I was reading evolutionary theory, and came across a question I didn't know the answer to, even though it's a common question. If species are evolving constantly, and we originally evolved from the apes, why then are there no species between us and the apes? In other words, why are there no Cro-Magnon or Neanderthals in existence today, if the apes have been undergoing evolution for the past hundreds of thousands of years?
How do discrete species fit in with evolutionary theory?
Deetee
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You'll find that hominids and apes have a common ancestor - we did not evolve from apes. There have been several lines of evolution running in parallel - some of these have ended blindly like the neanderthal one. Luckily for us, our particular hominid branch has flourished.
Edited to add - welcome!
Edited to add - welcome!
Deetee:
Thank you for the welcome! I've been reading JREF for years now, but didn't post until now. Let me ask you a question: Do you have a source (web or book) where I can read more about our (by our, I mean apes and humans) common ancestor?
Thanks.
Thank you for the welcome! I've been reading JREF for years now, but didn't post until now. Let me ask you a question: Do you have a source (web or book) where I can read more about our (by our, I mean apes and humans) common ancestor?
Thanks.
SGT
Critical Thinker
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Try this site:
http://www.talkorigins.org/origins/other-links.html
http://www.talkorigins.org/origins/other-links.html
gellerche said:
Although mutations are always taking place as are allele variations, it's a misnomer to think that species are in a constant state of evolution. Once a species find a comfortable niche, (reduced selection pressure), then there's no impetus for new speciation to take place. In others words, don't expect apes to evolve into anything else for quite some time. And if they did, there's no assurance what they would evolve into.
Johnny Pneumatic
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gellerche said:
Slight nit-pick, aren't we Cro-Magnon?
gellerche, just to clear up a minor confusion:
There is no longer any factual disagreement among scientists about the question ‘are humans apes?’. Bear in mind the concept of an evolutionary group, or clade:
‘Clade: A monophyletic taxon; a group of organisms which includes the most recent common ancestor of all of its members and all of the descendants of that most recent common ancestor.’
Informal (or ‘folk’) groupings of species in everyday language generally reflect similarities, and therefore (usually) relatedness, so they often correspond to clades (e.g. flies, ferns, birds). When they don’t (e.g. reptiles, apes), the reason is usually that one or more lines in a clade has evolved into something apparently very different, and the informal name refers to the rest of the clade.
The word ‘ape’ originally meant tailless primates not including humans, because no-one imagined that some apes could have a later common ancestor with humans than with other apes. However, this is now generally accepted to be the case. So, if we use ‘apes’ as an informal grouping then we need not include humans (and the other hominids); if we mean a clade, then we must.
There is something to be said for avoiding such misleading terms, but it’s a bit difficult to eliminate words like ‘fish’ from your vocabulary.
There is no longer any factual disagreement among scientists about the question ‘are humans apes?’. Bear in mind the concept of an evolutionary group, or clade:
‘Clade: A monophyletic taxon; a group of organisms which includes the most recent common ancestor of all of its members and all of the descendants of that most recent common ancestor.’
Informal (or ‘folk’) groupings of species in everyday language generally reflect similarities, and therefore (usually) relatedness, so they often correspond to clades (e.g. flies, ferns, birds). When they don’t (e.g. reptiles, apes), the reason is usually that one or more lines in a clade has evolved into something apparently very different, and the informal name refers to the rest of the clade.
The word ‘ape’ originally meant tailless primates not including humans, because no-one imagined that some apes could have a later common ancestor with humans than with other apes. However, this is now generally accepted to be the case. So, if we use ‘apes’ as an informal grouping then we need not include humans (and the other hominids); if we mean a clade, then we must.
There is something to be said for avoiding such misleading terms, but it’s a bit difficult to eliminate words like ‘fish’ from your vocabulary.
Crossbow
Seeking Honesty and Sanity
gellerche said:
Well, I hate to give a new poster a negative response, but alas I can find no other retort.
Modern Humans did not evolve from Modern Apes; rather Modern Humans and Modern Apes have a Common Ancestor.
As for why you do not see other hominds now, some 20,000 years ago Modern Humans did co-exist with other hominds, however they were unable to adapt to the substantial enviromental changes that have occured since then (the end of the Ice Ages, death of large land mammals, etc.) whereas Modern Humans could adapt to these changes. Thus, our species has lived while the others have not.
You may want to look at the 'talkorigins' web site for more detailed data if you are really interested in determing the facts of the case.
There are many organisms referred to as "living fossils"--fossils of organisms very similar, if not indistinguishable, from organisms alive today.
Also, if all previously-living species were alive today, it would be a lot more difficult to draw the line between "discrete species" within a clade. For that matter, if you consider certain types of organisms alive today, it can be extremely difficult to identify "discrete species."
Also, if all previously-living species were alive today, it would be a lot more difficult to draw the line between "discrete species" within a clade. For that matter, if you consider certain types of organisms alive today, it can be extremely difficult to identify "discrete species."
If all the creatures that ever lived would still be alive today, I fail to see how the concept of "distinct species" could have any meaning. But even with our present situation (that is, most creatures that once lived are long gone and dead), the concept of distinct species is troublesome. A common definition (in fact, the one I learned in school) goes along the lines: two populations belong to the same species if two representatives of both populations can have fertile offspring. This definition is rather worthless if you try to apply it to bacteria. And it forces you to examine differences in the genitals of insects you can only spot with a microscope. And what do we do with the following: two variations of crickets, one mate in the morning, one mate in the evening. Under natural circumstances, representatives of both variations never meet to propagate, so they could be counted as different species. But if you force them to meet with some artifficial tricks and traps, they can produce fertile offspring.
Another riddle: some birds living along a long coastline that goes from south to north. If you take two examples from the southmost and the northmost point of the coast, they obviously belong to different species (and can't have fertile offspring). But there is a continous link between them.
Even more confusing (although, as far as I know, quite rare): the same situation with a large island, where the northmost and southmost point are linked by two different coastlines, an eastern coastline and a western coastline, with represantatives of the westmost and eastmost point unable to produce fertile offspring.
I'm not an expert in biology, but from what I have been told, there are enough troublesome cases to make any taxonomist desperate and lonely, and there are many different (and sometimes rather complicated) definitions of what a species is, to address all the special cases.
Of course this kind of confusion is exactly what evolution theory predicts.
I'm not sure if this is what you intended to say, but it sounds a bit like "the apes are our primitive ancestors, we humans are their evolved descendants, why didn't the apes evolve during that time, wasn't the same selective pressure applied to them?"
As many have pointed out, modern, present-day apes are not the ancestors of humans (since they are present-day, that would be impossible). And they evolved as much as we did. As others mentioned, if a species has found a comfortable ecologic niche, change may slow down or perhaps even come to a halt, as long as the environment doesn't change. And, furthermore, there is no upward tendency built in evolution, and mankind is not the crown of evolution. Species become adapted, and that doesn't necessarily mean that they get a huge brain, the ability to speak and self-consciousness. Bacteria are well adapted, and that's the reason why they exist in abundance. Apes are also adapted. There is no contradiction that the Neanderthals vanished and the gorillas are still there.
Another riddle: some birds living along a long coastline that goes from south to north. If you take two examples from the southmost and the northmost point of the coast, they obviously belong to different species (and can't have fertile offspring). But there is a continous link between them.
Even more confusing (although, as far as I know, quite rare): the same situation with a large island, where the northmost and southmost point are linked by two different coastlines, an eastern coastline and a western coastline, with represantatives of the westmost and eastmost point unable to produce fertile offspring.
I'm not an expert in biology, but from what I have been told, there are enough troublesome cases to make any taxonomist desperate and lonely, and there are many different (and sometimes rather complicated) definitions of what a species is, to address all the special cases.
Of course this kind of confusion is exactly what evolution theory predicts.
I'm not sure if this is what you intended to say, but it sounds a bit like "the apes are our primitive ancestors, we humans are their evolved descendants, why didn't the apes evolve during that time, wasn't the same selective pressure applied to them?"
As many have pointed out, modern, present-day apes are not the ancestors of humans (since they are present-day, that would be impossible). And they evolved as much as we did. As others mentioned, if a species has found a comfortable ecologic niche, change may slow down or perhaps even come to a halt, as long as the environment doesn't change. And, furthermore, there is no upward tendency built in evolution, and mankind is not the crown of evolution. Species become adapted, and that doesn't necessarily mean that they get a huge brain, the ability to speak and self-consciousness. Bacteria are well adapted, and that's the reason why they exist in abundance. Apes are also adapted. There is no contradiction that the Neanderthals vanished and the gorillas are still there.
Re: Re: How do discrete species fit in with evolutionary theory?
What about random mutation? If species need an outside "pressure", then you are only including half of what evolution is about.
Why would there not be an impetus for apes to evolve?
mark tidwell said:
What about random mutation? If species need an outside "pressure", then you are only including half of what evolution is about.
mark tidwell said:
Why would there not be an impetus for apes to evolve?
Eos of the Eons
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Good points to put together. Apes are in a population decline, lessening the chances of any beneficial mutations coming into the population. Beneficial mutations cause those with it to survive better, and they become dominant. They may also increase in numbers to the point where those without the mutation are squeezed into extinction. This all without any climate changes.
If there was a climate change right now where apes are living, it is more likely they will die since they don't have the diversity to survive.
Humans have the population, and would survive most major calamities. There are humans right now that do not become infected with the HIV virus, even if they get repeated exposure. If we did not have the population that we have, then it is highly likely that no individuals would have this ability.
Evolution can only continue with the ability of the population to adapt. Some adaptations require mutation. They most certainly require a stable population base. Our ancestors lacked something, and we had to have contributed by taking up resources and space.
This is survival of the fittest. It's not certain, and it's not pretty.
Clause, what do you mean by "impetus"?
If there was a climate change right now where apes are living, it is more likely they will die since they don't have the diversity to survive.
Humans have the population, and would survive most major calamities. There are humans right now that do not become infected with the HIV virus, even if they get repeated exposure. If we did not have the population that we have, then it is highly likely that no individuals would have this ability.
Evolution can only continue with the ability of the population to adapt. Some adaptations require mutation. They most certainly require a stable population base. Our ancestors lacked something, and we had to have contributed by taking up resources and space.
This is survival of the fittest. It's not certain, and it's not pretty.
Clause, what do you mean by "impetus"?
Eos of the Eons
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CFLarsen said:
Sure, but what I meant was:
The lower the population, the less of a chance there will be that a beneficial mutation will arise.
This backed up by the HIV example.
A beneficial mutation that arises will be beneficial no matter if the population is large or small. A small population with no beneficial mutation will face extinction faster if faced with hardship. If the beneficial mutation in the small population gives no benefit when facing said hardship, then it will face extinction if it needs a mutation that will aid in adaptation.
Claus. While Iceland's population is certainly subject to restriction imposed by isolation, the gene pool is not so limited as you might expect. Remember that the 9-11th century settlers brought slaves captured in raids all over Europe. The position of a slave in early Norse society (while hardly great) was a lot freer than in more traditional slave based economies like Rome. Slaves actually had rights- as reflected in early Icelandic Law. Their contribution to the modern gene pool was significant because of the small size of the total population. As for modern Iceland- well. It's only a two hour flight to Glasgow you know. Icelanders get around.
(And yes, dammit, I am grinning at happy memory.)
(And yes, dammit, I am grinning at happy memory.)
Re: Re: Re: How do discrete species fit in with evolutionary theory?
Originally posted by CFLarsen
What about random mutation? If species need an outside "pressure", then you are only including half of what evolution is about.
Actually I referred to mutation in my first sentence. What half of evolution am I leaving out? Random mutation can only get you so far. Without a selection pressure to favor that mutation, it's only a bit more variation in the population. It could be passed on, it could drop out.
Why would there not be an impetus for apes to evolve?
????
Nothing has an "impetus" to evolve. Some traits get favored, some don't, depending on the environment. Is there some trait of some species of ape that you think is well favored to be inherited by future generations?
Edited to add: I just realized I used the word impetus in my earlier post. Bad choice on my part. Sorry for starting it off.
Originally posted by CFLarsen
What about random mutation? If species need an outside "pressure", then you are only including half of what evolution is about.
Actually I referred to mutation in my first sentence. What half of evolution am I leaving out? Random mutation can only get you so far. Without a selection pressure to favor that mutation, it's only a bit more variation in the population. It could be passed on, it could drop out.
Why would there not be an impetus for apes to evolve?
????
Nothing has an "impetus" to evolve. Some traits get favored, some don't, depending on the environment. Is there some trait of some species of ape that you think is well favored to be inherited by future generations?
Edited to add: I just realized I used the word impetus in my earlier post. Bad choice on my part. Sorry for starting it off.