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Talking Snakes: A Cautionary Tale

and they don't understand that there has never been a common ancestor of all and only the monkeys

This fact though -- that monkeys are paraphyletic -- argues in favour of (not against) the view that the common ancestor of monkeys and apes was itself monkey-like...

If you think about when the "ape traits" must have evolved, it would be after the new-world monkeys had already diverged away. The common ancestor of monkeys and apes wouldn't have had them, but must have had those traits common to both old and new-world monkeys. It itself has to be basically a monkey.

(I drew out a phylogenetic tree for this but couldn't get it to format, alas...)

Innate Mathematical Ability

That's also interesting... I think the two ways of looking at it are equivalent, i.e. any pattern that satisfies one should also satisfy the other. (Only because the XOR pattern works both vertically and horizontally.)

Rationality Quotes November 2013

The enemy of the enemy of my enemy is my enemy.

Harrap's First Law

Causal Diagrams and Causal Models

won't have the problem of being acyclic

Should that be "cyclic"? I take it from Richard's post that "acyclic" is what we want.

Can the Chain Still Hold You?

It should be pointed out here that biological genuses, families, orders, and so on do not exist.

Yes, this is true of course.

Can the Chain Still Hold You?

What I was saying is that humans are the only living member of the Homo family

So was the claim "Humans are the only single species mammal" simply a claim that humans are the only mammal with their own genus? That's certainly not true, see http://en.wikipedia.org/wiki/Category:Monotypic_mammal_genera

The reproductive isolation can be genetic, or it can be simply geographical or habitual.

This is probably not relevant to our point, but Futuyma (2005) Evolution p356 defines reproductive isolation as "reduction or prevention of gene flow between populations by genetically determined differences between them" - i.e. it's not enough that they are geographically separated.

homo sapiens exist in one giant gene pool

This just seems to be a claim that the population size of our species is quite large. There are other species of mammal with large populations. Again, the relevance of any of this to sex-determination is rather doubtful.

Can the Chain Still Hold You?

None of the things you mention are likely to affect the sex determination system.

the only single species mammal.

The only what?

Can the Chain Still Hold You?

Could you direct me to the comparative analysis of Mammalian reproductive systems that discusses hermaphrodites in other species?

What I meant was that we can think about other mammals ourselves, and note that no other mammal species has hermaphrodites at significant frequencies. I had no specific research in mind.

there would be a decent size population of hermaphrodites able to develop a stable social station; if there were a stable hermaphrodite community their genes would spread

This depends both on a genetic cause, and also on hermaphrodites having equal fitness to males and females.

I think the intentional elimination of hermaphrodites has made a huge impact on the demographic of humanity, do you disagree?

Yes, I disagree, for the reasons I've stated. Other mammals have had no "intentional elimination", yet hermaphrodites remain at very low levels. So "intentional elimination" isn't the reason for the very low levels.

Also I don't think you can use the fact other gonochronistic mammals have not developed more sexes as a reason why humans would not.

Of course I can; humans aren't particularly special, at least not in relevant ways.

Parapsychology: the control group for science

I don't think there's a prejudice against replying to old posts around here...

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