What causes death?

[ant80]

This discussion is getting absolutely ridiculous.

The better policy would be to make it so that the 'best' people reproduce a *lot*. Give subsidies -- hell, even pay the most intelligent people to do nothing other than have kids.

I am sure that would solve a lot of problems. Doesn't sound too different from the Nazi philosophy. Giving preferential treatment sounds like Gattaca. I agree. It takes away the basis of the human civilization and society. Take that away, and we are nothing but animals fighting over resorces instead of food. Humans have evolved far enough. We have the ability to think, the ability to know whether what we are doing is good or wrong. What is the use of having that discerning capability as long as we are stupid enough not to put it to good use? Now it is time to put that evolution to good use instead of thinking about evolving more and more.

Bottom line is evolution will not take place in humans anymore. Evolution is based on the philosophy of survival of the fittest. The term fitness can be defined several ways. Fitness does not matter as much as selection. Take the sickle cell anemia for example. What is the reason why that disease is so prevelant in africa? Because of malaria. The way the defective hemoglobin (Hb) is oriented in heterozygotes (one normal copy of Hb and one defective) is such that heterozygotes have an immunity to malaria. So, freq. of defective Hb is increasing. Why? Because selection favours those that have a defective copy of Hb.

Initially, when they sprayed DDT in India Cooum river, 99% of all the mosquitos died. 10 years later, when they sprayed DDT again, 99% of mosquitoes survived. Why? Selection. When DDT was sprayed the first time, the 1% of mosquitos that got selected were those that had an immunity to DDT. Since the other mosquitos got killed off, only the immune mosquitos bred for 10 years. So during the second spray, most of the mosquitos were immune.

Bottom line is evolution will not take place in humans anymore.

That was my quote a couple of paragraphs ago. What does that mean? Evolution is generally started by a mutation. But for evolution to occur, there has to be selection. During the european plague, there was selection. There must be a natural process in which people die, like the mosquios or malaria. Only then does selection occur. Selection redistributes the frequency of a gene in a gene pool. This is the next phase of evolution. Since we don't have selection, there is no redistribution of frequencies. Even historically, molecular genetists estimate that over 90% of (even favourable) mutations are lost due to (the lack of) selection.

I hope this answers everybody's questions.

 

[ant80]

Well, let me clarify this. Sometime in the future, there might actually be some disease that kills of a lot of the human population. Those that survive might be those that are heterozygous for cystic fibrosis, or those who are prone to cancer, or even those who have slightly defective eyes (and have to wear glasses). There is no way to know. So my point is we can't label a gene as defective and eliminate it. If that had been done to sickle cell hemoglobin, then africans would not have had any immunity to malaria.

It is not for you or me to decide. We observe. Nature decides. At least at this level of technology. Maybe when technology advances enough to predict protein conformation and function from gene sequence, we might have better luck at understanding the glorious ways in which nature works.

 

[exp]

What causes death?

No idea...your guess is as good as mine. But I do have some random comments about the human evolution tangent this thread has been diverted onto. Take 'em with a grain of salt:

(1) There is more to evolution than just natural selection (aka "survival of the fittest"). A population can exist inside a plastic bubble, completely isolated from any disease, predators, etc. and still evolve.

(2) There is no such thing as "devolution." There is evolution and there is equilibrium...that's it. If "stupid" people reproduce more than "smart" people in today's society that is not devolution--it is evolution...the implication being that stupidity has become a beneficial trait. :Q Strange but true.

(3) Our understanding of which traits are "good" and which are "bad" with respect to evolution is not necessarily accurate. Poor eyesight is an excellent example of this since AFAIK it has zero effect on reproductive success. If a trait does not reduce the ability of an organism to pass on its genes to the next generation then it is not a trait that will be selected against during evolution...its prevalence within the population is a complete nonfactor as far as Mother Nature is concerned.

(4) Our reasoning behind labeling certain traits as negative is flawed. For example, we have a natural tendency to believe that a weak physique is "bad"...the assumption apparently being that if mankind was somehow forced to return to our primitive origins--exposed to the elements and wildlife--we could not survive. But applying this twisted "what-if" logic to the history of evolution we can arrive at any number of ridiculous conclusions. Case in point: Would you argue that the development of lungs was a negative development for early land-based organisms b/c the new organs were not well-suited for a marine lifestyle? Of course not. This sort of reasoning makes little sense...organisms adapt to their present environment and the success of their evolution is measured with respect to that frame of reference *only*. If a weak physique is sufficient for survival in our modern-day insulated environment then it hardly matters how it affects our ability to emulate the feral lifestyle of early Man.

(5) As mentioned previously many of our physical shortcomings (e.g. obesity, poor vision) are not necessarily genetic defects, but rather products of external stimuli from the environment such as eating too much, staring at TV/computer screens, etc. Remember that Lamarckian evolution has been discredited...now we know that if a trait has no genetic basis then by definition it has nothing to do with evolution.

(6) Evolution takes time. Even under PE the brief history of modern civilization is far too short a time period to have produced any significant changes in our species. It is simply way too early to draw any conclusions--or even gather meaningful evidence--about how urbanization and technology has affected our genes (although wild speculation is always fun). Let's revisit this topic in a few dozen millenia, shall we?