When studying the life sciences, there are a lot of in-depth concepts to take in. Depending on the the type of science you are studying, biology vs. evolution, for example, you may even have to learn a handful of mathematical formulas to fully appreciate the material. Here, we are just having a light-hearted overview of the life sciences, so a light serving of sativa will do just fine. In my experience, sativa helps me to not get lost in wordy texts (reading that is not broken up by graphics/tables or formulas) and keep my mind sharp and able to take in all relevant information. Grinding about 60mg (less than 1/4 of a 1g bud) of sativa and smoking just a small pinch of that for over a 3-5hr period is perfect for maintaining a healthy attention span for learning. Black Flower Science Co. does not claim to be a medical professional and does not offer recommendations as a substitute for medical advice. All advice and recommendations are based on personal experience of the benefits of medical marijuana. If you are experiencing severe or declining mental health symptoms, please seek the advice of a medical professional.
Theory, by definition, is “a formulation of underlying principles of certain observed phenomena which has been verified to some degree.”
Scientifically speaking, it is an explanation derived via the scientific method, which has been repeatedly tested and confirmed, by use of observation and experimentation. In other words, though it still has the potential to be disproved, it has been shown to be true over and over and over again.
So, here and now, we leave the haughtily misinformed phrase, “evolution of animals is just a theory” behind. (For those of you fuming over this, check out this quick summary of the difference between scientific law and theory.)
Now that that’s out of the way… What is evolution?
Jean-Baptiste Lamarck (1744-1829) is the biologist responsible for what we now know as Lamarckian, or “straight-line,” evolution. He believed that primitive organisms were being continually created and were being driven to progress toward “more perfect” forms by biological “needs” and “life forces.” Lamarck is where most people get the idea that fish became walking fish, became lizards, and ultimately became mammals.
Close, but no cigar, Lamarck. His model was inaccurate, as the species that were eventually evolved from earlier life forms were not organized in their proper taxonomic relationships (AKA lizards were not each other’s closest relatives, and so on. In Lamarck’s model, a Gila monster could be most closely related to a tiger shark instead of a whiptail lizard.).
Georges Cuvier (1769-1832), on the other hand, subscribed to the Theory of Catastrophism. Cuvier thought that organisms were well-adapted as a result of catastrophic environmental episodes that led to extinctions which was then followed by the creation of new faunas (species).
Both of these ideas and more were the stepping stones to the concept of Natural Theology. Natural Theology states that the natural world is in a perfect state, having constant harmony and abundance in life and resources. Under this idea, there is no place for competition or other such ecological interactions, and no real need for evolution.
As charming as this is, even biblically speaking, this is wrong.
Charles Darwin (1809-1882) recognized this. He saw that the natural world was not full of harmony, but in disequilibrium, an “arms race” in which natural selection led to speciation and extinction, given that there is genetic variation, that the alleles in question are heritable and can effect fitness. He defined this general process, evolution, as “descent with modification,” change over time in a given population.
Darwin’s theory of evolution by natural selection is the most widely accepted evolutionary concept now. The “ingredients” of Darwinian evolution are as follows:
- A gene has to be variable
- A gene has to be hereditary
- A gene must affect fitness
Genes are expressed in two main observable categories: phenotype and genotype.
A genotype is simply the DNA that is inherited from the parents. It is an individual’s genetic code.
The phenotype is then the external manifestation of that genetic code. You can remember this physical expression of the DNA by connecting the root pheno to physical (that’s how I always remembered it).
So why are these the three necessities of Darwinian evolution?
Well, let’s start by defining “fitness.” Fitness is an individual’s ability to survive and reproduce – emphasis on reproduce. In an evolutionary sense, an organism’s value is largely determined by the extent to which it can contribute to future generations.
That can only be done by surviving – surviving well (thriving and living healthily for better success in attracting mates, defending territory, competing for food, etc.) – in order to have the opportunity to reproduce.
These reproduction events are a part of what natural selection operates on. Steve Shuster and Michael Wade coined a term, opportunity for selection, in 2003 as a way to describe the need for variation in fitness levels of populations for natural selection to proceed effectively.
This means that one subset of individuals in a population must have lower fitness levels than others, giving the stronger individuals the ability to out-compete, and ultimately, produce more offspring, than the weaker ones.
Terpene Food & Wine Pairing Chart Print – 18×24
Of course, here is the point at which both heritability and selection come into play.
The interaction between genetics and the environment is known as epigenetics, and is represented often by the formula G*E [in total, G + E + (G*E)]. Environmental processes, such as weather events, significant changes in landscape, etc., are all external factors that can have either direct or indirect effects on an organism’s phenotype.
For instance: let’s say there’s a blue toad that lives in a community of mostly blue toads with a few red toads. If some crazy earthquake occurred and split their community to where the red toads were left on their own, and there was no way to rejoin the two, the two populations would have to continue on separately.
After being separated for a significant amount of time, let’s say a few decades, the red toads have flourished once again, but – what’s this? – they’re all red now! Red toads are no longer the genetic/phenotypic minority because this red skin gene was brought to fixation (became the norm) because of an environmental change.
Now, this story can definitely go the other way. In the described scenario, selection acted positively on a heritable trait. The population split led to greater fitness, specifically reproductive success, of the red toads because the ladies just didn’t have another option, so the red toads became the hot shots.
What could’ve happened, though, was that – if there was a negative trait associated with the red skin gene, let’s say, deadly toad sneezes that result in spontaneous combustion – then the red toad population would have died off after separation because of the inability to incorporate good, beneficial genes (blue toad genes) into their gene pool.
There, then, is where the heritability and variability in genes work together to affect change in a given population.
These elements, when all three come together, are why evolution has never been the Lamarckian straight-line evolution. Selection, and therefore, evolution, happens on both an individual and population – and even global – scale: A single organism reproduces in great numbers and passes on a specific set of genetic information, the environment acts upon that genetic information, those offspring interact with other organisms, and the cumulative changes all happen simultaneously and repeatedly, forever.
The infinite changes are in no way simple or singular in effect or conclusion – if they were, we would certainly have a straight line of single cell organism to fish to reptile to mammal, or whatever order you’ve read elsewhere.
Rather, all of these coincidences have multiple effects, branching out to multiple organisms and populations and creating the multiple-ancestry cladograms we know and love today – not sure what that is? We’ll get into it the next installation of this series!
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