@King Edward 1
I'm not talking about the extinction of the human species because of applied technology, just trying to put some perspective into what we are doing with regard to relying on ever more complex technological interventions to keep an unreasonable amount of the population alive.
But more interventions require more resource. I'm sure I heard a discussion on the radio recently which suggested that many countries will be spending significant proportions of their GDP on healthcare within 20 years at current change rates, and the Economist has commissioned a report that presents this as a possibility.
I was actually going to say something about diverse genetic information, particularly what are apparently unused parts of the genome, but I was going to put that into the context of the pathogens keeping recessive attack vectors in their genome, although you are right, it runs both ways (but what is the survival advantage of cystic fibrosis, mongolism, Duchenne muscular dystrophy or even short-sightedness!)
My belief is that we will probably never be able to match the natural forces of evolution, although that does not mean that we should stand still. We need to discover replacements for antibiotics, otherwise we could have a new Black Death. MRSA and C.Difficile already provide pointers to this possibility, and TB is already on the way back.
BTW, and this is a bit of a diversion. Removing fire from our tool-chest cannot happen as long as there is organic material in our environment. But motorised transport? Or the technologies that sustain the Internet? We could lose all of those.
Remember that it is still within the span of a single human lifetime that *ALMOST ALL* of what we regard as modern life has come about (OK, the steam engine, and simple internal combustion engine are more like twice, but even 70 years ago, horses were still the primary power on the land). The rate of technical change has been staggering and accelerating. There is a chance that we could be knocked back into a pre-industrial society. It would not take that much, and if there was suddenly a critical shortage of energy (like if there was a cascade failure of the electricity grids caused by a serious EMP overload from sunspot activity [I am not normally a doom and gloom monger, but the chance is there, NASA says so]), we may lose the capability to rebuild the infrastructure, including the power grids themselves. It takes a lot of serious resource, and a long time, to build the number of large high-voltage transformers that might be needed.
We've used all of the easy-access energy and other resources, and if we were pushed too far down, it would be incredibly difficult to climb back up to where we are without opencast coal, iron, or copper ore mining or easy to extract oil.
And don't start talking about solar, wind or wave power. Without an existing technical and transport infrastructure, this cannot be deployed, maintained, or utilized. I challenge you to build a working wind turbine generator (with a reasonable capacity) with just the raw materials you can find within a 10 mile radius of where you are. You are not allowed to cheat by using existing motors or alternators because that is part of the wind-down, not the rebuild of technology.
The result of a breakdown would be chaos, and conflict over resource, and could lead to a new dark age where the remaining resources were controlled by force. It would be impossible to do anything at a national level. In such a world, there would be NO internet, NO national transport system, NO national electricity grid, and the road and rail systems would degenerate remarkably rapidly.
Just think what panic there was in the UK 10 years ago because supplies of petrol and diesel were disrupted. And that happened within a space of just days!
Do you actually remember a mere twenty years ago how useful (or not) personal computers were before the Internet! Answer, not very. Good for simple games and small data projects. There was a Society, however. Computers are vital for our current way of life, not our survival. They just make it easier.
But none of this would mean an automatic extinction of the human species. The genetic sieve would probably cut back in, and maybe, just maybe, inherited intelligence could prevent a fall back to the stone ages. But people would start dying to what we now regard as curable diseases merely because the technical interventions were no longer available to keep them alive.