Your inner Fish Analysis 1
Although Neil Shubin, the successful paleontologist partially responsible for the discovery of Tiktaalik, the aquarian fish who is the probable evolutionary link between aquatic life and land dwellers, was obviously not as successful financially as scientifically, which is why he wrote a book which, regardless of conveying interesting information, is so exaggerated with personal reminisces that it exceeds the limitations of a wikipedia article(making it profitable), the novel never-the-less presents a solid general summary of the history of evolutionary progress and how we have ascertained it . Furthermore, it highlights Tikaalik, an extremely important preserved specimen which has tremendous explanatory power of key portions of the evolutionary history which, although the paleontologist’s specialty, have remained unilluminated. Shubin commences by briefly describing that the evolution of species is ultimately the history of our genetic development, we being simply complex modifications of an unbroken lineage of primordial biological forms who, actually originally, posses and possessed may of the same basic structures as ourselves.These relations are perceivable even in the life which abounds around us today which, depending on how many similar complex structures they share with us, are closer or distant biological family members. Shubin then explains that, if one looks at rocks of the right age and type( generally sedimentary rock, as it was both present in the environment of the now deceased specimen and was affected by sedimentary processes(such as compression by settling particles at the bottom of a lake) more conducive then other violent(such as volcanic) processes to the formation of fossils) , this evolutionary history of developing complexity has been preserved in fossils which, excepting around scrambled layers of rock which have been disorganized by fault-lines, are are entombed in stratified layers of rock revealed by experiment to, from top to bottom, be organized chronologically.Through the study of these fossils, we can actually observe the lifeforms which were predecessors to ourselves and, through immensely long periods of evolution(millions to billions of years), eventually spawned our genotype.Furthermore, analysis of the rock in which they are contained endows us with understanding of the geological and climatic conditions of the time period in which they emerged.After finishing a brief evolution/Paleontology 101, Shubin describes his voyage to the Arctic and his discovery of Tikaalik, a fish with a flat head which possessed numerous primitive anatomical structures, forerunners, of the land dwelling mammal. It possessed bones and tissues resembling shoulders, arms, joints, a skull, and a neck, yet all structures relating to the the arms( bilaterally symmetric, duplicate, homologous structure to the fins), were encased within the fins, and the fish still possessed scales. This specimen, laboriously unraveled from the rock in which it was encased through high powered and sometimes mundane technology in a sophisticated laboratory, reveals in it’s convoluted anatomy a species experiencing the transformation from fish to amphibian, which is of course the forerunner to land mammal.It was dubbed Tikaalik in honor of the inuit tribe who granted permission for research expeditions to be carried put on their Arctic territory. The discovery also revealed that, chronologically, this evolutionary transformation was occurring approximately 375 million years ago. Shubin continues to explicate anatomical similarities, such as the near ubiquitous bone structure of the arm which is apparent in but all evolved species excepting certain primitive life forms such as fish, between discrete species to further illustrate the indisputable correlations between them that imply evolutionary lineage. However, this anatomical correspondence, like all structures, evolved from the hybrid amphibians in the devonian age approximately 375 million years ago. In actuality however, primitive limbs pre-existed Tikaalik, but it is in this specimen we see the emergence of primordial wrists and joints.However, it was not until the emergence of other structures, such as an altered pelvis shape and joints, through which our fish ancestors could adopt (or vice versa) our posture, partially through the reorientation of their limbs.The evolutionary significance of limbs to ancient fish and the mechanisms which caused the coherent development of this mutation are not totally understood, though they may have been twofold significant in that they allowed Tikaalik and it’s fellows to patrol the lakebed more effectively and leave the water to evade predators.What underlying mechanisms permitted immensely complex x chemical sequences to evolve in ways that produce phenotypical structures conferring a competitive advantage were neither explained nor touched on, and I am interested in the guiding force, so to speak, of evolution(if they exist, or if that is even a scientific question at all). The fundamental level at which evolution operates,mutation in the the genome of a species, has been scientifically explored. Experiments have been conducted which identify the genetic sequences which correlate with homologous structures in organisms sharing descent and, through intensive analysis and arbitrary experimental alterations( such as the removal/reorientation of specific tissues and the injection of chemicals to critical areas at critical stages of embryonic development) we have isolated the specific tissues,cells etc. which regulate and/or most profoundly impact the developmental process of various structures. Although these experiments cannot be applied to human embryo’s( by virtue of their functionality((size)) and accessibility the chicken embryo was a popular research specimen in the 50s,60s,and 70s), the genetic similarities between the structures in question give us insight into the genetic/biochemical factors which regulate and the cells/structures who contribute to our own development. An experiment of this character was that of Gasseling in which, through transplantation of minute tissue proximal to the eventual 5 digit of a chicken unto the opposite side of the developing wing, the chicken matured with a wing bearing a duplicate set of digits. This indicates that minute tissue and it’s active genes was responsible for the whole particular aspect of the wing. In summary, the 1st 4th of Your Inner Fish describes both how our biology is a direct derivative from an ancient revolutionary lineage, shown by Tikaalik, to be traceable to primordial fish and the scientific processes which, in the context of genetics,anatomy, and paleontology, have led to the understanding of this lineage. Although Shubin often comes off as scrounging for meaningless, juvenile, personal supplements to the hard scientific explication of the roots of human evolution, the fascinating nature of the subject matter makes the book worthwhile regardless. I still question whether their are any scientifically
formalizable processes underlying the complex mutation of chemical sequences in genes which allows them to produce functional adaptations providing a competitive advantage for survival( the odd against this rational progression of anatomical forms(even with the knowledge that most mutations are not rational or functional) seems astronomical from a purely statistical perspective), the distinctions between fossilized species from ancient chronological periods studied by paleontologists and the enduring species whose evolutionary development culminated essentially in earlier time periods( that is, could the life forms in Shubin’s zoos, those which, possessing simpler modifications of our own anatomical structures indicating they are evolutionary ancestors, be said to be almost identical to certain of our fossilized ancestors and hence animated remains of ancient periods), and to what extent our increasing knowledge of the genetic-chemical changes which are at the heart of evolution will allow us to dictate our biological future.