Franklin M. Harold
- Published in print:
- 2014
- Published Online:
- May 2015
- ISBN:
- 9780226174143
- eISBN:
- 9780226174310
- Item type:
- chapter
- Publisher:
- University of Chicago Press
- DOI:
- 10.7208/chicago/9780226174310.003.0011
- Subject:
- Biology, Biochemistry / Molecular Biology
The common understanding of evolution, formalized in the Modern Synthesis, is flawed by the neglect of the microbial world, together with most of biological history and diversity. The torrent of ...
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The common understanding of evolution, formalized in the Modern Synthesis, is flawed by the neglect of the microbial world, together with most of biological history and diversity. The torrent of genomic information, and the assimilation of microbes, have forced a drastic expansion of the evolutionary framework. Genes still hold center stage, but no longer rule alone; lateral gene transfer has eroded the conventional tree of life, whose lower reaches have melded into a web; not all evolutionary change is adaptive, much is neutral; the inheritance of acquired characteristics, by lateral gene transfer and by symbiosis, plays a major role in life's history; evolution is not always gradual, but may be punctuated by abrupt leaps. Those evolvable eukaryotes are a prime example, considered in some detail. It's definitely not the world Darwin knew; and yet, so long as the history of life can be construed as the interplay of heredity, variation and natural selection, it remains Darwin's world. That premise presupposes the existence of cells, or something like them. Of evolution before cells and genes, we know almost nothing.Less
The common understanding of evolution, formalized in the Modern Synthesis, is flawed by the neglect of the microbial world, together with most of biological history and diversity. The torrent of genomic information, and the assimilation of microbes, have forced a drastic expansion of the evolutionary framework. Genes still hold center stage, but no longer rule alone; lateral gene transfer has eroded the conventional tree of life, whose lower reaches have melded into a web; not all evolutionary change is adaptive, much is neutral; the inheritance of acquired characteristics, by lateral gene transfer and by symbiosis, plays a major role in life's history; evolution is not always gradual, but may be punctuated by abrupt leaps. Those evolvable eukaryotes are a prime example, considered in some detail. It's definitely not the world Darwin knew; and yet, so long as the history of life can be construed as the interplay of heredity, variation and natural selection, it remains Darwin's world. That premise presupposes the existence of cells, or something like them. Of evolution before cells and genes, we know almost nothing.
Franklin M. Harold
- Published in print:
- 2014
- Published Online:
- May 2015
- ISBN:
- 9780226174143
- eISBN:
- 9780226174310
- Item type:
- book
- Publisher:
- University of Chicago Press
- DOI:
- 10.7208/chicago/9780226174310.001.0001
- Subject:
- Biology, Biochemistry / Molecular Biology
The discovery of how the machinery of life works, and how it is constructed, is one of the glories of 20th century science. By contrast, we know little of the origin and evolution of cells and their ...
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The discovery of how the machinery of life works, and how it is constructed, is one of the glories of 20th century science. By contrast, we know little of the origin and evolution of cells and their parts, and what we have learned is in dispute. This book surveys ongoing efforts to make cell evolution intelligible. The text revolves around a small set of fundamental questions: 1. How many kinds of cellular designs does our world hold, and how are they related? 2. Is the traditional metaphor of a tree of life still useful, or has it been superseded? 3. What are viruses, and how are they related to cells? 4 Can one construct a timeline for the origin and early history of life? 5. Do all living things share a common ancestor, and what was its nature? 6. Why are eukaryotic organisms so much more complex than prokaryotic ones, and how did they arise? 7. Has functional, adaptive organization increased over time, and if so, why? 8. Is there a way to generate functional organization that does not depend on heredity, and selection? 9. How did life emerge from the lifeless world of chemistry and physics? 10. Can a generalized theory of evolution explain the origin of life? 11. Is the history of life a succession of contingent events, or does it have direction and meaning?Less
The discovery of how the machinery of life works, and how it is constructed, is one of the glories of 20th century science. By contrast, we know little of the origin and evolution of cells and their parts, and what we have learned is in dispute. This book surveys ongoing efforts to make cell evolution intelligible. The text revolves around a small set of fundamental questions: 1. How many kinds of cellular designs does our world hold, and how are they related? 2. Is the traditional metaphor of a tree of life still useful, or has it been superseded? 3. What are viruses, and how are they related to cells? 4 Can one construct a timeline for the origin and early history of life? 5. Do all living things share a common ancestor, and what was its nature? 6. Why are eukaryotic organisms so much more complex than prokaryotic ones, and how did they arise? 7. Has functional, adaptive organization increased over time, and if so, why? 8. Is there a way to generate functional organization that does not depend on heredity, and selection? 9. How did life emerge from the lifeless world of chemistry and physics? 10. Can a generalized theory of evolution explain the origin of life? 11. Is the history of life a succession of contingent events, or does it have direction and meaning?
Andreas Schmidt-Rhaesa, Steffen Harzsch, and Günter Purschke
- Published in print:
- 2015
- Published Online:
- March 2016
- ISBN:
- 9780199682201
- eISBN:
- 9780191813436
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199682201.001.0001
- Subject:
- Biology, Animal Biology
For many biologists the nervous system is a particularly fascinating organ system. The nervous system is involved in or is even responsible for many features that are regarded as being characteristic ...
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For many biologists the nervous system is a particularly fascinating organ system. The nervous system is involved in or is even responsible for many features that are regarded as being characteristic of animals in general. Since the last comprehensive work was published about 50 years ago, the time has probably come to provide a new review on recent, newly gathered knowledge on the structure of invertebrate nervous systems, especially since new methods have come into use. These advances now enable us to demonstrate neuronal architecture down to the level of the genes and the cell types involved, allowing a new view on nervous systems and comparisons among different taxa. These new findings may help in development of new hypotheses, or support of existing hypotheses on phylogenetic relationships and evolutionary pathways in the nervous system. In spite of many open questions we already have a good knowledge of how nervous systems work, how they are constructed, and how they may have evolved. There is certain evidence that the first nervous systems are represented by rather simple sensory–motor circuits, followed by nerve nets (plexus) located within the epithelia, and finally neuronal circuits composed of sensory cells, interneurons, and brains. Therefore, this book concentrates on invertebrates and structure and these new evolutionary aspects, here discussed as ‘research highlights’ or ‘perspectives’. Sensory structures are only touched on peripherally. Whereas some taxa have been studied extensively and well-written reviews may already exist, in other taxa our knowledge on the nervous system is still scant and scarce.Less
For many biologists the nervous system is a particularly fascinating organ system. The nervous system is involved in or is even responsible for many features that are regarded as being characteristic of animals in general. Since the last comprehensive work was published about 50 years ago, the time has probably come to provide a new review on recent, newly gathered knowledge on the structure of invertebrate nervous systems, especially since new methods have come into use. These advances now enable us to demonstrate neuronal architecture down to the level of the genes and the cell types involved, allowing a new view on nervous systems and comparisons among different taxa. These new findings may help in development of new hypotheses, or support of existing hypotheses on phylogenetic relationships and evolutionary pathways in the nervous system. In spite of many open questions we already have a good knowledge of how nervous systems work, how they are constructed, and how they may have evolved. There is certain evidence that the first nervous systems are represented by rather simple sensory–motor circuits, followed by nerve nets (plexus) located within the epithelia, and finally neuronal circuits composed of sensory cells, interneurons, and brains. Therefore, this book concentrates on invertebrates and structure and these new evolutionary aspects, here discussed as ‘research highlights’ or ‘perspectives’. Sensory structures are only touched on peripherally. Whereas some taxa have been studied extensively and well-written reviews may already exist, in other taxa our knowledge on the nervous system is still scant and scarce.
