Question That's Been Bugging Me About Biological Classification

[The Rose Dragon]

For the last half hour or so, at least.

How do we know that Homo sapiens is the only sapient species in the Homo genus? Do we even know that is true? If we don't, why did we name ourselves Homo sapiens?

Also, if there are other sapient species in the universe, would we give them the species name sapiens?

Also, what are subspecies? How do they work? Why are they defined differently than species proper?

Also, why didn't I pay enough attention to the classes where we covered all this stuff?

[Ravens_cry]

Well, for one, don't take the names too literally. A giraffe isn't a cross between a camel and a leopard, despite its taxonomic classification, Giraffa camelopardalis and Gathidium vaderi (http://www.starwars.com/kids/explore/reallife/f20060202/) is not a dark lord of the Sith, as cool as that would be.
And since they died out before any written human record, we really have no idea what their mental processes were like.
We do know that while Homo erectus had a good grasp of fire and that Homo neanderthalensis had some pretty good stone tools and possibly buried their dead, the whole idea of art for arts sake seems to have almost completely started with us Homo sapiens, though there may be some crude exceptions (http://news.bbc.co.uk/2/hi/science/nature/3256228.stm).

[The Rose Dragon]

Nitpick: when using the taxonomic name of a species, the genus name is always capitalized. :smalltongue:

EDIT: I know this, because I used a non-capitalized c when referring to C. elegans and lost marks for it.

[Ravens_cry]

Nitpick: when using the taxonomic name of a species, the genus name is always capitalized. :smalltongue:
Thanks for the heads up, it's the little things that make the difference.:smallsmile:
But my point still stands, even if my formatting was in error.

[hamishspence]

Also, what are subspecies? How do they work? Why are they defined differently than species proper?

While there are grey areas in classification (what might be species-level differences for one group are subspecies-level differences for another), the general principle, is that when two subspecies hybridize, there are no fertility problems, either in the first generation, or after several generations.

There are typically some physical differences between subspecies (bird subspecies having slightly different sizes, markings, or both).

[The Rose Dragon]

There are typically some physical differences between subspecies (bird subspecies having slightly different sizes, markings, or both).

Aren't there physical differences intraspecies anyway? At least in multicellular organisms. What separates two subspecies from one species?

[raitalin]

The classification system has a LOT of problems, only beginning with the difficulty of parsing possible human ancestors.

[Eldan]

Aren't there physical differences intraspecies anyway? At least in multicellular organisms. What separates two subspecies from one species?

Quite honestly, taxonomists have tried to come up with a good, solid difference between "intraspecific variation" and "subspecies" for a long time now. They don't have one. It basically boils down to "it's quite a bit different, but not two species yet."

Of course, you start to really run into trouble once you ask for a good definition of "species". And everything above that, i.e. genera, classes, families and so on are really iffy.

As for Neanderthals and other early Homo genera: it seems that they show all signs of at least some intelligence: large brain/body size ratio, probably large neocortex, use of fire, stone, wood and bone tools...
And if you look at chimpanzees today, you can't really say that they aren't sapient either.

[Pyrian]

Yeah, if you want hard-and-fast definitions without exceptions Biology is probably not the science for you.

[Eldan]

Mhm.

The classical definition of species more or less was "can have offspring which remain fertile over several generations".

Then you run into totally different looking plants which hybridize happily (i.e. Poa Annua, often used for golf courts and stadia, is a natural hybrid), asexual species, clonal species, micro-organisms mostly reproducing by fission...

[T-O-E]

How do we know that Homo sapiens is the only sapient species in the Homo genus? Do we even know that is true? If we don't, why did we name ourselves Homo sapiens?

Homo egotis may have been a better fit.

[Serpentine]

How do we know that Homo sapiens is the only sapient species in the Homo genus? Do we even know that is true? If we don't, why did we name ourselves Homo sapiens? Well, we're the only Homo still alive, for starters. More specifically, we don't. The sapiens more means "wise" than our "sapient", I believe, and it is no more considered to mean we're the only sapient species in this genus than... well, any other example you'd like to give.
Homo egoist may be more appropriate, for a variety of reasons.
Also, if there are other sapient species in the universe, would we give them the species name sapiens? We may do so, but we won't necessarily. Species names are only very loosely regulated. Basically, the person who discovers them get to name them - there's a few things named after cartoonist Gary Larson, and it means nothing except the discoverer/namer was a fan of his work.
The species name is nothing but descriptive, if that. Don't look too much into them.
Also, what are subspecies? How do they work? Why are they defined differently than species proper? The definition of "species" is still under debate. Ideally, a species is a group of organisms that successfully breed with each other but not other groups of organisms. However, there are many exceptions to this that we still consider species. There are other definitions of species. I recommend just looking it up in Wikipedia to get an idea.
Subspecies are populations that are capable of breeding with other populations, but are sufficiently different, or couplings sufficiently rare or difficult, or whatever, to be considered distinct. Basically, they're somewhere between "different species" and "same species". I believe races are more or less different again, more regional-specific varients of a species.
Ecologically speaking, a subspecies my represent: a population that is in the process of becoming a new species; a population that at one point was under the right conditions to speciate, but then had those conditions removed; a distinct population with contact with other populations rare enough to keep them distinct but often enough to prevent total differentiation; or possibly some other situation.
Also, why didn't I pay enough attention to the classes where we covered all this stuff? Looking at ladies?

[The Rose Dragon]

Looking at ladies?

I sit at the row closest to the instructor, though. It is highly unlikely I could look back without twisting my neck in a painful manner.

[Flame of Anor]

Also, remember that modern humans are not the only Homo sapiens. Neanderthals were Homo sapiens neanderthalensis, and we are Homo sapiens sapiens.

So, Rose Dragon, what were you writing about nematodes?

[The Rose Dragon]

Gah. Now you've confused me even more by introducing the third question into the first question.

[Coidzor]

I sit at the row closest to the instructor, though. It is highly unlikely I could look back without twisting my neck in a painful manner.

So you have a neck like an owl? Cool.

[Ravens_cry]

Also, remember that modern humans are not the only Homo sapiens. Neanderthals were Homo sapiens neanderthalensis, and we are Homo sapiens sapiens.

So, Rose Dragon, what were you writing about nematodes?
This will likely only add to Rose Dragons confusion but, depending on which anthropologist you speak to, Neanderthal was its own species, Homo neanderthalensis.

[Serpentine]

Yeah, that's definitely something to remember: compared to a lot of other parts of science, cladistics and phylogeny and the like are more like arts. Life is very much more a continuum than definite delienations (as would be expected from evolution :smallwink:), and all/most categories are artificial - that is, determined by man, rather than naturally occurring.

[The Rose Dragon]

I would probably be much more receptive to the world if man was a completely logical creature. Ah well, I guess there is no perfect world for anyone.

[golentan]

This will likely only add to Rose Dragons confusion but, depending on which anthropologist you speak to, Neanderthal was its own species, Homo neanderthalensis.

Well, it is hard to judge given the similarity of the genomes but the absence of direct observation whether Homo sapiens sapiens and Homo sapiens neanderthalis where interfertile.

Rose: A subspecies is generally when you have a distinct phenotype within a population which is interfertile with other subspecies. This does raise merry hob under some circumstances, but for the most part you can eyeball it. The thing is you're asking questions about Taxonomy, the single least precise item in biology. One that can't neatly be described by chemical formulae or mathematical equations. One where everything is having sex with everything else that's not eating it (okay, not quite, but...), often with an unexpectedly high rate of success.

[Serpentine]

Man might (arguably) be logical, but life certainly isn't :smallwink:

[golentan]

Man might (arguably) be logical, but life certainly isn't :smallwink:

Man is not logical. Life is not logical. The rules governing both, however, are.

It's easier to create a logical system than an illogical one, so that should tell you the evolutionary value of logic untempered by other things...

[hamishspence]

It sometimes happens that groupings, when they turn out to be more different than first thought, get split up.

Originally, there were two notable species of Brachiosaurus- Brachiosaurus brancai and Brachiosaurus altithorax.

Later, Brachiosaurus brancai turned out to be different enough, to be considered its own genus- Giraffatitan brancai.

Similarly, the Carrion Crow and the Hooded Crow were originally thought to be different subspecies of the same species Corvus corone- C. c. corone, and C. c. cornix. Now, they are considered different species: Corvus corone, and Corvus cornix.

[Pyrian]

Well, it is hard to judge given the similarity of the genomes but the absence of direct observation whether Homo sapiens sapiens and Homo sapiens neanderthalis where interfertile.Genomic evidence suggests they could and did interbreed.

http://www.sciencenews.org/view/generic/id/59585/title/FOR_KIDS_Your_inner_Neandertal

[Serpentine]

What I understand to be the currently most widely accepted theory is that we "bred out" the Neandertals.

[Sereg]

For the last half hour or so, at least.

How do we know that Homo sapiens is the only sapient species in the Homo genus? Do we even know that is true? If we don't, why did we name ourselves Homo sapiens?

We don't. However, this is irrelevant for classification purposes. The rules don't require naming according to a unique feature. Merely that the name is consistent and hasn't been used for something else.


Also, if there are other sapient species in the universe, would we give them the species name sapiens?

It is allowed as the specific epithet (the second part of the species name) may be repeated as long as the repition is for a new genus. However, the scientist whom first describes the species is allowed to choose and may use any name as long as it follows the rules.


Also, what are subspecies? How do they work? Why are they defined differently than species proper?

They are merely a variant of the species. If you do not specify the subspecies, it suggests that you are reffering to all variants of the species. When you say "species proper" if you are reffering to the most common varient, then it would also be a subspecies.


Also, why didn't I pay enough attention to the classes where we covered all this stuff?

Um, I guess that you had other things on your mind.

One thing that you should remember is that scientist disagree with each other on classification (like everything else) a lot. It's pretty much the way that science works. Therefore, reclassification occasionally happens.

@Serpentine: It appears that there was some interbreeding with Neandertals, but not enough to breed them out. Climate change and competition are believed to have played far greater roles. Neandertals were incapable of using ranged weapons, for example. (Note: this was not because they were unintelligent, but because they lacked the dexterity).

[Ichneumon]

Sereg is right.

Also, as far as I always understood, subspecies = race. The fact is, the complete classification is mostly based on guesswork. Species is the only thing we are, somewhat, sure about. Subspecies/race, Genus, family etc are not "real" or "absolute". They're human creations to try to classify different animal/plant groups.