explaining common ancestry

Hi Carico,I think a lot of the problem is that you think evolutionary theory says many things it doesn't actually say. One of the key facets of evolutionary theory is that in most cases species change is very gradual. Speciation is not like the border between countries with hard and fast boundaries, where one second you're in Belgium and the next your in France.Species change is more like the boundaries between inland and shore. Just as traveling toward the shore will see gradual reductions in dense forests, increases in sandy soil and changes in both flora and fauna, species change over time is also gradual. There was never a first primate, nor was there ever a first human. Rather, gradual change over time caused a species population to take on more and more of the qualities associated with primates, and later, gradual change over time caused an ape species population to take on more and more of the qualities associated with humans.Some of things that you're arguing against, such as that new animal species can be created suddenly, or that evolution occurs through the intermingling of existing species, appear just as ridiculous to evolutionists as they do to you, because evolutionary theory doesn't, for the most part, include these possibilities. While you *can* breed horses with zebras and tigers with lions, this is only because these species are already very closely related, and it has very little to do with the mainstream evolutionary process of gradual change over time through mutation and natural selection. (I was careful to deal with animal species because I didn't want to confuse the issue with plant hybridization and polyploidy.)--Percy

You have a fundamental misunderstanding of how mainstream evolution is understood to work. While there are a wide variety of evolutionary mechanisms, creating new species through cross-breeding is not a significant one for animals. Most new species are thought to arise through a gradual process that Darwin described as descent with modification combined with natural selection.Sticking with animals as the focus of the discussion, a species is a population of animals capable of interbreeding. The gene pool of the population includes a vast amount of diversity. What defines the population as a species is the gene profile, or more accurately, the allele profile, where an allele is one variety of a gene, such as eye color where there is a blue allele, a brown allele and so forth (the actual factors governing eye color are complex, so this example of alleles is oversimplified to the point of being wrong, but I use it because it provides a good illustration of what an allele is). The frequency of each type of allele in the population defines the species.The gene pool serves as a huge genetic library that the population can draw upon in times of environmental stress. When conditions are not ideal, natural selection will choose those individuals most suited for the new conditions, and over the course of time the allele profile for the population will change, and so will the internal and external morphology of the species, as well as its behavior. Mutations also play a role because they create new alleles not previously available to the species that the population can draw upon as it evolves to best take advantage of the new conditions. Reproduction is a key component of evolution. Darwin called evolution descent with modification, and there can be no descent without reproduction. No one here is insinuating or implying that reproduction is a waste of time. It is necessary in order for evolution to occur. And no one believes animals magically turn into other species. In the main, speciation occurs through a gradual process of descent with modification filtered by natural selection. It is the facts gathered by Darwin that enabled him to develop the theory of evolution, and all the scientists that came after him have uncovered mountains and mountains of more facts that confirm and enhance the theory. Mendel discovered the discrete nature of heredity, and in the 1920's the population geneticists discovered that genetics and Darwinian evolution were mutually supportive theories, combining them into what is known today as the modern synthesis.The Creationist perception that there is a lack of facts supporting evolution is due to the impossibility of observing speciation in the higher animals. We can observe speciation in the lab in bacteria and fruit flies and so forth, and there are a small number of observed speciations in the wild, but by and large change in the higher animals occurs at far to slow a pace for us to notice.So much of the evidence for evolution comes from other sources, such as cladistics, the fossil record and genetic analysis. We can discuss this and other evidence if you are interested.--Percy

I think you first have to realize that it would make no sense to claim that the only way to get another species is to breed with that species. Were this the case then the species would have to already exist in order to breed with it, but if it already existed then there would be no need to breed with it in order to produce it.Another part of this that makes no sense is that breeding different species together produces a hybrid, not one of the original species. Breeding a horse and a zebra produces a zorse, but not a horse and not a zebra. Breeding a lion and a tiger produces a liger, but not a lion and not a tiger.So the reason no one believes that one species can turn into another species by breeding with it is because it makes no sense in the couple different ways that I've described. No, birds cannot turn into dogs and cats cannot turn into wolves. That sounds more like magic than science. Evolutionary theory holds that species change gradually over time in response to environmental pressure through the processes of descent with modification (offspring are never identical to parents) and natural selection (organisms with traits ill-suited to the environment will not get a chance to reproduce and so will not pass their genes on to their offspring). This goes back to what I wrote earlier about populations. A species evolves as a population of organisms, not as individuals. The allele profile of the population gradually changes over time in response to environmental changes. If it changes sufficiently then the descendent population will be a different species than the original population of many generations before. They *do* change into new species without interbreeding with other species. That's what everyone has been telling you.--PercyThis message has been edited by Percy, 12-22-2005 05:21 PM

No one is lying to you. You just have the wrong idea of what an ape is.The formal genus/species name for human beings is Homo sapiens. This means we're of the genus Homo and the species H. sapiens. Homo sapiens are members of the Hominidae family, which is a member of the Hominoidea superfamily, which is apes. A more complete classification looks like this: From this table you can see that apes are a broad classification known as a superfamily, and that chimpanzees, gorillas, orangutans and humans are all members of this superfamily. In other words, humans are a type of ape. If you don't like being called an ape then use the more technical superfamily name, Hominoidea. This has been a consistent claim of creationists for the past 50 years or so. If scientists had truly been deserting evolution in droves for so long a period of time then there should be few scientists left by now who still accept evolution. Since this is not the case you might want to cast a more skeptical eye at the source of your information.--Percy

Many zoos have a primate section, part of which is devoted to apes. When you visit the gorilla cage, the cage is not labeled "apes". It probably says Gorilla beringei (eastern gorilla) or Gorilla gorilla (Western gorilla). Most likely there is a lengthy description of the gorilla, which will include the fact that a gorilla is a type of ape.When you visit the chimpanzee cage, the cage is also not labeled "apes". It probably says Pan troglodytes (common chipanzee) or Pan paniscus (bonobo or pygmy chimpanzee). The description at this cage will tell you that chimpanzees are a type of ape.The visitors watching the gorillas and chimps are also a type of ape. Of course we can breed with apes. Human beings breed with apes all the time. I've personally done it myself! But there is only one species of ape with which Homo sapiens can breed, and that is other Homo sapiens. We cannot breed with any gorilla species of ape, nor with any chimpanzee species of ape. Application of evolutionary theory to the fossil record and the study of genetic interrelatedness tells us that all modern apes descended from a common ancestor. In other words, human beings did not descend from gorillas and they did not descend from chimpanzees. Millions of years ago humans and gorillas and chimpanzees did not exist. They hadn't evolved yet. But there was a common ancestor from which all modern species of human, gorilla and chimp evolved. Yes, for the umpteenth time, species evolve on their own, through a process described as descent with modification combined with natural selection.--Percy Minor grammar fixes. --PercyThis message has been edited by Percy, 12-23-2005 12:26 PM

Sure it has. It takes many generations for one species to evolve into another, so we can't observe this happening for the longer lived species. For example, let's say it takes a thousand generations for a new species of primate to evolve. If a generation is 10 years, as it might be for gorillas, then it would take 10,000 years for a new species of gorilla to evolve. This is far, far too long for any experiment to observe.But many bacteria produce new generations in much less than an hour, and a thousand generations can be produced in only a week or two. Evolving new species of bacteria is easily done.Fruit flies also have a fairly short generation time. Not as short as bacteria, but short enough for evolution to be observable. New species of fruit fly have been bred in the lab.Plants provide many examples of speciation because there are more ways it can happen. In addition to the traditional method of descent with modification combined with natural selection there are also polyploidy (multiplication of the number chronosomes) and hybridization (cross-breeding).The technical literature is full of examples of speciation. There's a good article at Talk.Origins titled Observed Instances of Speciation that lists a number of them. More than one gene is involved in all these things. For talking, thinking and walking there must be thousands of genes involved. But for the sake of keeping the discussion simple, let's assume that eye color is under the control of a single gene. Each type of the eye color gene is called an allele.Continuing to keep things simple, let's further assume that there are only three alleles for the eye color gene: brown, blue and green (we won't worry about dominance, either). Each allele is a string of nucleotides at the place for this gene on a longer DNA strand. A mutation in one of these alleles would change it into an allele that is neither the green allele, nor the blue allele nor the green allele. It's a new allele. How it affects eye color is anyone's guess. It would depend on the new protein it produces and the effect of that protein on eye color. As the above discussion indicates, mutations cause genes to produce new proteins that they did not produce before. The effect of the new protein may be deleterious, neutral or advantageous. Except for the case where it is neutral, the new protein can produce new characteristics and behaviors in the cell that were not previously present.Look at it this way. A cake is a mixture of many ingredients. If you change the ingredients then the cake will come out differently. In a similar way, a cell is a mixture of many chemicals combined into DNA, RNA, proteins, catalysts and so forth. Change the composition of the cell by changing one or more proteins and the cell will come out differently. There's a good reason this doesn't work. Let's assume it is possible for cancer cells to mutate into healthy cells. In that case, some will mutate into healthy cells, but the rest will remain cancer cells and will continue dividing at the high and uncontrolled rate typical of cancer cells. Because the rate at which cancer cells reproduce is much higher than normal cells, even if some percentage of the cancer cells return to normal behavior, the remaining cancer cells will continue to produce new cancer cells. At best, if cancer cells can mutate back to healty cells, the effect would only be to slow the growth of the cancer. Evolution does not claim this. The outcome of mutation is often unpredictable. It is the filter of natural selection that determines which genes succeed and which fail.--Percy

Hi Carico,It might be faster to get through these issues with a real time dialogue. I'm going to wait in the chatroom for a while, why don't you join me there.--Percy

Thank you very much for helping out!It sounds like you might understand the point Carico is trying to make, and if that's true then clarifying it for us would also be very helpful. We can see that he is arguing that evolution cannot happen, but the reason he advances, namely that evolution cannot take place without interbreeding between species, makes no sense to anyone. If it makes sense to you then can you please express it in terms that make sense to others?--Percy

You're replying to yourself so it's hard to tell who this is actually addressed to, but in case it was me... The pace of evolution varies. It depends upon the amount of time per generation, and upon the amount of environmental pressure. Creatures in a stable environment for which they're well suited will evolve little, such as the horseshoe crab and the coelacanth, which persisted with very little change for millions of years. Creatures in a changing environment with great environmental pressure can change rapidly, in mere thousands of years, unless the pressure is so great that they go extinct. And in the case of bacteria, where many generations can occur in a single day, it can take as little as a week to breed a new species.So you see, there is no one time frame for evolution of a new species to occur. Some speciation is rapid, some slow, some glacial.--Percy