动物寿命与人类影响

Animal Lifespan and Human Influence

地球上各种生物有机体的寿命是有本质差异的 ,即使一些大小、形态和生理上大体相似的生物之间也存在着这种差异。早期的研究多集中在探讨基因、热量限制、药物与动物特别是人类寿命的相关性上 ,而环境因素以及日益加剧的人类活动对动物寿命的影响则很少被涉及。目前 ,越来越多的证据显示 ,人类以信人类活动对动物的寿命有着直接或间接的影响。正面的影响可以从近年来诸如自然保护区的建立等保护措施的实施活动中得到体现。然而 ,由于日益加剧的人类活动造成的自然生境的日益萎缩和片段化所带来的负面影响也是非常明显的 ,人们不应只关注人类活动如何导致物种的绝灭 ,也应研究人类如何改变动物的生存环境、寿命以及动物固有的生命轨迹。介绍了有关动物寿命研究的最新进展 ,呼吁更多的学者投身到环境因素对动物寿命的影响这一迅速升温的诱人的研究领域中来。植物方面的类似研究也应该尽早启动。

Lifespan differs radically among organisms ever lived on earth,even among those roughly similar in size,shape,form,and physiology.These differences have attracted intensive invrestigations.However,most early studies have been focusing on the links between genes,caloric restriction,medicine,and animal lifespan,especially human lifespan.Few studies have examined the role of environmental factors and increasing human activities on animal lifespan.Yet,emerging evidence shows strong direct and indirect effects of humans and human activities on animal lifespan.For example,a rescent article in the New Scientist showed that the lifespans of humans and human\|related and domestic animals are significantly longer than other animals.Positive effects can be seen through recent efforts in conservation(e.g.,establishments of natural reserves),and strong negative effects are also evident as natural habitats continue to shrink and become fragmented due to increasing human activities.Not only should we address how human activity causes species extinction,we should also investigate how humans have altered animal living conditions and modified animal life history traits such as lifespan.This article introduces recent progress in studies of animal lifespan and calls for greater efforts to investigate the environmental effects in this fast growing and fascinating research area.\;More specifically,it would be interesting to investigate whether the repeatedly reported regression lines between lifespan and body mass are ‘natural'(without the impacts of human dominance).The lifespan of humans likely increased because of improved social\|economic and medical conditions and life\|style changes.Certainly it is also true that noticed longer lifespans of domesticated animals(e.g.,dogs,cats,and horses)are partly because they are better studied,and also because they receive medical intervention and live in protected environments.Yet,such human\|induced changes may have depressed the `normal' lifespans of other animals.If these two forces are balanced,it might preserve the `real' regression but increase the variation.Otherwise,the regression line reported in the article might not be `natural' or `real'.In other words,the regression line could have been uplifted(i.e.,greater intercept)if the lifespans of other animals that are remotely related to humans are `true' or `real'.It could also be true if the regression line was corrected by the drop in lifespans of other animals due to depression or competition caused by humans and domestic animals(i.e.,the lifespans of these animals were shortened because of humans and related activities such as domestication).It would be also essential to examine(1)what caused the exceptions(i.e.,a few remote human\|related animals are also located above the regression line with great residuals)and why(e.g.,could brain size or intelligence be a covariate in addition to body size in predicting lifespan?),and (2)whether human activities have altered the `natural' regression line and how much.\;Great disparities exist when different life history traits are used.For example,it is clear that environmental variation have caused remarkable variation in the relationship between lifespan and body mass,it has not changed the intrinsic metabolic rate(r oxygen consumption rate)given any body mass.Is this mostly due to sampling or measurement error(i.e.,it is very difficult to accurately measure the lifespans of many long\|lived animals)?Lifespan can be directly and /or indirectly (e.g.,through body size)related to many other life history and biogeography factors such as diversity,abundance,and distribution.Further progress in theoretical and empirical research on allometry and physiology may help answer these interesting questions.Similar efforts should be made to the plant world as well.