,最適化アプローチは自然淘汰理論の抽象的な原理と現実世界の多様な経験的事実との間の橋渡しとして役立つ」（口蔵 2000:773）。

文献

口蔵幸雄、2000「最適採食戦略：食物獲得の行動生態学」『国立民族学博物館研究報告』24（4）：767-872．（→機関リポジト リー「国 立民族学博物館研究報告」）《YK_NME_Jap_24-767-2000.pdf》 パスワードつき

文化人類学入門

生態人類学

文献解題

最適採食戦略─食物獲得の行動生態学─
口蔵幸雄, 767,『 国立民族学博物館研究報告』 2000　24巻4号

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本稿は行動生態学で発達した最適採食理論を人間の食物獲得活動へ適用した研究のレヴューである。最適採食理論に基づく食物獲得活動の研究では， 利用可能な戦略（行動）の中でどのような戦略が進化するかを予測する最適化分析が用いられる。ここでは最適採食モデルとして，食餌幅，パッチ選択とパッチ 内時間のモデル，およびこれら古典モデルの仮定を緩和することによって修正されたモデルとして中心点採食，資源の変動や食物分配とリスクの関係，複数の 「通貨」を取り入れた線形計画法と無差別曲線分析などがあつかわれる。現在までのところ，最適採食モデルの人間行動への適用事例ではモデルの予測と実際の 観察がうまく一致しないことが多いが，むしろそこから人間行動の特性を引き出し，モデルを改良することが重要である。

This article reviews the basic principles of optimal foraging theory and their application to human foraging. The optimization approach used in behavioral ecology assumes that individual foragers behave so as to maximize some currency (usually net rate of energy return per unit of foraging time ) which is assumed to correlate with fitness, and employs models consisting of currencies to be maximized, decisions or foraglng problems to analyzed, and constraints specifying options available to the foragers and theire effcts.
The classical diet breadth model predicts a set of food resources that maximizes energy return rate under a set of assumptions: a“ finegrained ” environment ( homogeneous resource distribution) , random encounters, mutually exclusive search and handling costs, a rank of all food resource types on the basis of net return rate on encounter,and complete information. While the model can predict qualitative subsistence patterns, such as a fluctuation of diet breadth in accordance with changes in search or handling costs derived from technological changes, many of the quantitative tests have revealed discrepancies between the model‘s predictions and observed patterns. This is mainly due to the fact that the human foraging patterns in question sometimes violate the assumptions of the model. It is common that male foragers often ignore plant foods that would increase overall energy return rates of foraging if collected. Tests made within a set of animal foods or one of plant foods show close fits between predictions and observations. For a “ patchy ” environment, where resources are distributed in a heterogeneous fashion, optimal patch use models are used to predict an array of habitats ( patches ) to be exploited and how long a forager stays in a patch before leaving for another. The optimal patch choice model has the same structure and procedure as those of the optimal diet breadth model, while replacing resource types with patch types. The optimal patch residence time is soIved by using the marginal value theorem, which assumes diminishing returns and determines the point at which a forager should leave a depleting patch to search for another one to maximize energy return rate. We can so far find no anthropological studies of patch residence time that meet the assumptions of the marginal value theorem except for one case. Most of the studies incorrectly attempt to predict the proportion of time foragers spend exploiting different patches on the assumption that optimal foragers preferentially allocate foraging time to patches with higher return rates. Relaxing and changing assumptions can modify the classic diet breadth and patch use models. The central-place-foraging model in which foraging is modeled as a trip with a given point ( a camp or village ) of departure and return is more suited to human foraging than the classic models. Foraging models focused on acquisition and sharing of information about resource conditions among foraging groups and reduction of risk ( variancein food consumption ) by food sharing, which are unique to human foragers, allow interesting predictions to be made about choice behavior and social interaction. Humans are omnivorous animals and exploit simultaneously various food resources greatly different in nutritional composition. The classic foraging models reduce nutritional values of food only to energy. Most of the critiques of the optimal foraging models have been directed toward this point. The problem of multiple nutrient requirements has been treated with a linear programming model that aims to predict the least costly solution to an economic problem in which resources ( labor, energy, raw material, and money ) must be allocated among competing activities. Another approach to evaluating food resources along more than one scale is indifference analysis, borrowed from microeconomics. This analysis predicts a utility-maximizing mix of different but complementary and substitutable food resources. Each approach has its strengths and weaknesses.

* 岐阜大学，国立民族学博物館共同研究員
Key Words: optimal foraging theory, behavioral ecology, human foragers, diet breadth, patch use, central−place foraglng, risk, food sharing, linear programming, indifference curve analysis
キーワード: 最適採食理論，行動生態学，狩猟採集民，食餌幅，パッチ利用，中心点採食，リスク，食物分配，線形計画法，無差別曲線分析

1 序
2 行動生態学の理論と最適化の分析
3 古典的モデル
　1.　最適食餌幅
　2.　最適パッチ利用
4 古典的モデルの修正
　1.　中心点採食モデル
　2.　情報の獲得
　3.　資源の変動とリスク
　4.　栄養の制約と通貨の問題
　5.　最適採食理論におけるその他の論点
5 結論と展望」