Recent Problems in Evolution - 1993
Table of Contents
- Oxygen radical production in aerobic metabolism is a failure in the natural selection process
- Origin of simian An order of mammals including man, apes, monkeys, etc., often characterized by large brains and flexible hands and feet.primates remains a mystery
- The human lung is "primitive" compared to other mammals
- Mortality of All body cells, except the reproductive cells.somatic cells compared to germ cells
- Sudden appearance of new planktic species
- Lack of complexity of amphibian brain
Oxygen radical production in aerobic metabolism is a failure in the natural selection process
Oxygen radicals are involved in the development of many pathological states. However, oxygen radical production is a fact of aerobic metabolism. One would think that such harmful reactions would have been eliminated through the selection of evolution. (Barja G. Oxygen radicals, a failure or a success of evolution? Free Radical Research Communications 18 (2): 63-70, 1993.)
Origin of simian An order of mammals including man, apes, monkeys, etc., often characterized by large brains and flexible hands and feet.primates remains a mystery
Recent discoveries of fossil An order of mammals including man, apes, monkeys, etc., often characterized by large brains and flexible hands and feet.primate specimens have produced several surprises and challenged prevailing views of early An order of mammals including man, apes, monkeys, etc., often characterized by large brains and flexible hands and feet.primate evolution. Plesiadapiformes, long regarded as "archaic An order of mammals including man, apes, monkeys, etc., often characterized by large brains and flexible hands and feet.primates," may perhaps be linked to the peculiar colugos instead. Inferred relationships of the earliest known undoubted An order of mammals including man, apes, monkeys, etc., often characterized by large brains and flexible hands and feet.primates (adapids and omomyids) are in turmoil. Both groups have been proposed as sources for the simian An order of mammals including man, apes, monkeys, etc., often characterized by large brains and flexible hands and feet.primates. (Martin RD. Nature 363 (6426): 223-34, 1993.)
The human lung is "primitive" compared to other mammals
The human lung shows permanent retention of certain features (such as the absence of an infracardiac lobe, or the subdivision of the lobes in lobules) found in most mammal fetuses or youngsters. This phenomenon seems to be in line with the fetalization theory of Louis Bolk, who considered man as a retarded and unspecialized mammal. (Verhulst J. Louis Bolk revisited: I. Is the human lung a retarded organ? Medical Hypotheses 40 (5): 311-20, 1993.)
Mortality of All body cells, except the reproductive cells.somatic cells compared to germ cells
Similar to prokaryotic cells, the germ cells of animals are immortal, whereas All body cells, except the reproductive cells.somatic cells are mortal, that is, they are able to carry out only a finite number of divisions. Evolution has yet to explain the advantage gained when All body cells, except the reproductive cells.somatic cells acquired mortality. (Denis H. and Lacroix J.C. Trends in Genetics 9 (1): 7-11, 1993.)
Sudden appearance of new planktic species
The micropaleontological record of deep-sea sediments is demonstrably continuous through time and, therefore, is a good record by which to measure "evolutionary" processes. Several taxa, including Coccolithophorida, planktic Foraminifera, Radiolaria, and diatoms, are abundantly represented. Some species appear suddenly in the record while other species grade into different ones at rates that range from 100,000 years to millions of years. The rates are usually different for different morphological characters within the same lineage. Every few million years a mass extinction occurs--the disappearance of a number of taxa apparently caused by an environmental upset of some kind. The rapidity of replacement by new species is difficult to explain by evolutionary theories. (Emiliani C. Biosystems 31 (2-3): 155-9, 1993.)
Lack of complexity of amphibian brain
Comparative neuroanatomists since Herrick [1914] have been aware of the paradox that the brain of amphibians, especially salamanders, is less complex than one would expect based on their phylogenetic position among the Tetrapoda. Many features of the brain are less differentiated in salamanders than in tetrapod outgroups, including chondrichthyans and bony fishes, and for some brain characters, the salamander brain is even more simple than that of the agnathans. (Roth G., Nishikawa KC., Naujoks-Manteuffel C., Schmidt A. and Wake D.B. Brain, Behavior & Evolution 42 (3): 137-70, 1993.)
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