Jun 3, 2020 04:10 PM
https://theconversation.com/evolution-wh...ext-139706
EXCERPTS: . . . So natural selection operates from one generation to the next. It cannot plan ahead or have a goal. In addition, not all evolutionary change is a response to selection, but can be neutral or random. It is not even guaranteed to produce more species, since evolution can occur in a single lineage and this can go extinct at any time. How can we reconcile such an aimless process with the bewildering diversity and complexity we see?
Ecology and evolution are two sides of the same coin. The environment is not just the physical surroundings of an organism, but also the other biological species with which it interacts. We can see this environmental interaction deep in the history of life. For billions of years, organisms were “stuck” as single cells within the seas. Several groups independently evolved multi-cellularity (perhaps 25 times). But the first animals, plants and fungi with complex development, different tissues and organs only appeared around 540 million years ago, with the Cambrian “explosion” of diversity.
[...] Once animals had attained greater size and evolved guts, hard parts, jaws, teeth, eyes and legs, complex food webs became possible – along with “arms races” between predators and prey. Groups with adaptations that enabled them to live on land opened up even more opportunities. Once out of the bag, these innovations were difficult to “uninvent” – promoting diversity. ... as we can tell, the species count has been increasing for most of the last 250 million years. Even past natural mass extinctions were only temporary setbacks that may have created even more opportunities for diversity in the long run.
As organisms evolve more complicated systems of development, they may, however, become less able to modify certain aspects of their anatomy. This is partly because genes, tissues and organs often have several different functions, so it may become difficult to change one for the better without accidentally “breaking” something elsewhere.
[...] Clearly, there is an apparent contradiction at the heart of evolutionary biology. On one hand, the mechanisms of evolution have no predisposition for change in any particular direction. On the other hand, let those mechanisms get going, and beyond some threshold, the interwoven ecological and developmental systems they generate tend to yield more and more species with greater maximum complexity... (MORE - details)
EXCERPTS: . . . So natural selection operates from one generation to the next. It cannot plan ahead or have a goal. In addition, not all evolutionary change is a response to selection, but can be neutral or random. It is not even guaranteed to produce more species, since evolution can occur in a single lineage and this can go extinct at any time. How can we reconcile such an aimless process with the bewildering diversity and complexity we see?
Ecology and evolution are two sides of the same coin. The environment is not just the physical surroundings of an organism, but also the other biological species with which it interacts. We can see this environmental interaction deep in the history of life. For billions of years, organisms were “stuck” as single cells within the seas. Several groups independently evolved multi-cellularity (perhaps 25 times). But the first animals, plants and fungi with complex development, different tissues and organs only appeared around 540 million years ago, with the Cambrian “explosion” of diversity.
[...] Once animals had attained greater size and evolved guts, hard parts, jaws, teeth, eyes and legs, complex food webs became possible – along with “arms races” between predators and prey. Groups with adaptations that enabled them to live on land opened up even more opportunities. Once out of the bag, these innovations were difficult to “uninvent” – promoting diversity. ... as we can tell, the species count has been increasing for most of the last 250 million years. Even past natural mass extinctions were only temporary setbacks that may have created even more opportunities for diversity in the long run.
As organisms evolve more complicated systems of development, they may, however, become less able to modify certain aspects of their anatomy. This is partly because genes, tissues and organs often have several different functions, so it may become difficult to change one for the better without accidentally “breaking” something elsewhere.
[...] Clearly, there is an apparent contradiction at the heart of evolutionary biology. On one hand, the mechanisms of evolution have no predisposition for change in any particular direction. On the other hand, let those mechanisms get going, and beyond some threshold, the interwoven ecological and developmental systems they generate tend to yield more and more species with greater maximum complexity... (MORE - details)
