Let me address those reasons for strict sexuality

I thought about both of those reasons. And I'm not satisfied with either.

First of all, self-fertilization. It shouldn't be hard to avoid making self-fertilization an option, while still maintaining the option of being a hermaphrodite.

But even so, self-fertilization isn't bad for the reasons that most people think. True, were one of us to self-fertilize, the baby would be likely to have a horrible disease and die. But the problem of self-fertilization resembles inbreeding. As I recall, a population with routine inbreeding is supposed to settle on a steady state with the exact same number of people dying due to genetic disorders as a population with little inbreeding. The genes that would be so lethal for us get bred out of the population. The really bad stuff happens when you take a population without much inbreeding and then inbreed.

Certainly inbreeding is common among great apes. They live in small bands and most matings being within the band, with occasional matings between bands. In fact homo sapiens is believed to have followed a similar pattern for most of its history.

However the more subtle trap is the need to keep genetic diversity up. There is [link|http://www.skyaid.org/Skyaid Org/Medical/scent_of_a_man.htm|evidence] that humans have a mechanism to allow us to select mates whose immune system differs from our own. This gives our offspring good odds of having immune systems that can respond to a wide variety of challenges.

So there is a benefit to avoiding self-fertilization. But I'm dubious that you need to cut the pregnancy rate in 2 to do it.

Now the two parent issue. It is true that humans play a delicate dance around childcare issues. Babies do better with 2 parents. From dad's point of view it is often passable for someone else to raise your kids, but you certainly don't want to raise someone else's. Moms would like to have kids with the best dads possible, but also would really like to have help with childcare (which means convincing someone that this is their kid). And in this set of incentives I've stated the roots of a whole series of conflicting desires and drives in humans.

Similar games are played in many other species, particularly among birds.

However most species of mammals limit parenting to the mother. When you go back to reptiles, amphibians and various kinds of fish, most species have little to no active childcare at all. Yet they mostly use sexual reproduction. I don't see the need to have dual parents as a possible cause for this. (And you can't say, "They evolved it because it would be needed later" - evolution always addresses current issues, not possible ones down the road.)

So I see "avoiding self-fertilization" as dubious but not completely implausible. But I see the need for 2 parents in childcare as being an untenable explanation.

Cheers,
Ben

Post #193,386 by ben_tilly 2/7/05 11:15:06 AM Reply	Let me address those reasons for strict sexuality I thought about both of those reasons. And I'm not satisfied with either. First of all, self-fertilization. It shouldn't be hard to avoid making self-fertilization an option, while still maintaining the option of being a hermaphrodite. But even so, self-fertilization isn't bad for the reasons that most people think. True, were one of us to self-fertilize, the baby would be likely to have a horrible disease and die. But the problem of self-fertilization resembles inbreeding. As I recall, a population with routine inbreeding is supposed to settle on a steady state with the exact same number of people dying due to genetic disorders as a population with little inbreeding. The genes that would be so lethal for us get bred out of the population. The really bad stuff happens when you take a population without much inbreeding and then inbreed. Certainly inbreeding is common among great apes. They live in small bands and most matings being within the band, with occasional matings between bands. In fact homo sapiens is believed to have followed a similar pattern for most of its history. However the more subtle trap is the need to keep genetic diversity up. There is [link\|http://www.skyaid.org/Skyaid Org/Medical/scent_of_a_man.htm\|evidence] that humans have a mechanism to allow us to select mates whose immune system differs from our own. This gives our offspring good odds of having immune systems that can respond to a wide variety of challenges. So there is a benefit to avoiding self-fertilization. But I'm dubious that you need to cut the pregnancy rate in 2 to do it. Now the two parent issue. It is true that humans play a delicate dance around childcare issues. Babies do better with 2 parents. From dad's point of view it is often passable for someone else to raise your kids, but you certainly don't want to raise someone else's. Moms would like to have kids with the best dads possible, but also would really like to have help with childcare (which means convincing someone that this is their kid). And in this set of incentives I've stated the roots of a whole series of conflicting desires and drives in humans. Similar games are played in many other species, particularly among birds. However most species of mammals limit parenting to the mother. When you go back to reptiles, amphibians and various kinds of fish, most species have little to no active childcare at all. Yet they mostly use sexual reproduction. I don't see the need to have dual parents as a possible cause for this. (And you can't say, "They evolved it because it would be needed later" - evolution always addresses current issues, not possible ones down the road.) So I see "avoiding self-fertilization" as dubious but not completely implausible. But I see the need for 2 parents in childcare as being an untenable explanation. Cheers, Ben I have come to believe that idealism without discipline is a quick road to disaster, while discipline without idealism is pointless. -- Aaron Ward (my brother)
Post #193,492 by daemon 2/7/05 6:40:18 PM Reply	well if I were a hermaphrodyte I would never leave the house but seriously, it wouldnt work because there would still need to be a symbiotic relationship of some sort for late term and 20 days or so after birth when the pregnant parent is not as mobile and is more vunerable. There would have to be a division of work with something. Prior to late term and 20 days after labor a female is as capable in a hunter gatherer society of doing just that. The current design of slot/tab with chemical urgings to continue on seems to be working well. regards, daemon I love her dearly, far beyond any creature I've ever known, and I can prove it, for never once in almost seventy years of married life have I taken her by the throat. Mind you, it's been a near thing once or twice. George Macdonald Frasier Clearwater highschool marching band [link\|http://www.chstornadoband.org/\|http://www.chstornadoband.org/]
Post #193,493 by admin 2/7/05 6:48:57 PM Reply	Don't confuse "hermaphroditic" with "flexible"... Regards, -scott anderson "Welcome to Rivendell, Mr. Anderson..."
Post #193,500 by ben_tilly 2/7/05 8:15:47 PM 2/7/05 8:17:54 PM Reply	It works for nematodes And just try to get a bull sea lion to do anything other than sleep or breed. My point being that specifics of how things work for homo sapiens don't necessarily apply to the animal kingdom as a whole. Cheers, Ben I have come to believe that idealism without discipline is a quick road to disaster, while discipline without idealism is pointless. -- Aaron Ward (my brother) Edited by ben_tilly Feb. 7, 2005, 08:17:54 PM EST Expand All History
Post #193,503 by ChrisR 2/7/05 8:36:32 PM Reply	Y'all take all the mystery out of procreation Where's DRL when you need him to lively up a discussion on the difference in the sexes? :-)
Post #193,504 by ben_tilly 2/7/05 8:38:19 PM Reply	Out drinking? Reading Jung? Casting a horoscope? I have come to believe that idealism without discipline is a quick road to disaster, while discipline without idealism is pointless. -- Aaron Ward (my brother)
Post #193,555 by mmoffitt 2/8/05 9:41:10 AM Reply	OT: Where TH is Ross anyway? bcnu, Mikem Eine Leute. Eine Welt. Ein F\ufffdhrer. (Just trying to be accepted in the New America)
Post #193,558 by Yendor 2/8/05 9:59:26 AM Reply	Re: OT: Where TH is Ross anyway? [link\|/forums/render/content/show?contentid=184215\|Read all about it] -YendorMike "They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety." - Benjamin Franklin, 1759 Historical Review of Pennsylvania
Post #193,564 by mmoffitt 2/8/05 10:05:38 AM Reply	Ah. Thanks. Missed that. bcnu, Mikem Eine Leute. Eine Welt. Ein F\ufffdhrer. (Just trying to be accepted in the New America)
Post #193,561 by Another Scott 2/8/05 10:00:09 AM Reply	Atlanta, IIRC. ... Oh, you mean. Well, he ran away. :-(
Post #193,570 by Nightowl 2/8/05 10:23:20 AM Reply	I agree Ross would definitely add another dimension to this convo. I hope he comes back soon. Brenda Nightowl >8# "The people of the world having once been deceived, suspect deceit in truth itself." -- Hitopadesa 600?-1100? AD, Sanskrit Fable From Panchatantr
Post #193,506 by daemon 2/7/05 9:05:16 PM Reply	dont have to try, they fight real well (bull sealions) I think what we should be looking at is hominids in general and humans in particular. There has been many methods of running a herd of humans, most depend on the geographical complexity of the are they live in. regards, daemon I love her dearly, far beyond any creature I've ever known, and I can prove it, for never once in almost seventy years of married life have I taken her by the throat. Mind you, it's been a near thing once or twice. George Macdonald Frasier Clearwater highschool marching band [link\|http://www.chstornadoband.org/\|http://www.chstornadoband.org/]

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