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0 pointsthaumasiotes5y ago0 comments

> but for Homo sapiens that "other group" would be of a different species and we thus we shouldn't be able to produce fertile offspring with them.

That's one definition of "species" (specifically, it's "the biological species concept"), but like all the other definitions, it doesn't work and does not correspond to most usage of the term. You can read modern genetic work discussing how homo sapiens interbred with hominids of other species. You can also observe how easily different species interbreed today, like wolves (canis lupus, obligatory pack animals) and coyotes (canis latrans, solitary).

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Groxx5y ago

It also wouldn't surprise me if "can reproduce with" isn't a transitive property (edit: actually, I'd be very surprised if it always is. genetic stuff is never that simple). So even if you try to collapse species into that strict definition, you'll still have edge cases that don't fit.

Categories are hard.

bigbubba5y ago

You're right, it isn't necessarily transitive. So called 'ring species' are cases where it isn't.

scarmig5y ago

You don't even have to go as exotic as ring species. Climb up the evolutionary tree through each of your ancestors to some slime creature a billion years ago, and then climb down to your pet dog. Each connected node in that step can interbreed, but you can't mate with Fido.

I guess it's kind of a temporal ring species.

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thaumasiotesOP5y ago

> It also wouldn't surprise me if "can reproduce with" isn't a transitive property

"Can reproduce with" is not a transitive (or even a permanent!) property among individual humans. (For a more general transitivity allowing for the fact that it doesn't make sense to ask whether males can reproduce with males.)

chmod7755y ago

>You can also observe how easily different species interbreed today, like wolves (canis lupus, obligatory pack animals) and coyotes (canis latrans, solitary).

Their taxonomy predates the more modern biological classification systems though. Things have been reclassified before and I expect they will be again.

[A bit of a rant:] Any classification system that can't tell you something about the objects it classifies is objectively useless for anything but naming things. You might as well use a random name generator, draw lines in the sand in geometrically pleasing ways, and pretend it's a "system".

thaumasiotesOP5y ago

> Any classification system that can't tell you something about the objects it classifies is objectively useless for anything but naming things

They are both canis, you know. The difference in species designation tells you very little because that's not a problem that can be solved. It's not an issue of misclassification. The specific designations latrans and lupus tell you a lot.

ithkuil5y ago

Canis is the genus. Even barring classification mistakes, cross-species breeding across genus is not impossible, it's just very less likely to produce viable and/or fertile offspring.

A classic example is the breeding between Equus Caballus (horse) and Equus Asinus (donkey): it works and you get a Mule.

The genetic difference between the horse and the donkey is non trivial, they even have a different number of chromosomes (64 vs 62). Since the offspring gets half of their chromosomes from the father and half from the mother, the mule gets an odd number of chromosomes (63) which clogs the gamete production machine and renders the animal sterile. (See https://genetics.thetech.org/ask/ask225).

Now, dogs and wolves don't have that problem. Does it mean they are same species and that the classification was applied to eagerly?

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Groxx5y ago

Categories are hard.

bigbubba5y ago

You're right, it isn't necessarily transitive. So called 'ring species' are cases where it isn't.

scarmig5y ago

I guess it's kind of a temporal ring species.

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thaumasiotesOP5y ago

> It also wouldn't surprise me if "can reproduce with" isn't a transitive property

chmod7755y ago

>You can also observe how easily different species interbreed today, like wolves (canis lupus, obligatory pack animals) and coyotes (canis latrans, solitary).

Their taxonomy predates the more modern biological classification systems though. Things have been reclassified before and I expect they will be again.

thaumasiotesOP5y ago

> Any classification system that can't tell you something about the objects it classifies is objectively useless for anything but naming things

ithkuil5y ago

Canis is the genus. Even barring classification mistakes, cross-species breeding across genus is not impossible, it's just very less likely to produce viable and/or fertile offspring.

A classic example is the breeding between Equus Caballus (horse) and Equus Asinus (donkey): it works and you get a Mule.

Now, dogs and wolves don't have that problem. Does it mean they are same species and that the classification was applied to eagerly?

1 more reply

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