Detlev Arendt (left), Florian Raible and Peer Bork.
(Photo Credit: Marietta Schupp, Photolab, EMBL
Heidelberg)
Posted on 11/27/2005 7:11:52 AM PST by Pharmboy
Species evolve at very different rates, and the evolutionary line that produced humans seems to be among the slowest. The result, according to a new study by scientists at the European Molecular Biology Laboratory [EMBL], is that our species has retained characteristics of a very ancient ancestor that have been lost in more quickly-evolving animals. This overturns a commonly-held view of the nature of genes in the first animals. The work appears in the current issue of the journal Science.
Detlev Arendt (left), Florian Raible and Peer Bork.
(Photo Credit: Marietta Schupp, Photolab, EMBL
Heidelberg)
Genes hold the recipes for proteins. The genes of animals usually contain extra bits of DNA sequence, called introns – information which has to be removed as cells create new molecules. The number of introns in genes, however, varies greatly among animals. While humans have many introns in their genes, common animal models such as flies have fewer. From an evolutionary perspective, it was long assumed that the simpler fly genes would be more ancient. The current study reveals the opposite: early animals already had a lot of introns, and quickly-evolving species like insects have lost most of them.
To discover what early animals were like, scientists usually compare their descendents. This is difficult when comparing distantly-related animals such as humans and flies. In these cases, it helps to look at living organisms that have preserved many features of their ancestors. Detlev Arendt's group is doing this with a small marine worm called Platynereis dumerlii. "Similar animals are already found in the earliest fossils from the Cambrium, about 600 million years ago," Arendt explains, "arguing that Platynereis could be something like a 'living fossil'." This makes it an ideal model for evolutionary comparisons to find out what the common ancestors of humans, flies and worms were like."
Until quite recently, such comparisons could only be made by looking at physical characteristics such as the structure of bones, teeth, or tissues. But DNA sequencing now permits scientists to make comparisons of the genetic code and read evolutionary history from it. An international consortium involving researchers from EMBL, the UK, France and the United States has now sequenced a part of the Platynereis genome. "The fraction of Platynereis genes we have been able to look at tells a very clear story," says researcher Florian Raible, who performed most of the computer analyses. "The worm’s genes are very similar to human genes. That's a much different picture than we've seen from the quickly-evolving species that have been studied so far."
Raible is member of both Arendt's group and a second EMBL lab, that of Peer Bork, whose specialty is analyzing genomes by computer. "Human genes are typically more complex than those of flies," explains Bork. "Classicallystudied species like flies have far fewer introns, so many scientists have believed that genes have become more complex over the course of evolution. There have already been speculations that this may not be true, but proof was missing. Now we have direct evidence that genes were already quite complex in the first animals, and many invertebrates have reduced part of this complexity."
Not only are the introns there – the team also discovered that their positions within genes have been preserved over the last half a billion years." This gives us two independent measurements that tell the same story," Raible explains. "Most introns are very old, and they haven't changed very much in slowly-evolving branches of life, such as vertebrates or annelid worms. This makes vertebrates into something like 'living fossils' in their own right."
The discovery that Platynereis also represents a slowlyevolving branch of animal life has important implications for the study of humans. "We've already learned an incredible amount about humans from studies of the fly," Arendt says. "The marine worm might well give us an even better look at important conserved processes. Another thing that this has shown us is that evolution is not always about gain; the loss of complexity can equally be an important player in evolution."
Source article: Vertebrate-type intron-rich genes in the marine annelid Platynereis dumerilii F. Raible, K. Tessmar-Raible, K. Osoegawa, P. Wincker, C. Jubin, G. Balavoine, D. Ferrier, V. Benes, P. de Jong, J. Weissenbach, P. Bork and D. Arendt. Science, 25 November 2005
Also, as a relatively long-lived species (compared to insects, bacteria, etc.), with about 20 years or so between generations, we are rather slow when it comes to reproduction -- and thus evolution.
Which part don't you understand?
They weren't talking about Hominid evolution, or even primate evolution, as being slow evolvers, but vertebrates in general being slower evolvers than invertebrates.
"This changes a few concepts..." ~ Pharmboy
Nooo kidding? :)
"...If this new tree is correct, all the morphological characters that traditionally have been used to identify similarities between species will need to be reevaluated to understand how these traits evolved." ....
..."Because the current tree has been widely accepted for nearly a century, I think there is going to be a delay of maybe a few years before the general scientific community gets used to the new tree," Vidal says. "If other research groups working in this area find the same pattern with additional genes, then I believe the scientific community may accept these results more quickly."
http://www.astrobio.net/news/modules.php?op=modload&name=News&file=article&sid=1784&mode=thread&order=0&thold=0
A "kind" is by definition a distinction of physiological features that cannot be reached by another "kind". As such, creationists don't pin down "kind" because it's subject to change whenever new observations of changes in morphology occur, and they don't want to admit that they're just making things up rather than doing real science.
I see. So as omnivorous primates with all the same kinds of organs, Humans and Chimpanzees are the same "KIND". Thanks for the clarification!
Funny, statisticians have no problem with the concept.
I have no idea what concept you are referring to here.
So are you saying “A rat is a pig is a dog is a boy.”
No, I am not saying that.
That is the way I saw it too. Also I think the idea that humankind is a big evolutionary step away from its 2Mya ancestors is misguided.
It demonstrates biological complexity all the way back.
A Primer on using Vague Taxonomy against evolutionists
In Vague taxonomy, organisms are grouped into categories such as Kind, Sort and Ilk. A key advantage of Vague Taxonomy is that there are no rules. All we do is provide a number of generic words which you can plug into your own personal arguments against evolution. Here are the core words:
Kind Variety Sort Ilk Type
And here is an example senario in which they are deployed to sucessfully defeat an evolutionist:
Evolutionist: Birds evolved from reptiles
Answer: Nope that's impossible because birds and reptiles are seperate Kinds of animal
Evolutionist: A cunning argument indeed, but what exactly is a kind?
Answer: You'll know it when you see it, or rather I will.
Evolutionist: Well okay if you won't directly define what a Kind is then perhaps I can pin it down via example. Lets begin - are frogs and toads seperate Kinds of animal?
Answer: No, because they are of the same Ilk
Evolutionist: Okay well if frogs and toads are the same Kind then chimpanzees and humans must be the same Kind too as they are a lot closer.
Answer: I didn't say frogs and toads are the same Kind, I said they are the same Ilk. Also chimpanzees and humans are different Sorts of animal by the way. Ever seen a chimpanzee playing in an orchestra? Clearly a whole different Sort of animal there.
Evolutionist: Well aren't frogs and toads different sorts of animal too?
Answer: Nope because they are the same Ilk.
Evolutionist: Ilk?? Well what about salamanders, are they also the same Ilk as frogs and toads?
Answer: Frogs, toads and salamanders are the same Variety of animal
Evolutionist: But I asked about Ilk - are salamanders the same Ilk as frogs and toads?
Answer: Sorry you can't use the category Ilk in relation to salamanders
Evolutionist: Why not???
Answer: Because they are a different Type of animal
I don't suppose you had to look very far to come up with this.
yup it's almost plagiarism
Not necessarilly of the same ilk, but in the same vein..
Yes...I re-read it and you're right. But they did talk about hominids also. It is a bit confusing. Still, our species split about 6 mil years ago from the ape line, and to accomplish all of this in that period of time is huge--and quick.
lol
Beer Looter Dude is one of my heroes.
Some evolutionary steps 'look' larger than they are. We have a tendency to 'weight' some adaptations more than others even though the evolutionary advantage is no more than any other. I think this applies to the last few evolutionary changes humans have experienced. We give them more import than evolution deems necessary.
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