Unit 8 Reflection

In this unit, one of the first things we learned about was Darwin's research and how Evolution is caused by Natural Selection. Darwin had 4 observations: All sexually reproducing species has variation, traits are inherited, all species have capacity to grow over limits, and that there are lots of competition (two types being - introspecific, which is competition between same species, and interspecific, competition between different species. From these observations he concluded with 2 conclusions: the first one being that in the natural world there are winners and losers; he second conclusions was that in the end population usually looks like winners because of natural selection, a process of weeding out traits in a population that do not help individuals survive. So, because of natural selection: traits that are neutral or DO help an individual survive will be passed on. With natural selection comes change and in the gene pool there is constant change. The gene pool is the total of all the alleles, which are different variations of a gene that give different variations of that trait, in a population. Hence, genetic variations is stored in the gene pool and the pools change as new allele combinations form when individuals of the population give birth to offspring. In order to measure the genetic variation, the allele frequency needs to be measured. The allele frequency is how common an allele is in a  population. Though the beneficial and "good" alleles are passed on to offspring there are non-beneficial alleles that stick around called lethal alleles. If recessive, lethal alleles, can stay hidden in a population in heterozygotes, and then can be passed one when two creatures with the recessive lethal allele mate will have offspring that contain that allele. Natural selection results in evolution and in evolution there is speciation, the rise of 2 ore more species from 1 existing species. Without isolation there cannot be speciation and that is why speciation is caused by reproductive isolation, when a population is split into 2 and eventually the 2 populations can't reproduce with one another. There are 3 different causes of speciation. The first cause is called behavioral isolation which is caused by changes in courtship (mating behaviors or occupying different niches). The second cause is geographic isolation, which is when some kind of physcial divides the species into groups. And finally the third cause is temporal isolation which is when timing prevents reproduction between populations. With the different causes of speciation comes the two different patterns of it. There is gradualism which is when speciation occurs slowly but over many generations and there is punctuated equilibrium which is when new species arise "suddenly" and extremely fast. There are evidences of evolution, one of them being fossils. Natural selection can change a distribution of traits in one of 3 ways: Directional selection, stabilizing selection, and disruptive selection. On Earth, life may have formed through chemical and physical processes on early Earth that may have produced very simple cells through sequences of stages that result in the origin of self-replicating molecules. There are 3 main eras in history: the Precambrian Era, the Paleozoic Era, the Mesozoic Era, and finally the Cenozoic Era. Each of these Eras have periods in them where mass extinction and development of the world occurred (evolution).

I would like to learn more about how exactly the development of humans shaped the world. Thus my questions is: How exactly did the development of humans affect Earth?

In order to be more assertive and less aggressive when I'm under stress now I try not to speak too much because when I do speak I tend to say not so nice things to people. I'm also being more direct and speaking up more. For me, in terms of this, I still need to work on how aggressive I am when I'm under stress, I think for this I'll probably ask my peers or research on what I can do in order to stay calm during stress.