Evolution, evidence?

[reenagrace]

How did scientists know what happened millions of years ago if no one was there to see it?

And if we are going to teach this to our students, what is the best instructional material to used?

I am newly hired secondary teacher. I am just preparing myself on this topic. I hope someone will reply to my post.

Thanks in advance.

[StringJunky]

They extrapolate evolution from fossils; their similarities and differences between each other and to modern organisms and where they lie in the geological strata - by knowing the age range of a stratified layer they can know when those organisms were around and whether they were water-borne or land-borne, amongst other things. The oldest are at the lowest layers. The story is also told in DNA where the relationships between organisms, or not, can be discerned,

 

http://necsi.edu/projects/evolution/evidence/evidence_intro.html

[reenagrace]

Meaning to say, evolution can be determined by fossils? And where can we find fossils? How would they know that what they have is already a fossil?Thank you sir for your reply.

[StringJunky]

Meaning to say, evolution can be determined by fossils?

Yes, along with the other methods.

 

 

And where can we find fossils?

In sedimentary layers and rocks sourced from those layers.

 

 

How would they know that what they have is already a fossil?

Not sure what you mean with this question.

[DrP]

Check out the laryngreal nerve in a giraffes neck compared to that from a fish. It is an amazing clear example of how something has evolved over millions of years. Just type "Laryngreal nerve, giraffe" into google.

 

As for resources for your class, I am afraid I cannot recommend anything... other than looking up the thing with the giraffe and the extra long nerve.

[TheBeardedDude]

How did scientists know what happened millions of years ago if no one was there to see it?

And if we are going to teach this to our students, what is the best instructional material to used?

I am newly hired secondary teacher. I am just preparing myself on this topic. I hope someone will reply to my post.

Thanks in advance.

"How did scientists know what happened millions of years ago if no one was there to see it?"

 

The same way we determine what happened in other similar situations, we look for the evidence. Detectives can piece together what happened when someone is murdered from the evidence left behind. That's what paleontologists do, we find the fossils and we use the morphology of the fossil to help us determine what species it is and what it's related to. That helps establish the evolutionary lineage of a group of organisms. We also use the sediments the rocks are found in, as well as the geochemical signature of the sediments and fossils, to determine other pieces of information. The sediments can tell us the environment the organism lived in and the geochemistry can allow us to determine their diet/trophic level, the temperature of their environment (or their internal body temperature), and other factors about the environment too (like the role of the global carbon cycle).

 

"And if we are going to teach this to our students, what is the best instructional material to used?"

 

I'm not sure because I don't teach at the primary school level but I'm sure there are plenty of good online resources through groups like the Paleontolgoical Society of America, the Society of Vertebrate Paleontology, the Paleontological Research Institute, etc.

 

(A fun online activity titled "what did T. rex taste like?" is good)

 

Another question you asked is "how do scientists know they have a fossil?"

 

That's somewhat trickier to answer under certain conditions. The definition of a fossil can vary depending upon the paleontologist, I prefer "any trace of life preserved in the crust of the earth." So, what makes a fossil a fossil is that it is not from a recently dead animal and instead comes from the rock or sedimentary record. So it becomes tricky when looking at Holocene sediments because it may not be clear how old the specimen is. But this definition works well when looking at the vast majority of the fossil record.

[Phi for All]

How would they know that what they have is already a fossil?

 

Fossils are petrified. Petrification is easily identified.

[CharonY]

Another thing to consider, which may be slightly abstract is the fact that evolution basically means that the genetic composition of a population is changing over time. Everything else, like speciation is a consequence of this. For example, if two populations are separated so that there is no genetic exchange over time they may diverse genetically so much that they become different species. This does not necessarily take a long time, as it is dependent factors such as generation time, population size and so on. We can observe evolution in bacteria, for example, as they replicate that fast.

[Moontanman]

How did scientists know what happened millions of years ago if no one was there to see it?

And if we are going to teach this to our students, what is the best instructional material to used?

I am newly hired secondary teacher. I am just preparing myself on this topic. I hope someone will reply to my post.

Thanks in advance.

 

 

This is a great resource for information about evolution:

 

http://www.talkorigins.org/

[Itoero]

How did scientists know what happened millions of years ago if no one was there to see it?

And if we are going to teach this to our students, what is the best instructional material to used?

I am newly hired secondary teacher. I am just preparing myself on this topic. I hope someone will reply to my post.

Thanks in advance.

Wikipedia has a pretty big list of transitional fossils.(with explanations/pictures)

On the right on this page you find many links to Wikipedia pages concerning subjects related to evolution.

This might very helpful.

https://en.wikipedia.org/wiki/List_of_transitional_fossils

Edited December 10, 2016 by Itoero

[Moontanman]

Also fossils are not fount out of place. You wouldn't find a bunny rabbit in the Cambrian layers of rock, not would you find Dimetrodon with dinosaurs.

Edited December 11, 2016 by Moontanman

[arc]

I believe the most enjoyable way to be introduced to this subject would be David Attenborough's Rise of Animals: Triumph of the Vertebrates.

 

It's a two part documentary, 60 minutes each. I can watch these over and over. Great CGI effects and David Attenborough's unmatched presentation abilities.

https://en.wikipedia.org/wiki/David_Attenborough%27s_Rise_of_Animals:_Triumph_of_the_Vertebrates

[Delta1212]

I believe the most enjoyable way to be introduced to this subject would be David Attenborough's Rise of Animals: Triumph of the Vertebrates.

 

It's a two part documentary, 60 minutes each. I can watch these over and over. Great CGI effects and David Attenborough's unmatched presentation abilities.

https://en.wikipedia.org/wiki/David_Attenborough%27s_Rise_of_Animals:_Triumph_of_the_Vertebrates

And it's on Netflix streaming. Excellent.

[MigL]

Other than petrification of bones, which tells us very little about soft tissue structure, there are also amber preserved specimen.

Recently read about an amber sample bought at a market that contained a small dinosaur tail, completely covered in fine feathers. Not scales or leathery skin, but actual feathers, just like birds; finally putting to rest the dinosaur 'total extinction' myth.

 

Don't recall where I read it, should be easy enough to look up, and may teach research skills to the kids.

[Delta1212]

Other than petrification of bones, which tells us very little about soft tissue structure, there are also amber preserved specimen.

Recently read about an amber sample bought at a market that contained a small dinosaur tail, completely covered in fine feathers. Not scales or leathery skin, but actual feathers, just like birds; finally putting to rest the dinosaur 'total extinction' myth.

 

Don't recall where I read it, should be easy enough to look up, and may teach research skills to the kids.

Well, the feather imprints found in some fossils had already put the question of whether dinosaurs had feathers at all to bed, and there were past finds that were believed to be tail feathers in amber.

 

This was the first one that included some bone, so it could be definitively demonstrated to not only have been from a dinosaur but the specific one it came from was identifiable. It also gives more of a clue toward coloring, which obviously isn't possible with fossilized feather impressions.

[Phi for All]

And it's on Netflix streaming. Excellent.

 

Wow, the first part was excellent. Second part tonight.

 

What is it about those sites in China that gives them such fantastic soft tissue capture in the fossils? It's so exciting seeing more than just skeletal outlines. Was there no bacteria eating the soft tissue?

[BabcockHall]

Meaning to say, evolution can be determined by fossils? And where can we find fossils? How would they know that what they have is already a fossil?Thank you sir for your reply.

 

There are also DNA sequences of the same protein in different organisms, for example.

[seriously disabled]

If abiogenesis is a true theory about how life on Earth began from nonlife then this means that life is a form of chemistry or is it?

 

http://rationalwiki.org/wiki/Abiogenesis

Edited December 19, 2016 by seriously disabled

[Ophiolite]

If abiogenesis is a true theory about how life on Earth started from nonlife then this means that life is a form of chemistry or is it?

 

https://en.wikipedia.org/wiki/Abiogenesis

Whether or not abiogenesis is "a true theory" life is a form of chemistry. What is your alternative suggestion as to what it is, given that living organisms are composed of chemicals that are engaged in a complex web of chemical reactions.

[seriously disabled]

Whether or not abiogenesis is "a true theory" life is a form of chemistry. What is your alternative suggestion as to what it is, given that living organisms are composed of chemicals that are engaged in a complex web of chemical reactions.

Yes true but we don't know for sure how life on Earth really began or do we?

 

Abiogenesis is the only scientific theory we currently have but religious people may claim that intelligent design (ID) or any variant thereof is more likely what happened.

Edited December 19, 2016 by seriously disabled

[Sriman Dutta]

Whether or not abiogenesis is "a true theory" life is a form of chemistry. What is your alternative suggestion as to what it is, given that living organisms are composed of chemicals that are engaged in a complex web of chemical reactions.

Indeed, life is a complex chemistry. Life is the flow of energy from one generation to another through chemical reactions. That's what life is from a chemist's point view.

[hypervalent_iodine]

!

Moderator Note

Abiogensis =/= evolution. Please stick to the topic. Seriously disabled, if you wish to discuss abiogensis further, you are welcome to open your own thread.

[EvanF]

As a teacher, you shouldn't need to 'push' evolution theory, you should teach your students how to question everything and think critically.

But it certainly doesn't mean you should replace the well researched theory of Evolution with something like religious dogma.

 

Charles Darwin himself said, "The mystery of the beginning of all things is insoluble by us..."

A scientist doesn't pretend to know how life began or make assumptions based on politics, religion, or emotion...A scientist simply bases their theory on logic and the evidence that is available.

 

 

When speaking about the fossil evidence, you have to understand that 'macro evolution' is such a grand concept that there isn't perfect fossil evidence of a fish evolving into a cow, for example...

 

But there is significant evidence for Human/hominid evolution.

If you want to look through some of the fossils of early hominids then here's a decent Wikipedia article.

https://en.wikipedia.org/wiki/List_of_human_evolution_fossils

 

And here's a picture of just a few well preserved hominid skulls that show an evolutionary progression over millions of years. First skull-Australopithecus (4 million years ago). Second skull-Homo erectus (2 million years ago). Third skull-Neanderthal (600,000 years ago.) Fourth skull-Cro magnon (45,000 years ago).

Now not all of these hominids are necessarily directly descended from each other, but the first three are all very similar and show a clear relation to each other.

 

 

I'd think a good way to teach elementary Evolution theory is to simply explain that animals have the amazing ability to mutate their genetic code itself in order to adapt to an environment, and over time this can change the whole appearance and nature of a species. Explain that an animal's ability to change it's genetic code is an essential part of life and the survival of a species.

[Strange]

I'd think a good way to teach elementary Evolution theory is to simply explain that animals have the amazing ability to mutate their genetic code itself in order to adapt to an environment, and over time this can change the whole appearance and nature of a species. Explain that an animal's ability to change it's genetic code is an essential part of life and the survival of a species.

 

 

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.

 

I would rather start from the facts that

 

1. there are variations in populations (which can be brought about by things like mutation)

2. some of these variations are heritable

3. some of these variations may improve or reduce the chance of individuals surviving and reproducing

 

From that, evolution is a necessary end result. (It would take divine intervention to prevent it happening!)

[CharonY]

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.

 

I would rather start from the facts that

 

1. there are variations in populations (which can be brought about by things like mutation)

2. some of these variations are heritable

3. some of these variations may improve or reduce the chance of individuals surviving and reproducing

 

From that, evolution is a necessary end result. (It would take divine intervention to prevent it happening!)

It is only required that they have differential reproductive success, which may include stochastic effects and not necessarily be under selective pressure. Edited December 27, 2016 by CharonY