Why Are You Multicellular?
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Why Are You Multicellular?


[MUSIC] This episode is sponsored by Audible After our planet cooled from a glob of molten
space dust, survived the collision that made the moon, and endured 300 million years of
bombardment from space rocks, life showed up about as soon as it could. But for the
next 2 billion years, it got stuck. Just single cells, living the single life. Until around one and a half to two billion
years ago, when life started sticking together. Some people would say single cells are still
the dominant life form on our planet. But if bacteria and archaea have done so great
living alone, why and how did some organisms make the jump to living together? [MUSIC] We can count eight major transitions in evolution.
From the first replicating molecules all the way to societies and language. But of all of them, the invention of multicellular
life might have been the easiest. Because it didn’t happen just once. Or even twice.
We think it happened more than 30 times. The multicellular mashup that led to you or
your dog was different from the ones that led to seaweed, sequoias, and mushrooms. In the game of evolution, organisms are always
looking for unoccupied territory, new niches to fill, and being bigger than the biggest
thing around is always an open opportunity. The bigger you are, the more things you can
eat and the fewer things that can eat you. But one cell can only get so big before the
harsh realities of surface area and volume make life more trouble than it’s worth.
If you can’t get enough nutrients, or move things around the cell, eventually cells have
to band together. Getting bigger by getting multicellular brings
other advantages. Your insides are protected from the outside, so you can survive in rough
neighborhoods where you couldn’t before. You can live longer, because little bits of
you can die and be replaced. And the cells that’ll become the next generation are tucked
away safe and sound away from that cold, harsh outside world. But single cells aren’t known for their
self-motivation. It’s not like they suddenly had a great idea to go multicellular! So how
did it happen? Maybe one day, a mutant cell divided and failed
to separate. Or maybe related cells clumped together by coating themselves in biological
velcro. Different branches used both. But even some bacteria can do that, and we
wouldn’t call them multicellular. Cells also started to take on specialized
roles, maybe with the little guys on the outside flapping their flagella, or others catching
sunlight, and the ones on the inside digesting food, or tending to the birds and the bees. And those cells have to talk to each other,
so they rig up communication lines. Then, instead of letting the environment tell
you when to divide, your genes start controlling when it’s time to grow, to keep things nice
and organized. And some cells must be willing to die, so
the rest of you can live. Did you ever stop and wonder why, even though
we’re made of trillions of cells, we reproduce using only one at a time? It doesn’t have
to be that way. You could reproduce by dropping of a big chunk of your body, and making a
new you. But we do it this way to stop the cheaters. Cellular freebooters could invade another
group. These cheaters get the advantage of food and protection, but are more interested
in themselves than the greater good. I mean, can you imagine if one cell in your
body decided to start competing for survival with all the others?
Oh, wait… that’s called cancer. Things can get pretty scary when cells get selfish. Destin made a great video on Smarter Every
Day about Tasmanian Devil facial tumor disease. It’s an example of what happens when part
of a multicellular creature evolves to survive on its own. But by whittling ourselves down to our most
basic level, to single sperm and eggs, we guarantee that every cell in our offspring
is genetically identical. We are clones of those two joined cells. Our cells don’t
end up competing with themselves. And cheaters don’t prosper. Each time multicellular life evolved, nature
opened doors to new kinds of creativity, and it goes to show, life can do amazing things
when individuals stick together. Next week, we’re going to talk about a different
cellular mashup, one that didn’t happen dozens of times, but just a single time, what may
be the most important moment in the history of life. This episode of It’s Okay To Be Smart is supported
by Audible.com. Right now, Audible is offering our viewers a 30 day trial period. Check out
audible dot com slash ok to access all of their audio programs and titles. This episode was inspired by The Vital Question
by Nick Lane. We know a lot about the history of life on Earth, but there’s a black hole
in the middle of biology, question of how things got the way they are. How we went from
tiny bacteria to curious creatures like us. This book completely changed how I look at
questions about the origin of life, and how life got cool. It’s a beautiful theory full
of deep science but easy to read. You can go to audible.com/ok, make sure to
use that link to help us out and get your trial membership. Stay curious.

100 thoughts on “Why Are You Multicellular?

  1. I thought that seaweed and trees had a common ancestor, which is the green algae, the ancestor of all plant life. IIRC, all plants evolved from a single species of green algae, meaning multicellular clustering happened only once in all plants.

  2. Why am I multicellular? Cause if I was unicellular, I wouldn't watch videos and comment, I would be engulfing some tasty bacteria in my phagosome and then digest it in my lysosome

  3. Some bacteria are multicellular. For example, cyanobacterial trichomes have heterocysts to fix N2 from air, and those are permanently differentiated cells. And stromatolite fossils indicate that cyanobacteria with trichomes might have existed for billions of years. Of course, compared with eukaryotic multicellular organisation, trichomes are simple, but they still suit the definition of multicellular structure

  4. 1:40 not all single celled organisms are microscopic.

    https://www.google.com/search?q=largest+single+celled+organism&client=ms-android-att-us&source=lnms&prmd=inv&tbm=isch&sa=X&ved=0ahUKEwjuxJqxj83RAhWlxYMKHWBxBKUQ_AUIBygB&biw=360&bih=460&dpr=3#tbm=isch&q=valonia+ventricosa+size&imgrc=dTNiIoc3zmhfTM%3A

  5. ok I've just finished a 3 hour binge of "it's ok to be smart" and this was the cherry on top that made me subscribe and yes sir I will always stay curious!

  6. sorry man but it is only a theory and we can not believe a theory if there is no evidence . And then my question is : who pushed bacterias to land on earth ?

  7. comments:

    60% people who laugh at bad puns

    30% people referencing agario

    10% stupid complaining christians

  8. I've had this question for some time now: if tis happened before why isn't it happening now? why aren't unicellular beings joining each other and becoming multicellular beings allowing us to witness the birth of a new species? I realise the process would take lots of time. But still, if it's happening we could have noticed it already, no? Or scientist could be trying to replicate the event… Any answers to this?

  9. Hi Joe. I've subscribed before but this time it's for a different reason.This time I got an ideas for two awesome videos. The first idea is,WHAT WOULD HAPPEN IF THE EARTH STOPPED SPINNING , and,WHAT WOULD HAPPEN IF THERE WAS NO MOON.

  10. 3:44 Things can get pretty scary when cells get cellfish
    edit: 4:12 Our cells don't end up competing with them cellves

  11. It's wonderful that you don't even have to smart to understand evolution. Single cells , DNA , RNA , Multi-cellular organisms , fish then birds and well , just everything with just a bunch of randomness and some luck. Oh your probably thinking wait a minute , that's not what I said , no there's much more then that. Yes you would be 100% correct.The actual real scientific data doesn't agree with this simplistic explanation of things simply evolving along into other things.
    Everything from the functioning of the most simple cells , to the fossil records to the fine tuning of the Universe defy any evolutionary speculation .
    You present evolution as fact when the scientific evidence presents never ending dead ends to Darwinism. Yes , there is micro-evolution or variation in every species , but it lacks anything else as far explaining the magnitude of the changes needed to account for the incredible diversity of life.
    Unfortunately , for most evolutionists , most of these theories that pertain to unguided random nothingness exceeding what are smartest scientists and engineers can understand or design , turn out usually to be wrong.But not to worry , because we have lots of smart people that can just disregard current scientific data when it proves another of their theories wrong and just , well , make up another one. So , yes it's okay to be smart.

  12. All the puns in the library:
    1) Best-cell-er
    2) Cell-f help
    3) The book's author is Dr. R. Kaya (Archaea)
    4) Dr. R. Kaya wrote another book with Flagellum in it (Flagellum is bacteria tail)

  13. This video doesn't explain why we're multicellular. It only suggests reasons why being multicellular is advantageous.

  14. Multicellular life is like when countries stick together to create a better future…
    Too bad, countries can be like cancer too, and they won't work together with us.

  15. lol.. you really believe that? can you really observe that today? a single cell can evolve into a multicell? and you base it on maybe? 2:15

  16. Lovely presentation. Actually bacteria do form colonies and some are able to communicate with each other by electrical wires. Multicellularity only evolved in the Eukaryotes as the mitochondria provided enough energy.
    Out of the multicellular eukaryotes, only three develop from embryos. (Plants, Fungi & Animals.) Animals in particular develop from a blastula. I have never come across any evolutionary significance of embryos, yet they did lead to three Kingdoms. Any ideas??

  17. If I'm ever working on something with someone and they stab me in the back I'll tell them to stop being so cancerous

  18. I sure hope that if aliens come to earth, this channel is the first thing they see on the internet.

  19. Once upon a time….
    there lived a cell. It was the only cell that existed but it didn't know that. Eventually this cell got pretty lonely being single so it went to the bar to find another single cell. When it got there… there weren't any other cells. Now… this single cell was even more lonely. (If you would like to read more of this story….
    log onto: www.howthebigbangbegan.com)

  20. Pre-no offense.
    You went from talking about cells in every sentence to mentioning genes very briefly in an extremely critical role.
    That seemed unfair and wrong. Hold your position and explain the role of genes if need be. That cheap shortcut was beneath what I’m used to.

  21. Just finished the vital question. Best book hands down nick lane is an amazing author read his life ascending and oxygen now vital question and on to the next.

  22. WITH THE CELL WALL BROKEN ALL THE OPPRESSED GROUPS SHALL PROSPER ESPECIALLY THE MOST OPPRESSED OF ALL VIRUSES

  23. 30ish times that survived.

    But the fact is it could have happened a hundred times, or millions, and they didn't last more than one, or a few generations before dying/being killed off.

  24. You still had to competed with your brethren and sistren to born though… we killed million they they we were born so don't say your life is worthless. And you still have billions to support you.

  25. But Dr Joe, I currently have a Genetics class at university, and from what I've learned, cancer is just the result of the cell losing "control", 'cause of: mitosis without control, not answering to apoptosis signaling, gene's expression at wrong times… 
    Why do you say it's because the cell is being "selfish"?

  26. What did this video explain exactly? I'm just gonna assume we haven't found out why cells became multicellular organisms yet, so this video had to be made with just cell puns

  27. This may be creepy, but I'm totally crushing on Dr. Joe 💜 Smart, handsome, and tall. Mrs. Doctor Joe is a lucky lady 😁

  28. My cells are in constant conflict. My brain cells tell me to hook up with Anna but my heart cells tell me to hook up with Victoria.

  29. Oh my soul… I love these videos so much, keep up the great work guys… Nd thanks PBS you have alot of great channels

  30. Evolution fake🙄🤦🏾‍♂️ we aren’t star dust dummies. A star is like the sun it got no dust but flames. We all came from the dust of the earth . Y’all stupid..😂

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