What Killed the Dinosaurs? Essay Example

If natural selection is so good at maintaining and even improving a species’ adaptations, why do any species ever become extinct?

It was only within the last few hundred years that we began to understand that species are not “fixed” and unchanging. As we began to recognize that species changed over time, various theories were proposed to explain this process. Jean-Baptiste Lamarck proposed that an individual member of a given species could acquire a new physical  trait during its lifetime and then pas that trait down to its offspring, a notion that was eventually proven false. It was Charles Darwin’s theories on natural selection that finally offered a consistent, reliable explanation for how species change over time. His ideas –in combination with our understanding of genetics as first explored by Mendel- explain not only the variation among individuals in a given species, but also how the traits associated with these variations are passed down. Variations that prove to be adaptively advantageous are more likely to be passed down, as nature “selects” the individuals that are most well-adapted for survival.

This does not ensure the survival of any given species, or individual within that species. No matter how well-suited for an environment a species may be, it is still possible that changes within the environment can be too rapid or too drastic for a species to survive (Park, 2014).  Perhaps the most significant example of this phenomenon is the extinction of the dinosaurs. These reptiles had adapted in countless ways to fill innumerable environmental niches, and various species of dinosaurs evolved and survived on Earth for hundreds of millions of years. There are a number of theories about why the dinosaurs eventually died out, including the suggestion that an asteroid crashing into the Earth kicked up enough dust to block out the sun (‘Evolution: Extinction: What Killed the Dinosaurs?’, 2001). There is some disagreement about what happened to the dinosaurs, but most theories are based on the idea that massive environmental change(s) of some sort made it impossible for the dinosaurs to survive (‘The Great Mystery: Current Arguments’, 2014). The forces that drive adaptation include changes to a species’ environment or the species entering a new or different environment. These same forces are what can drive extinction when a species cannot adapt quickly or effectively to such changes.

References

Evolution: Extinction: What Killed the Dinosaurs?. (2001). Pbs.org. Retrieved 17 April 2014, from http://www.pbs.org/wgbh/evolution/extinction/dinosaurs/asteroid.html

Park, M. A. (2014). Introducing anthropology. 6th ed. New York, NY: Mcgraw-Hill.

The Great Mystery: Current Arguments. (2014). Ucmp.berkeley.edu. Retrieved 17 April 2014, from http://www.ucmp.berkeley.edu/diapsids/extinctheory.html