Natures wonders: bacteria can spear amoebas (Introduction)

by David Turell , Tuesday, August 29, 2017, 23:19 (2641 days ago) @ dhw

dhw: Do you really want me to ask you yet again how the complexities of the 8-stage whale, the monarch’s lifestyle and the weaverbird’s nest have contributed to the evolution of the human brain?

Again, to provide food sources for evolution to take time to do it.

See above. Once multicellularity had occurred, and more and more new organisms came on the scene, survivability would have been a crucial factor, though not the only factor.

We have no proof that survivability is a major issue due to population density, as you imply. Density is only an issue since WWII when we are displacing animal habitats.

dhw:Once and for all: bacteria have survived, so NO further evolution was necessary for survivability. Multicellularity happened, and then there were new ways of exploiting the environment, new threats to survival, new means of surviving those threats…etc.

See my comment re' population density. Survival of the fittest is an unproven conjecture.

DAVID: More and more complexity led to the brain, the most complex object of all.

dhw: So how does that make it logical for your God to have designed and redesigned and re-redesigned pre-whales, although his primary aim was to produce the human brain?

I will stick with a balance of nature in the oceans.

dhw: Neither you nor I know where the borderline exists between adaptation and innovation.> DAVID: Major phenotypic changes, as you describe, produces new species. that is the dividing line.

Phenotype simply means characteristics determined by genes or modified by the environment. Of course major changes produce new species. So if an organism moves from land to water, and its legs change into fins, enabling it to adapt and improve its lifestyle in the water, what is the dividing line between adaptation and innovation?

I agree that major adaptations of the kind you describe are innovations. I use 'adaptation' as minor alterations of existing species, and major 'innovations' as speciation. Just semantics.