The earliest animals had human-like genes

[Menydh]

The earliest animals had human-like genes

European Molecular Biology Laboratory
November 24, 2005

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.

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


[source]

[Awar]

Human evolution was slower, because we reach sexual maturity much later,
and live much longer than most other animals, on average.

[Agrippa]

Right Awar, but finally human evolution was faster than in most other big mammals, but mainly concentrated on certain structures without changing the general basics (compare with chimps) - and Hominids are more generalised then certain specialised big mammals as well. They just changed what was really advantageous but kept (like the general plan of the hand) more general characteristics which were finally more promising.

Changes were faster and more drastical in very primitive animals with fast reproduction and a general plan which was "easy to change" - in more complex higher animals chances to change something to the better are much lower and dangerous.

[Awar]

IMO, more evolution leads to more specialization.

[Agrippa]

Originally Posted by Awar

IMO, more evolution leads to more specialization.

Yes, but just from order to order (e.g. more complex structures), but not necessarily IN AN ORDER. Because in an order both more generalised or specialised (small niche oriented) development is possible.

F.e. compare Panda bears which are more primitive but at the same time (over-) specialised and generalist brown bears. So you are right about specialisation in the sense of developing certain organic structures more than others and specialising while reaching a higher, more complex order, but if its about adaption very low organised organism can be more one sided (f.e. bacteria adapted to the habitat of just one "very special" tarn).
Adaptation, specialisation is evolution finally, yes.

[Menydh]

Observing social and economical evolution, and through the specialisation of labour, it's easy to see how specialisation has been a key direction in the evolution up to modern societies. However, in my opinion, this is also being detrimental in the natural evolution of humans as individuals.

Since the Industrial Revolution, the evolution has increasingly worked into one single direction: specialisation. This forcing into a one-way direction is making man more dependable on the society, and thus more unable to cater for himself.

Perhaps it is about time to take evolution in a more balanced way, both in the direction of the society and that of the individual.

[Awar]

Originally Posted by Agrippa

Yes, but just from order to order (e.g. more complex structures), but not necessarily IN AN ORDER. Because in an order both more generalised or specialised (small niche oriented) development is possible.

I think evolution cannot be explained through laws of physics,
for the simple reason that living organisms are products of very complex biological events under the influence of surroundings and circumstance
, it's impossible to see what's complex and what simple, let alone foresee the outcome. Especially when one realizes that evolution is just a process of adaptation, with no goal in mind.

For example, so many species died out, it's obvious that evolution isn't "for the good" of a species, it's just something that happens.

F.e. compare Panda bears which are more primitive but at the same time (over-) specialised and generalist brown bears. So you are right about specialisation in the sense of developing certain organic structures more than others and specialising while reaching a higher, more complex order, but if its about adaption very low organised organism can be more one sided (f.e. bacteria adapted to the habitat of just one "very special" tarn).
Adaptation, specialisation is evolution finally, yes.

Panda bears are a bad example because of a few things,
namely, they aren't fully 'bears', neither are they really equipped to eat the food they eat.

Pandas are carnivores which took a wrong turn somewhere, and remained alive for such a long time thanks to weird circumstance rather than their own adaptation.

[Agrippa]

Originally Posted by Awar

I think evolution cannot be explained through laws of physics,
for the simple reason that living organisms are products of very complex biological events under the influence of surroundings and circumstance
, it's impossible to see what's complex and what simple, let alone foresee the outcome. Especially when one realizes that evolution is just a process of adaptation, with no goal in mind.

For example, so many species died out, it's obvious that evolution isn't "for the good" of a species, it's just something that happens.



Panda bears are a bad example because of a few things,
namely, they aren't fully 'bears', neither are they really equipped to eat the food they eat.

Pandas are carnivores which took a wrong turn somewhere, and remained alive for such a long time thanks to weird circumstance rather than their own adaptation.

Finally you gave yourself the right answer, first you say evolution isn't "for the good", then that Pandas "took a wrong turn somewhere".

So Evolution in itself might not have any goal, but from a rational point of view some developments are more versatile and have therefore higher chances of further development and survival - others are to one sided. So if the Panda would have been able to think in a rational manner before the "wrong turn", he should have used Eugenics to prevent himself from generating into something which has just very low chances of surviving even rather small changes of the environment.

There is no guarantee, but there are definitely more propulsive, versatile, therefore more desirable and less desirable specialisations from the group which evolves own perspective. Local niche (over-) specialisation is usually the way to long term extinction even without unpredictable huge catastrophies.

[Awar]

Originally Posted by Agrippa

Finally you gave yourself the right answer, first you say evolution isn't "for the good", then that Pandas "took a wrong turn somewhere".

Well, yes... they "took a wrong turn" in the sense they're probably bound for extinction.

So Evolution in itself might not have any goal, but from a rational point of view some developments are more versatile and have therefore higher chances of further development and survival - others are to one sided. So if the Panda would have been able to think in a rational manner before the "wrong turn", he should have used Eugenics to prevent himself from generating into something which has just very low chances of surviving even rather small changes of the environment.

Yep, but those Pandas should have a knowledge about biology and genetics far more extensive than Humans have today

There is no guarantee, but there are definitely more propulsive, versatile, therefore more desirable and less desirable specialisations from the group which evolves own perspective. Local niche (over-) specialisation is usually the way to long term extinction even without unpredictable huge catastrophies.

Well... specialisation isn't necessarily an end of evolution,
there's always potential to adapt to circumstances, even to go 'back' to some stages of evolution which prove to be better suited for the new surrounding.

[Agrippa]

Well... specialisation isn't necessarily an end of evolution,
there's always potential to adapt to circumstances, even to go 'back' to some stages of evolution which prove to be better suited for the new surrounding.

Thats true, but sometimes its crucial that this happens in time.

Yep, but those Pandas should have a knowledge about biology and genetics far more extensive than Humans have today

Nah, their case was pretty obvious from the beginning, the great Panda should have known it