In one sense, mortality is definitely selected for, though indirectly. Natural selection selects on the basis of number of offspring who go on to reproduce, not length of life. If 95% of the organisms in a species die from predation before 5 years, then an adaptation that causes muscular dystrophy after that age but increases the vigor of the organisms before that age so that they can escape predators and reproduce 10% more before that age, that trait will be selected for. Once there is a trait that causes one system to become fatally nonfunctional at 5 years, any trait that increases fitness for the first 5 years but causes another system to fail around 5 years out will also be selected for. So you would expect to see a large number of system failures around the maximum lifespan of an organism. This is actually what we see with humans—at 70-100 years, hearts, livers, and kidneys all start to fail. Neurological diseases like Alzheimer’s also become far more common around that age. My prediction is that when we figure out how to replicate the functions of hearts and kidneys well enough to allow artificial versions to function indefinitely, we will discover that the human body fails in new and interesting ways shortly thereafter.
It may well be possible to overcome these challenges, but it’s not likely to be a simple matter of tweaking the concentration of a couple of compounds that increase in quantity as we age. Instead, I’m guessing it will involve engineering replacement organs specifically designed to operate indefinitely.
As for death being net positive, I disagree, but can see his point. Historically, large societal changes have coincided with the old guard dying off, though not every instance of the old guard dying off caused a large societal change. But it’s a very easy and natural conclusion to draw, and reflects the society he was exposed to more than it reflects any huge irrationality on his part.
That’s one of the major theories of aging. The difference is that it doesn’t say aging itself is selected for, the way Eric Lander claims. It just says aging is accidentally genetically linked to something else that’s being selected for.
The failure of many systems at approximately the same time is selected for. Death as a result of the failure of those many systems is not itself selected for, but the reproductive benefits of systems that only have to function for a set amount of time are selected for. It’s not exactly correct, but it’s a reasonable approximation for talking to laypeople, as it’s close enough to the truth to allow people to make reasonably accurate predictions about the world (e.g. this new wonder drug won’t cure aging). Whereas if you say that aging is “accidentally linked” to another trait, that makes it sound like we just have to identify one or two traits and we can cure aging, so while it may be closer to being literally true, it’s also more likely to cause misconceptions in people who don’t have more than a layperson’s grasp on the mechanisms of evolution.
In one sense, mortality is definitely selected for, though indirectly. Natural selection selects on the basis of number of offspring who go on to reproduce, not length of life. If 95% of the organisms in a species die from predation before 5 years, then an adaptation that causes muscular dystrophy after that age but increases the vigor of the organisms before that age so that they can escape predators and reproduce 10% more before that age, that trait will be selected for. Once there is a trait that causes one system to become fatally nonfunctional at 5 years, any trait that increases fitness for the first 5 years but causes another system to fail around 5 years out will also be selected for. So you would expect to see a large number of system failures around the maximum lifespan of an organism. This is actually what we see with humans—at 70-100 years, hearts, livers, and kidneys all start to fail. Neurological diseases like Alzheimer’s also become far more common around that age. My prediction is that when we figure out how to replicate the functions of hearts and kidneys well enough to allow artificial versions to function indefinitely, we will discover that the human body fails in new and interesting ways shortly thereafter.
It may well be possible to overcome these challenges, but it’s not likely to be a simple matter of tweaking the concentration of a couple of compounds that increase in quantity as we age. Instead, I’m guessing it will involve engineering replacement organs specifically designed to operate indefinitely.
As for death being net positive, I disagree, but can see his point. Historically, large societal changes have coincided with the old guard dying off, though not every instance of the old guard dying off caused a large societal change. But it’s a very easy and natural conclusion to draw, and reflects the society he was exposed to more than it reflects any huge irrationality on his part.
That’s one of the major theories of aging. The difference is that it doesn’t say aging itself is selected for, the way Eric Lander claims. It just says aging is accidentally genetically linked to something else that’s being selected for.
The failure of many systems at approximately the same time is selected for. Death as a result of the failure of those many systems is not itself selected for, but the reproductive benefits of systems that only have to function for a set amount of time are selected for. It’s not exactly correct, but it’s a reasonable approximation for talking to laypeople, as it’s close enough to the truth to allow people to make reasonably accurate predictions about the world (e.g. this new wonder drug won’t cure aging). Whereas if you say that aging is “accidentally linked” to another trait, that makes it sound like we just have to identify one or two traits and we can cure aging, so while it may be closer to being literally true, it’s also more likely to cause misconceptions in people who don’t have more than a layperson’s grasp on the mechanisms of evolution.