Hi, Stephen.
Stephen Push writes:
I think almost everyone is altruistic to some degree.
Probably so. My point is that the altruism that everyone shows to some degree is pretty trivial evolutionarily speaking. Donating to a charity, volunteering for a community center, giving your brother the last piece of pie or letting your aging mother-in-law live in your basement are not really evolutionary sacrifices, so they’re moot points for this discussion.
Only more extreme versions of altruism (i.e., altruism involving the actual sacrifice or risk of one’s life or reproductive capacity) will have real implications for evolution. Any risks short of that could easily be outweighed by the benefits received from social living, so they can hardly be seen as challenges to evolution.
I’m certain that absolute altruism, or the willingness to sacrifice one’s life for someone else’s life, isn’t tested commonly enough to really know how prevalent it is among humans, but I suspect that it’s a lot lower than movies and books would have us believe.
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Stephen Push writes:
It's almost certainly not a single gene. The trait is probably affected by many genes, expressed to varying degrees in various situations, and enhanced or muted to a great extent by culture and learning.
Obviously. But, it’s just easier to consider conceptual problems in genetics when we assume that everything is due to a single gene.
The thing is that the trait may not be encoded on genes at all: it may be a side effect of traits that
are encoded on genes. For instance, a putative gene for cooperative behaviors and a putative gene for adrenaline-craving could easily intertwine to create an altruistic behavior---a hero complex---without the altruistic behavior itself being a distinct gene that evolution could work on directly.
In this case, cooperative behaviors and adrenaline-craving could be selected for in combination, but, selecting for the combination will also result in some individuals in the population that will have only one trait or the other. So, the heritability of the altruistic behavior would be somewhat low, which dampens the ability of evolution to work on it.
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Stephen Push writes:
Altruism need not require detailed risk calculations. It could be nothing more than a compulsion to help others that, in some situations, overcomes self-protecting drives such as fear or hunger.
No, there need not be a detailed risk calculation---at least, not one that is selected for with any precision. That was my point.
Selection is highly probabilistic, and it works on the level of a
population: so, while a trait of altruism may generally improve life for the individual due to the social benefits received in return, the same trait of altruism may occasionally drive some individuals to sacrifice themselves.
But, the question then becomes whether the beneficial effects of a trait for altruism outweigh the risks of martyrdom for
most individuals who have the trait. If only a small percentage of altruistic beings really make the ultimate evolutionary sacrifice, while, for the rest, the benefits outweigh the sacrifices, it’s hard to see how natural selection would work against the altruistic trait.
-Bluejay (a.k.a. Mantis, Thylacosmilus)
Darwin loves you.
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