Alien Biosphere Evolution #3: Contingency & Cambrian Explosions

The Cambrian explosion was when evolution
GOT REAL! Often called the “Big Bang” of biology,
it marks the period when the earliest animals diversified into a remarkably wide range of different life forms, leading to the major groups known today. Famed paleontologist Stephen Jay Gould made
the case that the Early Cambrian was exceptional stating:
“Wind back the tape of life […] and the chance becomes vanishingly small that anything
like human intelligence would grace the replay.” Gould’s idea of the magnitude of Cambrian
diversity did not stand the test of time, but his greater point of historical contingency
still holds true. This also goes for the developmental constraints
that are set by these early biological experiments for their respective descendants. At the same time, basic physics and environmental
factors work the opposite way by making creatures superficially more similar or convergent. So when speculating about alien biospheres
how can we apply the interplay of contingency, constraints and convergence? Let’s find out! [IF YOU STEAL MY CONTENT I *WILL* DCMA YOU] Something had stirred up the primordial oceans… A handful of worm-like creatures, which had
been scraping a living off the seafloor for millions of years prior, quite literally,
were suddenly empowered to grow limbs, fins, eyes, claws, armour, and more!
…but each in their own unique ways. The particular solutions each lineage of these
early worms came up with determined the kind of creature their respective ancestors eventually
would become. But it may have been a risky business with
far reaching consequences! At the time, it seemed the Early Cambrian
exhibited an extraordinary array of bizarre body plans that could not be placed in conventional
groups. So many, in fact, that the precursors to vertebrates,
and thus humans, disappeared into the crowd. Gould saw it as a biological lottery of body
designs with profound significance for later life on Earth. He believed these were all radically different
experiments with only a handful surviving. Like the Butterfly Effect, if one of these
species had been snuffed out, we may have missed out on butterflies themselves, and
also other bugs… Well, OK, maybe we could live with that. But for all we know, the strange worms that
evolved into vertebrates may have perished, along with the potential for us, human beings
ever appearing. However, Gould had overstated the uniqueness
of the different lineages of the Early Cambrian. Most of its peculiar creatures have now found
a home as basal branches of the existing main groupings called phyla. Gould’s exaggeration clearly stems from
his habit to poke at common misconceptions, especially our conceit that human beings are
supposed to be an inevitable outcome of evolution. Yet the myth of human exceptionalism persists. We are sitting here on one branch of the evolutionary
tree… And looking back down on the path that led
to us, it feels like an inevitable outcome. It gives us the idea that there is a direction
to biological evolution and it has always been heading toward us, human beings. What we tend to forget is that all the other
lineages have survived just as long as ours and many are successful in their own ways,
even though they don’t build computers or rockets. Nevertheless, the thought of evolution moving
up a ladder is commonplace and goes way back. Before Darwin’s theory of natural selection,
earlier ideas on evolution like those by Jean-Baptiste Lamarck, imagined evolution as a steady progression
through predetermined phases. And remarkably, this is still ingrained in
our way of thinking as it pervades popular culture. We still think of evolution as being in stages,
gradually moving up the stairs one step at a time. In science fiction, humanoids are always expected
to evolve on alien planets as a general rule. And for instance in the X-men franchise, the
mutants that turn into superheroes or supervillains respectively, are presented as the “next
step in human evolution” that spontaneously start appearing. But there are no next steps in evolution. Evolution doesn’t go in a long term direction
towards a specific goal. All it does is respond to the immediate conditions
that a population of creatures lives under. It feels its way ahead and fans out in all
favourable directions. Like a slime mold spreading. Take for instance early fish: It’s not like
they knew they’d eventually have to go on land. There was just a group of peculiar ones for
which crawling rather than swimming was a nifty solution to a challenge they were facing
in their local environment. Early tetrapod legs projected sideways and
could thus not carry the body over land already. The latest theory suggests legs first evolved
as a solution for crawling through thick, underwater vegetation in marshes or mangroves. Among these new swamp-clambering fish, there
was then another peculiar species that could drag itself briefly onto land, if need be,
to get a snack or just into safety, and it went on from there. These early ancestors of ours went through
all the trouble, so to speak, to become amphibians, only for some species to completely turn their
backs to land and become fully aquatic again! The early amphibian Eogyrinus is one of those;
and many later lineages of reptiles, birds and mammals also went back to the water again,
as if the conquest of land was just an old fad. Examples like these very clearly illustrate
that evolution is not unidirectional. It just goes with the flow for every single
species in very limited time frames, no matter what happened before and no matter what may
lie further ahead. * The direction of evolution is only centered
around populations directly dependent on their local environment during a small window of
time. This also means that evolution could have
gone entirely different directions, had some key factors in the environment been tweaked
one way or the other. These are the small contingencies that end
up making huge differences in the long run for evolution. Now, we’re still not sure what factors may
have triggered the Cambrian Explosion, but we do know that it was when one group of creatures
in particular rose up to dominate the Animal Kingdom. Aptly called Bilateria this group covers a
huge range of different creatures many of which have attained high degrees of complexity. We’ll go into more detail about this issue
in the next video, but in the meantime, I can recommend an excellent video series by
YouTuber Jackson Wheat on the Cambrian Explosion. Link in the description and in-video cards. In short, the more we learn about the Cambrian
Explosion, the clearer it becomes it was just a regular diversification event, which aren’t
actually that unusual in the history of life on Earth. Also known as radiations, these often follow
some radical change in the environment leading to mass extinctions. A whole range of ecological niches then opens
up ready to be taken over by less specialised and thus more adaptive species. And it’s often some evolutionary innovation
that then enables an unremarkable group of creatures, looming in the background, to take
advantage of the ecological vacuum, and take center stage. This lends credence to the idea, that had
these events not taken place or not at that time, evolutionary history would have gone
down a completely different path. Like how a minor tuck of gravity hurled an
asteroid towards the Earth ending the dinosaur dynasty thus enabling mammals to take control
of the global wildlife. Despite long being assumed to be “superior”
to the reptilian dinosaurs, a major upheaval was actually needed for mammals to be able
to take over. This flipping of the table, rather than a
steadfast progression of the “best designs” towards victory, seems to be the basic pattern. This is important to keep in mind: Evolutionary
contingencies undermine the idea of evolution supposedly being geared towards any particular
life-form; Especially humanoid life forms! But if you want to design an alien biosphere,
it’s in principle impossible to not have the goal in mind of the complex creatures
you want to populate it with. So what to do? Well, we can start with acquainting ourselves
with the different evolutionary contingencies that we know played out in our own planet’s
past. Apart from serving as inspiration, we can
consider similar events to happen on other planets that are like Earth. Are these events bound to happen elsewhere
no matter what or not? Are they universal or are they unique? Devising your own series of evolutionary contingencies
would add a lot of depth to your alien world. In the next video we’ll continue our quest
starting with the Cambrian Explosion itself. Would Earth-like exoplanets perhaps each experience
their own early “Cambrian” Explosion? Let’s look into it! For now, thank you for visiting Phrenotopia! Cheers and bye, bye!

Comments 32

  • Oooh, cant wait

  • Man! I am a bit disappointed that’s it’s a premiere. I mean, not REALLY, but I was excited to watch it now. Waiting 24 hours is gonna kill me!

    I cant wait for this one.

  • Looking forward to this video man.

  • only 45 minutes left … CAN'T WAIT


  • Yes it’s here!

  • I made a stupid "evolution tree" where it is really a trait tree… It is so freaking weird and you just reminded me I did that.

  • Nice, a new video.

  • Why does this one have no alien fantasy creatures? It's just explanations and junk.
    where are the neat speculative aliens phrenotopia?
    where are you hiding them?

  • do a video about MGTOW evolution

  • that guy with the mustache looks badass 😎

  • upload more often & do a video about the Kalabi Yau manifold!

  • do a video about the Fermi Paradox!

  • do a video about the dangers of AI

  • are we living in a simulation?

  • Thanks for uploading high quality videos

  • 04:55 Yeah, it bugs me as well. BTW In new Predator movie they call autism " the next step of evolution" 🙂

  • Well done! I enjoyed this a lot.

  • I would argue that nondirectional evolution is possible in fiction. I just think up the creature in stages, starting at the bottom, and roll for a random event. Of course, I have to create many different species to do this, but it is possible.

  • X-Men fact: the x gene, the gene that causes their abilities, was the result of the celestials meddling with the genes of humans while we were in the stone age

  • Film & TV sci-fi must use human actors. That is all we have. While I do get excited when I see non humanoid aliens: Founders, Hurts, Pyrians, etc, I can forgive TV and movies for having humanoid aliens.

  • While super powers are quite unlikely, X-Men's claims of "evolution being slow but every so often evolution leaps forward" is a real evolutionary concept called Punctuated Equilibrium.

  • I try to differ the events of my alien planets' evolutionary histories. I have one where basic life on one particular region of the planet was pressured to move onto land early on. They formed colonies on the beaches that evolved into coral like organisms covering the entire perimeters of some islands. As a result complex terestrial life was never able to form and the planet has been in a cambrian-devonian limbo for millions of years.

  • AFAIK didn’t the Cambrian explosion have something to do with predation becoming a thing?

  • OK Boomer, hilarious

  • Dinosaurs: We are the supreme beings of the Earth.
    God: KEK!

  • ok boomer joke had me there ngl

  • Evolution is not goal directed, but it does direct itself. In the same way that water going down a slope may veer left and right but never goes UP.

  • The goal directed ideas were influenced by the aristotelic philosophy of categorization forms of existence from minerals over plants towards angels and god at the other end. So got it a revival in hegelianism. The term is actually: Orthogenesis or progressionism in directed Evolution ideas not only by Lamarck, but names which are long forgotten as historical footnote like Haacke and Eimer.

  • It is highly debatable IF the cambrian explosion as over 12+ mio. year lasting time period is really such an "explosive" radiation. Reasons for doubts are that the larvae forms of the majority of famous critters like trilobites had already big similarities of some precambrian small shellies and fossil remains usually overseen, because of the tiny milimeter size of them and general lack of shells. We tend to look at animals when we don't need a microscope and at the adult imagos. For example: and & – also that the Anomalocaris were already relatively gigantic for cambrian circumstances (like around ~30cm) and complicated with eyes and grabbing appendages at the early cambrian. To be fully honest: I would not be surprised when they would find arthropodlike critters and more primitive larval forms sooner or later.

  • We are made in God's, nude image. God has a kingdom, that is not of this world. That makes us to be aliens. The church does not want people to know this.

  • I'd heard that the Cambrian explosion was not "the period when the earliest animals diversified into a […] wide range of different lifeforms", but that it was the period during which hard bodies developed for the first time and made it much easier for fossilization to happen. So, it's not that, suddenly, many different lifeforms appear, but rather that, suddenly, they are much easier to find. Am I wrong to think that?

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