the history of human is very long. then how come we do not have contageous deseases from millions years ago.?

Question

Homo sepiens history is millions of years. then how come we do not have contageous desease from millions of years ago. all the harshest contageous desease heppend in couple decades. and they likely to remain in our specie's gene pool. such as HIV. how come it didnot exist from millions of years ago. if its transmitted from monkey. we ate more monkey millions years ago. it is very mysterious. since some desease like HIV will likely to stay in our specie in the future but non have stayed since millions years ago. and we did not even have medication for cure millions years ago. isnt it interesting? can new desease still happen to human all the sudden? and why does it happen? if HIV existed millions of years ago wouldnt we all be extinct? or actually medication to prolong life is bad effect to the society as whole? because its cause more people to be contaminated and not die naturally. anybody know the answer ?

Answer 1

Due to differences of diversity of the human race, and the flora and fauna arond them, some diseases are localized only in certain areas, and due to genetic diveresity over time, people can develop immunities to certain diseases.

For example, it's been discovered that certain descendants of Scandinavians/Vikings are HIV immune.

It's for reasons like this that genetic diversity is such a good thing, and why imbreeding is so frowned upon.

Answer 2

So as not to anger the religious community, I can give the theoretic reasoning.
The best example is the flu virus. Sure, we have antibiotics that were and are effective means to fight the organisms, but the organisms evolve as man, animals, fish, and insects evolve.
At the present, the big fear is the bird flu virus. Just like all the like viruses, they cause the same symptoms as a familiar subject flu named the Hong Kong Flu (HKF). This flu killed many people worldwide in the sixties; then it sort of hid.
Some scientists believe the differing flu viruses evolve to different looking organisms. A case in point is the H5N1 bird flu. It has an ancestor virus that was eradicated, but not defeated. It is much like a cancer going into remission; it is not cured and many times will re-emerge.
There is good evidence the H5Ni is a mutant of another virus thought eradicated, but not defeated.
A virus is like a computer virus, in a way. The computer virus wills continue to change and adapt. It is due to the codes that are assigned to it. The virus will act in the same manner, the DNA will evolve or mutate.
Now back to the bird flu. Scientists realize the DNA of a virus can change as medications are introduced.
Think of it this way; if you keep cattle in a fence that has been electrified, the reasoning is the cows will remember the shock.
If you bombard the flu virus with certain antibiotics, the DNA will cause it to change, thus making the certain antibiotic to be useless.
Scientists don't have a clue as to how the H5N1 bird flu will mutate; but if it mutates to cause it to be susceptible to humans, we will have a pandemic.

Answer 3

We do have contagious diseases from millions of years ago. We evolved, they evolved, one unbroken chain of sniffling and sneezing.

The wild ancestor of HIV causes no problem to the chimps that have it, it will most likely evolve into a commonplace relatively benign strain the way many viruses do. Most viruses don't cause overt diseases, we only pay attention to those that do.

An infectious disease organism that kills off it's host species is essentially committing suicide. Many epidemics start off with a super aggressive organism that infects easily and kills a large portion of its hosts.
As the epidemic spreads, less aggressive, less deadly strains emerge.

It's in a disiese causing organisms best interest to not kill it's host because it allows greater opportunity for reproducing and spreading itself. Very deadly infectious diseases tend to be newly evolved variations.

Answer 4

The entire process of evolution took place not wihout infectious diseases but just because of them.Several years ago more young species of Homo sapiens died and became extinct because of rampant infections for which only "nature"supplied medication.The "fittest"survived and evolved further only to be infected with another set of "mutant"germs.As humans became more and more resistant to infections ,germs became "more"and "more" virulent.(germs also "evolve" to safeguard themselves from human "enemy" called " immunity.").

Answer 5

The humans who survived these epidemics in prehistoric times possessed genetic traits that made them less susceptible to these bugs. As these organisms survived and successfully reproduced, they passed their genetic resistance on to their offspring, so that genetic resistance to these diseases grew with each passing generation.

Answer 6

It's called evolution. Yes even the bugs evolve.

Answer 7

viruses and diseases mutate to better survive in their environment. so we can still get new diseases and find ways to cure older diseases. diseases from years ago just mutated into ones we see today.

Answer 8

1st

.... it's because of evolution ......

2nd

.... nasty scientist