LB021-022T

LB21-22
IV. GENETIC FOUNDATIONS OF BEHAVIOR
We have constructed a picture of behavior consisting of a fixed matrix (that is, species-specificities delimited by characteristic anatomical and physiological processes), which an individual can never learn to transcend, coupled with varying degrees of freedom for combining existing, built-in skills and traits. If these skills and traits are, indeed, programmed into the individual as is implied here, then we ought to be able to adduce evidence for inheritance of such traits. Moreover, the history of evolution should give us some clues regarding phylogenetic emergence of behavior. Such evidence and clues do exist.
我們已建造了一幅圖像，當中行為是由一組固定的矩陣來構成的 (亦即物種的特性是由其獨特的解剖學和生理學過程來界定的)，個體從來都不能藉由學習來超越這幅圖象，即便具有多樣的自由度以結合既有的內建技能和特徵。如果這些技能和特徵的確如此處所意指的，係設計至個體當中，那麼我們應該能夠為這類特徵的遺傳來舉證。此外，演化史應能提供我們一些有關行為在種屬發生上的線索。這樣的證據是存在的。

Genetics of behavior were first summarized by Hall (1951) and more recently treated in greater detail by Fuller and Thompson (1960). Genetic influences upon various aspects of behavior have been demonstrated for many species. Several studies were made on the fruitfly. Erlenmeyer-Kimling et al. (1962) bred Drosophila melanogaster selectively to produce strains with vastly different geotactic responses (going against or toward the pull of gravity in an appropriate maze). Selective breeding experiments on rats were reported by Rundquist (1933), varying the amount of spontaneous activities in the strains developed; by Tryon (1940), producing maze-bright and maze-dull strains, and by Hall (1951), varying emotionality (as measured by frequency of urination and defecation). It is true that in these experiments it is often not clear exactly what is transmitted genetically. Searle (1949), for instance, pointed out that the behavioral difference demonstrated by Tryon may be a result of a factor of congenital timidity, the dull rats actually being upset about the experimental arrangement, whereas the bright ones are undaunted by the maze. Searle’s interpretation may very well be correct, but it does not alter the basic fact that genes do make a difference in the execution of behavior (Fuller and Thompson, 1960). In some instances, the breeds resulting from artificial selection of mates may behave differently from each other because of morphological differentiations (James, 1941). In other instances, morphological changes that are usually inevitable in breeding experiments may be irrelevant to the behavioral changes observed. In this case, physiological processes are altered, thus raising or lowering thresholds of responsiveness.
行為的遺傳學由Hall(1951)首度概述，後來Fuller和Thompson(1960)作了更詳盡的探討。遺傳對行為眾多方面的影響可見於許多物種。對於果蠅已有很多研究。Erlenmeyer-Kimling et al. (1962)對 Drosophila melanogaster育種，以產生趨地性反應有很大差異的品種(在一適當的迷宮裡飛向或飛離重力的牽引 )。Rundquist (1933)報告了對老鼠的育種實驗，自發性活動的總額在培養出的不同品種中表現出差異；Tryon (1940)的實驗培養出擅長和不擅走迷宮的品種，Hall(1951)的實驗呈現出有差別的情緒性(以排泄的頻率來衡量)。的確，在這些實驗中，何者係經由遺傳傳遞並不確切。例如，Searle (1949)指出，Tryon呈現出的行為差異可能是天生膽怯的結果，不擅走迷宮的老鼠實際是被實驗的安排嚇到了，而擅長迷宮的老鼠卻不畏懼。Searle的解讀
極有可能是正確的，但那並不改變基本的事實，也就是基因對於行為的實行的確有影響(Fuller and Thompson, 1960)。在一些個案中，人工配對產生的品種可能因為形態的區分而在行為上彼此不同(James, 1941)。在其它個案中，在育種實驗中通常免不了的形態改變，可能和觀察到的行為改變沒有關係。在這種情況下，生理學的過程改變了，因此提高或降低了起反應的閾值。

This was most directly demonstrated by Herter (1936) who showed different thermotactic optima in gray and white mice (where the color of the coat is apparently irrelevant) and by Setterfield et al. (1396), who showed that the inability to taste phenylthiocarbamide is inherited in man as a recessive Mendelian trait. Scott and Charles (1954) make a similar point, extending it generally to the interaction between the genetically given and the environmentally modified. In summarizing their work on dogs, they state: ”…different thresholds of response to minimal…stimulation tend to produce all-or-none responses, and the process of habit formation tends to cause individuals to react one way or the other, producing increasingly clear-cut differences.
此一現象最直接的展示可見於以下研究，Herter(1936)呈現了灰毛和白毛老鼠具有不同的趨溫最適條件(在此，毛色顯然不相關)，以及Setterfield et al. (1396)，他指明了無法嚐出苯基硫代尿素PTC （phenylthiocarbamide）是一項在男性中隱性遺傳的孟德爾式遺傳特徵。Scott and Charles (1954)提出相似的論點，並普遍地延伸到遺傳給定事項和環境調整事項間的互動。在摘要他們對狗的研究時，說明”…對於最小…刺激起反應的不同的閾值，傾向產出全有或全無的反應，而習慣形成的過程，傾向使得個體有這樣或那樣的反應，於是產生了愈來愈多明確的差異。

This point is very well taken. It seems unlikely that genes actually transmit behavior as we observe it in the living animal because the course that an individual takes in its peregrinations through life must necessarily depend on environmental contingencies which could not have been “programmed and prepared for” in advance. Inheritance must confine itself to propensities, to dormant potentialities that await actualization by extra-organic stimuli, but it is possible that innate facilitatory or inhibitory factors are genetically transmitted which heighten the likelihood of one course of events over another. When put into these terms, it becomes quite clear that nature-nurture cannot be a dichotomy of factors but only and interaction of factors. To think of these terms as incompatible opposites only obscures the interesting aspects of the origin of behavior.
此論點備受肯定。我們所觀察到行為在動物中的傳遞，看來似乎不可能真的是藉由基因辦到的，這是因為，一個個體在其一生中經歷的過程必定是取決於環境的或有情況，而這些情況不能事先”計畫或預備”。遺傳必然只於限於傾向、休眠的潛在性，這些都有待生物體外的刺激才能實現，但情況可能是內在的促進或抑制因子係經遺傳來傳遞，而這些因子使得某一事件路徑(course of events)的可能性高於其它。用這些說法來陳述時，天性-教養就顯得很清楚地不可能是因子間的二分法，而是因子間的互動。把這些說法當作不相容的對立項，只會讓我們看不清行為起源有趣的面向。