The March 15 New York Times reports on the mysteries surrounding the evolution of animal life on earth. Below are a few sketchy points that the article, which you should read, makes. Notice the nice start and the abrupt ending, not sure what that is about. The excerpts:
The origin of animals is also one of the more mysterious episodes in the history of life. Changing from a single-celled organism to a trillion-cell collective demands a huge genetic overhaul. The intermediate species that might show how that transition took place have become extinct.
“We’re just missing the intervening steps,” said Nicole King, an evolutionary biologist ...Now scientists are trying to figure out how a single-celled organism like Capsaspora ... became a multicellular animal. Fortunately, they can get some hints from other cases in which microbes made the same transition. Plants and fungi evolved from single-celled ancestors,...
Primitive multicellularity may have been fairly easy to evolve. “All that has to happen is that the products of cell division stick together,” said Richard E. Michod of the University of Arizona. Once single-celled organisms shifted permanently to colonies, they could start specializing on different tasks. This division of labor made the colonies more efficient. They could grow faster than less specialized colonies....
The origin of animals depended on genes that were already in place,[in single celled ” Dr. King said.In the transition to full-blown animals, Dr. King argues, these genes were co-opted for controlling a multicellular body.
...Animals didn’t just evolve multicellular bodies, however. They also appear to have evolved new ways of generating different kinds of bodies. Animals are more prone to mutations that shuffle sections of their proteins into new arrangements, a process called domain shuffling. ...
MicroRNAs don’t seem to exist in single-celled relatives of animals. Sponges have eight microRNAs. Animals with more cell types that evolved later also evolved more microRNAs. Humans have 677, for example.
MicroRNAs and domain shuffling gave animals a powerful new source of versatility...
[A phosphorous enhanced environment, made possible by receding ice age changes created an algae powered oxygen rich] niche to be occupied,” said Dr. Ruiz-Trillo, “and it was occupied as soon as the molecular machinery was in place.
The origin of animals is also one of the more mysterious episodes in the history of life. Changing from a single-celled organism to a trillion-cell collective demands a huge genetic overhaul. The intermediate species that might show how that transition took place have become extinct.
“We’re just missing the intervening steps,” said Nicole King, an evolutionary biologist ...Now scientists are trying to figure out how a single-celled organism like Capsaspora ... became a multicellular animal. Fortunately, they can get some hints from other cases in which microbes made the same transition. Plants and fungi evolved from single-celled ancestors,...
Primitive multicellularity may have been fairly easy to evolve. “All that has to happen is that the products of cell division stick together,” said Richard E. Michod of the University of Arizona. Once single-celled organisms shifted permanently to colonies, they could start specializing on different tasks. This division of labor made the colonies more efficient. They could grow faster than less specialized colonies....
The origin of animals depended on genes that were already in place,[in single celled ” Dr. King said.In the transition to full-blown animals, Dr. King argues, these genes were co-opted for controlling a multicellular body.
...Animals didn’t just evolve multicellular bodies, however. They also appear to have evolved new ways of generating different kinds of bodies. Animals are more prone to mutations that shuffle sections of their proteins into new arrangements, a process called domain shuffling. ...
MicroRNAs don’t seem to exist in single-celled relatives of animals. Sponges have eight microRNAs. Animals with more cell types that evolved later also evolved more microRNAs. Humans have 677, for example.
MicroRNAs and domain shuffling gave animals a powerful new source of versatility...
[A phosphorous enhanced environment, made possible by receding ice age changes created an algae powered oxygen rich] niche to be occupied,” said Dr. Ruiz-Trillo, “and it was occupied as soon as the molecular machinery was in place.
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