evolution #2

[Rip:20]

What do you mean animals only? Animals evolved form simpler organisms, why the perceived disconnect?

 

The disconnect is that not all life has followed the pattern of evolving from simpler forms into complex multi-cellular forms. So the premise of the article you site is not a generalizable principle of evolution. My counter-example was bacteria, but there are many others too. The bacterial lineage is just as old as our own Eukaryota, it's just gone a very different, but highly successful direction. Sometimes evolution selects for simplicity.

Edited September 6, 2010 by Rip:20

[CharonY]

It is not necessarily so that evolution selects for simplicity. In fact bacteria are able to settle specific niches that eukaryotes cannot because they got a more complex metabolic abilities, which eukaryotes lost during their development. On the other hand eukaroytes have created new ecological niches. In fact, most eukaryotes represent ecological niches for bacteria.

But the overall point is accurate. Once a certain evolutionary path has been started it is possible that for whatever reasons there is a pressure towards complexity in certain branches to remain competitive. It is highly dependent on the habitat and the ecological niches. Parasites, for instance tend to lose traits that they required for free-living survival.

In fact, the authors of the paper made the very point that it is not universal.

[Rip:20]

It is not necessarily so that evolution selects for simplicity. In fact bacteria are able to settle specific niches that eukaryotes cannot because they got a more complex metabolic abilities, which eukaryotes lost during their development. On the other hand eukaroytes have created new ecological niches. In fact, most eukaryotes represent ecological niches for bacteria.

But the overall point is accurate. Once a certain evolutionary path has been started it is possible that for whatever reasons there is a pressure towards complexity in certain branches to remain competitive. It is highly dependent on the habitat and the ecological niches. Parasites, for instance tend to lose traits that they required for free-living survival.

In fact, the authors of the paper made the very point that it is not universal.

 

But sometimes evolution does select for simplicity. Think of the genome reduction in Pelagibacter ubique, or your own example of loss of unused traits in parasites (could be drift in some cases, could be positive selection to reduce waste). The point is there is no one direction or plan that evolution follows for all life forms.

 

In terms of Eukaryotes v.s. Bacteria, yes the bacterial domain has far more metabolic diversity in total, and some members are massively versatile (i.g. large genome pseudomonads), but no one individual bacteria rivals a crown Euk (i.g. human) in terms of differential multicellularity, or even total protein diversity.

Edited September 8, 2010 by Rip:20

[kitkat]

But sometimes evolution does select for simplicity. Think of the genome reduction in Pelagibacter ubique, or your own example of loss of unused traits in parasites (could be drift in some cases, could be positive selection to reduce waste). The point is there is no one direction or plan that evolution follows for all life forms.

 

In terms of Eukaryotes v.s. Bacteria, yes the bacterial domain has far more metabolic diversity in total, and some members are massively versatile (i.g. large genome pseudomonads), but no one individual bacteria rivals a crown Euk (i.g. human) in terms of differential multicellularity, or even total protein diversity.

 

You are right in no one individual bacteria rivals a crown Euk. That is why 2 or more individual bacteria cooperated or became captive to become the modern eukaryote that we are today.

 

We all live in an extremely complex conglomeration of niches. Species who were once at an advantage because of their physical attributes can suddenly find themselves facing odds that will lead to their extinction. These odds could be caused by environmental factors including other competing species and environmental stresses such as meteorites, droughts, earthquakes. Or it can take a long time, as you've described.

 

There are always stresses on a species. Evolution is not always a procedure going from simple to complicated. Look at the cockroach (if you can stand to). It's been essentially the same for an awfully long time and has been one of the most successful species time-wise. It has adapted so well that it can live just about everywhere. I doubt it will become more complicated simply because it is so successful in its current form.

 

That is a very valid point in that the cockroach has not changed due to its success. There are many others that since their origin have appeared then as they are today. How could evolution that is not directed exclude the successful ones while the rest went through undirected modification through time?

 

Not only that but all of the ones that are successful live close to the base of the food chain web where life begins for larger life to evolve.

[Neta]

I was a kind of bored and got reading some stuff in this evolution area.

I think evolution is misunderstood. (my opinion)

As a read threads here, it seems that the concept of evolution is that of a conjecture where all species (including plants) develop along a line from simple living beings into more sophisticated & adapted ones.

It is a part of the conjecture, but IMO it is not the whole story. At each moment of the living Earth history, the whole biosphere must have worked as an interlace of relations between species, a net in constant dynamic equilibrium.

If a specie is not adapted to its environnement, it is believed (as I read here around) that evolution is supposed to drive this specie into more adaptatation. But it can also drive this specie to extinction. Not because the specie was "bad formated', but because environemental conditions change.

You can be a wonderful specie and suddenly disappear because your place will be, bit by bit, set at the edge of the net. At some point, a little push will set you out. Some other specie can remain in the eco-system for million of years, never reaching the edge of the net, and never falling out.

 

So, IMO evolution is not always a procedure going from simple to complicated. Simple organisms can evoluted or can disapear, and so for complicated organisms.

As a resume, i believe that evolution don't work always for better. It can also drive to extinction.

[Mrs Zeta]

I believe that evolution by natural selection is coming to an end with reference to humans.

 

It may be possible for humanity to continue evolving by means other than natural selection, for example through a developmental singularity process (see general discussion at http://www.accelerationwatch.com/developmentalsinghypothesis.html).

 

 

This is based on the fact that, for the first time in human history, we have now access to global technology that can enhance human abilities in a very short time, rather than waiting for the slow process of natural selection to increase our fitness (as a race) any further.

 

See a discussion here: https://acrobat.com/#d=MAgyT1rkdwono-lQL6thBQ

[michel123456]

I believe that evolution by natural selection is coming to an end with reference to humans.

 

It may be possible for humanity to continue evolving by means other than natural selection, for example through a developmental singularity process (see general discussion at http://www.accelerationwatch.com/developmentalsinghypothesis.html).

 

 

This is based on the fact that, for the first time in human history, we have now access to global technology that can enhance human abilities in a very short time, rather than waiting for the slow process of natural selection to increase our fitness (as a race) any further.

 

See a discussion here: https://acrobat.com/#d=MAgyT1rkdwono-lQL6thBQ

 

There is an avalanche of information in your links. Most of it is highly speculative. There is no way to discuss it as a whole. I see you are a supporter of transhumanism.. Maybe you should start a thread on the subject if you want to get a reaction.

 

----------------

edit.

Maybe transhumanism is even too complex. Human Enhancement perhaps?

Edited December 29, 2010 by michel123456