Hi. This is Mr. Andersen and the second Life on Earth podcast on classification.
When we're talking about classification we have to talk about this guy, Carolis Linnaeus
or we'll just call him Carl. Carl was a Swedish botanist. And basically what he liked to do
is discover new species, name them, classify them. And so if you're familiar with like
order and class and species, this all comes from Linnaeus. We call this our Linnaean classification
system. And so if we play this through time, way back in 1735 Linnaeus develops this. Basically
he would classify life vegetable or animal. If we play this forward in time we've had
a number of different taxonomists who come up with different systems. So we've added
things like protists, prokaryotes, monerans and now finally we have a three domain naming
system today. And this will probably change in the future. But we have another Carl. Carl
Woese who's come up with this idea of how to classify life. So we've gone Carl to Carl
and changed quite a bit. Especially the technology that we have. But we've also made a huge shift.
Because Carolis Linnaeus didn't believe Darwin was right. He didn't believe in evolution.
And now we build our whole naming system on the idea of natural selection and evolution
over time. And so the goal in classification today is to have monophyletic naming and monophyletic
groups. So what does that mean? Well basically right here we've got a phylogenetic tree.
And so what we want to create is what is called a monophyletic grouping. So if we look at
this group right here, we want this whole group here, all the individuals inside here
to share this common ancestor and to not leave anything out. In other words we want to make
sure that we're putting, you know, if birds were to be classified as mammals, that would
screw everything up. So we want it to be in one big group. And we want our naming system
to kind of reflect that. And so as we go from this huge tree of life. So if we go from this
first tree of life where we branch it off to bacteria and archaea and eukarya, we want
this naming system to keep going along with this phylogenetic tree of life. And so ironically
the Linnaean system is used to basically classify life according to the work of Darwin. And
so the problem with that is this. If you look at these two plants. This plant here and this
plant here, Linnaeus would have picked both of those up and said, let's classify those
in the same group because the look a lot alike. But the reason they look a lot alike is they've
convergently evolved. In other words they look the same because they fill the same niche.
Or they fill the same role. If we were to look at this pill bug and this pill millipede
you would say they're classified the same. Let's put them in the same group. However,
they're not related at all. They just look the way they do because of the environmental
pressures that make them look that way. And so that's why Linnaeus had a problem. That's
why scientists for a long period of time have had this problem of grouping individuals according
to the way they look. But the rescuer in this whole thing is DNA and genetic material. In
other words we can look at the the DNA of individuals now. Or in this case we're looking
at, this is two dimensional protein electrophoresis. So we're actually separating proteins. And
so we can look at how similar they are and we can see oh, we're more related to a chimpanzee
then a gorilla and an orangutan. And we can even lay out this phylogenetic tree. Once
we've done that, then classification kind of comes right after that. And so basically
the system of classification is giving each organism on our planet a specific name. And
that name is based on binomial nomenclature. So all living things get two names. A genus
and a species. And so you are Homo sapiens. But a wolf is Canis lupus. So what is this
organism right here? Well you might know this as a cougar or a mountain lion or a puma.
You might know it by one of the 40 different names that it has. And I'm not even including
different languages. And so the problem in science is coming up with a standard naming
system. So in the literature when we're talking about a mountain lion, we know exactly what
we're talking about. And so basically this is the way we classify life. We classify life
from life all the way down to species. And so if you've been in biology for awhile, you
know this. I remember this in my head. Dumb King Phillip came over from German soil. So
I can just say that without reading it here, because I've learned, we'll pretend that this
is dumb King Phillip came over from German soil, is just a way for your to memorize all
the different divisions in the classification system. And so that is domain, kingdom, phylum,
class, order, family, genus, species. And so when we talk about the scientific name
then we're talking about this last two right here. And so let's go through the mountain
lion. So it's alive. So it's classified as a living thing. It's in the domain eukarya.
That means it has you know a nucleus inside that. It's an animal. It's a chordate, so
it's got a spinal cord. It's a mammal. It's a carnivore. It's a cat. And it's Puma concolor.
And so that's going to be it's scientific name. So when we write out what is this? All
scientists are going to write this out as Puma concolor. And so that is it's scientific
name. Or we might just abbreviate it as this in the literature. We also, I can't do this
in my writing, have to write this in italics to represent it as that. And so all living
things on our planet that we've identified as a species is classified according to this
system. Now the problem right now is that the biodiversity on our planet is really depleting
quickly. And so we have species going extinct faster than we can actually name them. But,
what is the naming system? It's based in latin. And there have been some kind of changes on
that over time. But basically that's our classification system. Again it reflects evolution. It tries
to be monophyletic. But again it's a science that's rapidly changing as technology kind
of catches up with it. And I hope that's helpful.