Acta Scientiarum Naturalium Universitatis Pekinensis

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Rate of Evolution and Unification of Evolution Theories

ZHANG Yun   

  1. College of Life Science, Peking University, Beijing, 100871
  • Received:1997-07-28 Online:1997-11-20 Published:1997-11-20



  1. 北京大学生命科学学院,北京,100871

Abstract: The recent debates between different evolutionary views involved mostly in rates of evolution. Contradictory conclusions have been drawn from the studies of evolution rate at different levels of organization, and led to exclusion between different doctrines of evolution. The random molecular evolution with a stable and uniform rate, interpreted by the neutral theory, is in conflict with the nonuniform adaptive evolution at phenotypic level; the adaptive and gradual evolution under natural selection at population level, advocated by the modern synthesis based on microevolution, could not coupled with the "punctuated", "explosive" or "catastrophic" macroevolution, demonstrated by fossil records. These contradictions were mostly resulted from using different variables for measurement of evolution rates. The rates of evolution measured at different levels of organization may have different senses, thus the controversies between the different doctrines may have no equivalent words. The timing of major evolutionary events in the long history of life on Earth shows apparent nonuniformity:most important evolutionary events occurred in the earliest and latest stages of the life history, and in relatively short time. The prebiotic chemical evolution, origins of life, the fundamental cell structures and metabolic pathways, and the foundations for biological evolution and biosphere formation were established in about 300-500 Ma time interval in the beginning of life history (4.0 to 3.5 Ga ago). Emergence of the advanced organisms and remarkable increase of biodiversity, as well as most major innovation of organism structures took place in the latest stage of life history (since 700 Ma). This nonuniformity of megaevolution here is interpreted as the results of coevolution between the life and the Earth's physical environments. The present dissension in evolution theory is temporary, resulted from the progresses of biology and related sciences. The different doctrines of evolution will certainly toward to unification and to a new synthesis.

Key words: evolution, rate of evolution, megaevolution, nonuniform evolution

摘要: 不同进化学说之间的争论大多与进化速率问题有关。在生物组织的不同层次上的进化速率研究得出了截然不同的结论,并导致相关的进化学说之间的互不相容。恒速的、匀速的、随机的分子进化(中性说)与非匀速的、适应的表型进化相矛盾;在自然选择作用下的渐进的适应进化(综合论)难以解释古生物记录所揭示的停滞与跳跃相间的、有时是爆发式的大进化现象。这些矛盾大多源于对进化速率的度量的不同,各层次的进化速率的含义也不同,各学说之间缺乏统一语言。生命史的重大进化事件发生的时间表显示出明显的非匀速特征:绝大多数重大进化事件发生在生命史的早期(40至35亿年前)和晚期(7亿年以近)。前生命的化学进化、生命起源、细胞生命的基本结构和代谢途径、以及生物进化和地球生物圈赖以建立的基础早在生命史开始后的几亿年内就已完成或确立了;复杂的高级生命和生物多样性的产生与重要的结构的进化革新发生在生命史末端的数亿年间。本文将宏进化的这种非匀速现象解释为地球生命与地球环境协进化的结果。当前进化理论的分裂是由生命科学及相关科学的发展所引起的,进化理论也必将随着各学科领域研究的深入而走向统一,走向新的综合。

关键词: 进化, 进化速率, 宏进化, 非匀速进化

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