Geologic Timeline Reflection

The three major events in Earth’s history include the formation of Earth itself, the mass extinction that marked the end of the Cretaceous Period, and the first humans. Earth was formed 4.6 billion years ago and without the creation of Earth, none of the history that followed would have occurred. So, as a result, the creation of Earth, is pretty obviously an integral event in Earth’s history. Next, the mass extinction during the Cretaceous Period was extremely important in Earth’s history. During this extinction, dinosaurs went extinct, and a fair amount of species on the planet also went extinct. With an abundance of animals going extinct, there was room that opened up for other smaller, but modern animals to come into existence. This mass extinction was extremely important and significant in Earth’s history because it not only made dinosaurs, an influential organism, extinct, but also opened up the possibility for more animals to come into existence. Lastly, the evolution of the first humans were extremely important. Although humans haven’t been on the Earth for too long, we have made a significant impact on the Earth. We have been extremely influential in the history of Earth, making it another significant event in Earth’s history.

As I previously stated, the Earth has been in existence for 4.6 billion years, but of those 4.6 billion years, humans have only been there for only a small portion. It really surprised me that although humans have made a significant impact on the Earth, we have been on the Earth for a very small time. Our impact is far greater than many of the other species on Earth. For example, we’ve made many advancements in technology and many other things.

The scale of Earth’s history really surprised me when my group and I were making our geologic timeline. Our timeline was about 9.2 meters and 1 million years was shown by every 2mm. This really put the time period into perspective for me, because I was able to understand truly how gradual change really is.

After doing this timeline, this unit came full circle. I have no questions. Before this timeline, I was still not understanding truly how long evolution and change takes, and by completing this timeline, my questions were answered.

      

Unit 8 Reflection

This unit revolved around the concept of evolution, specifically what drives evolution and its effect on other populations. Evolution is caused by either artificial selection or natural selection. Artificial selection is calculated and less random than natural selection, in the sense that artificial selection has breeders breeding a specific population for the best, desired traits. Natural selection is the survival of the fittest, as the traits that don’t help the individuals survive get weeded out and the better traits become more common in the population, as concluded by Charles Darwin.

As the better traits become more apparent, the population is evolving, and the best evidence to support evolution is the measuring of genetic variation. In order for evolution to be occurring, the allele frequency for the desired trait will increase, showing, genetically, that the population is starting to look like winners. In the Hunger Games Lab, we were able to see how competition and other external factors lead to the population looking like winners.

But as the population evolves, the different traits can cause different species to come about, which is speciation. We learned about two types of speciation, one being gradual speciation where new species arise very slowly and after many generations, and the other being punctuated equilibrium, where the new species arise suddenly.

There is much evidence out there showing that evolution has occurred, but the best evidence comes from fossils. With fossils, scientists can physically observe the changes that had happened over time instead of inferring a common ancestor.

Towards the end of the unit, we learned about how long evolution truly takes. I had been struggling to truly understand how long this process really is, but the geologic timeline truly put it into perspective.

I also learned how to become more assertive throughout this unit. By really understanding the concepts, I started to become more confident in my knowledge and thereby more assertive.