Come Evolutionists?

Question

From a former question (for evolutionists), I've learned that according to the evolution theory, humans and apes evolved from a common ancestor.

From the same question I was also wondering what humans would change into (if anything). They said they didn't know, but humans are getting a tiny bit taller over the centuries. If evolutionists think this, they believe (or at least I assume because this is obvious) that the slight change could not be noticable in one or even two generations.

Assuming this, the change from the common ancestor would be unnoticeable in one generation. The two seperations (not knowing they were seperating because of a unnoticeable change) would either reproduce together, which would continue the common species (which in my own mind is humans alone), or they wouldn't reproduce, and the chain would die out.

If you do not understand what I am saying, please correct me. Could you explain this?

Answer 1

This was a problem that plagued Darwinists for ages - why positive mutations didn't die out through dilution. The answer came through Gregor Mendel's discovery of dominant and recessive genes. Look it up.

Answer 2

It's the environment that matters. If there is a significant mutation and it produces a survival advantage, the mutant is more likely to live to produce viable offspring. If it is a disadvantage, the odds are not so good. If it's neutral, the change may get lost in normal genetic variation, to re-express when conditions change.

When an environment changes significantly (climate, food supply, whatever) and becomes inhospitable, mutations that provide a survival advantage will enable their bearers to survive better than the dominant genome. An extinction event is sometimes an opportunity for evolution.

As an example, if an antiseptic does not kill all the bacteria in a target area, only the most resistant bacteria will survive to reproduce and replace the population. Suddenly, the antibiotic is no good. The same thing holds for insects and insecticide, or flu viruses. The simpler the organism, the more drastic the mutation. Complex organisms are not as adaptable, but the same mechanisms are at work.

Answer 3

" I've learned that according to the evolution theory, humans and apes evolved from a common ancestor."

Correct.

"but humans are getting a tiny bit taller over the centuries"

That has been statistically proven, yes.

"that the slight change could not be noticable in one or even two generations."

Well, variations in hight are indeed noticeable by individual offspring, but as a whole, the change for the entire human species would not be noticed in one, two, or even a dozen generations.

"Assuming this, the change from the common ancestor would be unnoticeable in one generation. The two seperations (not knowing they were seperating because of a unnoticeable change) would either reproduce together, which would continue the common species (which in my own mind is humans alone), or they wouldn't reproduce, and the chain would die out."

You are correct. If nature does not force a specieis to evolve than traits such as slightly taller, faster, etc. will simply mix back into the gene pool and be "lost". However if at the same time nature is forcing hte specieis to change, then those traits that yield a slight advantage over those individuals without said traits will increase in frequency inthe population.

If you follow the genetic frequency of allels (nucleotide combinations) you will see a gradualy increase in the over ll frequency for those traits that benefit the society.

Take a look at heterogenic sickle cell anemia in africa. Individuals with H-Skc are immune to malaria. The allele frequency for this trait is highest in those parts of africa with the greatest concentration of the malaria parasites.

Answer 4

We evolved from apes. It's more correct to say that humans and chimps have a common ancestor.

The "humans are getting taller" is false. It's an artifact of better nutrition. People who are taller don't necessarily have more children than short people -- and it wouldn't show up in the four hundred years or so that we've had more cheeseburgers, anyway.

> the change from the common ancestor would be unnoticeable in one generation
Correct!

> The two seperations (not knowing they were seperating because of a unnoticeable change)
Ah, and there's the problem. The separation wasn't because of an unnoticeable change. It's more likely because our ancestors got physically separated from the other lineage -- possibly ours on the east side of the Great Rift in Africa; and the chimp lineage on the west. Genetic drift is more likely with an isolated population -- and natural selection in one part of Africa would be different from natural selection in another part. Our lineages remained apart long enough for speciation to occur.

Answer 5

It doesn't work quite like that.

You usually need to have several mutations over time for the people to become so different from the original that they can no longer mate. One gene mutation will not likely be enough. Think more in terms of many generations, and you be on to it.

This is not set in stone, by the way. They just discovered a type of jellyfish that was able to mutate into a new species in just a couple of generations, but this doesn't appear to be the norm. Usually, it takes a lot longer and with more mutations (human chromosomes have a lot more information than jellyfish).

Answer 6

Many times, a single species will be divided physically. They will not have an opportunity to mate until many generations later, at which point, the differences are so numerous between the two they treat each other like different species.

Answer 7

If you mean are humans evolving right now as opposed to thousands or tens of thousands of years ago, that is a bit of a controversial subject because with humans it is so very difficult to separate 'nature' from 'nurture.' Many changes (larger body sizes etc.) can be explained at least theoretically by cultural effects or environmental effects such as improved nutrition, and are not necessarily genetically determined. Global travel and mating are also mixing gene pools that were previously slightly different, and thus diluting evolutionary changes that had begun to develop when they were isolated.

Rapid mutations point to bigger human brains: as seen in Edmonton Journal Sept. 11, 2005, page A11
Human brain may still be evolving---- This points to evidence for variations dating to as recently as 6000 years ago in genes that are important for brain development. These variations are claimed to be now maintained in human populations by selection. Other scientists urged caution in interpreting these results.

One fairly obvious possibility is that humans alive today might be genetically resistant to some diseases that devastated earlier societies, because we are descended from the survivors. That would be interesting to pursue.

Another possibility is that selection has actually been relaxed in many ways, for example by global sharing of food and by medical care. There is thus less intense selection than there used to be (more individuals survive to reproduce than would have in earlier centuries). This might make us less fit than our ancestors would have been in the event of a future environmental crisis.

Answer 8

Don't forget environment. We're increased our food supplies in Europe and the U.S., so people have the opportunity to grow to their genetic potential.

Malnourished populations are often shorter and have lower intelligence than their more nourished counterparts.

Evolution is gradual and occurs over a scale of millions and billions of years.

Answer 9

I'm not completely sure what you are getting at. If I'm correct, you are trying to understand the change in species and how it continued. Obviously, one hominid had an evolutionary change, most likely by a genetic mutation. He and his mate had children and that mutation was passed on through his children and proceding generations. Obviously they did, because here we are.

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Answer 10

It may help you understand if you realize life is dynamic and because of that it cannot be placed reliably into a static system of nomenclature like Linnaeus tried to do with the binomial names.

It's a little like mixing your own colors and trying to assign them all to colors in a standard box of crayons.