You're a fish and your bird is a dinosaur
So the title sounds a bit like an insult you might hear in a schoolyard in Dublin. But it does have some merit, if by fish you are referring to all humans, and with dinosaur, you mean all Aves(birds).
This is the first of a series of blogs that I will post weekly, to explain the basics of Evolution, hopefully in a fun and easy to digest way. I will keep them short to begin with, as it might be easier to grasp. However, it will evolve with your engagement and feedback. If you have a suggestion, I have thick skin, fire ahead please.
Firstly,
What is Evolution?
Evolution is change in the heritable characteristics of biological populations from generation to generation
Okay, so that is the simplest form of the definition, ripped more or less from Wikipedia. It is open to interpretation but it will do as a good starting point. Lets take it piece by piece.
Heritable means something that will be passed from parent to offspring.
Characteristics refers to any trait (scienctists use the word phenotype) an individual has. This can be external such as eye colour, or on a biochemical level such as an amino acid, and everything in between. If you were missing an ear because you were a crazy, but brilliant artist, this is also a pretty obvious trait.
Together, heritable characteristics are traits that can be passed to your offspring.
If I chop my ear off, will my kids be born with one ear?
Well, most of us know this is a silly question. But why is it not passed on?
You have two cell lines which go in separate directions very early on after you are conceived. The germ line (all your future sex cells, eggs or sperm depending on your gender), and the somatic line (all your other cells, such as muscle, fat, nerves, blood etc.). The germ line keeps the recipe for all the traits you received at birth more or less intact, in all sorts of combinations, from the traits your mother and father gave you. Chopping your ear off in anger at a co-worker, will probably get you called up by HR, but it won't effect your future children's ear count. Lamarckism is having a revival, referring to passing on acquired traits, but this is complicated enough without detouring at this point
Gregor Mendel, a 19th century Augustinian friar and scientist, described a way for predicting inheritance, back in the 19th century using a now famous pea plant experiment.
Biological populations are groups of interbreeding individuals. In a nut shell, you could call a biological population a species, such as a rabbit, or an oak tree. It is a bit contentious as there are many, many definitions of species, and even more exceptions to each definition. I will explain species in a future blog, but for now, lets say that biological population means species.
Generation is straight forward. From parent to offspring. What is important here, is to note that an individual does not evolve, but that the change occurs over subsequent generations.
So now we can put the sentence back together ...
Evolution is change in the traits that parents pass to offspring.
Evolution applies to all forms of life, from microbes such as Bacteria, to Fungi, Plants and Animals. It also applies to viruses, which are not considered by some as life. Below is the tree of life. The tree shows how all the different groups are related. We will come back to this tree another time. I only put it here to give you an idea of what life is. It may surprise some of you that Animals occupy such a small part of the tree. Microscopic life dominates biological diversity.
And we can't talk about evolution without mentioning the Big Doggs of the field, Charles Darwin and Alfred Russel Wallace. Together in 1858, they published On the Tendency of Species to form Varieties; and on the Perpetuation of Varieties and Species by Natural Means of Selection.
That is quite the mouthful!
A year later, Darwin published his most famous work, On the Origin of Species. The two men had changed the face of biology forever, pushing evolution into mainstream science for the first time.
So why study Evolution?
I will let a famous Evolutionary biologist give the shortest answer I can think of!
Nothing in Biology Makes Sense Except in the Light of Evolution
Theodosius Dobzhansky, 1973
Maybe not a very satisfactory answer, we will come back to it in another blog.
So, why are you a fish, and why is a bird a dinosaur.
We still have a bit to go before I can explain that. Stay tuned .....
Thanks for reading. All feedback welcome
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