How can the human race be still evolving when the weak members don’t die off?

Question

Modern medicine can help people born with congenital disabilities to survive and even procreate whereas if we weren’t sapient and were still animals, these people would be dead thereby assisting the evolutionary process. Surely the evolution of the human race has at least dramatically slowed down if not ceased completely?

Again, I’m asking here because there seems to be more people here with knowledge of this particular science than in the biology section.

That’s odd; post a question about evolution and religion is the default section…strange.

Answer 1

Evolution is simply a change in the frequency of alleles in a population over time.

While natural selection is the most common, and most well known mechanism of evolution, it is not the only method via which this shift in gene frequencies can occur.

Things like genetic drift, founder's effect and others can also cause changes in an organism's population over time.

Plus, the fact that "weak" members aren't dying out doesn't mean that evolution cannot occur, even through natural selection.

It's impossible to tell what selection pressures might occur in the future. Perhaps a virus might arrive that affects everyone except those who are also prone to asthma, astigmatism and below normal body weight - perhaps through genetic linking, or some trait of those 'weaknesses' actually helps the victims survive the virus. In that case, the wheezy, skinny, near-sighted folks who might be 'weaker' than other humans actually have a genetic advantage, and may survive better than big, perfect-visioned people.

By helping those congenital disabilities to survive, we not only preserve the bio-diversity represented by their genetic heritage, we also preserve their collective brain power. Not so long ago, great minds like Stephen Hawking would have been lost to us through their 'weak' bodies - but they still a lot they can contribute to our society and learning, things that may help us to survive something that might otherwise have destroyed our species.

Perhaps the adaptation we are currently selecting for is the ability for us to preserve that knowledge, that genetic diversity, and also the development of our own complex, inter-connected society. These traits have certainly helped us survive in the past, and even come to dominate the globe today.

When evolution is boiled down to the aphorism "Survival of the Fittest", it's important to remember that "Fittest" doesn't necessarily mean the strongest, it only means whatever adaptations work in that environment to help an individual survive and reproduce.

Answer 2

Our conclusions about natural selection is distorted, due to our own insufficient time as a species. We simply have not been around long enough to adequately assess ourselves as a race. The results from the current millenium, with it's severe worldwide human overpopulation, (and whatever the resolution of this overburden will turn out to be) will not even suffice to show enough data to get an arithmetic mean. We may never get one: we may be forced to MAKE one! China has shown the initiative concerning this issue. Perhaps all countries would do the same, if they had been around as long as China, perhaps not. Basically, the bible has this to say: If we don't learn to control ourselves and then DO IT, we will suffer the gravest of consequences. This, more than anything, has shown itself true time and again. So then the survival of the 'strongest' is to be measured by the 'strength' of both individual and national self-control, rather than in the 'strength' of medicine, technology, or brute force. This is what the bible advocated for Israel all along, however, it applies equally to all. Whoever puts this principle into action will eventually emerge as not the 'victor', but as the 'survivor', as those seeking victory will fight, kill and eat one another, while the prudent look on.

Answer 3

Evolution is "Change over Time". The idea of "Survival of the fittest" is not accurate. It should be "Survival of the most well adapted". It doesn't matter that the 'weak members' don't die off since we are affecting our own evolution as a species. For example: I wear glasses. Ages ago poor eye sight was enough to get one killed by a predator that could not be seen coming. I probably would not have survived to pass on my genes, but today there are many people with poor eye sight who do and our ability to adapt has overcome our weaknesses. So we are still evolving. There can never be an end to the 'Change over Time' that takes place in any species. Evolution doesn't automatically imply a positive direction. In the natural world where pure natural selection is the mechanism for evolution that would be more true, but because we have such a unique ability to overcome great adversity due to our ability to reason we are affecting our own evolution on many levels.

Answer 4

You answered your own question. Instead of dying off, many contribute their dna to the gene pool. That alone will have an effect over time and, like all evolution, some negative changes will come from this as well as some good. That's the way it goes.

Although I will agree with the first responder in that many people with severe genetic disabilities often do not have children.

Answer 5

Well most of that medical stuff that removes the evolution pressure is relatively recent. It's really only effected the last two or three generations in a very meaningful way.

But there are other pressures. Whatever makes you more likely to reproduce is going to spread your DNA more. So maybe you are unattractive or very shy. Maybe you hate kids. Those things will still self select out.

But you are probably right. There isn't much pressure for us to change right now. Evolution moves fast in isolated groups that have something unique in their environment. We don't have much of that.

Answer 6

That is a good question. I think evolution is such a slow process it takes tens of thousands of generations to produce a visible result. We have been enjoying our current human state for over 100,000 years so obviously evolution is not something we could record or remember firsthand.

What worries me is dumb people making babies at a faster rate than smart people. You should watch the movie "Idiocracy" with Luke Wilson.

Answer 7

Evolutionary processes continue(mutations at the genetic code level), but natural selection has been short cicuited in many places around the world.

However, there is more than individual natural selection at work in evolution. Group natural selection is a valid concern in some populations - especially when the group as a whole workd to overcome problems(ex. some insects).

Answer 8

Some scientists are speculating that the next step in human evolution will include a half human and half machine with a computer helping the human mind.

Answer 9

We are still animals, first of all. And your assessment is correct, if we hadn't developed the medical techniques and technology we have then they would die because they are "unfit" for their environment. You're also correct that evolution for humans is fairly slow now as we have developed the ability to change our environment to suit us, rather than us changing to suit it. We are still evolving though, just much more slowly.

We're still evolving through other pressures such as sexual selection and also through genetic drift (i.e. "random" mutations in the DNA of our offspring).

Answer 10

sexual selection still occurs, remember evolution is all about passing your genes onto the next generation and spreading them throughout the population. although people don't tend to live longer due to genetic traits (better hunter, better at escaping from predators) living longer is only useful because it gives you more time to have more children, and pass your genes on.

For people who have a mutation which give an advantage in having more children, evolution will still select them.