The Descent of Man, and Selection in Relation to Sex

The main conclusion arrived at in this work, namely, that man is descended from some lowly organised form, will, I regret to think, be highly distasteful to many. But there can hardly be a doubt that we are descended from barbarians.

总结章把三卷内容压缩为清晰命题——人由低等形式演化而来——并逐一回顾证据链（同源结构、胚胎发育、残留器官、心智连续性）；单看此章即可掌握全书，故清晰度为 80。

(Part II 开篇) With animals which have their sexes separated, the males necessarily differ from the females in their organs of reproduction... When the sexes differ in structure, in colour, or in any other character, the difference has often been attributed to the direct action of the conditions of life; but I hope to show that most of these differences can be explained by sexual selection.

三段式结构（人从何来→性选择是什么→性选择如何塑造人）逻辑明确；Part II 占 2/3 体量看似失衡，实是达尔文有意将理论创新（性选择）与应用（人类）分离，以便分别接受审查，故结构为 85。

With birds the voice serves to express various emotions, such as distress, fear, anger, triumph, or mere happiness... The male alone of the tortoise utters a noise, and this only during the season of love... With birds, the power of song, or of emitting unusual sounds, stands in an intimate relation with their courtship.

性选择论证建立在数百个物种的具体观察之上——每个论断附物种名、观察者、出处；证据的密度、广度与可核查性在 19 世纪科学著作中堪称极致，故例证为 97。

(Conclusion) Man still bears in his bodily frame the indelible stamp of his lowly origin.

核心结论（人类演化的连续性、性选择作为机制）已被现代综合演化论确认；但无遗传学基础导致机制解释多处错误（泛生论、用进废退残留），且人类学部分包含明显的 19 世纪种族等级论（把"野蛮人"置于文明人与猿之间的"中间位置"），须按现代科学标准大幅扣分，故准确性为 75。

During many years I collected notes on the origin or descent of man, without any intention of publishing on the subject... The sole object of this work is to consider, firstly, whether man, like every other species, is descended from some pre-existing form; secondly, the manner of his development; and thirdly, the value of the differences between the so-called races of man.

达尔文明确以专业论辩为目标；性选择部分假定自然选择已被接受，直接引用《物种起源》而不重述论证；解剖学与分类学术语无插图辅助（Gutenberg 文本版），故可达性为 72。

(Ch.3) We have seen that the senses and intuitions, the various emotions and faculties, such as love, memory, attention, curiosity, imitation, reason, &c., of which man boasts, may be found in an incipient, or even sometimes in a well-developed condition, in the lower animals.

从形态到心智到道德到审美到语言，人类"独特性"的每个候选维度都被逐一检验；对社会性动物道德感起源的分析（同情→社会本能→良心）构成完整的演化伦理学雏形，故完整性为 90。

This depends on the advantage which certain individuals have over other individuals of the same sex and species, in exclusive relation to reproduction... Sexual selection depends on the success of certain individuals over others of the same sex, in relation to the propagation of the species; whilst natural selection depends on the success of both sexes, at all ages, in relation to the general conditions of life.

把繁殖成功从生存成功中独立出来，建立第二套选择机制——解释自然选择无法解释的"浪费性"特征（孔雀尾、鹿角、华丽羽色）；该理论被冷落半个世纪后成为行为生态学基石，超前性无可争议，故创新为 90。

We are not here concerned with hopes or fears, only with the truth as far as our reason permits us to discover it; and I have given the evidence to the best of my ability. We must, however, acknowledge, as it seems to me, that man with all his noble qualities, with sympathy which feels for the most debased, with benevolence which extends not only to other men but to the humblest living creature... with all these exalted powers—Man still bears in his bodily frame the indelible stamp of his lowly origin.

结尾段落是科学散文的名篇：先列举人类的高贵品质（同情、仁爱、神性般的理智），再以一句话落定"身体上仍带着卑微出身的不可磨灭的印记"——庄重、克制、无可回避，故文笔为 80。