I think the real issue is that when it comes to complex animals, it's much easier to build a brand new one than to repair existing ones. Our genes encode how to grow a human from scratch, but now how to deal with the myriad of problems that can occur as a result of normal wear and tear. Repairing an ageing body is a completely different problem from growing one.
We do have some DNA that deals with maintenance processes, but I think the issue is that these processes inevitably can't cope. It's like trying to patch up an old house. You can keep doing little fixes here and there, but at some point, serious renovations are needed, and we're just not genetically equipped to do that.
You have to wonder what it is nature could do anyway, if humans living to be extremely old had been selected for. Old human bodies are so broken, we'd need to be able to grow entirely new ones and shed body parts, even regrow brain tissue. We'd need a metamorphosis on the level of what butterflies go through.
Matt Ridley's The Red Queen also talks about the effects of parasites, which also maps in to why there are genders (more accurately sexual reproduction). The problem is the mismatch between lengths of generations. A parasite that has one generation every week gets 52 shots a year at an unchanging host. As time passes the probability of success for the parasite increases. The human with ~20 years per generation has to withstand that long before making a new one that is different and (partially) resets the clock.
Gender comes in because asexual reproduction would produce offspring virtually identical to their parent which means a successful parasite would have a large number of hosts to exploit. By combining DNA from two different individuals (note how much we avoid individuals from the same family with substantially similar DNA) things are mixed up enough to give a head start against the parasites.
> Natural selection seems to have little regard for longevity.
I'd argue the opposite, that natural selection depends entirely on death, not just to weed out the less fit, but also because Without death, there would be no evolution. This is by definition, at least for an environment that can only support a limited population. Corollary: The maximum rate of evolution is proportional to the rate of generation turnover, that is to say it is inversely proportional to life span. (http://qr.ae/L5v6z)
Mother Nature did not build us to last, but quite "intentionally".
Second, there is no contradiction between the two theories. According to r/K selection, long life-span is a typical characteristic of K-selected species, while short lifespan is typical for the r-selected. The theory I espouse would simple add that the continuum between K-selected and r-selected species would tend to correspond to a continuum of evolutionary rates.
If you still disagree, please follow the link and point out flaws in the argument.
>The theory I espouse would simple add that the continuum between K-selected and r-selected species would tend to correspond to a continuum of evolutionary rates.
Looking at the last 2B years who has shown higher "global" evolutionary rate - the line of living matter leading to humans or the line leading to fish?
While of course it is obvious that the "local" evolutionary rate - rate of producing and churning through minor changes - is higher for shorter lived.
In short - giving the result the human rate of evolution
>You have fallen for the false assumption that evolution is teleological
it isn't false, it is true - the evolution leads to exponentially more complex systems. There is a very simple mathematical reason for that - evolution changes are small continuous deltas and a delta-changes to a more complex system cover more volume in the parameter space. Very rough - an organism with 2 times more types of cells, limbs, other morphological and behavioral features, etc.. will produce 2 times more of survivable variations.
>humans are the farthest along that teleological path.
mammals are farthest down the complexity path and humans just a bit further as it seems that we have a bit more complex brain.
Your Harward link is wrong on at least 2 metrics of biological systems both of which shows clear [exponential] increase as result of evolution - complexity and entropy increase integrated over given biological system's life-path in the space-time (that ability to maximize entropy beyond what can be achieved by following local gradient is the main differentiator between live and regular matter)
Natural selection doesn't work how you think it does. It's about fitness for making to the point where you have reproduced. Dying after that point doesn't come into it much, except in that surviving after is a result of other properties that are also good.
Nothing I said contradicts your description of natural selection, that "fitness for making to the point where you have reproduced." But you are missing my point that the rate of evolution produced by natural selection is dependent on the turnover of the population. The parents need to die to make room for more fit offspring once the carrying capacity of the eco-system has been reached.
If you still disagree, can you follow the link and point out flaws in the logic there?
