In my understanding, natural selection occurs by means of a combination of different factors. Firstly Organisms will tend to mutate when reproduction occurs. Secondly, they will tend to - for the most part - resemble their parents and therefore perpetuate traits. Thirdly, Those organisms that have traits that improve their chances of surviving and eventually mating will have more of a chance of producing offspring.
This process is still very much at work in the wild but has virtually ground to a halt in humans. The sick and infirm recieve medical attention and couples who are unable to bare children naturally can be aided to do so.
When the sperm meets the egg, only the most disasterous combinations will not survive. The weak combinations will be nursed to life.
Does this mean that the human gene pool is degenerating? In the future will the world be full of sickly people or will we eventually be force to breed ourselves as we have for so long bred animals? As a species the human race is becoming weaker physically. The overall effect will probably be low for always though. Look at Stephen Hawkings, the man is selectively a defect and allowing him to live and reproduce will physically be against selection. However, the man is a genius mentally despite his disability, and his effect on your overall civilization has been positive.
Unfortunately, most sick and disabled people are not quite that productive, but most do a service to our civilization. I have thought a lot about this. In previous generations weak and handicapped people just couldn't make it unless they were very lucky. Now, we have becoming such a supporting civilization that for the first time people with huge disabilities such as down syndrome are reproducing and large amounts of recessive genes are being spread into the gene pool for negative effects. However, these genes will never become hugely prevalent for multiple reasons, though there will be many sickly people alive than ever before.
One reason is because of the fact that while these sickly people are reproducing, they are not in any way more attractive to others of the opposite sex. Assuming there are no negative traits that inhibit attraction (which is not true in many cases) the worst that will happen is that a constant proportion of our population will be sickly. There is no risk in us all becoming disabled from it. The second reason is environmental factors. People don't realize that 50-70 percent of any given trait is caused by their environment. Look at old asian people, they tend to be very very short. Now look at the current generation, while they are perhaps slightly shorter than average, they tower over their elders. This is because of improved diet. In the same way, we are stronger as a whole than we ever were before, regardless of disabilities. Finally, there is still natural selection. Intelligence and physical prowess is highly valued, doctors still get the pick of the mates. Highly trained athletes as well. There is not indiscriminate mating in our species, and while intelligence has become a more and more necessary trait, this just changes the selection but not the fact that the absence of desired traits limits reproduction. yes yeahhhhhhh Yes. I think our intervention in Africa has proved this. Well it sure is looking that way. Oh dear!
However the gene pool in the first place apparently wasnt that wide. Do genes adapt? Wow thank you I have been thinking of this for years now. I even wrote my doctoral thesis on a close subject to this. You are thinking ahead of your time. Thank you you for posing this question and keep thinking outside the box. This is actually being seen already. Look at eyesight. In general the human eye is becoming weaker over time due to advances that have allowed the weak eyed to survive and breed. Contact lenses are greatly increasing this problem as it is no longer visible who has corrected vision and who does not, thus we find even those with little vision attractive and healthy in appearance. An interesting thought. I take a more optimistic view and say that because medical science and technology has progressed, and is progressing so far, that the human race will in face become healthier and longer-lived than we currently are. I've said this for years - definitely.
I completely agree with you for exactly the reasons you stated. i'm not sure it will lead to disaster, but i agree with you on that somewhat.
thats like the extremely dumb and unattractive having babies (i'm not saying they shouldnt) but all their offspring will also be dumb and unattractive.
so people with hereditary illnesses are also contiuning the problem yes, possibly we are more prone to diseases because the power of natural selection is weakening through the aid of medicine.
that's why medicine has to keep one step ahead.
because after all natural selection is what gave us our big brains to come up with solutions other than what our bodies can produce (other than antibodies) The concept of natural selection will always play a role no matter how advanced medical technology becomes, because the best and brightest humans will naturally choose a mate of similar stature.
Though couples who arguably should not reproduce will be able to, it will not effect the overall strength of humanity's gene pool to the point where the species will be degraded. Natural selection is always at work. All we have done is shift the selection favor away from the natural pattern.
The main factors that drive natural selection in the wild are food supply and predation. If an individual can find more food, or avoid predators faster, they are more likely to breed. In civilization, the main factors that drive selection are attractiveness and social standing. If an individual is sexier, or has more influence (via money or posistion or family ties etc.) they are more likely to breed. "Civilized selection" is much slower than natural selection, becaue we don't let the worst die, but the difference in breeding rates does make an evolutionary process.
Basically, instead of moving towards stronger, faster, healthier people, we are moving towards sexier people who are better at making money. I think we are being temporarily weakened. Our meddling has stopped a great deal of natural selection but keep in mind, nature always wins. A couple hundred years of modern medicine is nothing to millions of years of existence. There are still many killer diseases out there and we are creating our own weakness to boot. (prime example, the destruction of our immune systems through 'cleanliness' and medication) Just because we haven't sprouted wings or developed gills does not mean that evolution has stopped, it just means that it's a slow process and we're only beginning to see the next stage of it. Yes and no.
Humans have a very unique effect of actually changing Natural Selection by conciously choosing to intervene.
From a human perspective, Yes because centuries of 'social evolution' has turned us towards protecting the weak and infirmed while also allowing criminals to live (even though in jails to rehaiblitate them), this dramatically affects our future.
From the No:
1) Humans have the ability to actually change our genome so that less desireable traits can be lessened or removed all together while good traits can be enhanced.with genetic engineering.
2) By protecting many of the 'weak' and 'infirmed' we also increase our talent base into many other skills such as sciences, art, leadership which in time can continue to influence our future development. if i understand you argument, you're saying that the typical
chance of surviving/reproducing has reached such a high rate that the "more of a chance" through natural selection means is now an insignificant "more".
the species is surviving and mating. so there you go, your natural selection is working just fine.
so what if people are "sickly"? the "quality" of the gene pool is just your arbitrary perception of how you think people should be. from the viewpoint of evolution and natural selection, such concepts are meaningless. basicly yes- we are becoming weaker. also, globalisation encourages homogenisation of the gene pool, so local variations begin to becom less. look at colonialism- white man moves to hot country, breeds with native black man, children have lighter skin than other natives and burn more easily in the sun, several million years of evolution buggered.
black man moves to cold country with less sunlight. breeds with white man. skin of offspring darker than other natives, and cannot produce enough vitamin d. again, selecition process is disrupted.
oh and as i realise some internet forums get very agressive over the sligtest mention of the word "black", its the most easily visualised answer ok?
also, in scotlan there was an isolated coastal colony in the pre-roman times. they had lived in isolation for so long that they had modifies ankle bones that let them climb cliffs with ease and harvest birds eggs. you dont see cool stuff like this anymore! outbreeding is healthy, but not on a global extent Not really..
People with serious illnesses (MS, down syndrome, etc.. there's a long list) have always been able to have kids. Of some of those diseases, it's not even evident until after a standard age of having children that they even start to get the symtons of the condition. Some mental health issues (such as schizophrenia) are not usually diagnosed until people are in their 30s, often much older.. there's a high chance they also have children before being diagnosed, and I believe that schizophrenia is genetic?
On the other side of it, there are many reasons perfectly healthy people would be unable to have children, birth defects that aren't genetic, for example. A good friend of mine has a disease - they're not even sure what causes it, but this disease makes her almost infertile. But her child has no higher chance of having that disease than any other woman.
No, people will not get sicker. While someone made a point of more people having bad eyesight, it's still a trait that is most often seen in people over 40! It's good to know that you seem to think anyone with glasses unhealthy and unattractive, though... Your question was answered when I read Callums question about dumb Brits. in current events.
Interbreeding clones like him will mean the end of life as we know it. What do you mean, "eventually"? | 