Hi, this is Kate from MinuteEarth.
The fact that we humans - or any complex life forms - exist on our planet is kind of amazing.
Somehow, the blob that debuted four billion years ago found the resources it needed to
survive and reproduce, and its offspring found the resources they needed to survive and reproduce,
and so on and so on.
Those blobs evolved and diversified to occupy pretty much every nook and cranny on Earth.
But here’s evolution’s dirty secret: mostly, blobs - and species in general - go extinct.
More than 99% of the species that ever evolved on Earth have gone the way of the dodo…
like, well, the dodo, the giant ground sloth and billions of other species.
So what determines whether a species makes it or not?
Well…
[Jasper] Psst!
Kate!
Hey Kate!
[Kate] Oh...hi Jasper...can this wait?
I’m kind of in the middle of a video...
[Jasper] I know - sorry to interrupt!
But I built something that might help illustrate this whole extinction thing; The MinuteLabs
Evolution Simulator!
It’s based off of the blob world built by our friend Justin of the Primer YouTube channel,
and I’ve spent the last few months making it interactive.
[Kate] So...
[Jasper] … did I mention the viewers can see it at www…
[Kate] Jasper!
Can you at least wait until the end of the video?
[Jasper] Right!
Sorry, I’m just excited.
[Kate] Ok… so how does this help explain extinction?
[Jasper] Well, we can use it to show different situations that result in total blob-creature
extinction!
We start the simulation with blobs on the edge of the board and a certain amount of
food pellets sprinkled around.
The blobs all have particular traits that can change with each new generation - like
speed, size, and ability to detect food - and they move around the board trying to find
a pellet of food and get back to the edge before they run out of energy and... meet
their maker.
Any blob that finds two pellets before running out of energy will reproduce and create a
new blob with traits that are slightly - and randomly - different... it’s a simplified
version of genetic mutation.
I think it’s so cool to see how the traits of blobs change over time… and whether they
make it at all.
[Kate] Oh, ok, cool!
So what have you found out about blob die-offs?
[Jasper] Well, so what I found was that the main cause of a population surviving or dying
off was often a result of how quickly the environment changed.
For example, if I decrease the amount of food available by 80 pellets over ten generations,
the traits of blobs across the population can change fast enough to compensate for the
lack of food.
But if the change happens too quickly - like if I reduce the food available by 80 pellets
in a single generation - the blob population won’t have enough time to evolve and adapt,
and they all just die off.
[Kate] OK, interesting.
The same thing happens in the real world...take, say, ferrets, which can generally deal with
fluctuations in their favorite foods, and their diets often change over time as their
environment changes.
But when a horde of Western settlers suddenly started obliterating the population of prairie
dogs - the black footed ferret’s favorite-est food - the ferrets couldn’t adjust to the
sudden drop in their food supply, and they went extinct in the wild.
Of course, in nature there are usually a few species competing for the same food...any
chance your blob world can handle more than one species?
[Jasper] Actually…
I just added that feature!
[Kate] And?
[Jasper] Well let’s try it... here’s a simulation with two blob species; the orange
ones are faster, but the blue ones can see farther.
Hmm…
As long as the amount of food remains the same, they both can coexist for quite a long
time.
But… wait… let me try something… hey! if I suddenly reduce the food supply, all
of a sudden the blue blobs start to take over and the orange ones die off.
[Kate] That’s just like Tasmanian tigers and dingoes!
[Jasper] Wait, what?
[Kate] Well, those two carnivores used to coexist without too much trouble, even though
they ate more or less the same food, which would ebb and flow over the years.
But humans - once again! - pretty much decimated the available prey.
The dingos, which were stronger and hunted cooperatively, had an edge in finding scarce
snacks, so they ended up surviving while the Tasmanian tigers couldn’t get enough to
eat, and went extinct on the Australian mainland.
[Jasper] Oh that reminds me!
Predation can also be a factor in blob-world extinction, like when a big predator blob
is dropped onto a board filled with little blobs.
Basically, any blob that is at least 20% bigger than another blob can, well, eat it.
If there’s no initial variation in size, blobs will slowly diversify into big blobs
that quickly snag any food available to them - including their neighbours - and small blobs
with lots of energy to spare that bop around looking for leftovers.
But look at this: if I start off with a world of small blobs, and I introduce even a single
large blob into this world, it - and its progeny - will decimate all the small blobs in just
a few generations.
It seems that if the blue blobs had a chance to coevolve with the pink blob species, they
might have time to adapt and avoid getting eaten, but things happened so fast they didn’t
stand a chance.
[Kate] Exactly!
Those poor little - delicious - blobs.
This is what we see so often when invasive species dominate native ones.
Take snakes and birds, which are species that coexist all the time - assuming the birds
evolved with the snakes and know to be wary of them.
But when a single brown snake hitched a ride into Guam, in just a few years she and her
descendents killed off 12 native - and naive - bird species.
[Jasper] Hmm…
I’m starting to see a pattern… it seems like all the extinction scenarios you’ve
brought up happened because of us humans.
[Kate] Yeah, I mean, we humans tend to change things at a speed that evolution just can’t
keep up with.
As a result, species are going extinct at at least ten times the historical rate.
But we aren’t the only bad guys - massive change-y things like meteors and ice ages
also seem to cause huge extinction events.
[Jasper] But, at least for blobs, sometimes it seems like extinction can happen without
any grandiose event at all… look at this: Sometimes, when I run this simulation, these
few blobs happily reproduce for hundreds of generations.
But other times - when I keep the exact same parameters - they suddenly all die off in
a few generations, with no interference at all!
[Kate] That’s what’s so interesting about evolution!
Sometimes, whether a species flourishes or fails can come down to luck.
We know that, especially for certain kinds of animals - like those that naturally exist
in low numbers and have big home ranges - small, random changes can kill off an entire species.
I mean, the cave bear seemed to be doing fine for tens of thousands of years with new humans
around, but they suddenly went extinct because, well, we dunno.
[Jasper] Ugh, that’s a hard one to bear.
I have one last thought that’s maybe a bit philosophical…
The simulator can run for a long time, and the blob population can keep evolving for
hundreds… or thousands of generations.
But by the time the blobs are on their, I dunno, 600th generation, they are really different
than when they started - like in this example, if we color the blobs a brighter shade of
red the faster they are, you can see that they become way faster and way bigger than
they were at the start.
So… are these blobs a new species?
So...are these blobs a new species?
And, if so, did the old species go extinct?
[Kate] I mean, maybe?
One of the really interesting things is that extinction isn’t necessarily about failure...Like,
modern cows have changed so much since they descended from a kind of wild ox - they’re
way smaller, they have much bigger udders - so the two bovines are generally considered
to be totally different species.
And since there aren’t any more wild oxen, we consider them to be extinct, while cows,
obviously, are still milking life.
But since they evolved directly from the wild oxen, that extinction wasn’t really a dead
end.
In the same way, the very first blob species in the world likely went extinct not too long
after it made its debut, but before it did, a subgroup of the population evolved into
a totally new species, which in turn evolved into other species and so on, to form billions
of species, 10 million of which are still alive and kicking...and flapping and crawling
and...whatever this guy is doing - all thanks to a long-gone blob.
[Jasper] … sooo… can i tell them where to find the app now?
[Kate] Yeah, this is the ending screen, so...go for it.
[Jasper] Oh!
Ok.
So… you can find the Evolution Simulator using the link I put in the video description
or you can visit minutelabs.io and find a ton of other fun labs to play around with
too.
I also made a video that goes into some of the inner workings of the evolution simulator
over on the MinuteLabs youtube channel… it’s right over here if you want to watch
it.
Anything else, Kate?
[Kate] Yes!
I want to thank The Great Courses Plus for sponsoring this video; we’re so excited
to be able to let you all play around with the simulator, and we couldn’t have done
it without their financial support.
As you all know by now, the Great Courses Plus is like Netflix for learning, with a
library of more than 11,000 lectures.
If you’re into evolution, I think you’ll love the course called “Major Transitions
In Evolution” which - over 24 30-minute episodes - takes you on life’s journey from
the first blob all the way through modern humans.
Now that’s a binge watch!
To get a free trial subscription to The Great Courses Plus and show your support for MinuteEarth,
go to TheGreatCoursesPlus.com/minuteearth, or click the link in the description below.
Thanks Great Courses Plus!