Fish? No Such Animal!

[Sorcerer]

Who are you quoting?

Arne, post 6.

 

[Fraggle Rocker]

Is that a very obscure joke relating to Latin declensions?

Of course: avis/aves, etc.

You are a rara avis in terris nigroque simillima cygno, Fraggle.

Then perhaps we are both rarae aves. Sorry, my Latin doesn't cover the inflected words between terris and cygno.

. . . . whom we may still sensibly call "Mr Gould" even though he is dead.

That's common practice in American English--although we still use the period after Mr. Do you guys--oops, "blokes"--have a special honorific for people who are dead? "The late Mister Gould"?

If you even want to call it a joke. It's not like Fraggle to misread things though.

I make my share of mistakes. But yes, it was a joke, built on the assumption that an obviously well-educated Brit would have been taught basic Latin in his childhood--and/or recognize the Latin plural paradigms in English, e.g., synopsis/synopses.

Humans of the same sex are 99.9% genetically identical. There is extremely little variation between human geographical populations and most of the variation that does occur is in the personal level within local areas, and not between populations. Of the 0.1% of human genetic differentiation, 85% exists within any randomly chosen local population, be they Italians, Koreans, or Kurds. Two randomly chosen Koreans may be genetically as different as a Korean and an Italian. Any ethnic group contains 85% of the human genetic diversity of the world. Genetic data shows that no matter how population groups are defined, two people from the same population group are about as different from each other as two people from any two different population groups." -- I've seen this stat many times and it seems to me that it might be flawed. There may be only a few genes that influence the things that define what we call race, primarily size, skin colour, facial features, things like that. It doesn't mean that racial differences are important, just that we notice them.

I don't understand why you think the statistic might be flawed. It is indeed widely repeated. I have seen it in such august and carefully reviewed milieux as exhibits in the Smithsonian.

Remember that Homo sapiens underwent a population crash around 60KYA--the cause of which is yet to be determined--leaving about 10,000 people to repopulate Africa and then the rest of the planet. I can't find the data right now, so it might have been 10KY earlier and a somewhat smaller remaining population.

Regardless, it was members of the San tribe (or "Bushmen") who migrated out of Africa both times, establishing both the Native Australian population around 70KYA and then the rest of our ancestors around 60KYA. So we are indeed descendants of an extremely small gene pool. The San still exist (although the desertification of northern Africa pushed all of its inhabitants southward so they now live down in the continent's southeastern region) and they are still obviously close relatives to all non-African humans. We're talking about 6 billion non-African people who are all descended from a few hundred adventurers--many of whom surely died on the trek before having children!

Also bear in mind that (at least today) the genetic trait to which we give the highest importance in identifying "race" is skin color. This is controlled by the amount of melanin in the skin, which evolves rather quickly as a tribe migrates to a region with more or less intense sunshine. E.g., the dark-skinned Bengalis and the light-skinned Lithuanians are Eastern Indo-Europeans separated only by 3-4 thousand years of migration in opposite directions.

Skin color is the trait that we can see from the greatest distance, so it's a powerful identifier.

 

[lpetrich]

To address this question, I'll introduce some taxonomic jargon. A taxon is...

• Monophyletic -- it includes all descendants of some organism, and no other organisms.
• Polyphyletic -- it includes more than one monophyletic taxon without being monophyletic.
• Paraphyletic -- it is a monophyletic taxon minus some descendants of its shared ancestor.

Let's now see about fish, which we can call Pisces Linnaeus 1758. It is monophyletic if one ignores Tetrapoda, the land vertebrates and their aquatic descendants. Since members of Tetrapoda are descended from a member of Pisces, we conclude that Pisces is paraphyletic. It may be defined as Vertebrata - Tetrapoda, where both Vertebrata and Tetrapoda are monophyletic.

So far so good. But over the last half century, a school of thought about taxonomy has emerged, cladistics. It states that the only legitimate taxa are monophyletic ones, meaning that Pisces is thus illegitimate, and that there is thus no such thing as a fish.

However, Pisces is a convenient taxon for identification, like various other commonplace paraphyletic taxa, like reptiles, invertebrates, non-flowering plants, protists, etc.

Some polyphyletic taxa are also convenient for identification, like flying animals, land animals, worms, trees, etc.

Such paraphyletic and polyphyletic taxa are sometimes called grades of organization instead of clades.

 

[Sorcerer]

To address this question, I'll introduce some taxonomic jargon. A taxon is...

• Monophyletic -- it includes all descendants of some organism, and no other organisms.
• Polyphyletic -- it includes more than one monophyletic taxon without being monophyletic.
• Paraphyletic -- it is a monophyletic taxon minus some descendants of its shared ancestor.

Let's now see about fish, which we can call Pisces Linnaeus 1758. It is monophyletic if one ignores Tetrapoda, the land vertebrates and their aquatic descendants. Since members of Tetrapoda are descended from a member of Pisces, we conclude that Pisces is paraphyletic. It may be defined as Vertebrata - Tetrapoda, where both Vertebrata and Tetrapoda are monophyletic.

So far so good. But over the last half century, a school of thought about taxonomy has emerged, cladistics. It states that the only legitimate taxa are monophyletic ones, meaning that Pisces is thus illegitimate, and that there is thus no such thing as a fish.

However, Pisces is a convenient taxon for identification, like various other commonplace paraphyletic taxa, like reptiles, invertebrates, non-flowering plants, protists, etc.

Some polyphyletic taxa are also convenient for identification, like flying animals, land animals, worms, trees, etc.

Such paraphyletic and polyphyletic taxa are sometimes called grades of organization instead of clades.

Where do the prophylactics figure in this scheme?