Hey again! We're baaaack onto evolution! Garsp.
Specifically, we'll be covering some myths regarding evolution in general because this
will explain a ton of the questions that people will have before they crop up in the actual
stuff we'll be covering, and that way, when we go through how this all applies to world
design, it'll make a ton more sense. Soooo since there's a lot of these, let's
just dig right in! So first off, "natural selection is the only
form of evolution." No. No it's not. It's the naturally occuring variety, but we can
have directed forms as well. Like for example, dog and horse breeds - we didn't even know
about genetics in the slightest when we started intentionally breeding dogs and horses for
specific desirable traits. This follows the same concept as natural selection in that
the creatures with the preferred traits for their environment breed more often and therefore
we get exaggerated features of one type or another.
In nature, the "desired" traits aren't really chosen, more so just whatever you stumble
across first by blind chance that works well in that given situation tends to proliferate
at a faster rate than those without whatever that benefit happens to be. A shorter beak's
better for cracking open nuts, a longer beak's better for reaching grubs inside the hollows
of a tree for example; what happens to be handy is what you get.
In this early form of genetic engineering, because that's basically what it was, we took like...
dogs which had a good sense of smell, and whichever dog was best able to smell out a fox,
you'd breed that with the others who also had a good sense of smell, and eventually
you'd get a bloodhound who's specifically adapted to that task.
In modern genetic modifying of stuff, we can isolate the genes which do what we want
with a lot more precision than before and ensure they get used, while those that we don't want
get removed intentionally. It's still basically the same concept though, as we need example
reference points to know what works and what doesn't; without a dog with a strong sense
of smell, we can't really "breed" the bloodhound equivilent genetically, either, without an
enormous amount of additional research which basically boils down to trial and error.
In any case, "breeding" also applies to actual species' mate selection as well. Things like
the peacock, as a prime example, shows that natural selection can be overridden by the
choices of individuals. A peahen picks a mate based upon how pretty the male is - more vibrant
feathers and such is a real turn on. Genetically, it's BAD, because it means you're more likely
to DIE due to A: attracting more predators, B: having a harder time escaping predators
due to way more weight being thrown into those tail feathers, and C: it costs way more nutrition
to support the pretty display. Now, this has the advantage as well of showing individuals
as being stronger than others - if you can have that many penalties tacked onto you and
still survive despite that giant bull's eye around your neck, you must be pretty awesome.
In this case, it's really not natural selection at work, which is more along the lines of
how the peacocks with more pretty feathers tend to DIE because of the aforementioned
reasons. So yeah, there's our genetically modified
stuff, intentional breeding, and the choices of individuals as well, plus there are also
natural disasters as well - natural selection makes you good for a given situation,
but if that situation rapidly changes, like BAM ICE AGE OUT OF NOWHERE, which happens pretty
quick in only a few years as we've covered in prior episodes of Playing God(dess), then again,
this's essentially an artificial change of the evolutionary path, even though the
event itself may be natural in origin. Anyway, lots of different ways in which evolution
takes place! Our next myth is that evolution always improves
the creature towards its environment! ...No. As we mentioned with the peacock example just
a moment ago, the evolutionary path they've taken specifically moves them away from being
ideally suited to their environment. The key thing to understand is that evolution is based
around the selfish gene mentality - whatever produces a copy of the gene, as in children,
is what gets carried on. The perfect adaptation to an environment that reduces the chances
of breeding does not tend to survive long term in the gene pool.
On AVERAGE, you will see a clear trend that things that generally make the creature or
tree or virus or whatever better at surviving in their environment will tend to produce
more offspring over time and therefore tend to become more pronounced in the gene pool...
but it's only a generalized trend. Evolution is not a consistent, forwards motion you have
to keep in mind - it's random and erratic and most of the changes are either useless
or go off on random tangents. Those that are actively harmful do tend to disappear,
those that are beneficial tend to become more common over time, but a lot of it's just going to
be random stuff that gets tacked on with no real noticible harm nor benefit and the fate
of such will depend on if it just happened to also get tacked onto another trait which
was beneficial or harmful. Uhm lessee... related, and similar, but not
quite the same, is the myth that evolution always improves creatures just in general.
Again, not the case. Note that the biggest issue with this is the
definition of "improved" - what is an improvement over what came before? In one of the examples
last week, we came to the conclusion that lizards underground may lose their eyes. This
"improves" the creature because the cost to grow eyes in terms of nutrition requirements,
was higher than what benefit they paid out. So just because one creature may be "better"
than another in some way, shape or form... there's always a price tag attached, a cost incurred.
We see this in a lot of dichotomies, where
"good" genes may sometimes be bad, or "bad" genes may sometimes be good.
Look at humans - some humans build fat very easily, others build muscle easily.
We (tend to) think of people who gain fat easily as bad genes, but the thing is, in our history, this was
a good thing! If you had a tribe of say... 50 people we'll say, then when it came to
a time of famine... well, you want most people in the tribe to build fat very easily - what
little food there is, you want to keep as much of it as possible for reserves when food
is scarce. At the same time, you also want a small portion of your tribe to build muscle
extremely easily - that muscle is needed to hunt game and collect other forms of nourishment,
but muscle has a very high energy cost. Those with lots of muscle need to eat way more than
the people with lots of fat, so ideally you only want a few muscled hunters to get more
food for everyone else because if everyone grew muscle easily, it'd lead to most people
dying of starvation. Another example in terms of nutrition would
be supertasters - about a quarter of the world's population of humans have a much greater sense
of taste and texture to other humans, and a smaller percentage are even more vastly
enhanced at their ability to taste than others. Now this's a really handy trait when it comes
to things like poison detection! If food's even a little bit "off", it's much, much easier
for a supertaster to recognize this and they'll tend to want to avoid it. Unfortunately...
there are drawbacks with such as well. This same supertasting dealie leads to people
who have a very narrow diet due to tastes and textures being amplified so much beyond
what normal people taste. Paired with being much less likely to eat things that are even
a little rotten, and you find that these super tasters would be much less well nourished
under normal conditions... but at a time when everyone else is horribly ill and barely able
to move due to food poisoning, these same individuals would tend to be relatively unscathed
and able to take care of the others. As such, it's really hard to say that a creature
is generically just "improved" by having certain genes or traits, because there's pretty much
always something that's being given up in order to gain that benefit, and sometimes
those situations may not be readily apparent most of the time. Like until everyone's sick
from food poisoning, the concept of the supertaster doesn't even make sense as being a benefit
at all - heck, my last ex could barely eat much of anything. He had an exceptionally
limited palette of what he could stomach at all, but you could pretty much guarantee that
he was probably never going to get food poisoning off almost anything.
Anyway, our next myth is that microevolution exists, but macroevolution doesn't. These
are terms which don't actually exist within science, but they do get brought up by people
who don't really understand the concepts in play here.
The basic argument is that, sure, evolution can account for small variations, such as
like the finches in the galapagos islands having many specialized variations with differences
to things like beak length and width and such, but the idea behind this myth is that these
small changes can't alter an entire species - a finch will always be a finch, and can
never have larger adjustments take place over time because evolution only works on a small scale.
Well... that's the thing, small changes take
place over time in ways that you get little effects which pile up on top of one another
until you're simply left with something that isn't what it used to be. Some of these changes
are more difficult to understand than others. Instead of fully explaining this myth, let's
actually move into the next myth which furthers the same argument, since we'll be answering
both of these when we cover the next one. And that next myth is the myth of irreducible complexity.
This's an argument which's provided consistently by young-earth creationists and
the argument basically goes like this: there are some changes which are just so large and
fundamentally complex that they can't possibly be broken down into smaller parts that are
simple enough that evolution could ever have been the cause of such.
The big case study that was given for awhile was the argument that the bacterial flagellum
is irreducibly complex - it's a small, little propeller tail type assembly in bacteria that
allows them to essentially swim. The argument here was specifically that it's such an immensely
complex and difficult mechanism to produce, and it's completely useless without all of
it intact, that there's no way it could've been the result of evolutionary processes.
Aaaand this is why creationist "science" isn't science. See, science is when you get to something
and you're like "Huh... I don't know how that could possibly happen. I wonder how I could
find out?" and then you devise tests and figure out ways to study it so that you can understand
it. The creationist "science" basically goes "I don't know, therefore God" and that's the
end of the argument. This doesn't mean that science and creationism
are mutually exclusive - it's quite possible, and even semi-reasonable, that if you had
some omnipotent, omniscient being, that they could very well have known how things would
naturally evolve after setting up the rules for the universe. That's an argument for another
time, but the point is that there's no real conflict between the concept of there being
some sort of deity or even a pantheon of deities and evolution.
But let's get back to this flagellum... I mean, it's really complex... let's face it,
it didn't all just magically appear all at once! Evolution doesn't work that way. So... what happened?
Ah, well... once it was brought up as an example
of irreducible complexity, other scientists were just like "Huh, yanno, that really IS
weird... how DID that happen?" And then they found that the flagellum is
actually comprised of three much smaller, simpler component pieces which all have perfectly
legitimate and valuable uses elsewhere, and it requires almost no effort for those three
to be built on their own independantly of one another, nor for those three to then be
formed together into a whole with minimal alterations. So it turned out the flagellum
wasn't irriducibly complex at all. In fact, we've never found anything which
is irriducibly complex to the point that it couldn't be reasonably explained by evolutionary
processes. Another good example of this is DNA - it's
really complex... and in fact, it needs to also have things like proteins and mitochondria,
which provide more complex mechanical instructions for how to do things with enzymes for example,
and raw power generation. You'd have to have all three of these develop independantly...
so what gives? Well, there's no argument in science that
life began with DNA is the thing - it's not even a reasonable argument. No one's even
postulating that such is the case. Instead, the belief is that the biogenesis of life
on earth (well, there were probably two biogenesis events, actually, in that there are also some
sulphur based microorganism extreemophiles which probably weren't from the same origin
point, but we're still studying that), anyway, the biogenesis on earth would've originated
with RNA, instead of DNA, which kiiiinda sucks at DNA's job. It also sucks at a protein's
job, and the job of mitochondria as well, buuuut the important part is that RNA can
do all of these things independantly by itself, even if not very well. Even more important,
is that RNA uses a simpler sugar molecule than DNA does, and is a single helix chain
instead of a double-helix, making it vastly, vastly easier to be created by chance.
Other highly handy features of RNA are that it's way more reactive than DNA is as it's
built in such a way that it can manage enzymes directly without needing proteins to perform
those actions; this can be bad as enzymes can attach to and damage the RNA or corrupt it...
or they can enhance it and perform the role which DNA uses proteins for instead.
Now this's fine for smaller organisms, but it'd suck really badly for large scale, multi-cellular
creatures like humans. Another semi-handy feature is that RNA's not very stable compared
to DNA so instead of existing for a long period of time, it's created, then used, degrades
and gets recycled very quickly, allowing for a very high rate of genetic mutation, meaning
it can potentially improve itself quicker than DNA can on a cellular level. With shorter, simpler
chains, it's just easier to make and don't require stuff like mitochondria or proteins
at all, but can be used to produce proteins. So it's a handy lil thing, and it's why a
lot of single-celled organisms, like lots of viruses and such, still use RNA instead
of DNA - it's not that effective compared to the later tools, but it can do everything
needed in a very small space. Anyway, most likely life began with RNA, and
then these other things were gradually built up over time and replaced the RNA's functions
one at a time as they were able to, until the RNA just became obsolete when all of its
functions could be better performed by other, newer and more advanced tools, then the RNA
fell to the wayside as a primary source of genetic information and instead was repurposed
to programming amino acids and transferring information for protein production instead
and other tasks now that it was no longer needed to do the job that DNA took over because
the DNA was better at it. So yeah, this's how irriducible complexity
and macro vs microevolution don't really exist in reality. If you don't understand that there
are alternative uses for things and that they can be built up to perform wildly different
tasks, then repurposed later on, you're going to get really confused and it's going to look
like it's impossible to exist. Wings, for example, are normally used for
flight - but they're still useful even before you can fly. Same thing with feathers and
hollow bones. Uh... the velociraptors of the dinosaurs have semi-recently been found to
have had feathers which don't tend to fossilize very well, but we've lately discovered that
they did in fact have these features. So... why? They couldn't fly! Well, those same feathers
let a raptor jump up on top of it's prey, dig its' talons into it's back, and it could
use them for stability, letting it stay latched on and biting and clawing at its' prey without
falling off or getting shaken free. Over time, the feathers grow more pronounced
at being able to perform that action... and the arms grew longer for better stability,
and... oh, hey, then they got repurposed when those same bigger wings and feathers became
large enough to the point that they could be used to glide short distances to
swoop down on prey. And then they got repurposed again into proper flight later on when they
specialized further to become better at gliding, which also just happens to make the wings
better at actual flight as well. Each step wasn't with an end goal of flight,
but rather a more short term different purpose which just happened to also be beneficial
at another task later on after a certain point is all.
So yeah, moving right along! Oh, I accidentally covered a few other myths
without trying to with those examples. Well, those myths were going to be about how
creatures couldn't evolve with DNA, which we covered under the RNA dealie, and the myth
that creationism and evolution can't coexist. They totally can, though whether they need
to or not is another question entirely. There's no reason there COULDN'T be some deity or
pantheon of deities that exist, but there's no absolute need for them to exist either.
That doesn't mean they don't exist, just that we don't need them to explain evolution, but
evolution doesn't disprove their existence either.
Anyway, well let's just get into our final myth since this's a really long video already.
And that myth is... a ridiculous one, but one that does come up surprisingly often - that
evolution violates the second law of thermodynamics. The second law basically is that any time
there's a thermal reaction, entropy increases. Or things just get more random and less organized
over time and new information can't be created without a source of energy to produce such.
The argument basically boils down to the claim that random genetic mutations can't have any
useful or valid information, and can't produce anything new in general, because it would
mean that they're reducing entropy rather than increasing it.
This argument hinges upon the concept that there is no energy source present which is
feeding new energy into the system to allow for increases to occur.
Okay, do me a favour. Go outside. I know, I know, it's anathema to internet geeks. Standard
allergies include fresh air, natural sunlight and social contact. But seriously, just go
outside for a moment, or even to a window if it's during the day.
Now look reaaaaaaaaally hard... is there anything out there which may produce energy?
Anything at all. Something which may just add a bunch of energy to terrestrial plants and animals.
IT'S CALLED THE SUN.
Yes, this argument hinges upon the fact that
the sun doesn't exist. Since that's kiiiinda obviously a ridiculous statement to make,
yeah that's... that's not the case. Life couldn't exist without an external energy
source though, this much is true - without something like the sun, geothermal heating,
or some other form of large-scale energy input, evolution couldn't exist. But we have geothermal
heating, chemical reactions, the sun itself, and so on and so forth.
In a fairly basic example of this, the sun generates heat and light, plants photosynthesize
such into usable energy, and that allows them to use other materials to grow larger and
to potentially alter their genetic code over time.
Even earlier species, like the first single-celled organisms, would have benefitted from the
energy of the sun and geothermal heating, though not in the same way. Most likely, the
biogenesis of life on earth would've begun in a volcanic region with warm water. Ah,
yeah, heat from volcanoes and the sun again would heat the water up, and that would allow
for things like the first amino acids, RNA chains and so on to form. There wouldn't be
much information present at first, but it would be possible to increase that due to
the fact that there would have been those external sources of energy to that first single
celled organism, allowing it to grow more complex over time.
So yeah, anyway, basically we needed to cover this stuff before we got into the actual evolutionary
processes in terms of world design because we're going to be looking back on a lot of
these same principles in the future and it's just easier to get them mostly out of the way now
so we can see them put into use without having to explain each one later on as they come up.
There are some other concepts we'll need to
include eventually, but those will be more easily explained by walking through the creation
of an example ecosystem within the world design process. Stuff like how life will always find
a way to eventually make use of a food source - so long as a food source exists, sooner or later
something will find a way to exploit it, which means ecosystems naturally evolve
to build multiple tiers of different creatures and plant types - you will pretty much always
get some combination of plants, prey, predators, parasites and carrion feeders no matter what
world you create because they naturally produce one another. If one doesn't exist in an ecosystem,
within a few generations there will be one developed because there's simply a food source
available to be exploited. But yeah, that's something we'll be getting
into next time on Playing God(dess). For now there's no real homework, but there will be
soon enough, so get ready for it! Anyway, right now, I'm out. I'll see you next time!
It's funny how we, as adults, unlearn evolutionary concepts.
Kids understand evolution just fine.
I fire my lasers at you!
Oh yeah? Well I have everything shields!
Well then I have everything shields lasers!
Evolution is, essentially, an arms race.
With lasers!
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