How Can Programmed Death Be Adaptive?
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Researchers who theorize that aging is the result of damage accumulation have to explain why evolutionary processes fail to select for longer lives by favoring, say, better mechanisms for damage repair. These explanations exist and are generally robust, though there is always some ongoing level of debate over details, such as why we humans live for so long in comparison to other primates or other mammals our own size. Researchers who theorize that aging is an evolved genetic program have the opposite challenge, which is to explain how evolution selects for shorter lives than would otherwise be the case: what is the value of death-assurance mechanisms? Here too explanations exist, are generally robust, and there is an ongoing level of debate over details.

The mainstream consensus of the research community supports the view of aging as damage rather than aging as a genetic program, both from the point of view of molecular biology and evolutionary considerations. It is worth noting that even in a world in which aging is damage accumulation, the world in which I believe we live in, there can still be species that appear to suffer programmed aging on top of that. Salmon are a good example: it's worth looking into what that looks like as a response to external environmental factors.

Here, as a matter of interest, is a paper on the core issue relating to the hypothetical evolution of programmed aging: how can internal death-promoting mechanisms be adaptive for a species? This paper is open access, but note that it has no abstract - you'll have to click on the "Full Text" tab to view it, or alternatively download the PDF version.

Are Internal, Death-Promoting Mechanisms Ever Adaptive?

The idea that self-inflicted organismal death could be adaptive sounds, at face value, absurd. An adaptation is a trait that is suitable (apt) for the current circumstances or environmental challenges, and archetypal examples include traits that promote survival. Natural selection is the mechanism that produces adaptations. In describing natural selection, Darwin (1859) emphasized the struggle for survival: "Two canine animals in a time of dearth may be truly said to struggle with each other which shall get food and live. But a plant on the edge of a desert is said to struggle for life against the drought......". How could an inherited trait that promotes death, rather than survival, possibly be adaptive?

Four categories encompass the major possible evolutionary explanations for the cause of death of an organism. First, death (or an increased probability of death) could inevitably occur despite the efforts or traits of the organism. Second, internal mechanisms that promote death could exist in spite of selective pressure against them. Third, death could occur as a side-effect of a mechanism within the organism that has another function or benefit. Fourth, death could occur because of a mechanism within the organism that evolved explicitly to cause death. This fourth category is the only one in which the mechanism promoting death is an adaptation for promoting death, and cases in this category can only be explained by selection at a hierarchical level other than the organism.

In all categories except the first, we can reasonably expect to see active mechanisms within an organism that promote death. This review was motivated by the observation that diverse organisms apparently have such active, internal death-promoting mechanisms and by the subtle and difficult conceptual issues that understanding the evolution of this kind of trait raises.

Comments

Hey Reason I think you would find this interesting: http://valleywag.gawker.com/andreessen-horowitzs-newest-hire-thinks-death-can-be-d-1490397953

Mr. Srinivasan is the founder of https://www.counsyl.com

If you read through his twitter timeline you will see he linked to the SENS website (amongst programmed aging research, etc).

I think it would be a good idea to directly address and welcome him with a post. We NEED allies like him, specifically allies from the tech community who prioritize biotechnology over "non-living" tech.

Posted by: Johnathan at January 1, 2014 7:13 PM

Just to be clear:

*specifically allies from the tech community who prioritize biotechnology over "non-living" tech in regard to human longevity.

Posted by: Johnathan at January 1, 2014 7:17 PM

@Johnathan: SENS is far removed from programmed aging. It is damage repair, work explicitly based on the idea that aging is damage accumulation, not a genetic program.

I think we're doing to see a lot more attention given to aging and longevity science from the Bay Area venture community in the future. It has been brewing for a time, but Google's public commitment to Calico will greatly accelerate the process - all the people who care deeply about only holding public positions that have mainstream support can now feel comfortable talking about extending human life through medicine.

As with all new influxes of interest, this will be of varying usefulness and quality when it comes to advancing the bottom line of getting SENS done (versus adding money to NIH investigations or getting the Longevity Dividend going, neither of which is going to move us towards human rejuvenation in any meaningful way). But a rising tide floats all boats: the more people who are interested and talking about it, the more people there are to persuade that SENS is the best way forward, and indeed the only current way forward if you want rejuvenation and radical life extension rather than just modest slowing of aging.

Posted by: Reason at January 1, 2014 7:32 PM

"but Google's public commitment to Calico will greatly accelerate the process - all the people who care deeply about only holding public positions that have mainstream support can now feel comfortable talking about extending human life through medicine."

I've read through Calico's establishment, and this is extremely exciting. However, I wanted to gauge the communities thoughts on this. Google, needless to say would have exponential funding, and if trust can be established, do you think SENS would be willing to share research information?

I personally think that everything Google has touched up until this point, even if not the most popular items, has displayed follow-through and received exponential funding to the point of completion. Would we see some sort of similarity in this particular project?

I understand that the previous question is not one that can be definitively answered with pin-point accuracy; I'm more interested in how some of the more learned individuals (such as those of Mf, SENS and Fight Aging!) have responded to Googles involvement in the field.

Posted by: Leon at January 1, 2014 8:13 PM

@Reason

I know SENS is about damage repair. I meant he posted a link to SENS AND other anti-aging research which included research on programmed aging.

I was also suggesting that it might be a good idea to directly address him in a post. A virtual handshake if you will. It's important to solidify these social connections.

Posted by: Johnathan at January 2, 2014 8:55 AM
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