How Certain is Evolution Theory?

[sciborg]

I understand that the idea that humans and other current species are evolved from earlier species is essentially a scientific certainty. There is all sorts of fossil evidence backed up by genetic evidence, backed up by comparisons of existing species, etc.

However, according to this evolution site (http://www.azinet.com/evolution/) there is a lot of scientific disagreement with other parts of Darwin's theory. Some questions that were raised:

Is survival of the fittest the only factor affecting evolution?

Does evolution require benefit to individual organisms?

What do you think?

 

[spidergoat]

Other factors effecting evolution are sexual selection and cooperation. The benefit might not be to individuals, as with ants, but with the community as a whole.

 

[fadingCaptain]

There is also the random component of gene mutation that factors in as well as survival of the fittest.

It is true the details of evolutionary theory are still being worked out, but the theory on the whole is probably as certain as they come.

 

[Avatar]

For a little laugh: http://www.besse.at/sms/descent.html

 

[devils_reject]

Evolution and creation is not a mutualy exclusive event. Both could have easily happened, though I think evolution has an upper hand when you ask " where did God herself come from?"

 

[valich]

Evolution is a "theory," but that's only because all "facts" are relative; but philosophically speaking, I think it is safe to say now that evolution is more of a "law" than just a "theory," at least on our earth, as anyone who wants to can see it happen: as Mendel did with his initial pea plant experiments that proved the scientific basis for Darwin's "Theory of Natural Selection."

As mentioned above, evolution occurs on a community level and not on the level of the individual. Although the individual may benefit through a mutation to survive ("survival of the fittest"), ultimately it is the entire community that must change with that mutation(s) to keep up with the changes in its environment. Many predator species vs. their prey vs. their predators constantly evolve through adaptable mutatrions back-and-forth so that each species still survives.

"Survival of the Fittest" is not the only factor affecting evolution and a good example of that is with humans today. Look how much we care for the aged, disabled, the sick, and all other humans with defects - and if possible, if they want, they are able to marry and have children. These children may be carriers of inferior defective mutations that are then still passed on to future offspring. So maybe we are now being the current witnesses to the disproof of the "survival of the fittest" in all cases. But thus is evolution.

 

[sciborg]

The "way evolution works" is supposed to be that individual organisms that have some desirable trait live longer and breed more and therefore the trait is "selected" by natural selection. Mutations that cause an animal to die earlier are rejected by natural selection. Therefore it is apparently impossible to evolve a trait that causes individuals to die earlier or breed less even if that trait is helpful to the "community" or "society" or "the species".

There is what is known as the "cheater problem". Suppose some trait helps the community at the expense of individuals. Cheaters that don't have that trait could take advantage of its community benefits while simultaneously living longer, breeding more, and passing their cheater genes to a larger number of descendents. Eventually the cheater genes would become universal.

This is one of the issues that continue to represent questions about the certainty of evolution theory. We all agree that evolution happened but how it happened still seems to be somewhat unclear.

 

[Wings]

Ahh, but if the individual who sacrifices saves those with the genetics closest to him, then the purpose is still fullfilled. This is the basis of cooperation. Think of plants: if they reproduce with those nearby, the genetic traits occur over a gradient, with a greater concentration at one point. If a sacrifice occurs at this point, which saves those nearby, then in essence it has been successful in preserving it's genetic make-up.

 

[spidergoat]

Mutations that cause an animal to die earlier are rejected by natural selection.

Only if it causes them to die before breeding, or if that particular animal doesn't breed, like a worker ant.

Therefore it is apparently impossible to evolve a trait that causes individuals to die earlier or breed less even if that trait is helpful to the "community" or "society" or "the species".

Obviously not. What about the male spider that lets himself get eaten by his mate?

There is what is known as the "cheater problem". Suppose some trait helps the community at the expense of individuals. Cheaters that don't have that trait could take advantage of its community benefits while simultaneously living longer, breeding more, and passing their cheater genes to a larger number of descendents. Eventually the cheater genes would become universal.

But a community full of cheater ants that don't give up their lives to make a bridge, for instance, would soon die off in the first flood. The community without any cheaters would survive to breed.

This is one of the issues that continue to represent questions about the certainty of evolution theory.

The cheater problem will never be cause to discount evolution, after all, we can observe evolution in the lab.

We all agree that evolution happened but how it happened still seems to be somewhat unclear.

Happened, is happening, will be happening into the future.

 

[Ophiolite]

sciborg, some of the following points have been made implicitly above, but I believe they are worth repeating.
Point 1: to a layperson theory suggests something uncertain, a speculation, or possibility. This is not the case in science. Nothing really stands above theory. In a few cases we call a succinct rendering of a theory, a law, but this is a minor difference.
Point 2: Evolution is not in dispute amongst scientists. The fact of evolution is absolute. What is debated, and rightly so, for that is the nature of science, is the mechanism by which evolution operates.
Point 3: While evolution by natural selection is an important mechanism, it is not the only. Equally the exact way in which this and the other mechamisms operate, and the character of mutations on which natural selection works, are not defined in total detail.
Point 4: Evolution theory has moved well past Darwin. His work remains pivotal, but he would fail to recognise the detail of his theory in today's work, whilst recognising, and I think applauding, the advances that had been made.

 

[valich]

Very well said and summarized. Point 1 is what I meant, without using layman's terms, by suggesting that we might as well call it a law - on earth at least, or in our universe.

I do not understand the question posed above: "how it happened still seems to be somewhat unclear"? Answer: Random events. Chance. Murphy's Law. Mutations are random chance events. I don't think we're just talking about the evolution of humans, are we? I suppose on this thread we're referring to how life - as we know it - began on earth, and then how life on earth evolved. To this we can look at the Miller-Urey experiments that showed us how amino acids could be formed under the right environmental conditions that existed on earth 4.5 billion years ago. Going a bit further, new evidence seems to be supporting the view that RNA came before DNA.

Actually there are two main theories for the origin of life on earth: 1) spontaneous generation, aka Miller-Urey's "primeval soup", or 2) panspermia: brought to earth from somewhere else such as from a meteor impact.

A good website on this would be "Origins of Life," www.resa.net/nasa/origins_life.htm
Their Homepage is titled "Life On Other Planets in the Solar System," but that's a different thread.