Hello, this is Dr.. Claire
And this is our lecture on the scientific method so all scientists including
biologists use the scientific method in order to
Investigate questions that they're interested in so just remember if you're doing science keep calm and use the scientific method
So we're going to talk a little bit about the steps of the scientific method you probably are familiar with this
And so hopefully this is going to seem pretty familiar
Alright, so the first step of course is to make an observation now in the case biology that's going to be an observation of the natural
world an observation of some sort of organism
Something interesting that you've discovered so you make an observation you see something that that is there that you're interested in
Then from there you start to ask questions. Why is this happening? What's going on?
What do I think is the reason for this
particular version
so then you're going to come up with a hypothesis your hypothesis is an explanation that answers your question, so
Let's take an example. Let's say that I'm interested in
Why some birds have red heads really brightly colored red plumage?
So I observe I see that these birds have these red heads, and I think oh, that's awfully
Obvious maybe that makes them easier to be found and eaten by predators
So why would you have such a bright colored plumage?
If that makes you more obvious, I'm going to think about that for a minute
There's my question and then it could be okay
Well, maybe that plumage color helps them to attract a mate okay, so there's my hypothesis, okay?
And so then from there, you would make some predictions. If this hypothesis is true
What do we expect to see, what could we detect that would support that hypothesis? so if my hypothesis
Is that the brightly colored red plumage on the bird helps it to attract a mate then a prediction of that might be that
Males or birds that have these more brightly colored feathers
Have more mates than birds that have less brightly colored feathers
maybe can find some different birds in the area and compare them to each other see which ones are brighter which ones are duller and
Then and then see how many mates they're able to attract
Okay
So that would be an additional
Observation that I would then make I would observe
How many how many mates each of these birds have. Now, you can design an experiment
Oftentimes the best thing to do is design an experiment
So maybe I would take a red sharpie
and I make some of the male's even brighter than others that would be an
experiment
Or maybe I just go out and I collect observations about the natural variation in that trait either one is actually perfectly acceptable
So you design and conduct your experiment or you go and you collect your additional data
and then you analyze that data usually using statistics to
Determine
if your predictions are
statistically true, and you'll learn more about statistics further on in your biological career here at CSU Pueblo but
For now just bear in mind that you want to have some sort of pretty solid evidence that
Your results the data that you've collected either support, or don't support your hypothesis, so those are your two options
Here's your hypothesis is supported or is not so a lot of times in science this happens all the time you
Come up with this great hypothesis and you
Conduct an experiment you collect your data and your data
Does not support your hypothesis at all and so you go oh
Okay, now well now what well there's two possibilities one. Maybe your experiment wasn't very good
Maybe using red Sharpie to color the heads of these birds makes them stinky because sharpies stink and no one wants to mate with them
so maybe you should think of a different way to color the heads of your birds or
Maybe your hypothesis is wrong, and if your hypothesis is wrong, then maybe you need to go back and think of another reason
Why birds might have bright red colored plumage and test that hypothesis, okay?
So that happens all the time it is not a problem for your hypothesis to be wrong
Is an incredibly common thing and it does not mean that you're a bad scientist it just means that
You were wrong. You learn from your mistakes and you try again
but sometimes you're lucky, and you test your use statistically test your results, and you find that there is a
significant effect there so you find that indeed the birds with the brighter red heads have
Three mates whereas the Birds with the dull red heads only have one and you can
Conduct a statistical analysis on that and determine that it is a statistically significant result. great! You've just
Supported your hypothesis. No. I did not say that you proved your hypothesis
I want you all to remove the word prove from your vocabulary in science
We do not prove things we support things, okay
So you've supported your hypothesis and then the great thing about science is
you've provided some support for your hypothesis. You think this is what's going on
and then hopefully and other scientists somewhere else will actually go in and replicate your analysis and
perhaps they find the same thing that you found and that lends more support to your hypothesis so a
Hypothesis that is tested by many many scientists and has lots and lots of support and doesn't have any cases where
Where there's data that
fails to support the hypothesis
Those are what we eventually call scientific theories
Okay, so let's take a look at another example
So here's an observation
There are no more. Well, okay birds are technically dinosaurs. I'm a bird biologist
You're going to get a lots of bird examples get used to it
Birds are technically dinosaurs, but aside from birds there are no more dinosaurs on the planet. They went extinct we have fossils that
That show us what they may have looked like and lots of them
Dinosaurs once were probably the dominant land vertebrate on the planet, but they're no longer here, okay?
So so what happened well if you look at the rocks
From which they find these dinosaur fossils you'll see layers and layers and layers of raw
with dinosaur fossils all of these layers of dinosaur fossils
And then there's this layer of rock that's full of iridium and above the layer of rock that's full of iridium
no dinosaurs, okay, so
Scientists made this this observation now. Iridium is an element that is found in high
concentrations in
meteors
okay, so this is an
observation that we've made of the fossil record lots of dinosaurs layer of Iridium
No dinosaurs, okay, that's our observation now the question is why is this layer of iridium
present between
Those borders well maybe a hypothesis might be that a large meteor struck the planet
caused Massive destruction and
disrupted the communities and the land and the sea and caused the extinction of the dinosaurs okay, so there's a hypothesis a
big meteor
struck the Planet and
there was a huge explosion in the global winter and and it the trees couldn't grow and bad things happened and
Poof no more dinosaurs, okay, all right. So that's our hypothesis it is
supported by that evidence of iridium because the iridium found in meteors, so
Layer of iridium all throughout the planet suggests that maybe a big meteor
Struck planet got turned into dust and that dust settled throughout all over the surface of the planet
But what other predictions can we make based on that hypothesis?
Well if a enormous meteor that caused that much ecological damage struck the planet you would expect to see other
geological signals that would indicate that there had been a meteor strike and
so we can then go out and collect additional data and see if that supports our hypothesis if you go out and
Sure enough there is some additional information that indicates that there was a very large meteor strike
Right around that time in addition to iridium there are these crystals these quartz crystals?
This is an image of one right here that I'm circling with the pointer
Those are only formed under a high temperature and very high pressure like you would find if a very large meteor struck the planet
So those quartz crystals are interspersed scattered with that iridium layer
And also there is a enormous crater right off the Yucatan peninsula
That dates to the same time when the dinosaurs went extinct so that would be where that enormous meteor
struck the Planet, so this is an
Image of that crater, so the Yucatan is right here in Southern Mexico, and then this is the image of that crater
So we still have that evidence of that crater in
Mexico and based on estimates from the size of this crater they have
Approximated that the meteor that created that crater was approximately the size of the island of Manhattan
So really really big chunk of rock all right. So what can you conclude from these observations?
Hopefully, you would you just said to yourself this supports my hypothesis right, so it supports your hypothesis
it does not prove your hypothesis, but it does provide more support and
overtime we can build that support to
Figure out what has happened, and what is happening now, okay? That's it. Have a good day
