Geologic Timeline Reflection

Three of the major events in Earth's history are the mass extinction at the end of the Cretaceous period, the appearance of prokaryotic cells 3.5 billion years ago, and eukaryotic cells 2.1 billion years ago. The extinction at the end of the Cretaceous period eradicated over 1/2 of the Earth's population, including but not limited to the dinosaurs. The appearance of prokaryotes and eukaryotes was important because there are many organisms now that are prokaryotes or eukaryotes including humans. These events are important because without them, the species that exist today wouldn't exist today. 

The majority of Earth's history was the Archean era and the Proterozoic era. What surprised me was how recently the dinosaurs existed. As humans, we feel they've been gone for so long but in the scale, they are very close to us. 

In such a short time, we've caused so much destruction to our planet with climate change and global warming. The earth has been around for 4.6 billion years, yet our impact has been the biggest.

I want to know about life during the Archaean period more. It seems so strange that there once was a world with barely any animals or even eukaryotes. How long is the Earth estimated to continue to have life?

Here is a segment of our timeline.

Unit 8 Reflection

This unit was about evolution, and how we, amongst many other species came to life on Earth. One of the main themes of this unit was natural selection vs. artificial selection. Artificial selection is how breeders, for example, are able to breed so many types of dogs with very different traits. Natural selection is what Darwin observed, which eventually weeds out undesirable traits in a population, eventually making the better traits more common.

 From there, we learned that evolution is the change in allele frequency in the gene pool over time. There is lots of evidence supporting evolution, but to me, the piece of evidence that stands out are the similarities in embryos. For example, the Hunger Games lab helped illustrate evolution, as the allele frequency of the species changed over time. 

The rise of new species contributes to evolution when members of a population are reproductively isolated. Other than natural selection, some other factors that also affect evolution are genetic drift, gene flow, mutations, and sexual selection. 

The best theory as to how life started is that first, macromolecules were formed, leading to protocells, eukaryotes, and eventually sexually reproducing organisms. The timeline of the Earth is broken into eras and periods, during which, the Earth and life underwent many changes and 5 mass extinctions.

I thought this unit was very interesting because I like to understand how humans came about, and the origins of life. I would like to learn more about vestigial structures and some examples because its really cool that there are evolutionary left overs. I also want to learn more about the age of the dinosaurs. 

On being more assertive, in the survey last month, I found out that I am slightly aggressive. I've been trying to give people in my group a chance to do what they want more because I usually take charge.
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