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Evolution is one of the most interesting stories of the modern age as it tells us of our origins and the relationship we have with the living world. The certainty of scientific evolution concedes that evolution takes place in tradition of origin myths along with that of other cultures and tines. Some f the well known people who have dealt in the evolution debate includes Richard Dawkins and Stephen Jay Gould and Maynard Smith. This paper will discuss Stephen Jay Gould’s assumption that the rise of complex organisms like human beings was accidental rather than a progression.
Stephen Jay Gould
Stephen Jay Gould was born in September 10, 1941 and died in May 20, 2002. He was an American evolutionist, paleontologist and a science historian. He was an influential writer of popular science and taught at Harvard University and worked at the American Museum of Natural History. His most celebrated contribution to science was the punctuated equilibrium developed in 1972. The theory postulates that evolution results by long evolutionary stability punctuated by infrequent branching instances. This theory contrasts against the phyletic gradualism that asserts that evolution is as a result of continuous and smooth change in the fossil evidence.
Amongst the evolutionary scientists, there is competition as to the pre-eminent storyteller. This paper however will strict itself to the theory of punctuated equilibrium suggested by Stephen Jay Gould. For over two decades now, it has been the subject of heated debate. Several scientists including Steven Stanley, Alan Cheetham, and Elizabeth Vrba have used the theory as a basis for their researches while others like John Maynard Smith and Richard Dawkins have argued against the existence of such a theory (Evolution).
Stephen Jay Gould’s Critique of the Progress
Stephen Jay Gould struggled in his attempts to come to terms and understand the interplay of historical particulars. His theory was a sophisticated and nuanced that it recognized the importance of the role of a possibility. This means that the world could have been different from what we know it. The punctuated equilibrium was first postulated by Niles Eldredge and published in 1971 in the journal Evolution. It is widely regarded that it is an alternative to Phyletic Gradualism. Gould criticized the biases that assumed progressive nature which were seen in evolutionary theory that recently emerging species are superior to those that emerged earlier. But Gould countered this argument asserting that although natural selection may have led to degree of progress, but it was on limited sense over a long-term period of time. It seems that Gould’s thinking was based on the fundamental importance of contingency (York and Clark 2011).
Gould was a consummate student of Darwin and he often referred to his work. He often reflected on Darwin’s thinking that explains the struggle for existence. He recognized the extent to which the progressive trend emerged in the life history and that dissimilar species occur at dissimilar chronological scales. However, Gould’s argument is that the process of evolution occurs at three tiers; the normal ecological tier, normal geological time and the last tier that is dominated by mass extinction of events due to reducible factors from the other earlier tiers (York and Clark 2011).
The Question of Convergence
One of the vital discussions that Gould had with scholars was about the extent to which the issue of convergence made the outcome of history unique especially with its unique features. By definition, convergence refers to the phenomenon where two different species from different lineages and that are not related come to share some common features. An example is morphological similarities between marine animals (fish, dolphins) due to their shared environment. An evolutionary scientist that he is, Gould realized this phenomenon and recognized its importance and its ubiquity illustrating how natural selection has helped in shaping organisms fit their current environments. Gould however was doubtful of the hyperadaptationist hypothesis that attributed to the similarity across the varied species. He noted that many examples of convergent may have resulted as a common structural underpins giving an example of the Hox genes that is shared by many phyla. The Hox genes control developmental processes and are presumed to have originated in early history of multi cellular animals. In spite of accepting the importance that is convergent evolution, he was skeptical of meta-convergence (that argues that overall patterns of evolution had to be like they are).
But another scientist, Conway-Morris argued against Gould’s assumptions that evolutionary convergence is the reason for historical contingence. He termed it ‘unimportant’ and said that although it may be true that destiny of some lineages may be decided by a random process, that is particular to biological features may as well be manifested. Maynard Smith gave an example of eyes and flight that has evolved independently several times. These two scientists’ criticism can be seen from the light of debasing Gould’s claims about evolution; that it is fundamentally not adaptive in the long-term.
According to this convergent evolution, the acquisition of the same biological characteristics is due to unrelated lineages. One such classic example is the wing of bats despite the fact that their ancestors did not have any. The wings of bats and birds are similar is construction, what is argued as due to same physical constraints that are imposed on the shape of wings. Another classic example of this convergent evolution is the camera eye of cephalopods (where such animals like the squid, octopus, and cuttlefish belong). The cephalopods’ last common ancestor had just a simple photoreceptive spot but due to a range of some processes, they have developed a refinement of this spot to an advanced ‘camera eye.’ At the level of protein and DNA convergence levels, proteins have been implicated in high frequency hearing in some mammals that have undergone several amino acid substitutions in dolphins. This has evolved and resulted into ultrasonic hearing for the dolphins and other mammals. Thee last of such convergent examples is antifreeze proteins in fish. This refers to a class of polypeptides that are produced by some fish that permeates their survival in frozen areas. The antifreeze proteins are able to bind themselves into small crystals to inhibit recrystallization of ice. The recrystallization of ice can be very fatal to the fish resulting even to death (Conway and Simon 2005).
The significance of convergent evolution is usually associated with Charles Darwin since the 1940s. But the degree to which convergence has affected or is affecting evolution products is a subject for more debates (New World Encyclopedia). Gould argues that if life’s tape would be rewound, then life could take a totally different course. But other scientists like Conway Morris counters Gould’s argument and suggests that convergence is a central force in life and that life is likely to evolve to some characteristics of say primates and dolphins at some point in time. The convergence debate is a difficult point that cannot just be quantified easily. Therefore, thorough measures should be input to progress on this topic.