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Darren Lissaman

Has Evolution Stalled?

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I know I haven't blogged for a long, long time but I have some ideas I need to get down and, well lets face it, no one is going to publish a paper by a 41 year old, 2nd year Under grad!

This has been prompted by a discussion I had with a friend who is a firm believer in God. it got me thinking about one of the points that usually come up in these situations, where is evolution today? why is nothing changing? Of course the standard answer is because it happens over huge timescales but what if? what of evolution has indeed stopped? how could this happen and why did it start in the first place?

At this point I must make some assumptions about the reader. The first is that you are prepared to read this through to the end with out dozing off, another is you are versed in current theories involving planet formation and geological processes.

Darwin's theory of evolution by natural selection gives us the processes. The why it happens. A creature developers a variation which makes them more suited to a particular problem. They do better because of it and, as a result, their genes get passed on to the next generation. So far so good. The question that is raised next is how do these variations occur? Thanks to advances in gene research we now know that it is how the genes are encoded in our D.N.A. that make us what we are. It is changes in these codes that allow variation. So again where is this variation. One way we know for sure to affect the gene sequence is with radiation. The blasts of Hiroshima and Nagaski are proof of this. Here we see genetic mutations that deform their victims. but what if genetic mutation is the tool that allows the variation in evolution? Obviously I am not saying that a tumour is an advantage in the survival of the fittest but we know radiation can and does rewrite gene sequences. could long term, lower level radiation exposure drive evolution.

 

So now we must travel back in time, before life began, to the formation of the planet itself.

Current theory is that the Earth, its moon, the sun and all the objects in the solar system were created from the decaying remains of a dead star. These atoms slowly drew together under gravity to build every thing we are, see and can touch. Our sun was still young and cool but the Earth was warm. How can this be? (and doesn't it make a joke of the term Solar Constant?) The answer lies within the Earth itself. From my studies of geology I know that the Earth creates its own warmth through radiogenic heating. As radioactive elements decay they lose energy as heat and they decay because nature dictates that they have to be in a steady state. We can now accurately date the Earth thanks to knowing how long certain isotopes take to decay into a more stable form. Once in that form it no longer gives off energy so is no longer radioactive. Knowing this we can state now that the reason our Earth was warmer was because it was more radioactive then than it is today.

And so to my hypothesis. I believe that once the back ground radiation had dropped enough and other conditions allowed life to form, radiation was capable of mutating D.N.A. and these mutations formed the toolkit of life. As single celled and then multicelled creatures started to appear, radiation allowed for mutations to occur. Some proved worthless and the creature would have perished but small adaptations were able to mutate and where they gained an advantage the mutation was passed on. Could this be how evolution started? radioactive mutation caused by the environment?

As the eons passed radiation has reached a much lower background level. Is it possible that it can no longer affect the changes to D.N.A. that it did and we have reached a point where we are now frozen in these forms?

If this is so it may answer the question would evolution ever happen again? If radiation is indeed the driving force then no.

 

Thank you for your time

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An interesting read. I'd like to make a couple of points. I'll state my position before I start. I believe in God and a theory of evolution i.e. all living things can be traced back to a common ancestor and the same chemical building blocks ( I studied chemistry before I defected to the arts).

1. Science only ever explains HOW things happen. It cannot answer questions like 'Why is there something rather than nothing?' or 'What makes an entity alive?". It can describe what conditions and substances are needed but not what provides the spark.

2. i think we are still slowly changing but this could be due to adaptation, evolution or a combination of both.

Incidently, i do agree with you about radiation playing a significant part.

Darren Lissaman

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Thank you for your input. As I said to my friend, she still is my friend I hasten to add, her beliefs are her beliefs and I do not have a problem with that. I just wish to move my own personal understanding forward and would never impose my views on someone else so thank you for taking the time to read them. At least I know there is one person in the blogosphere smile

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Hi Daz,

What gives you the impression that evolution has stopped, or even slowed?

One example: doorways in old buildings are small.. ok this is crude, but people have become significantly taller in recent human history.

Is this not evolution? The background count has not significantly reduced in this timescale.

Any mutations in simple organisms are bound to have a more profound effect than in complex organisms. Viruses and bacteria are evolving as we speak, on a very short timescale, hence the problems with antibiotic and antiviral treatments.

So, interesting theory, and background count may have been/be a contributing factor, but it is certainly not the only force driving evolution.

I have some figures on half-lives and heating levels, its in the S279 material, I will try to do a calculation to ascertain the difference in output between the late precambrian and the present.

Steve

Warmer earth

Just a point about the earth being warmer in easrlier life. The Earth was orgiginally molton during its formation due to the heat created with the early impacts of its formation. This coupled with the size of the earth is where most of the earth's internal heat was created and why its still warm today. This is believed to be why smaller bodies such as mars are now geologically dead, the Internal heat from the planet has been lost in to space. Basically the smaller the planet the quicker it loses its internal temperature. Some of the moons of Jupiter are geologically active not from their creation of radioactive decay but from tidal heating (The planet gets squashed by Jupiters massive field of gravity). I feel the internal radiation probably had little to do with the evolution of modern species, maybe some of the very early stuff (i.e way before the dinosaurs). To this day the earth is bombarded with solar radiation, granted the magnetosphere stops most of this reaching earth. With continental drift however the continents have moved around since formation resulting in the climate chaged significantly over the years which I think probably would have had more of an effect on evolution than radiation from the Earth. Hope that makes sense, its 5:30am just now - I couldn't sleep.
Darren Lissaman

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Thanks for your comments gents and you make some good points.

Steve, People getting taller though, to me seems more like unnatural selection. Its akin  to what dog breaders or pigeon fanciers do. If you are tall and you chose a tall mate your children will be tall. I'm short and would never chose a mate taller than myself. Maybe there are still changes possible because the genes that allow these changes are already part of the toolkit. What got me thinking was that there seems to be no more radical changes. Developing eyes, although passing through stages of simple photoreceptors to the complex eyes we have today, must have been a radical departure at the time. Maybe Radiation just provided the kick start to get things going and as I finished saying that kick start has now gone.

Brian, I concur with your comments on tidal forces and that collisions caused the initial heating. However radiogenic heating is a very important part of the geological processes we know as plate tectonics now. An example of this is during continental collisions. Although friction causes some heat the primary cause of magma melt in these situations is by a build up of radioactive uranium, thorium and potassium. As we know these elements decay to a more stable state so it is easy to see that they are more stable now that they once were so therefore were more radioctive in the past. As you rightly suggest the other bodies, such as our moon and others, are geologically dead due to their heat escaping to space. the heat from radiation can and will be lost in exactly the same way. not only does the "greenhouse gasses in our atmosphere trap returning solar radiation, they also trap and retain the Earth's internal radiation.

 

Anyway, thank you all again for your comments. As stated this is just a hypothesis and I have done no where near enough work on it to consider ever calling it more than that. So far my research is a mind map on a sheet of A4 paper. Might make an interesting thesis at the end of my studies though.