I'd also recommend to see the lecture "Genesis" by Robert Hazen ( http://www.youtube.com/watch?v=YrMuFpGlcpk ) which I think could serve as a good short introduction into this issue.Raist said:That's OT
But the most plausible hypothesis right now is abiogenesis, starting from RNA.
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My attempt at an Evolution thread! OhgodwhatamIdoing.
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Wazzim said:
A very good question!
What if we were to take humans apart down to the molecular level. Hydrogen, carbon, break everyone down to their components. I mean, without water, we're just a pile of dust.
Humans are a combination of electrical impulses and chemicals.
This isn't to degrade the value of life at all, it's a celebration that this particular unique combination is what makes all of us, well, alive. We should be grateful to even exist, that this unique and wonderful combination came together to make us the walking talking formation of atoms that we are.
A bucket of paint cans, some paper and some wood are just things. You can mix those things 1000000000 different ways and it's just a mess. But combine them in just that RIGHT way, and you have a great work of art and beauty.
That's life.
Mgoblue201
Won't stop picking the right nation
At the 45 minute mark, his slide says that, "RNA is an implausible prebiotic molecule, because there's no known way to synthesize it in a prebiotic environment." I realize that the presentation was from 2008, but didn't we discover a prebiotic provenance of RNA since then? This article claims:Jasup said:
For a long time the synthesis of RNA monomers under prebiotic conditions appeared to be a fundamental problem since the condensation of sugar (ribose) and nucleobase (purines and pyrimidines) does not work (Orgel, 2004). The prebiotic synthesis of purine ribonucleotides is still unclear, yet recently a breakthrough has been made with regard to the synthesis of pyrimidine ribonucleotide monomers (which incorporate cytosine and uracil). It now appears in principle to be solved, in a completely unexpected manner. The study by the group of John Sutherland (Powner et al. 2009) shows how nature could have spontaneously assembled pyrimidine ribonucleotide monomers from prebiotically plausible molecules through intermediates that contribute atoms to both the sugar and base portions of the ribonucleotides, thus avoiding a condensation step of sugar and base altogether (Fig.1). See also Nature News for the impact of these findings. While a good pathway for synthesis of purine ribonucleotides (incorporating adenine and guanine) still remains to be found, Jack Szostak argues in a comment accompanying the article (Szostak 2009) that it is precisely because this work opens up so many new directions for research that it will stand for years as one of the great advances in prebiotic chemistry.
Mgoblue201
Won't stop picking the right nation
I'd like to post some of the interesting articles that have been written over the past week:
1. Jonathan Eisen of UC Davis explores the possibility of new domains of life. A domain is essentially the highest rank of taxonomic classification, derived in the 1990s, that encompasses all of known life. It's just above kingdom and only includes three main classifications: bacteria, archaea, and eukaryotes. Eisen and colleagues present evidence of a possible fourth domain. As Carl Zimmer explains:
Their evidence comes from a voyage Craig Venter and his colleagues took in his yacht, scooping up sea water along the way. They ripped open the microbes in the water and pulled out all their genes. The advantage of this approach is that it allowed the scientists to amass a database of literally tens of millions of new genes. The downside was that they could only look at the isolated genes, rather than the living microbes from which they came.
They looked at certain segments such as subunit rRNA, recA, and rpoB to discover relatedness between species. Needless to say, they found certain genes that were quite different than anything that exists in the present three domains. For his part, Eisen demures from a clear conclusion and seems to think that novel viruses are the answer:
We do not have a conclusive explanation for the origin of these sequences. They may be from novel viruses. The may be ancient paralogs of the marker genes. Or they may be from a new branch of cellular organisms in the tree of life, distinct from bacteria, archaea or eukaryotes. I think most likely they are from novel viruses. But we just don't know.
Viruses themselves can be very diverse and unique. Zimmer says that scientists recently discovered new viruses that are about the size of bacteria (viruses are typically less than a micrometer in length, whereas bacteria are more than a micrometer) and contain more than a thousand genes, vs. the ten genes in a flu virus. Life appears to be even more diverse with each subsequent discovery.
2. The NY Times recently ran a series of articles pertaining to animals. Zimmer, as usual, has the most interesting, as he writes about the evolution of animals. I can't pick out any one part of it: he talks about the origin of multi-cellular organisms, potential sources of diversity, and the relative simplicity of the first animals.
Sean Carroll also discusses mutations and cats.
1. Jonathan Eisen of UC Davis explores the possibility of new domains of life. A domain is essentially the highest rank of taxonomic classification, derived in the 1990s, that encompasses all of known life. It's just above kingdom and only includes three main classifications: bacteria, archaea, and eukaryotes. Eisen and colleagues present evidence of a possible fourth domain. As Carl Zimmer explains:
Their evidence comes from a voyage Craig Venter and his colleagues took in his yacht, scooping up sea water along the way. They ripped open the microbes in the water and pulled out all their genes. The advantage of this approach is that it allowed the scientists to amass a database of literally tens of millions of new genes. The downside was that they could only look at the isolated genes, rather than the living microbes from which they came.
They looked at certain segments such as subunit rRNA, recA, and rpoB to discover relatedness between species. Needless to say, they found certain genes that were quite different than anything that exists in the present three domains. For his part, Eisen demures from a clear conclusion and seems to think that novel viruses are the answer:
We do not have a conclusive explanation for the origin of these sequences. They may be from novel viruses. The may be ancient paralogs of the marker genes. Or they may be from a new branch of cellular organisms in the tree of life, distinct from bacteria, archaea or eukaryotes. I think most likely they are from novel viruses. But we just don't know.
Viruses themselves can be very diverse and unique. Zimmer says that scientists recently discovered new viruses that are about the size of bacteria (viruses are typically less than a micrometer in length, whereas bacteria are more than a micrometer) and contain more than a thousand genes, vs. the ten genes in a flu virus. Life appears to be even more diverse with each subsequent discovery.
2. The NY Times recently ran a series of articles pertaining to animals. Zimmer, as usual, has the most interesting, as he writes about the evolution of animals. I can't pick out any one part of it: he talks about the origin of multi-cellular organisms, potential sources of diversity, and the relative simplicity of the first animals.
Sean Carroll also discusses mutations and cats.
Thanks for the articles Mgoblue (You need to change it to Mogblue so it's easier to remember) I've only read one so far, but it's fascinating stuff, the idea of a new 'domain' is almost intimidating. But really, the categorization of species has always seemed a bit ambiguous to me anyway.
Right now I am looking into mutations that 'surface' long since 'dormant' genes. Example, tails in humans, leg-nubs in whales, etc. Does anyone have a database or any articles I can look into? In particular I wanted to see if apes have been known to present 4 nipples - as far as I know our genetic ancestors did?
Right now I am looking into mutations that 'surface' long since 'dormant' genes. Example, tails in humans, leg-nubs in whales, etc. Does anyone have a database or any articles I can look into? In particular I wanted to see if apes have been known to present 4 nipples - as far as I know our genetic ancestors did?
mclaren777
Member
No, that seems rather crazy.Vincent Alexander said:
Mgoblue201
Won't stop picking the right nation
That's called an atavism. Nature and Talk Origins both have in depth explanations. The Wikipedia page gives several more examples. You can probably find more with a Google search.Kinitari said:
Mgoblue201 said:
Thanks for the links, very informative and it's nice having a new word in my vocabulary. It even led me to stumble across the multiple breast thing - which apparently is a form of Atavism. But what's weird is that I am seeing no explanation, as far as I've looked into, none of our mammalian ancestors had multiple breasts. I'll do some more reading, thanks again for the links Mog.
Mgoblue201
Won't stop picking the right nation
It appears that, according to Scientific American, a set of 18 human footprints have been found molded into volcanic ash around Lake Natron in northern Tanzania dating back to about 120,000 years ago.
No reports of dinosaur footprints accompanying them.
Anyway, it has been more than a month and I am still awaiting a reply from mclaren777, who claimed that he would get back to me. It seems that Sanky Panky and JCRedeems have also absconded from this thread after questioning certain aspects of evolution.
No reports of dinosaur footprints accompanying them.
Anyway, it has been more than a month and I am still awaiting a reply from mclaren777, who claimed that he would get back to me. It seems that Sanky Panky and JCRedeems have also absconded from this thread after questioning certain aspects of evolution.
mclaren777
Member
What was I supposed to get back to you about? I'm afraid that I don't remember now.Mgoblue201 said:
crazy monkey
Banned
Mgoblue201 said:It appears that, according to Scientific American, a set of 18 human footprints have been found molded into volcanic ash around Lake Natron in northern Tanzania dating back to about 120,000 years ago.
No reports of dinosaur footprints accompanying them.
Anyway, it has been more than a month and I am still awaiting a reply from mclaren777, who claimed that he would get back to me. It seems that Sanky Panky and JCRedeems have also absconded from this thread after questioning certain aspects of evolution.
lol 120000 is nothing age wise.
Cow Mengde
Banned
crazy monkey said:
Yup, this is relatively modern by geological time.
Mgoblue201
Won't stop picking the right nation
I'm not quite sure what the dominant theory of human migration is, but those footprints appear to occur from the time that man began to leave Africa. Yet Tanzania had probably been populated by humans long before that.
The posts are here and extend back a few pages beyond that. The fact that you were intending to respond was obviously implied in the post on that page.mclaren777 said:
Kinitari said:
crazy monkey
Banned
May be it was posted before but came across this
" al-Jahiz (c. 776-869) was the first of the Muslim biologists and philosophers to develop an early theory of evolution.
"Animals engage in a struggle for existence; for resources, to avoid being eaten and to breed. Environmental factors influence organisms to develop new characteristics to ensure survival, thus transforming into new species. Animals that survive to breed can pass on their successful characteristics to offspring."
but if you go looking for history of evolution theory topic most of them will stat that the the topic started in Europe around 1600 AD.
" al-Jahiz (c. 776-869) was the first of the Muslim biologists and philosophers to develop an early theory of evolution.
"Animals engage in a struggle for existence; for resources, to avoid being eaten and to breed. Environmental factors influence organisms to develop new characteristics to ensure survival, thus transforming into new species. Animals that survive to breed can pass on their successful characteristics to offspring."
but if you go looking for history of evolution theory topic most of them will stat that the the topic started in Europe around 1600 AD.
A lot of European science was influenced by Islamic scholars from earlier periods. Didn't know about this though, kind of cool.crazy monkey said:
Wikipedia has this to say: http://en.wikipedia.org/wiki/History_of_evolutionary_thought
crazy monkey
Banned
Dead Man said:
the reason why i mentioned is that you will not hear this names when learning in school.
Mgoblue201
Won't stop picking the right nation
Several ancient philosophers, including Anaximander, Herodotus, and Lucretius, had posited something like the mutability of living forms, albeit with a lot of ancient myth mixed in. I admit that I have not heard of al-Jahiz until now, but someone said - I forget the provenance of the quote - that it was surprising it took so long for evolutionary thought to gain ground. I would hypothesize a few reasons why it took until the 19th century. 1. The emergence of geology. Having millions of years and the fossil record to work with greatly ushered in acceptance of evolution. Almost all of the best evidence has only been unearthed in the last 130 to 140 years. 2. The ability to travel. Darwin's own thoughts were motivated by his voyage aboard the Beagle, and he devoted a few chapters to geographical distribution in Origins, which ended up being incredibly powerful evidence for evolution.Dead Man said:
In fact, Origins is a really remarkable book, despite its imperfections, and probably why, beyond even the idea of natural selection, he is remembered as such an eminent scientist.
Mgoblue201
Won't stop picking the right nation
Here's a map from National Geographic, beginning about 100,000 years ago:
Yellow is mitochondrial, blue is Y-chromosome.
Yellow is mitochondrial, blue is Y-chromosome.
mclaren777
Member
Great map, but where's the rest of it?
And is there a story to go along with it?
And is there a story to go along with it?
So I was thinking today about 'obvious' speciation and 'transitional' creatures. While the term species and transitional are completely human construct, I was thinking more along the lines of "What could I show someone who was doubting, that said "Hey, look, isn't this what you wanted to see?"".
So I was thinking about land-mammals to ocean dwelling mammals. I know there are a lot of transitional fossils that show the departure from land to sea - and I have discussed that with people, but sometimes even then I get things like "How am I supposed to believe fossil evidence?".
So, I was thinking in terms of a transitional species - in a sense that adheres to the term having any sort of importance - seals. Seals are essentially creatures that 'look' like they would be transitional between a land mammal and a sea mammal.
But that's still not good enough for me, I want to have more in my quiver to pull out when need be. What else can people think of, animals that are currently alive that 'look' like 'transitional species'?
So I was thinking about land-mammals to ocean dwelling mammals. I know there are a lot of transitional fossils that show the departure from land to sea - and I have discussed that with people, but sometimes even then I get things like "How am I supposed to believe fossil evidence?".
So, I was thinking in terms of a transitional species - in a sense that adheres to the term having any sort of importance - seals. Seals are essentially creatures that 'look' like they would be transitional between a land mammal and a sea mammal.
But that's still not good enough for me, I want to have more in my quiver to pull out when need be. What else can people think of, animals that are currently alive that 'look' like 'transitional species'?
I'm not sure you should really spend your time trying to convince people. Often people don't believe evolution is the most accurate description of how things actually happened because of a combination of ulterior motives and a misunderstanding of what constitutes evidence.Kinitari said:
For example, people will ask for transitional fossils, but the reason they aren't satisfied is because they have their own concept of what a transitional fossil is, and what you show doesn't match it.
Here's an example (I think it was posted earlier) : http://www.youtube.com/watch?v=FPxGDXSJZfc&feature=feedwll
And even if you show transitional fossils, some people will simply see more gaps, and then ask for more transitional fossils, until you get to a point where the transitions are small enough that a typical person will identify changes as merely small, insignificant changes, and won't realize where you just brought them conceptually.
ianp622 said:
It's not so much that I am trying to 'convince' people - I understand that those who I debate with, more often than not, are not going to change their opinion. Sometimes however, when I debate, I have an audience - people who sometimes aren't really well versed or understand evolution so much, maybe who don't feel as though they can lean in one particular direction over the other, I'd feel better if I presented a stronger argument for their sake (I recognize that to present the strongest argument in regards to speciation and transitional, I should debate the misunderstanding of the terms, but I do that anyway - when I use it in a debate however, it feels like a cop out).
Oh ok, well this might help: http://www.youtube.com/watch?v=o92x6AvxCFgKinitari said:
Whales still have hip bones that aren't used anymore, so you don't even need to rely on fossil evidence.
Well, sticking with water mammals, dugongs and manatees are great examples, they still have fingernails, and mostly walk along the bottom on their front flippers. There are cormorants on the Galapagos that have lost the ability to fly but retain their wings, they are similar to penguins in that they swim in the ocean and eat fish, but they are not much more adapted for that than normal cormorants. Many species of salamander have vestigial or no limbs, even though the base form has limbs. And of course, there are many types of fish that can breath air to different degrees. I don't know if those were exactly what you were looking for, but maybe they were.Kinitari said:
Just finished watching inside the human body on bbc1. To go with it there's a page on the bbc website explaining how the traces of our fishy ancestors cause problems for us today, including why 1 in 700 babies have cleft lips or palates.
I think it might be useful when trying to explain how our design really isn't very intelligent.
http://www.bbc.co.uk/news/health-13278255
I think it might be useful when trying to explain how our design really isn't very intelligent.
http://www.bbc.co.uk/news/health-13278255
DragonGirl
Member
pootle said:
Fascinating stuff. I knew about the hiccups and tadpoles, though I forget where I read it.
Angry Fork
Member
This hasn't been bumped in a while but I figure it's best to ask here, I have a couple simple questions. Basically humans and chimpanzee's have both descended from a common ancestor correct? I just would like to know if a name was given to this common ancestor so that you could say that name instead of just saying 'common ancestor' all the time, or what it would look like and so on, is it like a hybrid of both human + chimp or caveman or something?
Mgoblue201
Won't stop picking the right nation
Since species are always branching off, it's difficult to identify the last "true" common ancestor (if we ever manage to find it). This Wikipedia article should help. However, I admit that I haven't really given the topic much thought. Most of the fervor related to human evolution is concentrated on Australopithecus and onward. Reading up it a little, it doesn't appear that there is a clear answer to your question.Angry Fork said:
Angry Fork
Member
Is that because we haven't found the fossils or something for such a creature or is it absolutely impossible to physically find remains of that ancestor?
edit - thanks @ 2nd reply.
I'm just interested mainly because I feel like it's important to know where we've descended from but everywhere I read it just says common ancestor without much information about it lol. Maybe it's not that important though? Just the fact that we know it existed is enough? I'm not sure.
edit - thanks @ 2nd reply.
I'm just interested mainly because I feel like it's important to know where we've descended from but everywhere I read it just says common ancestor without much information about it lol. Maybe it's not that important though? Just the fact that we know it existed is enough? I'm not sure.
Mgoblue201
Won't stop picking the right nation
As I understand it, it would be hard to identify a last common ancestor anyway. How do you distinguish between two related species, one that met an evolutionary dead end and another that branched off to form other species? I'm not aware of how to distinguish between the two. Biologists are still debating the significance of homo erectus, I believe, in the context of hominid evolution. It probably makes more sense to identify a last common genera.
Mgoblue201
Won't stop picking the right nation
With so much interesting evolution news lately, I feel compelled to bump this.
First, A. sediba may be closer to modern humans than previously thought:
As Amirox posted in the other thread, paleontologists have discovered a new species of Devonian fish:
Finally, what appears to be dinosaur feathers from the late Cretaceous have been found encased in amber:
First, A. sediba may be closer to modern humans than previously thought:
As Amirox posted in the other thread, paleontologists have discovered a new species of Devonian fish:
Finally, what appears to be dinosaur feathers from the late Cretaceous have been found encased in amber:
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