Monday, 4 December 2017

Ecology section: Gaia hypothesis

“Gaia is a tough bitch”: Remembering Lynn Margulis, scientific pioneer

Biologist Lynn Margulis died on November 22nd, 2011

Lynn Margulis essay here on the significance of symbiosis in evolution:
Gaia is a tough bitch — a system that has worked for over three billion years without people. This planet's surface and its atmosphere and environment will continue to evolve long after people and prejudice are gone. (LINK

Ridiculed when she first proposed it; biologist Lynn Margulis‘ theory of symbiosis in cell evolution is now considered one of the great scientific breakthroughs. A co-developer of the ‘Gaia hypothesis’ and a sharp critic of the Richard Dawkins-led school of Neo-Darwinist biology, Margulis was also a remarkable personality, as this interview with clearly demonstrates.


Gaia Hypothesis:

The Gaia hypothesis, also known as Gaia theory or Gaia principle, proposes that all organisms and their inorganic surroundings on Earth are closely integrated to form a single and self-regulating complex system, maintaining the conditions for life on the planet.

What is the Gaia hypothesis?
MAY 17, 2017


Propounded by British scientist James Lovelock (who is now 97) in the 1970s, the Gaia hypothesis conceives of the earth as a self-regulating system, much like a single organism. The earth’s living organisms and its physical components (air, water, soil), according to this hypothesis, form a complex system that interacts with each other in such as way as to maintain the conditions essential for the sustenance of life on the planet. This equilibrium, Lovelock argues, is being skewed by heightened human intervention that threatens not just the planet’s biodiversity but the future sustenance of human beings themselves.

Natural selection and evolution :

Lovelock accepts a process of systemic Darwinian evolution for such biological feedback mechanisms: creatures that improve their environment for their survival do better than those that damage their environment. However, some scientists dispute the existence of such mechanisms. In 1981, W. Ford Doolittle, in the CoEvolution Quarterly article "Is Nature Motherly" argued that nothing in the genome of individual organisms could provide the feedback mechanisms Gaia theory proposed, and therefore the Gaia hypothesis was an unscientific theory of a maternal type without any explanatory mechanism. In Richard Dawkins' 1982 book, The Extended Phenotype, he argued that organisms could not act in concert as this would require foresight and planning from them. Like Doolittle he rejected the possibility that feedback loops could stabilize the system. Lynn Margulis, a microbiologist who collaborated with Lovelock in supporting the Gaia hypothesis, argued in 1999, that “Darwin's grand vision was not wrong, only incomplete. In accentuating the direct competition between individuals for resources as the primary selection mechanism, Darwin (and especially his followers) created the impression that the environment was simply a static arena.” She wrote that the composition of the Earth's atmosphere, hydrosphere, and lithosphere are regulated around "set points" as in homeostasis, but those set points change with time.She also wrote that there is no special tendency of biospheres to preserve their current inhabitants, and certainly not to make them comfortable. According to her, the Earth is a kind of community of trust that can exist at many discrete levels of integration. All multicellular organisms do not live or die all at once: not all cells in the body die instantaneously, nor are homeostatic "set points" constant through the life of an organism. W. D. Hamilton, one of the greatest evolutionary theorists of the 20th century, called the concept of Gaia Copernican, adding that it would take another Newton to explain how Gaian self-regulation takes place through Darwinian natural selection.



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