Evolution: why is it not continuous?
- Thread starter srimukh
- Start date
Correction: Nature is not responsible for where human beings are at this very moment. Everything related to "being human" has been developed by human civilizations artificially, not by any natural and supernatural forces.
And yes, human distinction is also subject to evolution.
One could also argue that artificial and natural are actually same concepts. What would this tell us?
Just to clarify my original post where I said Homo Erectus was successful - I meant that they were around for a very long time with little or no anatomical changes. Homo Erectus survived several large climate shifts and they expanded their territory greatly to boot.
Plus the species has a sophomorically funny name.
Plus the species has a sophomorically funny name.
It is a continuous process. However, that does not mean that it is a smooth progression. An organism adapted well to its environment will change slowly if at all; an organism poorly adapted will change rapidly or go extinct.
?? Other mammals have intelligences similar to man's. They just don't have the same language or tool-using capabilities.
It's really not that huge. It seems huge to us because we are so used to looking at other people. But overall we're really pretty similar. Similar skeletons, organs, circulatory systems, eyes etc. Our DNA is 96% the same. We care for our children the same way, have similar relationships, similar moods, get similar diseases etc etc.
The chimpanzees were better than the transitional forms. So the transitional forms died and the chimpanzees survived.
At some time in the past, there were probably population of apes with intelligence between those of present-day average human and present-day average chimpanzees. Those populations are dead now. Thus a gap exists today between chimps and man.
http://talkorigins.org/indexcc/CB/CB805.html
http://talkorigins.org/indexcc/CC/CC201.html
Humans and Chimps are related yes, however that is due to both species steming from a single common ancestor, that ancestor would lead to chimps in one divergence while the other would lead to small tree of hominids and hominods(inculding us of course)
http://www.evolutionpages.com/homo_pan_divergence.htm
http://www.sciencedaily.com/releases/2009/05/090519104643.htm
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Ardipithecus kadabba, Sahelanthropus tchadensis, and Orrorin tugenensis. http://en.wikipedia.org/wiki/Chimpanzee-human_last_common_ancestor
Taking only natural selection into account (which may be a gross simplification of the story), it's not a matter of being better "overall" (which isn't something that even exists in biology), but better within a given ecological niche.
The chimp-like ancestors of chimpanzees and the "ape-man" ancestors of humans were not competing in an environment where the only way to survive and reproduce was to be more human-like.
Rather, there were advantages both in being more chimp-like and in being more human-like, the intermediates being worse off against both "sides". That's divergent evolution:
http://en.wikipedia.org/wiki/Divergent_evolution
Or perhaps even more relevantly:
http://en.wikipedia.org/wiki/Disruptive_selection
Add to the story random events and environmental changes, epidemics, etc, and then there's even the possibility that the intermediates would have gone extinct even if they were somewhat superior by some sort of analysis of fitness under "fair" competition conditions. (Not that they were, or that it's likely that they were; could as well have been that chimps were better adapted than the "ape-men" types all along, and random environmental changes had an effect of delaying the extinction of the otherwise less fit ape-men)
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Perhaps it also helps to take the logic to the extreme, which would be to ask, "why there is not only one species"?
If the intuition that evolution was supposed to be continuous in such a way is right, not only we'd not expect to see chimpanzees around, but pretty much nothing else but humans, not even bacteria or plants.
Not that there could never be intriguing particular cases of coexistence of related species where one could be expected to have led the other to extinction, but the core of the answer is the same, the lineages diverge without outcompeting everybody else, even though they will outcompete someone every now and then.
If the intuition that evolution was supposed to be continuous in such a way is right, not only we'd not expect to see chimpanzees around, but pretty much nothing else but humans, not even bacteria or plants.
Not that there could never be intriguing particular cases of coexistence of related species where one could be expected to have led the other to extinction, but the core of the answer is the same, the lineages diverge without outcompeting everybody else, even though they will outcompete someone every now and then.
DaveC426913
Valued Senior Member
Some critical takeaways from this thread, in case they got lost.
There is a hypothesis that an ecosystem (such as a planet) will only support one highly intelligent species at a time. One will wipe the other out.
Chimps and humans both evolved from a common ancestor that was neither chimp nor human.
There were many hominids more developed than chimps and less developed than man. Neanderthal was one.
There is a hypothesis that an ecosystem (such as a planet) will only support one highly intelligent species at a time. One will wipe the other out.
We didn't. This has been a misunderstanding since Darwin's time. Nothing personal Reiku, but that is the kind of ignorance* that that made the fight for understanding of evolution very difficult for more than a century.
Chimps and humans both evolved from a common ancestor that was neither chimp nor human.
Why do you claim this? Who said chimps' ancestors were more refined?
It seems he's assuming that we descend from chimps, and that being more human-like in a chimp-human scale equals being "more evolutionarily refined"/fit.
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It's a bit ironic that according with some people/standards, it's a bit more appropriate to say that "chimps descended from humans" rather than the opposite, which is the more common misunderstanding. Not present-day, Homo sapiens or even erectus-type humans, but australopithecines or ardipithecines, who had a more human-like body. Coincidentally or not there was at least one study claiming that chimps had suffered more positive natural selection than humans.
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It's a bit ironic that according with some people/standards, it's a bit more appropriate to say that "chimps descended from humans" rather than the opposite, which is the more common misunderstanding. Not present-day, Homo sapiens or even erectus-type humans, but australopithecines or ardipithecines, who had a more human-like body. Coincidentally or not there was at least one study claiming that chimps had suffered more positive natural selection than humans.
The word "extinct" can be misleading to someone who isn't well versed in evolutionary theory, because it can mean two similar but distinct things. First, there is extinct in the sense that we would apply the term to Neanderthals. They evolved, thrived for a while, and then died out. End of lineage (aside from the small amount of genomic DNA it seems they contributed to some of us through interbreeding). Then there is extinct in the sense that we say that the particular australopith species that we are descended from is extinct. They didn't die out as such, rather, they gradually evolved into something else. They are our ancestors.
Evolution is not continuous, because it is based on discontinuous data. In other words, even if evolution was continuous (for the sake of argument) discontinuous fossil data would make it impossible to prove that, since discontinuous data better support a discontinuous model.
Let me create an analogy. I make a continuous circle of popcorn, so each piece of popcorn touches the next. This is analogous to the circle of life where all the data is accounted for.
I go to get the experts to see the circle. But as time goes by, birds eat the popcorn and what remains of my continuous circle of life, is no longer continuous (random fossils). It may still appear to be expressing a circle, but it is now a broken circle with gaps. Even though it was originally continuous, based on the remaining popcorn data, you would need to infer discontinuous. I could not prove the circle was continuous even if I made it. The experts would deny this was true based on the broke circle they see.
The scientific method will not allow you to infer what the data does not say. In the case of the popcorn circle, although the circle was continuous initially, the broken data will not support this truth. There is a break down in the method.
A better way would be to start with an aspect of data (modern things) where we have all the variety in place instead of bits and pieces. For example, we have that with humans and will see what appears to be a continuous progression. People often don't think modern human evolve because they expect to see fossil jumps and not continuous change that is less obvious.
We don't need tonsils, but humans retain these. They go away slowly into the setting sun and not disappear like a discontinuous model might imply. If only have a hundred fossils spread over 100K years, we can create a discontinuous impression.
Let me create an analogy. I make a continuous circle of popcorn, so each piece of popcorn touches the next. This is analogous to the circle of life where all the data is accounted for.
I go to get the experts to see the circle. But as time goes by, birds eat the popcorn and what remains of my continuous circle of life, is no longer continuous (random fossils). It may still appear to be expressing a circle, but it is now a broken circle with gaps. Even though it was originally continuous, based on the remaining popcorn data, you would need to infer discontinuous. I could not prove the circle was continuous even if I made it. The experts would deny this was true based on the broke circle they see.
The scientific method will not allow you to infer what the data does not say. In the case of the popcorn circle, although the circle was continuous initially, the broken data will not support this truth. There is a break down in the method.
A better way would be to start with an aspect of data (modern things) where we have all the variety in place instead of bits and pieces. For example, we have that with humans and will see what appears to be a continuous progression. People often don't think modern human evolve because they expect to see fossil jumps and not continuous change that is less obvious.
We don't need tonsils, but humans retain these. They go away slowly into the setting sun and not disappear like a discontinuous model might imply. If only have a hundred fossils spread over 100K years, we can create a discontinuous impression.
What has been proposed is that the Theory of Evolution is flawed, or science in general is faulty, based on an opinion that hinges on some naive ideas of what fossils are and what they reveal, and of what evolution says and what it means.
This is one of many common methods used (mainly) by fundamentalists to attack ideas which they believe threaten their religious beliefs. This includes a vocal group who disavow any allegiance to fundamentalism while professing the same flaws they pretend to disavow. Little or no understanding of the natural world is required to follow the analysis, nor any of the work of any credible professionals who have established themselves as experts in the study of nature. The line of reasoning relies on a laundry list of errors in fact and logic which obstruct dialogue and understanding.
Nothing changes about the world, or how it works, or of the continuum of human discovery and ingenuity, just as nothing changes about the patterns of human fallibility and its erosion of our comprehension of the world and of human progress in understanding how and why it works.
The world is at it was before humans usurped it and declared it to exist in the image of their own ideas. It's a world that brought us to our present stage of development through billions of years of evolution. So what does it matter if we have evolved into the only species that can express denial?
Even denial is something we can explain biologically.
This is one of many common methods used (mainly) by fundamentalists to attack ideas which they believe threaten their religious beliefs. This includes a vocal group who disavow any allegiance to fundamentalism while professing the same flaws they pretend to disavow. Little or no understanding of the natural world is required to follow the analysis, nor any of the work of any credible professionals who have established themselves as experts in the study of nature. The line of reasoning relies on a laundry list of errors in fact and logic which obstruct dialogue and understanding.
Nothing changes about the world, or how it works, or of the continuum of human discovery and ingenuity, just as nothing changes about the patterns of human fallibility and its erosion of our comprehension of the world and of human progress in understanding how and why it works.
The world is at it was before humans usurped it and declared it to exist in the image of their own ideas. It's a world that brought us to our present stage of development through billions of years of evolution. So what does it matter if we have evolved into the only species that can express denial?
Even denial is something we can explain biologically.