... biologists are a bit arrogant in their assertions. They seem to assume that because they can quantify molecular divergences; that is, fill their journal contributions with numbers; that their data is more sound than fossiliferous strata. But their crucial assumption of constant DNA divergence in time may be their undoing. References Ref. 1. Anonymous; "Deflating the Biological Big Bang," Science News, 150: 335, 1996. Ref. 2. Perlman, David; "Origin of Animals -- 1.2 Billion Years Ago," San Francisco Chronicle, October 25, 1996. Cr. J. Covey. Ref. 3. Wray, Gregory A., et al; "Molecular Evidence for Deep Precambrian Divergences among Metazoan Phyla," Science, 274:568, 1996. Homology vs. DNA. Until the molecular biologists recently arrived on the scene, evolutionary family trees were based upon similarities in appearance; that is, homology. Animals that look alike must be closely related. But molecular biologists have discovered that some animals that seem identical to the eye differ significantly in their DNA complements. Thus, the Pacific skinks may undermine homology. Inhabiting many, far-separated Pacific islands, these small lizards all look pretty much alike externally. For many years, biologists assumed that they all belonged to the same species. Recently, scalpels in hand, they found that the skink innards differed enough to define two species: Emioa cyanura and Emioa impar . Next, the molecular biologists got into the act. They discovered that the mitochondrial DNA (mtDNA) of the Guam ...
Terms matched: 1 - Score: 44 - 15 May 2017 - URL: /sf109/sf109p08.htm
... Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Bones Of Contention Introduction. This item needs an editorial because it shows how a very tiny and obscure brick in the Temple of Science, long thought to be structurally sound, might lead to widespread collapse. Are there other sleepers? A group of burrowing lizards (the amphisbaenians) possess a heavy bone in their heads that helps them ram their ways through the soil. In surface-living lizards this structure is merely a soft, flimsy cartilage. It was long assumed that the bone in the burrowing lizard developed from the cartilage of its surface-living kin. But a study of embryos now shows that the head bone of the burrowing lizard actually developed from a membrane instead of cartilage. The two similarly located structures are not homologous after all. They had different origins. Superficially this doesn't seem very anomalous and especially not very exciting. But vertebrate evolution in particular has been charted on the basis of homologous structures. If these structures have different biological origins -- even in just some cases -- the evolutionary family trees may be drawn wrong. (Anonymous; "Lizard Bone Shakes World of Taxonomy," New Scientist, 98:221, 1983.) Comment. No one yet knows how serious this problem really is. Basically it means that some animals that look alike (at least bonewise) need not be closely related. To use an analogy, if nature has the plans for a house stored in genetic material, it may be able to build that house out of wood, brick, ...
Terms matched: 1 - Score: 24 - 15 May 2017 - URL: /sf028/sf028p11.htm
... Evolves Much Faster Than Nuclear DNA BHG11 Disparity between Human and Ape Phenotypes and Genotypes BHG12 Chimpanzee Mitochondrial DNA More Diverse Than That of Humans BHG13 Human Mitochondria Radically Different from Those of Other Organisms BHG14 Paternal Mitochondrial DNA can Be Inherited BHG15 African Nuclear DNA Is Distinct from That of Other Populations BHG16 Chromosome Banding Analysis Incompatible with DNA Analysis BHG17 Involucrin Analysis Conflicts with Mitochondrial DNA Analysis BHG18 Human Molecular Clocks Run More Slowly Than Those of Apes BHG19 Absence of Transitional Forms of Cytochrome C DNA Analysis and the Origin of Modern Populations High Deleterious Mutation Rates in Hominids Fetal DNA in Mother's Blood Epigenetic Inheritance Unique Human Lack of Retroviruses Neanderthal mtDNA Different Persistence of Cystic Fibrosis Gene Humanity's "Missing" Mutations Persistence of ITD Gene Overall Human Mutation Rates Very Low "Junk" Genes and Human Evolution Curious Genetic Homologies HIV-Like Gene in Human DNA BHH HEALTH BHH1 Health and Environmental Electricity BHH2 Health and Weather BHH3 Disease Epidemics Correlated with Solar Activity BHH4 Epileptic Seizures Correlated with the Moon BHH5 Disease Epidemics Correlated with Volcanic Eruptions BHH6 Anomalous Periodicities in Disease Epidemics BHH7 Anomalous Appearance and Propagation of Disease BHH8 Epilepsy and Rhythmic Phenomena [BHB7, PBH] BHH9 Health-Problem Synchronicities in Identical Twins BHH10 Extreme Longevity BHH11 Historical Changes in Average Longevity BHH12 Longevity Correlated with Brain Size in Hominid Evolution BHH13 Longevity Correlated with Lifeline Length BHH14 AIDS without Measurable HIV Antibodies BHH15 HIV-Infected Persons Who Do Not Develop AIDS BHH16 Anomalously Small Fractions of HIV-Infected T-Cells in AIDS BHH17 Anomalous Levels of HIV Antibodies in AIDS BHH18 Deliberately HIV-Infected Simians and Accidentally HIV-Infected Humans Who Do Not Develop AIDS BHH19 ...
Terms matched: 1 - Score: 11 - 15 May 2017 - URL: /cat-biol.htm
