McClearn G E
Center for Developmental and Health Genetics, Pennsylvania State University, University Park 16802, USA.
Exp Gerontol. 1997 Jan-Apr;32(1-2):3-10. doi: 10.1016/s0531-5565(96)00064-2.
Theories of age and aging engage a wide variety of phenomena and levels of explanation. There is a general consensus that aging is a complex process or set of processes, involving many "causal" inputs and manifold consequences. Two general theoretical orientations that explicitly address complexity are sketched here-the differential theory of quantitative genetics and systems theory. Among the suggestions derived are that it may be advantageous to consider aging to be hierarchically organized, with the corollary that subsystems of an organism can have different functional or biological ages, and that several or many indices will be required to provide an adequate characterization of a single individual. Aging probably proceeds by saltation rather than continuously. Uncertainty associated with bifurcations in complex systems, together with individual differences in timing and magnitude of step changes, may constitute fundamental limitations to the predictability across the full life trajectory. Genetic and environmental influences will differ from hierarchical subsystem to subsystem, and may differ within a subsystem across chronological age.
关于年龄与衰老的理论涉及各种各样的现象和解释层面。人们普遍认为，衰老是一个复杂的过程或一系列过程，涉及许多“因果”输入和众多后果。这里简述两种明确探讨复杂性的一般理论取向——数量遗传学的差异理论和系统理论。由此得出的一些观点包括，将衰老视为分层组织可能是有益的，其必然结果是生物体的子系统可能具有不同的功能或生物学年龄，并且需要若干或许多指标才能充分描述单个个体。衰老可能是跳跃式进行而非持续不断的。与复杂系统中的分岔相关的不确定性，以及步长变化的时间和幅度方面的个体差异，可能构成对整个生命轨迹可预测性的根本限制。遗传和环境影响在不同分层子系统之间会有所不同，并且在一个子系统内可能随时间年龄而变化。
