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1608155 
Journal Article 
The Gaia hypothesis: Fact, theory, and wishful thinking 
Kirchner, JW 
2002 
Yes 
Climatic Change
ISSN: 0165-0009
EISSN: 1573-1480 
52 
4 
391-408 
English 
WOS:000173985600003 
Organisms can greatly affect their environments, and the feedback coupling between organisms and their environments can shape the evolution of both. Beyond these generally accepted facts, the Gaia hypothesis advances three central propositions: (1) that biologically mediated feedbacks contribute to environmental homeostasis, (2) that they make the environment more suitable for life, and (3) that such feedbacks should arise by Darwinian natural selection. These three propositions do not fare well under close scrutiny. (1) Biologically mediated feedbacks are not intrinsically homeostatic. Many of the biological mechanisms that affect global climate are destabilizing, and it is likely that the net effect of biological feedbacks will be to amplify, not dampen, global warming. (2) Nor do biologically mediated feedbacks necessarily enhance the environment, although it will often aear as if this were the case, simply because natural selection will favor organisms that do well in their environments - which means doing well under the conditions that they and their co-occurring species have created. (3) Finally, Gaian feedbacks can evolve by natural selection, but so can anti-Gaian feedbacks. Daisyworld models evolve Gaian feedback because they assume that any trait that improves the environment will also give a reproductive advantage to its carriers (over other organisms that share the same environment). In the real world, by contrast, natural selection favors any trait that gives its carriers a reproductive advantage over its non-carriers, whether it improves or degrades the environment (and thereby benefits or hinders its carriers and non-carriers alike). Thus Gaian and anti-Gaian feedbacks are both likely to evolve. 
VOSTOK ICE-CORE; ATMOSPHERIC CO2; CLIMATE; EARTH; FEEDBACKS; HOMEOSTASIS; GREENHOUSE; SULFUR; CARBON; CYCLE