Heredity/Evolution English
등록일 : 2018-04-11 14:09 | 최종 승인 : 2018-04-11 14:09
Cedric Dent

[리서치페이퍼=Cedric Dent 기자] The world-renowned, American paleontologist from Harvard, Stephen Jay Gould, published his book, Wonderful Life: The Burgess Shale and the Nature of History, in 1989, and in it, he focused primarily on the evolution of animal life in the Cambrian Period, a dispensation of the Paleozoic Era. He broached parts of the subject by presenting readers with the hypothetical scenario in which time is rewound to the beginning of evolution and asking whether or not evolutionary events would all occur exactly the same way they did in our reality. He, instead, suggested that rebooting evolution would actually subject life to all the same variables as before and, thus, practically guarantee innumerable differences in how evolution would play out.

Gould gave the scientific community a deeper picture of how probability factored into evolutionary history in that book, spurring the idea seen in many a movie or TV show today wherein one travels to the past trepidatiously with the fear that, should he or she so much as step on a butterfly, it could change the course of history and humanity's future as a result. Genetic mutations and recombination constitute the variability of behaviors and phenotypic features that living organisms have, and these things account for that "Gouldian" view of natural selection. Natural selection is like a Brita filter, and all those variables are like water; theoretically, selection "purifies" the variables, at least in the sense that it solves for gene expressions that yield the greatest reproductive advantages for each species.

Today, though, there are many biologists out there who disagree with this mode of thinking and, instead, embrace "convergent evolution." This is the concept that unrelated organisms are all evolving toward some singular perfection — that there's an ideal organism still yet to be realized by natural selection and that every species of living organisms on this planet is just a different attempt at reaching that ideal being. This "ideal" condition is typically thought to be ideal for immediate environments, mind you, not ideal the world over, so take two very different animals from very different environments and note how they have similarly adapted to their respective environments like bats and whales.

Bats and whales are both naturally adept at echolocation; they don't see with their eyes but, rather, hear how sound reverberates off of objects around them in order to "see" where those objects are. They don't forget their surroundings easily, and they are two animals who hear better than anyone else on the planet despite existing in extremely different environments. The driving idea behind convergent evolution is that there are only a few ideal ways to adapt to any given environment, and if you look at natural selection that way as an evolutionary biologist, you can theoretically predict how an animal will evolve over time. In that case, if you time-travel to the past and accidentally step on the very first butterfly to ever exist, a very similar insect will eventually come to fruition anyway because the butterfly was already representative of a favored set of features naturally selected for that environment.

Recently, a study along these lines was published in Current Biology finding further evidence that convergent evolution might actually be the optimal way to view natural selection. Several publications covering scientific news have picked it up already, talking about how stick spiders evolved in the Hawaiian Islands evolving in ways similar to other spiders elsewhere. Part of the significance of that location (the Hawaiian Islands) is that islands are always viewed as natural evolutionary labs because of their natural isolation.

The target insects mostly have gold, dark or white bodies to camouflage them from birds and other predators, and the research team used their DNA to figure out how they evolved over time. Ancestors were apparently gold, yet dark and white spiders have repeatedly been produced from those gold ancestors six and two times respectively. It suggests that the environment is determining to a large degree what features will be selected, and in that environment, selection will usually be the same; however, it's not ruling out the contribution of probability.

Other scientists recently traced the evolutionary history of tropical forests in general on this planet and found interesting insights that they think may inform the fight against global warming. Even though all tropical forests might look the same on the surface, they differ greatly. Only four percent of any tropical forest tree species can actually be found on all three continents that bear tropical forests, which are South America, Asia, and Africa. Palm fronds, for example, are ubiquitous to the point of being found not only in South American tropics but also in Asia, yet you still can't find them in African forests. All these environments, mind you, differ in small but distinct ways — small because they're still all tropical but distin

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