Modern Humans are Evolving - Fast

Evolving?

 

I also thought it should be evolving - not evoluting. There are two points here. On the one hand, the larger the population, the more potential diversity - this would favor evolution. On the other hand, modern medicine runs completely counter to evolution - it allows the survival and passing on of genes of those who would have been considered "unfit" centuries ago.

 

So we're evolving, but not necessarily in the way that we should be. Hail mutation! Everyone, wriggle your third ear to show support for unnecessary evolution

 

I'm waiting for an extra middle finger myself...

 

So, when are all the X-Men and Heroes-style people gonna start appearing?

 

I'd be happy with a pair of wings...

 

I'd settle for space-time manipulation.

 

Oh, I'm certainly not OPPOSED to modern medicine. I'd much prefer to be treated for a potentially lethal infection than taking a chance on whether or not my immune system is capable of fighting it off. I was just putting out modern medicine as a counter-arguement to evolution.

 

On the other hand, by relying more on modern medicine we are increasing our natural life spans beyond what our bodies alone could manage. I would call that a form of evolution towards mutual symbiosis: Science improves because we are more dependent on it, and we live longer because of the advances in science.

 

Actually, the prevalency near-sightedness is one of the things that baffles me about humans. I, too, am near-sighted, and most people who wear glasses or contacts do so because they are near-sighted. Given that a large chunk of human evolution was thought to take place on the African savanna, where there were large open and flat landscapes, it seems like near-sightedness would have been strongly selected against. You wouldn't see that lion stalking you until it was much too late, and you'd have difficulty taking precise aim with your throwing spear while hunting.

The point being, there does seem to be a heredity linkage in eye sight, and being near-sighted is a fairly common occurance. The only way I can see it remaining in the population is if it had some type of benefit, despite some of the obvious drawbacks, but I can't think of anything. Generally, any trait that decreases your survival chances tends to be eliminated from the popuation, unless it also provides some greater benefit. Take the human hand as an example. By converting from quadrapedal to bepedal, we became much slower and easier for predators to catch, which is obviously bad. However, becoming bipedal also allows us to use tools, which turns out to be a bigger benefit than being slower is harmful.

 

Our ancestors lived much shorter lives and this may possibly be why near-sightedness didn't get eliminated from our genes. I, too, am near-sighted and my half-brother is near sighted. According to an article in Wikipedia Myopia varies a great deal according to ethnicity and region. Interestingly it is lowest in Africa. Maybe as we get further from our roots it increases for some reason. Prehaps near vision is more important in hilly, mountainous terrain?

 

I agree with Nakia. I had 20/15 vision until in my 20's, now I have 20/40. Such a combination way back would have been good enough to ensure survival of the species (late 20's is long enough for several children).

 

Evolving? Not fast enough, I say! Where is a radioactive insect when you need one. Where I live that will most likely be a scorpion. Youch.

So, what exactly do we need to evolve for in this day and age? We live in relative safety, so there isn't some sort of huge need for survival oriented evolution. Maybe eyes in the back or side of the head for driving... But really, what "needs" do we as modern day human beings need to survive more fitly in this world? Genetic changes to better cope with sickness is all I can think of.

 

Brains. Better brains but that probably ties in with medicine. Genetic/DNA research will probably advance human evolution quite a bit. But will we actually be a better species or just a bunch of weak, physically unfit think tanks?

 

That's not how evolution works Giles. Evolution is not working toward some goal, or towards fulfilling "needs" as you say. Even species that have survived for millions of years don't have "perfect" adaptations. Evolution doesn't even necessarily guarantee improvements - just something that works.

Also I think you are misinterpreting what "fitness" means as well. When speaking of evolution, "fitness" is defined as how many offspring an individual produces (that themselves survive to reproduce) relative to the average in the population. It's a common misconception of evolution. Dawin's maxim of "survival of the fitest" doesn't mean that the strongest, fastest, biggest are the most fit - simply the ones that reproduce most.

It's calculated simply by dividing the number of offspring you have that survive to reproduce by the average number for your species. Those with a fitness over 1 have their genes represented to a greater degree in the subsequent generation, while those with a fitness less than 1 have their genes represented to a lesser degree in the subsequent generation. It can also be looked at beyond one generation. For example, a person with one child and six grandchilren is actually more fit than someone with two children and four grandchildren. If, at any point - even hundreds of years from now, and regardless of how many children you had - your family line dies out, your fitness is reduced to zero, as you would at that point have no genes in the current population.

So the only thing modern humans need to do "to survive more fitly in this world" (which isn't even the proper terminology by the way) is to have more children.

 

Alright, my terminology was not exactly correct. I am not close to an expert on the topic and I found your explanation of evolutionary fitness to be enlightening, so thank you. I do realize, however, that no creature in the history of this planet ever developed a beneficial attribute by "working toward it" as you say. No polar bear ever thought "I need to work toward being whiter" and no fish ever saw the need for another fin and made sure its children had one. I wasn't talking about needs as if I thought that was how evolution worked. I was just asking what sort of adaptations humans 'could benefit from', 'need to have', or '<insert whatever terminology I should have used so that people can get what I'm asking>'.

The article in discussion states that humans are evolving fast and my question is what for?

 

Well it's impossible to predict what they are evolving to - and I'll get into more detail later on - but the basic answer is that anything that improves survival to adulthood or improves the ability to pass on your genes would be considered something humans could benefit from.

The first thing that needs to be pointed out is that any adaptations that aid survival in the early years of life are far more beneficial than adapatations that help you out in the later years. Things that affect your health later in life don't have much of an impact on evolution, because by that time you have already had children of your own that have grown to adulthood themselves. From an evolutionary standpoint, you only need to live long enough to pass your genes on to children that will survive to adulthood. So once all of your children are adults, it makes very little difference if you live to be 60, 80, or 100. (Note - surviving to adulthood is critical - it's not simply the total number of children you have. It's all about passing genes to subsequent generations, and children who do not live to adulthood do not have the opportunity to pass their genes on.)

To take an example, say there was a gene that made people with it resistant to heart disease. That's great for the individual, but it doesn't really help their fitness, because heart disease is something that generally affects people later in life. It will help the individual live longer, but since it won't help him have more children, or improve his children's chances of surviving to adulthood, it doesn't give him any type of evolutionary advantage over someone without the gene.

The article itself did an OK job of describing WHY we are evolving faster. Any new adaptation that humans may gain will come from a random mutation. For the purposes of this discussion a mutation can be simply defined as a set of genetic instructions that cause your body to make or do something differently than everyone else. Now humans are already pretty well adapted, so usually if your genetic instructions cause you to do something different, it's not going to be a positive change. Well over 99% - probably more like 99.999% - of all mutations are deleterious.

That having been said there is a tiny number of mutations that are beneficial. The larger the population the better the chance of having one of the good ones show up. Since the current world's population is bigger than it has ever been before, and is growing at a faster rate than it has even been before, is why evolution is occurring faster. Of course, with a large population it also increases the chances of the deleterious mutations as well, but that's not a big concern because most "bad" mutations prove fatal, and thus the individual with them doesn't pass on the bad genes to subsequent generations. Only the mutations that help get passed on.