This is, in fact, part of evolution itself. Our intelligence evolved, which enables us to live better and longer lives than we otherwise would have.
Your use of words like “normally” and “should have died” implies that you think our existence without medical technology (and other factors) was somehow the default, and we’ve gotten away from what our lives “should” be. Not true. Our intelligence (actually our volitional consciousness) is what makes us unique, and everything that develops from it is part of our species’ evolution.
Yes. Technology allows greater genentic diversity in humans because it allows people who would normally have a hard time surviving - the nearsighted, the excessively small or large, the slow, the weak - to survive and reproduce. Also, our technological advancements have been within the past 1000 years (100 for most of the ones that have allowed our population to explode). Evolution takes place over 100,000s or millions of years.
Of course, you can always wait around another hundred years and ask the first genetically enhanced, cybernetic implanted humans with a lifespan of 300 years if we are still evolving.
Evolution is not something that gets switched off and on. It’s an ongoing process. In every generation there’s going to be a new mix of genetic variation. In some case, changes in the environment will favor a different set of genes than the ones that were best in the past. In other cases, the same genes that came out on top in the past will be the best ones again. But even in a stable environment, there’s possible room for improvement. A million generations of genetic variation haven’t produced a new combination of ginko genes that are better than the ones that were around a hundred million years ago. But next year some ginko seed may be born that has the genes for telekinetic weather control and these new superginkos will take over.
The reason people think the environment is stable is because we’re thinking of those things in the environment that exert selective pressure on us. Having to learn something new is what we do as a species, so it doesn’t shape us, as a species. If what you said were true, then a mentally retarded person today would have less of a chance for survival than 100 years ago. In fact, the opposite is true.
The fact that I had to learn to use a computer and my grandfather didn’t, does not affect how many children I have.
To add another only-slightly-tongue-in-cheek answer to the OP’s question: Evolution stops all the time.
Evolution has stopped for 99% or so of the species that ever lived. They were unable to adapt to some change (to be fair, “some change” occasionally included the liquification of the Earth’s mantle) and became extinct.
The biggest killers in the world ATM are linked to heart disease, obesity and other factors realted to a sedntary lifestyle, alifetsyle that was unknown just 50 years ago. The current generation is being subject to a selective pressure that has never applied before in our evolutionary history, while simultaneously all the major selective pressures of the past such as homicide, disease and starvation that we have evolved ot cope with will never have any impact on the vast majority of people.
To suggest that the human environment is more stable WRT things that exert selective pressure is unsupportable. The human environment in more dynamic in that respect than for any other species.
True. But the heart disease and obesity et al generally take their toll well after a person’s reproductive years have passed. If one dies at 60 instead of 70 or 80 because of any of those factors, one has had ample opportunity to pass along both any related genetics and behavior.
Crocodiles, poster children for the hasn’t-changed-in-one-hundred-million-years crowd, now have four-chambered hearts. They can hardly even be called reptiles anymore at their present level of metabolic sophistication. Just because the chassis looks the same doesn’t mean nobody slipped a whole new engine under the hood.
First off heart disease and obesity are amongst the leading causes, in fact probably are the leading cause, of reproductive problems. Preeclampsia, erectile dysfunction, problems with sperm motility and irregular menstruation maongst many others are all major causes of infertility and all strongly linked to heart disease and obesity.
Secondly input from grandparents/great grandparents are a major factor in the success of children. If grandparenst aren’t available to provide childcare, income support, family support and so forth the reproductive sucess of the child is compromised. This is believed to be the reason why humans live so long after their reproductive years.
Thirdly a hell of a lot of people are killed or rendered effectively sterile because of herat disease in their forties and increasiningly in their thrities. That is hardly post-reproductive in a society where the average woman gives birth at ~30 and the average man at ~35.
Crocodiles always did have (psuedo) four chambered hearts.
Nonsense. Crocodiles are very typical archosaurs. If anything they are a particularly primitive and unsophisticated example of an archosaur. Try comparimg a crocodile with a bird, a dinsoaurs or a pterosaur and you will see just how primitive they are.
The evidence says exactly the opposite. The ancestral archosaurs were all active, warm blooded animals like the birds and dinosaurs. Crocodilians have secondarily evolved a cold blooded metabolism as an adaptation for life as aquatic ambush predators. IOW crocodiles have a sports car chassis and someone has slipped a steam engine under the hood.
I think Blake is absolutely correct that the environment faced by humans is changing very rapidly.
And there are still plenty of things that stop people from reproducing. Maybe not disease and starvation. Instead, things like birth control, tolerance of homosexuality, acceptance of women into the professions, and so forth.