Abiogenesis - New Study

[Berzerker]

evolution "predicts" our ancestors were primates, the evidence supports the theory

[lightblue]

Interesting article. My most recent readings have postulated that life initially arose in a RNA world, probably within the confines of the mineral deposits surrounding thermal vents on the sea floor (which is porous and can thus contain the chemicals without the need for for a cell membrane).

As for Ben... The reason you cannot predict what will happen is due to the complexity of interacting factors that influence the eventual evolutionary destiny of a species. If you control the environment and limit the number of extraneous variables then more testable hypotheses can be formed.

A standard one that might be used is the development of strains of bacteria with multiple antibiotic resistances in places where a large number of antibiotics are used (e.g. hospitals). Similarly, when looking from a founder event (e.g. the populating of a volcanic island by a limited number of species), you might be able to predict some evolutionary outcomes as a result of the available ecological niches that are available. If you get a population of humans that currently live at sea levels and make them live at high altitude for hundreds of generations (e.g Tibetan or Andean highlands) then you can make some predictions about the their increased lung capacity and the oxygen-affinity of their haemoglobin as we have this data on existing populations.

Without knowing what the future environment is like there is no way to predict what humans might evolve into.

[Sava]

lightblue

[Ben Kenobi]

So if some other star goes nova first, then you'd be in favour of dismissing current stellar development theories as pseudoscientific claptrap. Nice. I'll see if I can remember this post when the relevant event happens.

Some other prominent star? Depends on the star. And I'm sure that when a prominent star finally goes that there will be a tremendous amount of science into the process.

'Evolution' doesn't make any claims about what human beings will evolve into. It just states that, given sufficient selective pressure, certain genes/traits will be favoured over others.

So, IOW, it doesn't make testable predictions which is a core part of any scientific theory. Thanks Nestor!

[Ben Kenobi]

As for Ben... The reason you cannot predict what will happen is due to the complexity of interacting factors that influence the eventual evolutionary destiny of a species. If you control the environment and limit the number of extraneous variables then more testable hypotheses can be formed.

Then it's not a scientific theory, lightblue. It's nothing more than a conjecture. An actual scientific theory would be able to predict how species would evolve over time within a reasonable amount of precision. Now, you're stating that evolution cannot even do that.

It seems blindingly obvious to me that evolution cannot be falsified. If one species changes in any sort of fashion that's regarded as 'justification' for the theory, which is not science. It is, however, religion.

[Ben Kenobi]

It is also said by Chaos theoreticians that in order to accurately model such a system the model must contain at least as many variables as the reality.

Insofar as their models make testable conclusions it's a scientific theory. Also, comparing evolution to chaos theory isn't exactly a particularly robust defense.

Evolution is orders of magnitude more complex than the weather.

Then perhaps biologists should refrain from asserting that evolution is a scientific theory until they actually understand the process well enough to know how it works.

Evidence: the weather is one of the many drivers of evolution. Once we've nailed computer modelling of the weather, individual stimulus/response for each and every individual organism, tracking and anticipating each and every movement of each and every soil particle, fine-grained prediction of erosion, solar activity levels, etc, then one might be able to come up with somewhat accurate predictive models for evolution.

You don't even understand protein and gene expression. How is it possible to understand evolution without understanding proteins? It's impossible. All we have is the conjecture that 'species evolve through natural selection'. That's it. This is no different from Aristotelianism asserting that heavy objects like to seek other heavy objects. Correct, but worthless.

Just because we don't have accurate predictive models of something doesn't mean that that thing doesn't exist, or isn't a valid theory.

If you lack predictive models that work - you're not a scientific theory. All scientific theories make predictions. Atomic modeling made predictions about the nature of the atom. When Rutherford actually tested this, he was shocked to find that the model was wrong because, "if it worked this way, we should see x".

We don't fully understand gene expression, proteins and how they work. To me it's senseless for biology to assert that 'other theories are wrong', when they've not put in the work they need to do to establish their own theories.

[Ben Kenobi]

evolution "predicts" our ancestors were primates, the evidence supports the theory

Evolution makes a ton of assumptions. It finds a couple of bones in the ground and asserts that just because they are what they believe to be the right age that there is a direct relationship between men and these bones in the ground. Something that's not actually provable.

We cannot - legitimately, establish a descent going back more than 1500 years because the records simply are not there. It may be that these bones are our ancestors. It may be that there is no direct connection to any living human from these ancestors at all. If so, the evolutionary theory is incorrect in asserting there is a direct relationship. It may be that our ancestors and the direct ancestors, that their bones no longer exist.

[lightblue]

I am about to put the twins to bed and eat dinner, but I will get back on your assertions later this evening. In the meantime can you tell me what we don't understand about proteins and gene expression and how that is exactly related to ricketyclik's example of a complex system? Might as well get it all done in one post..

[N35t0r]

So, IOW, it doesn't make testable predictions which is a core part of any scientific theory. Thanks Nestor!

What? Where do you get that from what I said? Go learn english and then come back please.

[lightblue]

Then it's not a scientific theory, lightblue. It's nothing more than a conjecture. An actual scientific theory would be able to predict how species would evolve over time within a reasonable amount of precision. Now, you're stating that evolution cannot even do that.

It seems blindingly obvious to me that evolution cannot be falsified. If one species changes in any sort of fashion that's regarded as 'justification' for the theory, which is not science. It is, however, religion.

How is it conjecture? If you investigate a theory and set up an experiment then you need to be able to control any extraneous variables to allow any valid prediction to be carried out. Let's go for a school-level example. If you were doing an experiment that was looking at the effect of different pH levels on the activity of an enzyme you would need to control the temperature, the substrate concentration and the enzyme concentration (among other variables). If these changed from repeat to repeat then you would not be able to predict the outcome.

Evolution is caused by the increased chance of survival in the gene pool of the combination of genes that confer the greatest reproductive advantage in a particular environment. If the environment changes then different gene combinations would be more advantageous. As we cannot predict the future with any certainty we can't predict the eventual outcomes of evolution outside of controlled experiments.

In a less controversial context it is like the weather example mentioned earlier. We can predict the future with regards to weather with some degree of accuracy about 5 days into the future. Longer-term predictions carry greater uncertainties and the error range becomes greater. What you are asking is to predict what the weather would be like in on September 3rd in a million years. Could we make an approximation based on current climate models? Possibly. Realistically though anything could happen. We could destroy the atmosphere, volcanoes can erupt or meteorites hit the Earth as some larger scale examples. These would throw our predictions completely out of kilter.

Same with evolution. Can we make some gross predictions about what might happen? Maybe. The error rate would be too great though. Within the smaller context I described earlier though, there would be fewer variables that might change and as such you are more likely to be able to predict an outcome that matches reality.

I would imagine predicting human evolution is particularly difficult seeing as our technological abilities prevent natural selection from acting in many areas. An example of natural selection of humans you might be familiar with though is the protection from cerebral malaria conferred by the sickle-cell form of haemoglobin. In areas of high malarial incidence (e.g Gold Coast, Congo Basin and Southern India) the gene that causes sickle cell anaemia has a high frequency in the population (an allele frequency of 0.15-0.18) even though being homozygous (having two copies) for this allele results in reduced life expectancy and decreased likelyhood of reaching reproductive maturity. Heterozygous individuals however are more resistant to the most severe complications of malarial infections (for those interested, apparently it has to with the production of carbon monoxide induced by the sickled blood cells (http://www.cell.com/cell/abstract/S0...74(11)00384-9)) and are more likely to survive malarial infections than those people who have no copies of the HbS allele.

If the threat of malaria is removed then you would expect the HbS allele frequency to be lowered over time as those with two "normal" copies of the Hb gene are no longer selected against. You can see this if you track African populations in areas where is no malaria over time (whilst not fully significant ane xample would be that the African American population has a allele frequency of about 0.014 for the HbS allele).

[lightblue]

Writing that piece made me wonder about rats... In particular whether or not there are any differences between population of Rattus norvegicus in any of the various climates it has made its home. I can't see if anyone has done any work on this though. The numbers and speed of reproduction could make this a reasonable subject to study divergence and adaptation to a particular ecosystem.

[Ben Kenobi]

In the meantime can you tell me what we don't understand about proteins and gene expression and how that is exactly related to ricketyclik's example of a complex system?

You can't understand the operation of the complex system without knowing how all the parts fit together. F'instance - if all the proteins in the human bodies have different ways of interacting with each other - this would be crucial to understanding human evolution. Not knowing even a single one could lead you to wrong and erroneous conclusions. It's not just enough to know how one protein works in isolation, but how they all work together. To my understanding, we've just recently sequenced a human genome and don't have a great understanding of many proteins and how they operate, as well as specific parts of our dna and what they are useful. I'm in the camp that there's a purpose for all of it, even if we don't understand what that purpose might be.

The usual example is sickle cell anemia - things that seem to have a trade-off have a benefit to certain types of environments. If say, we aren't sure what exactly a protein does - it might provide a substantial survival adaptation in a way that we don't currently understand.

[Ben Kenobi]

How is it conjecture? If you investigate a theory and set up an experiment then you need to be able to control any extraneous variables to allow any valid prediction to be carried out. Let's go for a school-level example. If you were doing an experiment that was looking at the effect of different pH levels on the activity of an enzyme you would need to control the temperature, the substrate concentration and the enzyme concentration (among other variables). If these changed from repeat to repeat then you would not be able to predict the outcome.

That's how science works - we'd have to be able to alter the dna in such a way as to confer an expected survival benefit. This is difficult to do under laboratory conditions - even with the simulated conditions - you don't have a closed system, and what you alter things for may not be the same as the world is later on.

So, say, you find a gene for something, and are able to control to create a population of say, flies, that express it in such a certain way. Even if you were to release these flies out into the general environment you still wouldn't be able to get reliable results on survival benefits. And even if you did - you'd only get for a certain period of fittedness. Assuming perfect information and understanding of genes and their expression, the environment itself changes and would mean that your fit may no longer work. How could you be certain that a null result under testing would actually be a null result and not, say, something else changing?

Evolution is caused by the increased chance of survival in the gene pool of the combination of genes that confer the greatest reproductive advantage in a particular environment. If the environment changes then different gene combinations would be more advantageous. As we cannot predict the future with any certainty we can't predict the eventual outcomes of evolution outside of controlled experiments.

This is the biggest problem. You don't have a way to control for the variables even given perfect information (which we do not at present possess). That's what leads me to believe this is a dead end. If even with perfect information (we don't get reliable information), then it leads me to believe that the theory in itself is wrong.

In a less controversial context it is like the weather example mentioned earlier. We can predict the future with regards to weather with some degree of accuracy about 5 days into the future. Longer-term predictions carry greater uncertainties and the error range becomes greater. What you are asking is to predict what the weather would be like in on September 3rd in a million years.

No, what I'm asking for is a general direction. Will the earth get cooler, hotter? Over a specific period of time? Climatology is really in it's infancy as a science, which is why the comparison is not a great one for biology. Stellar evolution is a misnomer. It's not evolution insofar as it is stellar development. Stars do not change their substance, but they change their size, and their structure. It's the same star from beginning to end. This is why the science works - it's making the assumption that it's the same star and running population dynamics.

Stellar 'evolution' pertains to genetics - where you are recording the sequences of a large population - something we can actually do just very recently. There is a ton of science here that will be done in the near future that will allow us to trace patterns within people as a whole.

THIS is where the real science lies.

[lightblue]

You can't understand the operation of the complex system without knowing how all the parts fit together. F'instance - if all the proteins in the human bodies have different ways of interacting with each other - this would be crucial to understanding human evolution. Not knowing even a single one could lead you to wrong and erroneous conclusions. It's not just enough to know how one protein works in isolation, but how they all work together. To my understanding, we've just recently sequenced a human genome and don't have a great understanding of many proteins and how they operate, as well as specific parts of our dna and what they are useful. I'm in the camp that there's a purpose for all of it, even if we don't understand what that purpose might be.

The usual example is sickle cell anemia - things that seem to have a trade-off have a benefit to certain types of environments. If say, we aren't sure what exactly a protein does - it might provide a substantial survival adaptation in a way that we don't currently understand.

Things have moved on a little since then. We are pretty certain what most of the DNA in our cells is for (I think the definitive map was published in 2012 or early 2013). Many of the non-coding regions are involved in regulation of expression or histone interactions. Whilst we are still working on the function of all protein products and the interactions between them, we are getting closer to modelling whole cells (it can be done for simple bacteria). Once computer power catches up we can start looking at eukaryotic cells and then multicellular organisms.

I think you are seeking to over complicate matters so you don't have to deal with cognitive dissonance in your mind. Evolution acts on the individuals in a population over time. It is the whole organism that counts rather than reducing it to its individual. What your saying is that you need to know what every quark in every atom of every star us doing to predict what will happen to the star over its lifespan.

[Ben Kenobi]

I think you are seeking to over complicate matters so you don't have to deal with cognitive dissonance in your mind. Evolution acts on the individuals in a population over time. It is the whole organism that counts rather than reducing it to its individual. What your saying is that you need to know what every quark in every atom of every star us doing to predict what will happen to the star over its lifespan.

Stars are governed pretty much by gravitation. Once you know it's mass, and it's spectral class, you can pretty well figure most other things from it. The same is not true of human beings and evolution. Again, the two are not analogous at all. The star is always the same star through it's development - it's more akin to aging of one person over time.

In order to predict whether something is fit or to predict the direction of evolution - you would have to know how all the parts fit together.