Hypothetical scenario: Human biology experiences a sudden change...
 

Alright; if this is too random for general, I apologise. It's just one of those odd thoughts, so my feelings won't be hurt if someone moves or deletes this. Anyway:

No one can explain why it occurs, but all of a sudden one day, things like cell decay and loss of muscle mass just stop happening. In addition to the fact that the human body no longer weakens with age, it actually starts to just naturally get stronger. Even if one isn't pointedly excersizing, they will still gain strength and fortitude over time. Most diseases are still in effect, so people can still die, just not as easily. Conditions directly related to aging (such as Alzheimer's) cease to exist though. Basically; we've become like your D&D dragons, getting stronger with age instead of weaker. People who are already older at the start of the scenario don't experience the change suddenly; rather their bodies just start to "recover" as it were, mental and physical prowess both slowly coming back over a period of time.

All possible negative effects something like this change would have on the body itself are suspended without pay for the course of this scenario. They have a shitty union, so it's cool.

How long does it take the world to realise this is happening? How do people react when they do? What are the short and long term effects on society?

I don't know how to respond to this.

Pretty much, you're saying the human race becomes immune to all forms of natural death? Well, that logically means one thing. Unnatural death. Read: People kill one another.

First of all, the religious undertones to this would be astronomical. Everyone and their mothers would be claiming their god brought it about and the fact that it happened meant they were correct. The end of "science", as we know it, since biology would be COMPLETELY undermined, and thus all subsequent discoveries or theorems would be invalidated.

Then, people become anarchist and realize that a government needs a much smaller role. Lots of wars, I'd suspect government starting to bomb their own countries to aim for population control.

All in all, I'd suspect the end of the human race in, give or take, ~50 years.

Nah, there's still disease and such, just nothing specifically related to aging. So a lot FEWER people die of natural causes, but no one's immortal.

Good point about biology. I don't know that science would be eliminated, but this would certainly get thrown in its face a lot.

Science and Technology would evolve rather fast, thanks to this new Threshold of human power.

But society itself would collapse over time. We already have an overcrowded Planet, with people getting stronger, less people die per year... there is a problem. Also, all form of industry that needs death to survive would have to be reconstructed...

That's what i see in the first 10 years after we notice it and go "Hey! Im-a lifting this-a car! I could-a not do that-a before!"

So, uh do we get some kind of functional tail thrown in the mix for this evolution of sorts?

Somewhat seriously, is there a cap on how far a human's strength will grow in this scenario? If it doesn't eventually stop we'll have flightless supermen, and women, running about. Simple acts may become near impossible as one may not be able to control their own strength.

Lets say yes. We're not orks with a limitless capacity for packing on muscle, but we do pack it on to the limits of our biology.

You mean human biology. Biology studies a lot of different things. And actually, the emphasis of biological research would just change so that to try and explain what has happened and why. And nobody said that the human bodies "ordinary" functions would change either.

If that were to really happen, I'd say more like 200 years. Long enough for people to be immortal for such a period of time that we'd forgett our mistakes and to learn from them.

Ok, so then a lot of diseases would last for a longer period of time. Propably.

If this happens to everyone, doesn't that kind of balance it out?

To an extent, absolutely.

Probably, yes.

This is like, what happens on Children of Hope, only reversed. And that book/movie was terrible.

But I suppose it'd be...A bit bizarre...We'd be like elves, only less pacifistic. The problems with living forever ( save for other beings killing you ) are the overpopulation and that, one day, you'll get bored immensely and that'll probably cause suicides. A lot of it.

Our overall society shouldn't change much, because besides the removal of natural death, this doesn't really help us a lot. Unlike virtually every other immortal being in fiction, our powers are pathetic. Elders won't gain any power, the population will be large and continue to grow at it's current rate, and science will pull yet another "Whoops, funny that."

Fleshy meat humans can easily kill each other with the simplest of their inventions, no matter how much muscle mass they have.