why do humans been are not evolving now? we have thousands of years but we don't have changes?

Answer 1

To answer your question we must first address what evolution is. Evolution is conditional on variability within a population, and how this variation is selected for within the environment via reproductive success. Fortunately for humans we are the most generalized mammal on the planet and as of such have found a nearly universal sucess throughout most of the environments that we encounter. That said it is difficult to imagine a figurative future environment that would be different enough to allow natural selection to act upon the effected population for long enough to create any kind of significant morphological change in our species. This is why we "appear to not be evolving", but this is far from the truth. We as a species are truly defeating the few acts of natural selection that are acting upon us with advances in medicine. With this in mind the changes that might occur could be much like your thanksgiving Turkey, a creature who has been put under so much unnatural selection that it no longer is capable of mating due to humans artificially breeding them for nothing else but size. If humans were no longer present to do this service for Turkeys, they would go extinct. Through "unnatural selection" humans are doing very similiar things to themselves. Undoubtedly a woman who goes in for infertility medicines has a greater chance of having children who will require the same treatments to reproduce. Children that have severe enough allergies/asthma that may have killed them in the past will now grow to a reproductive age with the assistance of asthma/allergy medicines will produce offspring who have higher occurances of asthma/allergies. This is a bit of a concern, seeing as at the same time we are making ourselves more susceptible to asthma and allergies we are also taking actions that are converting the environment that we will have to adapt to, to contain more contaminants. If it gets serious enough those who are persevering with the assistance of medicine may be the first to become too sick to be reproductively successful such that the power of natural selection might overbear unnatural medical selection once again in this area? Some areas where medicine is making slow progress, like cancer and Aids, there will be a continued true evolutionary process. Already there have been a few case studies that have discussed a truckstop in Africa where the prostitutes, despite an alarming exposure rate, are not catching or dying from Aids suggesting that natural selection has already discovered a variant within one ethnic group that appears to have selected for white blood cells which are not as susceptible to the AIDS virus, much like sickle cell trait does the same red blood cells resistance for Malaria. As this gene now becomes more prominent due to the pressure of AIDS we may also see the advance of a new genetic disorder if a person is born with two recessives, much like two recessive copies of sickle cell results in anemia instead of trait. If people do begin to die from a worse environment that causes increases in Asthma/Cancer/AIDS, undoubtedly natural selection will find many variants within our population, which now far exceeds 6 billion people, and will come up with the needed solutions to combat these problems so that enough people make it to a reproductive age. If there is also enough disruption in the sociopolitical structure such that medicine is no longer readilly available, at least to the poor, then natural selection will also reclaim the realm of fertility and those who can't reproduce naturally, won't. So depending on what our actual environment and our sociopolitical and medical environment has in store for us, our aesthetic changes will be minimal, although there will be significant microbiological changes, seeing as that seems to be the only realm of our existance where Darwin's natural selection still has a footing (antibiotic resistant bacteria, AIDS, possibly cancer if the uv becomes harsh enough that it begins to affect our reproductive success on a larger scale?) So as you can see from my analysis, we are evolving and we will continue to evolve, just more on a micro scale rather then a macro scale.

To address some of the previous points. Becoming taller is since medeival times is not evolution. It is a tribute to having more sustanance available throughout our lifespan in modern times. Well having more nutrition should allow us, if we chose to, to have more children in our lifespan, those countries which enjoy good nutrition have also reduced their reproductivity through the use of contraceptives. If you fed medeival Europeans well throughout their lives then they would have been much taller and would have been able to have birthed more children. As medieval Europeans were managing to birth many children anyways, however, poor diet did not seem to be selecting against them that heavily. Interestingly their was a mini ice age that started in 1250, and it was during this time coupled with the introduction of the bubonic plague and cholera where a reduction in European population was evident. In fact at times like this small bodies that require less daily calories would have been the most successful in evolutionary terms, yet once our nutritional inputs were returned to our species a growth spurt occured. Some of this growth could be attributed to sexual selection and this would be evolutionary, but it is my belief that malnutrition was exhibiting itself in the population and this was resulting in the reduced stature (genes for height were present) and once the nutritional inputs were returned to the population the genes that bring height now had the materials to express themselves again. I'll call this "gene hibernation" because the conditions neccessary for these genes to express themselves became temporarily withdrawn. That is not to say, however, that an increased stature has not been selected for over a longer period, but I don't believe it has over the last 750 years. Their are however gene traits that can be seen in our DNA as a response to the Bubonic plague and also for Cholera which was prevalent during these times. Cystic fibrosis is a genetic disorder when two recessive alleles are aquired and was aquired in our genetics as a response to Cholera. The single allele of this diseases is genetically non-detrimental to the body while at the same time giving significant protection from cholera. So again, this period of history shows significant micro adaptation but nominal macro adaptation.

Answer 2

Humans use their intelligence and technology to change the environment to suit us instead of the other way around, so we have no reason to evolve. If we live in an area that's too cold we kill something else and steal its fur, so we there's no reason for us to evolve our own. If we live in an area that's too dry we dig a well, so we don't have to evolve to live without water. If we live in an area that has malaria we have quinine so we don't have to evolve immunity to malaria.

Come back in a hundred million years and (assuming we're still around and haven't all downloaded our minds into robots by then) we probably won't look all that different than we do now. We'll have become living fossils, like the coelacanth.

Answer 3

Human beings are still evolving, but it's a very slow process. As many have mentioned natural selection isn't taking place as it used to, but that in itself is causing evolution.

For example: How many people do you know with glasses or contacts? A couple of thousand years ago or even a few hundred, impaired sight was not as common as it is today. If you couldn't see, your hunting skills were lacking which didn't allow for you to provide for a family, therefore, you were not chosen as a mate and your faulty sight gene was not passed on. With just the introduction of glasses, humans have evolved from perfect sight to over half the population requiring tools to improve their vision. Future generations will have to see what effects this will have on our species.

Answer 4

For starters, the reference others have made to average height isn't an indicator of evolution. It is more likely related to better nutrition than average people had access to 100 years ago.

Second, organisms only evolve when they need to. Humans have reached a point (though most likely temporary) when we have no need to evolve. This can be seen in crocodiles and sharks. They have evolved into something so efficient that their evolution has be slowed to almost nothing for a long time now. We are in the same position. No physical adaptations are needed for our species right now.

Answer 5

Humans did nopt evolve from a fish or a monkey but alongside both, get a grasp on the concept of evolution before belittling it. Written record of mankind's existence is only a couple of thousand years at best and scientific study of human anatomy is an even shorter period of time. Two thousand years is only a drop in the bucket when compared to hundreds of millions of years.

Answer 6

These people are wrong. People live longer because of advances in medicine and care. People are taller because of better nutrition. However people no longer need to have specific traits to survive and almost everyone procreates in society. Another factor is time and evolution takes a lot of it. Even if natural selection worked in society it's effects wouldn't really be all that obvious over a few thousand years.

Answer 7

Hi! I think that the best way to compare if the humans being has evolved; is seeing the difference in the different ethnic groups. For Example:, Asian and Indians are mostly people with a short stature .
IT would be good to see , if in these 2 groups the New Generations are also taller than those of 80 years ago.
¿ But.... How about the genes in the family history ?, to determined how tall or how short one could be, without considering evolution.!

Answer 8

Our enviorment has not been changed in a way were we do not have to evolve. In the Ice Age we had to change to survive. We had to stand up right in a new enviorment to see further and to escape from new dangers. We could evolove if global warming hits. But also in a faith aspect. I believe that on the seven days of Creation we did not know how long one day was in God's time so that is how we changed.

Answer 9

Because it doesn't just take thousands of years, it takes millions. We are physically evolving just not at rate that we can measure by sight. Thousands of years ago they didn't have electricity, we do now. That can be considered evolution of technology and intellect.

Answer 10

Humans are constantly evolving & continue to mutate even today. The human genome actually consists of 3% virus genes or fragments of virus genes. Besides causing many diseases the virus gets into cells & attatches itself to genes, thus causing many mutations that are passed on to future generations.
Recent genetic researchers have found many cases of evolution taking place among the human population... I'll be back with some good referance sites if you have an interest.

Answer 11

We are changing. AND there's evidence as recent as the Ancient Greeks.

As a race, Humans now are surviving (even without using "modern" medical practices) simple injuries that were documented as killing Ancient Greek Soldiers during wars.

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