So I find myself fortunate enough, this semester, to be taking multiple biology classes at once. I know this might seem like a “duh” statement but really, since I was getting my associates at a community college, most of my biology courses were to be saved for the university years, and that is where we are. I am taking Genetics and Evolution & Ecology, both of which help me understand where we came from and maybe a little bit about why.
I, having grown up in Texas, with the bible belt flattening my education, found myself in a very exciting place once I was ready to take biological courses in college. My very first was biology for majors with an amazing teacher, Dr. Maines. She made things relatable and relatively easy to understand, the course was hard but she made it as easy as possible. I learned more in that class than in the culmination of all my previous years of education. I had not had a biology course since my freshman year of high school. I don’t remember everything as my memory is fairly poor, I cannot recall anything truly specific from more than a few years ago, freshman biology was 10 years behind me when I stepped into Dr. Maines’ class. I was raised (in school) on the Christian fed mentality of, “if we came from monkey then why aren’t monkeys turning into humans right now?!” I do not remember actually being taught about evolution until college, so I would like to make a fairly simple and concise post about evolution. To explain the basics (and maybe a bit more) without you having to take a majors bio class.
The basic concept of evolution is simple: the change of a population over time. Evolution works through a process called natural selection. Natural selection is the favoring of certain traits that are present in a population. Selection for traits that give an individual in that population an advantage over other individuals. This means that the individual with the advantage will be more fit and able to pass on more genes to the next generation. “Survival of the fittest” is a phrase that is often heard in conversations pertaining to evolution. Fittness in this case does not mean a very foxy lioness or a muscly tiger. Fitness in the context of survival and evolution refers to passing on your genes to the next generation. For example, the off spring of a donkey and a horse is a mule. Mules can live healthy lives and even fight off predators as well as the parents but mules are sterile. This means that they cannot produce off spring so mules are not fit animals.
The way an individual can have an advantage over other members of the population is by inheriting better genes than everyone else. When two member of a species come together to have a child (for means of this conversation, through sexual reproduction) their genes mix together at random. The child, hopefully, will end up with the best of both parents and be more fit than either of the parents were to survive. With this in mind the following statement should make a lot of sense: evolution doesn’t act on individuals, it only acts on populations. To further explain this point I introduce to you Darwin’s finches. Darwin was the man who introduced the idea of evolution to the mass population of the world. He spent a lot of time in and around the Galapagos Islands studying different species of birds, finches, black birds ect. He had collected many samples and sent them back to the mainland for analysis. To his shock, when he received word from them, the bird were actually all finches. They just looked very different from each other because they had separated and specialized on the multiple smaller islands. This brings up the idea of how evolution acts on a population. The theory about Darwin’s birds is that one group traveled (probably blown off course) from the mainland to the islands. There they had to find new food, different from what they were used to and they had different predators. These changes are called selective pressures. Under these new selective pressures the birds started changing over generations. There beaks became different sizes and their coloring changed. This process happened on every subsequent island the birds spread to. The islands were close enough together for the birds to spread there in the first place, but not necessarily close enough together for them to continue mating with the birds from other islands. This geographical isolation prevented all the birds on all of the different islands from looking the same and is a process called allopatric speciation, where by one species can diverge into two when separated geographically. Therefore, all of the bird populations were changing to better suit their new environments but there wasn’t any individuals that were simply morphing and teaching the others how. It happens slowly and over many generations, it happens more quickly when the pressure to survive is more but it still takes time. Let’s look a little bit more a the beaks of the birds. The mainland birds arrived with small beaks but some of the island birds had very large beaks for cracking nuts. This means that over the generations the birds that had slightly larger beaks were more easily able to get food and the well fed birds had the energy to pass on their genes to the next generations. Birds with beaks that were too small either couldn’t get enough food to be as prolific or in some cases didn’t make it at all, thus not passing on their small beak genes to as many offspring.
So to everyone who wants to have a conversation with me about shape shifting animals, know that I am open to it but will not consider it a conversation about evolution.
(A post hidden in my drafts from more than a year ago. Enjoy.)
Please let me know if you have any questions. I would be more than happy to answer them if I can.