Patri's Peripatetic Peregrinations - Would you lay down your life for your brother?

Would you lay down your life for your brother?

Jul. 16th, 2004 at 12:17 AM

I should hope not. Your requirements should be 2 brothers, 8 cousins, 32 second cousins, or 128 third cousins...

(based on a quip by JBS Haldane, old to the world but new to me. He also has an excellent piece on the implications of square-cube laws for biology, written in 1928.)

Mood: sleepy
Music:Sarah Mclachlan-Fumbling Towards Ecstasy-Circle

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songmonk wrote:

Jul. 16th, 2004 12:51 am (UTC)

Fascinating

Excellent readings.

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herooftheage wrote:

Jul. 16th, 2004 04:35 am (UTC)

Now of course, the case is not nearly so neat. Suppose you're impotent, and your brother is not. This is one explanation of why grandparents start preferring their grandchildren to their children, though not the only one, of course. (If $1 spend on a grandchild has three times the effect it does spent on the child, for example, grandpa should in fact spend it on the grandkid.)

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gustavolacerda wrote:

Jul. 17th, 2004 04:51 am (UTC)

I know where these numbers come from (they come from the probabilities that the person has a rare gene given that you have it), but when you consider that the human race is "inbred", and that your brother actually has >99% of the same genes as you, then why shouldn't his life be worth 99% as much as yours? Likewise, the life of a worm should be worth 30% as much as yours. Why is this not the case?

Why should those few variation genes be more selfish than the genes that we all share?

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patrissimo wrote:

Jul. 20th, 2004 11:15 am (UTC)

well

Genes that everyone has wash out of the equation when you compare to 1 person. If I have the option of me dying or my brother dying, both options result in exactly one copy of all the genes we both definitely have (ie that were on all parental chromosomes at that locus) being in the world. So that's not relevant to my choice, when comparing to one person. What matters is the fate of genes that may be different. Since there's only a 50% chance that each of these genes are shared by my brother, and 100% chance that each is shared by me, 1 brother is not enough.

But you have a good point that when it comes to *two* brothers, now if they die there is only 1 copy of each gene we share, and if I die and they live there are 2 copies...hmm....perhaps you could get around this by saying that genes care not about their absolute number, but about their proportion in the gene pool? Then genes that everyone has would be irrelevant.

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gustavolacerda wrote:

Jul. 20th, 2004 11:25 am (UTC)

Re: well

perhaps you could get around this by saying that genes care not about their absolute number, but about their proportion in the gene pool?

This would be the case if there is a limiting factor... for example, if we are all competing for the same resources.

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Would you lay down your life for your brother?

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