Evolution, evidence?

[EvanF]

 

 

I don't like the way you have phrased that. "Animals have the ability to mutate their genetic code" suggests it is under their control somehow; and that they choose when, and maybe how, mutations should occur.

 

Well, I don't really mean the animal consciously chooses to mutate, just that their body has the ability to mutate the genetic code through biochemical signals.

But a Human's conscious actions can of course change their genetic code over time(exercise for example changes our DNA)...and who knows...maybe the will power/intent of an animal to survive/adapt is part of what sparks the genetic change itself.

 

But back to the OP...

 

A lot of times students or yourself will ask for evidence of macro evolution, (one creature turning into a totally different creature.) You could mention that Metamorphosis is part of the life cycle for many different organisms on the planet, a caterpillar turning into a butterfly is a good example.

 

There is this idea that "evolution" is a very slow process, but that's not necessarily the case. Genetic mutations in humans or other animals can happen very rapidly.

One good example of rapid change to adapt to an environment are peppered moths, who actually developed a completely different color in only a few years in order to adapt to the pollution of their environment.

Edited December 27, 2016 by EvanF

[Strange]

 

Well, I don't really mean the animal consciously chooses to mutate, just that their body has the ability to mutate the genetic code through biochemical signals.

 

 

Really? I am not aware of that.

 

 

 

But a Human's conscious actions can of course change their genetic code over time(exercise for example changes our DNA)

 

Does it?

[Delta1212]

 

 

Really? I am not aware of that.

 

 

Does it?

He might be talking about epigenetic effects, but calling that a change to the DNA is a bit of a stretch.

[EvanF]

He might be talking about epigenetic effects, but calling that a change to the DNA is a bit of a stretch.

http://www.bionews.org.uk/page_132849.asp

[Delta1212]

http://www.bionews.org.uk/page_132849.asp

Yeah, that headline is somewhat misleading. It's talking about an epigenetic process that regulates gene expression but doesn't actually do anything to the underlying sequence of base pairs.

[EvanF]

Yeah, that headline is somewhat misleading. It's talking about an epigenetic process that regulates gene expression but doesn't actually do anything to the underlying sequence of base pairs.

Altering the genetic code itself presumably takes many generations, but it is possible for a species to 'evolve' very rapidly.

http://discovermagazine.com/2015/march/19-life-in-the-fast-lane

 

"Alter the DNA" isn't necessarily misleading. It's simply saying that the DNA alters in it's function.

Edited December 28, 2016 by EvanF

[Delta1212]

Of course it is possible to evolve rapidly, but that isn't related to active efforts to attempt to mutate by the organism.

 

And altering the genetic code doesn't require many generations, depending on how you're defining that. A mutation happens in a single generation. It may take many generations to spread and become fixed in a population. Alterations in the genetic code don't start with epigenetic processes like the above. Those are separate things, generally speaking, than mutations and are not primary drivers of evolution, though obviously they have some effect.

 

Think of most epigenetics of this nature as being like little switches on your DNA that control how genes are expressed. Things that happen to you, or that you do, can flick the switches on or off. And what state a switch is in can, in some cases, be heritable. But you aren't fundamentally changing the DNA in any way. The switches can be flicked back and forth.

 

Flicking a switch doesn't change the lightbulb. It just changes what state it is in.

 

And, just like mutations, while things that happen to you during the course of your life can certainly affect the traits that your offspring inherit, there is no simple correspondence between the thing that happens and the trait that is passed on as a result being helpful for that circumstance.

 

It's like blindfolding a person and having them flick a light switch and assuming the position they put it in will help the next person see better. They're blindfolded. For all they know, they just turned the lights out entirely.

 

You seem to be ascribing to this process a responsiveness to the environment that does not exist to the requisite degree for it to be meaningful. The peppered moth in coal country is not an example of this process, for example.

 

There were always moths with the different coloring, just not as many because they weren't as good at camouflaging themselves. Then the environment changed and suddenly their coloring was a very good disguise so their population exploded and outpaced the old coloring.

 

That is the extent of the cause-effect relationship between the environment and the evolution of traits. And yes, it can happen very quickly, especially when, as stated, the advantageous trait already exists in some form within the population.

[CharonY]

Rapid evolution refers to significant changes in a gene pool in a relatively short amount of time. It does not even require strong selective sweeps (though they may be one possible means), but also simple e.g. by having a small population. Minor changes from one generation to the next can result in significant changes in a few generation, e.g. simply due to genetic drift.

[rainsign]

When DNA sequences of the same conserved gene in multiple species are aligned ( called BLAST analysis ), the specific differences can be identified and quantified. The differences are small but detectable in similar species and more and more numerous in more different species. Cladograms (family trees) can be created from this which match very well with cladograms from purely morphological data.

[Arete]

- We have direct observational evidence, like the Lenski experiment which has evolved E. coli populations for 25 years and shown how through evolutionary processes, they can develop new phenotypic traits. We also have instances where a population of organisms has diverged into two species during historical tiime, like the apple maggot fly and the yellow fever mosquito.

 

- We have biogeographical evidence that organisms share common ancestry. For example, many of the organisms which are found on the former continents which made up Gondwana are more related to each other than the places they are near to now, providing evidence of common ancestry.

 

- We have macro-morphological evidence, like vestigial organs like tail bones in humans and leg bones in whales, which support common ancestry with animals with tails and legs, respectively.

 

- On the cellular level, the evidence for common ancestry becomes even more compelling. Despite the obvious differences between say an dandelion and a horse, when you look at the the structural components of the cells, they are largely the same. This suggests that, despite the massive differences in external morphology you see today, they share common ancestry.

 

- Prehaps the most elegant (or maybe I'm just biased by working in genetics) evidence comes from genetics. All organisms on earth share the same basic structure and code for their blueprint. The study of genetics provides a comprehensive understanding of the mechanism by which phenotypic traits are inherited, how they can change, and provide the co-ordinates required to map the evolution of life.

 

This is not an exhaustive list of the lines of evidence we have for evolution - but when you "overlay" each of these "jigsaws" with each other, you can put together a more complete picture of the overall evidence, and the image we get is overwhelmingly consistent with evolutionary theory. As we look more, get more pieces of each puzzle, learn how to reshuffle the pieces we have more accurately, we get a better overall picture, and it only keeps looking more and more like evolution is the right fit for the data.

 

As an ending, I don't believe that evolutionary theory is exclusive of religion - it would seem that the Pope strongly agrees, calling the argument "absurd". You can believe in evolution and God - I have had the pleasure of collaborating with Professor Francisco Ayala who is a former Dominican Priest, a Professor of Evolutionary Biology at UC Irvine and former president of the AAAS. You might find some of his essays on religion and science interesting, especially, his book - "Am I a monkey?" which addresses the question of what evolution is and whether it is compatible with belief in God. http://www.washingto...0042603381.html

http://www.faculty.u...faculty_id=2134

Edited January 30, 2017 by Arete

[Nature Geek]

As a tool for teaching and learning about evolution, I would highly recommend the videos put out by Stated Clearly

 

 

At Stated Clearly we focus on the theory of evolution which is often misunderstood and even rejected by many members of our society. Our animations and writings aim to explain the science in clear language that anyone can understand, and in a friendly tone with a sensitivity to the cultural issues that many people have with the science.

We feel that the basic principles of biology should be freely accessible to all,
independent of race, age, gender, creed, or level of education.

 

http://statedclearly.com/

 

https://www.youtube.com/user/sciencestatedclearly

 

(and if anyone is curious, no I am not a member of the group, but I have supported them and I am a big fan of one of the artists)

[paragaster]

Of course it is possible to evolve rapidly, but that isn't related to active efforts to attempt to mutate by the organism.

 

And altering the genetic code doesn't require many generations, depending on how you're defining that. A mutation happens in a single generation. It may take many generations to spread and become fixed in a population. Alterations in the genetic code don't start with epigenetic processes like the above. Those are separate things, generally speaking, than mutations and are not primary drivers of evolution, though obviously they have some effect.

 

Think of most epigenetics of this nature as being like little switches on your DNA that control how genes are expressed. Things that happen to you, or that you do, can flick the switches on or off. And what state a switch is in can, in some cases, be heritable. But you aren't fundamentally changing the DNA in any way. The switches can be flicked back and forth.

 

Flicking a switch doesn't change the lightbulb. It just changes what state it is in.

 

And, just like mutations, while things that happen to you during the course of your life can certainly affect the traits that your offspring inherit, there is no simple correspondence between the thing that happens and the trait that is passed on as a result being helpful for that circumstance.

 

It's like blindfolding a person and having them flick a light switch and assuming the position they put it in will help the next person see better. They're blindfolded. For all they know, they just turned the lights out entirely.

 

You seem to be ascribing to this process a responsiveness to the environment that does not exist to the requisite degree for it to be meaningful. The peppered moth in coal country is not an example of this process, for example.

 

There were always moths with the different coloring, just not as many because they weren't as good at camouflaging themselves. Then the environment changed and suddenly their coloring was a very good disguise so their population exploded and outpaced the old coloring.

 

That is the extent of the cause-effect relationship between the environment and the evolution of traits. And yes, it can happen very quickly, especially when, as stated, the advantageous trait already exists in some form within the population.

 

What I gather is : There should already be some moths with different coloring. This trait may be passed to the next generation of moths. The differently colored moth are able to pass the trait is because they survive or their chances of survival are more than other moths. Right?

[StringJunky]

 

What I gather is : There should already be some moths with different coloring. This trait may be passed to the next generation of moths. The differently colored moth are able to pass the trait is because they survive or their chances of survival are more than other moths. Right?

Yes, in the case of those moths the mutation is already present and some offspring express it but, being non-camouflaged, they get eaten until the environment changes and their survival and reproduction then swings in their favour.

[Zinalu]

Fossils are found in different types of stone that is shaped and made out of different materials depending if it was soil, bottom of the sea, lake etc, the layers of the rocky ground tells you what time period they are from, when it comes to human remains they tend to be more on the surface since the modern lifestyle of houses and tools is very recent in the earths history, there are of course lot of times where fossils come up to the surface due to the movement and overlapping of tectonic plates, so something that was on the bottom can then end up on top on the surface ( like these footprints https://twistedsifter.files.wordpress.com/2013/10/cal-orko-wall-of-dinosaur-footprints-sucre-bolivia-2.jpg?w=800&h=600 ), one way of dating is with radiometric dating ( https://en.wikipedia.org/wiki/Radiometric_dating).

Fossil really means "dug up", but typically we think of fossils as remains from beings that lived millions of years ago, it's "easy" to know that since todays animals we can easily take skeletons from, and if we dig up a skeleton that looks nothing like the animal skeletons of today, it's something that have gone extinct, the skeleton and teeth also gets a darker color as it lays underground for millions of years due to the surrounding minerals. One thing to see if it's a dinosaur is if the skull has a fenestra, which also means that theres a lot of misconceptions about what is a dinosaur, not all prehistoric giant lizards are dinosaurs, and that is why birds are dinosaurs, they have a fenestra in their skulls ( https://blogs.scientificamerican.com/tetrapod-zoology/files/2012/08/Darren-Naish-Tetrapod-Zoology-corvid-skull-bird-pelves-CDII-Aug-2012-340-px-tiny.jpg ) and birds are the only animal of today that has an antorbital fenestra.

We humans have been finding fossils for about 2000 years, tough back then it was thought to be dragon bones, so since then we have been finding more bones, and that have given us lots of time to puzzle the skeletons togheter into an evolutionary tree, tough a lot is still missing and theres questionmarks how subject 1 evolved into subject 3 since subject 2 is not found yet.

Theres a lot of studying modern animals to understand prehistoric animals, if we take the famous T-rex as an example of logic in evolution, it has big strong jaws, long strong tail and then the silly little arms, why? If we look at the dinosaurs that T-rex evolved from, they have smaller jaws and head, the T-rex evolved to kill pray with strong bites, which meant more muscle in the jaw, however it then became to heavy in the front and the arms shrank, the T-rex didn't need arms with a killerjaw anyway.

When it comes to if an animal had feathers, scales or skin, there are sometimes marks ont he stone that shows scaley skin, feathers etc, like with this specimen http://i2.cdn.cnn.com/cnnnext/dam/assets/150717010131-zhenyuanlong1-super-169.jpg you can clearly see the lines from the feathers, or this one that shows clear scales http://www.sciencebuzz.org/sites/default/files/images/amia.jpg

Evolution wasn't about survival of the fittest, but more of "you're good enough" and if they happened to be lucky, if there was a flooding all land aimals would drown while flying animals can simply fly to another place and therefor that spiecies survived.

 

Something to always remember is that there is proof that dinosaurs existed millions of years ago and we can puzzle the skeletons togheter into an evolutionary tree, but since we can't time travel a lot is still theory and imagination, the color of prehistoric animals is impossible to know unless we are lucky to find mummified pieces which is extremly rare, like this tail http://edition.cnn.com/2016/12/08/health/dinosaur-tail-trapped-in-amber-trnd/ and there we also see clear feathers, but a lot of time, behaviour among other things, are logically theorized comparing the remains of prehistoric animals to todays living animals, tough theres no proof.

Edited February 9, 2017 by Zinalu