Over 600 million years ago, sheets of ice coated our planet on both land and sea. How did this happen? And most importantly for us, why did the planet eventually thaw again? The evidence for Snowball Earth is written on every continent today.

Thanks to Julio Lacerda and Franz Anthony from Studio 252mya for their wonderful illustrations. You can find more of their work here: https://252mya.com/

Special thanks to Judy Pu for answering our questions about Snowball Earth.

Produced in collaboration with PBS Digital Studios: http://youtube.com/pbsdigitalstudios

Super special thanks to the following Patreon patrons for helping make Eons possible:
Katie Fichtner, Anthony Callaghan, MissyElliottSmith, The Scintillating Spencer, AA, Zachary Spencer, Stefan Weber, Ilya Murashov, Charles Kahle, Robert Amling, Po Foon Kwong, Larry Wilson, Merri Snaidman, John Vanek, Neil H. Gray, Esmeralda Rupp-Spangle, Gregory Donovan, الخليفي سلطان, Gabriel Cortez, Marcus Lejon, Robert Arévalo, Robert Hill, Todd Dittman, Betsy Radley, PS, Philip Slingerland, Jose Garcia, Eric Vonk, Tony Wamsley, Henrik Peteri, Jonathan Wright, Jon Monteiro, James Bording, Brad Nicholls, Miles Chaston, Michael McClellan, Jeff Graham, Maria Humphrey, Nathan Paskett, Connor Jensen, Daisuke Goto, Hubert Rady, Gregory Kintz, Tyson Cleary, Chandler Bass, Joao Ascensao, Tsee Lee, Sarah Fritts, Alex Yan

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References: https://docs.google.com/docume....nt/d/1dRTf9IcH_1vA5S

Check out Monstrum! https://www.youtube.com/monstrumpbs
From our deepest origins in Africa all the way to the Americas, by looking at the fossils and archaeological materials we have been able to trace the path our ancestors took during thee short window of time when we took over the world.

Thanks to Julio Lacerda and Studio 252mya for the human migration illustration. You can find more of Julio's work here: https://252mya.com/gallery/julio-lacerda

Produced in collaboration with PBS Digital Studios: http://youtube.com/pbsdigitalstudios

Super special thanks to the following Patreon patrons for helping make Eons possible:

Katie Fichtner, Anthony Callaghan, Stefan Weber, Ilya Murashov, Charles Kahle, Robert Amling, Po Foon Kwong, Larry Wilson, Merri Snaidman, Renzo Caimi Ordenes, John Vanek, Neil H. Gray, Esmeralda Rupp-Spangle, Gregory Donovan, الخليفي سلطان, Gabriel Cortez, Marcus Lejon, Robert Arévalo, Robert Hill, Todd Dittman, Betsy Radley, PS, Philip Slingerland, Jose Garcia, Eric Vonk, Tony Wamsley, Henrik Peteri, Jonathan Wright, Jon Monteiro, James Bording, Brad Nicholls, Miles Chaston, Michael McClellan, Jeff Graham, Maria Humphrey, Nathan Paskett, Connor Jensen, Daisuke Goto, Hubert Rady, Gregory Kintz, Tyson Cleary, Chandler Bass, Maly Lor, Joao Ascensao, Tsee Lee, Sarah Fritts, Jacob Gerke, Alex Yan

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Sea scorpions thrived for 200 million years, coming in a wide variety of shapes and sizes. Over time, they developed a number of adaptations--from crushing claws to flattened tails for swimming. And some of them adapted by getting so big that they still hold the record as the largest arthropods of all time.

Thank you to these paleoartists for allowing us to use their wonderful illustrations:
Franz Anthony: https://252mya.com/gallery/franz-anthony
Ceri Thomas: http://alphynix.tumblr.com/
Lucas Lima: https://252mya.com/gallery/lucas-lima
Julio Lacerda: https://252mya.com/gallery/julio-lacerda
Nobu Tamura: https://spinops.blogspot.com/


Produced in collaboration with PBS Digital Studios: http://youtube.com/pbsdigitalstudios

Super special thanks to the following Patreon patrons for helping make Eons possible:

Katie Fichtner, Anthony Callaghan, Robert Amling, Po Foon Kwong, Larry Wilson, Merri Snaidman, Renzo Caimi Ordenes, John Vanek, Neil H. Gray, Marilyn Wolmart, Esmeralda Rupp-Spangle, Gregory Donovan, Ehit Dinesh Agarwal, الخليفي سلطان, Gabriel Cortez, Marcus Lejon, Robert Arévalo, Robert Hill, Kelby Reid, Todd Dittman, Betsy Radley, PS, Philip Slingerland, Jose Garcia, Eric Vonk, Tony Wamsley, Henrik Peteri, Jonathan Wright, Jon Monteiro, James Bording, Brad Nicholls, Miles Chaston, Michael McClellan, Jeff Graham, Maria Humphrey, Nathan Paskett, Connor Jensen, Daisuke Goto, Hubert Rady, Gregory Kintz, Tyson Cleary, Chandler Bass, Maly Lor, Joao Ascensao, Tsee Lee, Sarah Fritts, Ron Harvey Jr, Jacob Gerke, Alex Yan

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References:
Braddy, Simon J., Richard J. Aldridge, Sarah E. Gabbott, and Johannes N. Theron. "Lamellate book-gills in a late Ordovician eurypterid from the Soom Shale, South Africa: support for a eurypterid-scorpion clade." Lethaia 32, no. 1 (1999): 72-74.
Braddy, Simon J., Markus Poschmann, and O. Erik Tetlie. "Giant claw reveals the largest ever arthropod." Biology Letters 4, no. 1 (2007): 106-109. https://royalsocietypublishing.....org/doi/full/10.109
Brezinski, David K., and Albert D. Kollar. "Reevaluation of the Age and Provenance of the Giant Palmichnium kosinskiorum Eurypterid Trackway, from Elk County, Pennsylvania." Annals of Carnegie Museum 84, no. 1 (2016): 39-45.
Briggs, Derek EG, and WD Ian Rolfe. "A giant arthropod trackway from the Lower Mississippian of Pennsylvania." Journal of Paleontology (1983): 377-390. https://www.jstor.org/stable/pdf/1304661.pdf?seq=1
Elliott, David K., and Michael A. Petriello. "New poraspids (Agnatha, Heterostraci) from the Early Devonian of the western United States." Journal of Vertebrate Paleontology 31, no. 3 (2011): 518-530.
Lamsdell, James C., and Simon J. Braddy. "Cope's Rule and Romer's theory: patterns of diversity and gigantism in eurypterids and Palaeozoic vertebrates." Biology Letters (2009): doi.org/10.1098/rsbl.2009.0700
Lamsdell, James C., Simon J. Braddy, and O. Erik Tetlie. "Redescription of Drepanopterus abonensis (Chelicerata: Eurypterida: Stylonurina) from the Late Devonian of Portishead, UK." Palaeontology 52, no. 5 (2009): 1113-1139.
Legg, David A. "Sanctacaris uncata: the oldest chelicerate (Arthropoda). "Naturwissenschaften 101, no. 12 (2014): 1065-1073.
Manning, P. L. and Dunlop, J. A. “The respiratory organs of eurypterids.” Palaeontology, 38, no. 2 (1995): 287–297.
McCoy, Victoria E., James C. Lamsdell, Markus Poschmann, Ross P. Anderson, and Derek EG Briggs. "All the better to see you with: eyes and claws reveal the evolution of divergent ecological roles in giant pterygotid eurypterids." Biology letters 11, no. 8 (2015): 20150564.
Poschmann, Markus, Brigitte Schoenemann, and Victoria E. McCoy. "Telltale eyes: the lateral visual systems of Rhenish Lower Devonian eurypterids (Arthropoda, Chelicerata) and their palaeobiological implications." Palaeontology 59, no. 2 (2016): 295-304.
Selden, P. A., and John David Lawson. "Eurypterid respiration." Phil. Trans. R. Soc. Lond. B 309, no. 1138 (1985): https://royalsocietypublishing.....org/doi/pdf/10.1098
Tetlie, O. Erik. "Distribution and dispersal history of Eurypterida (Chelicerata)." Palaeogeography, Palaeoclimatology, Palaeoecology 252, no. 3-4 (2007): 557-574. https://pdfs.semanticscholar.o....rg/6434/bc6cdbfd7613
Vrazo, Matthew B., and Simon J. Braddy. "Testing the ‘mass-moult-mate’hypothesis of eurypterid palaeoecology." Palaeogeography, Palaeoclimatology, Palaeoecology 311, no. 1-2 (2011): 63-73.
Whyte, Martin A. "Palaeoecology: a gigantic fossil arthropod trackway." Nature 438, no. 7068 (2005): 576.

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The short-faced bears turned out to be remarkably adaptable, undergoing radical changes to meet the demands of two changing continents. And yet, for reasons we don’t quite understand, their adaptability wasn’t enough to keep them from going extinct.   

Thanks to Fabrizio De Rossi and Studio 252mya for the Arctodus and Arctotherium illustrations. You can find more of their work here: https://252mya.com/gallery/fabrizio-de-rossi

And thanks to Ceri Thomas for the Plionarctos and Arctotherium reconstructions! Check out more of Ceri's paleoart at http://alphynix.tumblr.com and http://nixillustration.com

Produced in collaboration with PBS Digital Studios: http://youtube.com/pbsdigitalstudios

Super special thanks to the following Patreon patrons for helping make Eons possible:

Katie Fichtner, Anthony Callaghan, Robert Amling, Po Foon Kwong, Larry Wilson, Merri Snaidman, Renzo Caimi Ordenes, John Vanek, Neil H. Gray, Marilyn Wolmart, Esmeralda Rupp-Spangle, Gregory Donovan, Ehit Dinesh Agarwal, الخليفي سلطان, Gabriel Cortez, Marcus Lejon, Robert Arévalo, Robert Hill, Kelby Reid, Todd Dittman, Betsy Radley, PS, Philip Slingerland, Jose Garcia, Eric Vonk, Tony Wamsley, Henrik Peteri, Jonathan Wright, Jon Monteiro, James Bording, Brad Nicholls, Miles Chaston, Michael McClellan, Jeff Graham, Maria Humphrey, Nathan Paskett, Connor Jensen, Daisuke Goto, Hubert Rady, Gregory Kintz, Tyson Cleary, Chandler Bass, Maly Lor, Joao Ascensao, Tsee Lee, Sarah Fritts, Ron Harvey Jr, Jacob Gerke, Alex Yan

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References: https://docs.google.com/docume....nt/d/1Eg5riA7VgBKCFv

Check out Origin of Everything: https://www.youtube.com/channe....l/UCiB8h9jD2Mlxx96ZF

If you’ve ever been to, or lived in, or even flown over the central swath of North America, then you’ve seen the remnants of what was a uniquely fascinating environment. Scientists call it the Western Interior Seaway, and at its greatest extent, it ran from the Caribbean Sea to the Canadian Arctic.

Thanks to Dmitry Bogdanov, Nobu Tamura, C.R. Scotese, NASA and the many others listed throughout the video for making their images available to use.

Produced in collaboration with PBS Digital Studios: http://youtube.com/pbsdigitalstudios

Super special thanks to the following Patreon patrons for helping make Eons possible:

Katie Fichtner, Anthony Callaghan, Neil H. Gray, Marilyn Wolmart, Esmeralda Rupp-Spangle, Gregory Donovan, Ehit Dinesh Agarwal, سلطان الخليفي, Gabriel Cortez, Marcus Lejon, Anel Salas, Robert Arévalo, Robert Hill, Kelby Reid, Todd Dittman, Betsy Radley, PS, Colin Sylvester, Philip Slingerland, John Vanek, Jose Garcia, Eric Vonk, Tony Wamsley, Henrik Peteri, Jonathan Wright, Jon Monteiro, James Bording, Brad Nicholls, Miles Chaston, Michael McClellan, Jeff Graham, Maria Humphrey, Nathan Paskett, Connor Jensen, Sapjes, Daisuke Goto, Hubert Rady, Yuntao Zhou, Gregory Kintz, Tyson Cleary, Chandler Bass, Maly Lor, Joao Ascensao, Tsee Lee, Sarah Fritts, Ruben Winter, Ron Harvey Jr, Jacob Gerke, Alex Yan

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References:
Oceans of Kansas: A Natural History of the Western Interior Seaway (Second Edition) by Michael J. Everhart.
https://www.tandfonline.com/do....i/abs/10.1080/027246
https://www.researchgate.net/p....ublication/259517413
https://www.researchgate.net/p....rofile/Joshua_Slatte
https://www.researchgate.net/p....ublication/321632109
https://www.tandfonline.com/do....i/abs/10.1080/027246
https://www.jstor.org/stable/1306568
https://www.sciencedirect.com/....science/article/pii/
https://pubs.er.usgs.gov/publication/pp1561
http://rspb.royalsocietypublis....hing.org/content/278
https://link.springer.com/arti....cle/10.1007%2FBF0299
https://pubs.geoscienceworld.o....rg/gsa/geology/artic
https://www.rushcounty.org/Pos....tRockMuseum/PostRock

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Tyrannosaurus rex was big, Tyrannosaurus rex was vicious, and Tyrannosaurus rex had tiny arms. The story of how T-Rex lost its arms is, itself, pretty simple. But the story of why it kept those little limbs, and how it used them? Well, that’s a little more complicated.

Thanks as always to Nobumichi Tamura for allowing us to use his wonderful paleoart: http://spinops.blogspot.com/

Produced in collaboration with PBS Digital Studios: http://youtube.com/pbsdigitalstudios

Super special thanks to the following Patreon patrons for helping make Eons possible:
Aldo Espinosa Zúñiga, Svetlana Pylaeva, Colin Sylvester, Philip Slingerland, John Vanek, Jose Garcia, Noah offitzer, Eric Vonk, Tony Wamsley, Henrik Peteri, Jonathan Wright, Wilco Verweij, Jon Monteiro, James Bording, Brad Nicholls, Miles Chaston, Addison Baker, Michael McClellan, Elysha Nygård, Jeff Graham, Maria Humphrey, Southpoint, Connor Jensen, Ehit Dinesh Agarwal, Sapjes, Dave, Daisuke Goto, Zachary Winkler, Hubert Rady, Yuntao Zhou, Gregory Kintz, Tyson Cleary, Chandler Bass, Maly Lor, Joao Ascensao, Mario Morales, Tsee Lee, Sarah Fritts, phil parker, Ruben Winter, Ron Harvey Jr, Joshua Mitchell, Johnny Li, Katie Fichtner, Budjarn Lambeth, Jacob Gerke, Katie M Vasilescu, Brandon Burke, Alex Yan, Jordon Sokoll

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References:
Baron, Matthew G., David B. Norman, and Paul M. Barrett. "A new hypothesis of dinosaur relationships and early dinosaur evolution." Nature 543.7646 (2017): 501.
Bates, Karl T., and Peter L. Falkingham. "Estimating maximum bite performance in Tyrannosaurus rex using multi-body dynamics." Biology Letters (2012): rsbl20120056.
Brusatte, Stephen L., and Thomas D. Carr. "The phylogeny and evolutionary history of tyrannosauroid dinosaurs." Scientific Reports 6 (2016): 20252.
Burch, Sara. Osteological, Myological, and Phylogenetic Trends of Forelimb Reduction in Nonavian Theropod Dinosaurs. Diss. The Graduate School, Stony Brook University: Stony Brook, NY., 2015.
Carpenter, Kenneth. "Forelimb biomechanics of nonavian theropod dinosaurs in predation." Senckenbergiana lethaea 82.1 (2002): 59-75.
Erickson, Gregory M., et al. "Bite-force estimation for Tyrannosaurus rex from tooth-marked bones." Nature 382.6593 (1996): 706.
Fowler, Denver W., et al. "Reanalysis of “Raptorex kriegsteini”: a juvenile tyrannosaurid dinosaur from Mongolia." PLoS One 6.6 (2011): e21376.
Gillingham, James C., and Jeffrey A. Chambers. "Courtship and pelvic spur use in the Burmese python, Python molurus bivittatus." Copeia 1982.1 (1982): 193-196.
Gould, Stephen Jay, and Richard C. Lewontin. "The spandrels of San Marco and the Panglossian paradigm: a critique of the adaptationist programme." Proc. R. Soc. Lond. B 205.1161 (1979): 581-598.
Hutchinson, John R., and Stephen M. Gatesy. "Dinosaur locomotion: beyond the bones." Nature 440.7082 (2006): 292.
Makovicky, Peter J. "A new small theropod from the Morrison Formation of Como Bluff, Wyoming." Journal of Vertebrate Paleontology 17.4 (1997): 755-757.
MIDDLETON, KEVIN M., and STEPHEN M. GATESY. "Theropod forelimb design and evolution." Zoological Journal of the Linnean Society 128.2 (2000): 149-187.
Personal communication, Amy Atwater & Dr. John Scanella, Museum of the Rockies
Pontzer, Herman, et al. "Control and function of arm swing in human walking and running." Journal of Experimental Biology 212.4 (2009): 523-534.
Ruiz, Javier, et al. "The hand structure of Carnotaurus sastrei (Theropoda, Abelisauridae): implications for hand diversity and evolution in abelisaurids." Palaeontology 54.6 (2011): 1271-1277.
Sellers, William I., et al. "Investigating the running abilities of Tyrannosaurus rex using stress-constrained multibody dynamic analysis." PeerJ 5 (2017): e3420.
Sereno, Paul C., et al. "Tyrannosaurid skeletal design first evolved at small body size." Science 326.5951 (2009): 418-422.
Stanley, Steven M. “Evidence that the Arms of Tyrannosaurus rex were not functionless but adapted for vicious slashing.” Geological Society of America Annual Meeting 2017.
Sullivan, Corwin, et al. "The asymmetry of the carpal joint and the evolution of wing folding in maniraptoran theropod dinosaurs." Proceedings of the Royal Society of London B: Biological Sciences (2010): rspb20092281.
Therrien, François, and Donald M. Henderson. "My theropod is bigger than yours… or not: estimating body size from skull length in theropods." Journal of Vertebrate Paleontology 27.1 (2007): 108-115. [108:MTIBTY]2.0.CO;2
USAMI, Yoshiyuki, and Ryuta KINUGASA. "A Possibility of Fast Running of TYRANNOSAURUS." DEStech Transactions on Engineering and Technology Research amma (2017).
Xu, Xing, et al. "A basal tyrannosauroid dinosaur from the Late Jurassic of China." Nature 439.7077 (2006): 715.

The story of sloths is one of astounding ecological variability, with some foraging in the seas, others living underground, and others still hiding from predators in towering cliffs. So why are their only living relatives in the trees?

Thanks to Ceri Thomas for allowing us to use few sloth reconstructions! Check out more of Ceri's paleoart at http://alphynix.tumblr.com and http://nixillustration.com

And thanks as always to Franz Anthony and everyone at http://252mya.com for their great paleoart.

Produced in collaboration with PBS Digital Studios: http://youtube.com/pbsdigitalstudios

Super special thanks to the following Patreon patrons for helping make Eons possible:

Katie Fichtner, Aldo Espinosa Zúñiga, Anthony Callaghan, Esmeralda Rupp-Spangle, Gregory Donovan, Ehit Dinesh Agarwal, الخليفي سلطان, Gabriel Cortez, Marcus Lejon, Anel Salas, Robert Arévalo, Robert Hill, Kelby Reid, Todd Dittman, Betsy Radley, PS, Colin Sylvester, Philip Slingerland, John Vanek, Jose Garcia, Noah offitzer, Eric Vonk, Tony Wamsley, Henrik Peteri, Jonathan Wright, Jon Monteiro, James Bording, Brad Nicholls, Miles Chaston, Michael McClellan, Jeff Graham, Maria Humphrey, Nathan Paskett, Connor Jensen, Sapjes, Daisuke Goto, Hubert Rady, Yuntao Zhou, Gregory Kintz, Tyson Cleary, Chandler Bass, Maly Lor, Joao Ascensao, Tsee Lee, Sarah Fritts, Ruben Winter, Ron Harvey Jr, Jacob Gerke, Alex Yan

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Want to follow Eons elsewhere on the internet?
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References:
https://link.springer.com/arti....cle/10.1007/s10722-0
https://www.tandfonline.com/do....i/abs/10.1080/004382
http://www.pnas.org/content/102/33/11763
https://www.cambridge.org/core..../journals/journal-of
https://www.jstor.org/stable/2400207
https://onlinelibrary.wiley.co....m/doi/abs/10.1111/j.
https://www.tandfonline.com/do....i/abs/10.1080/104209
https://palaeo-electronica.org..../2009_3/189/index.ht
https://link.springer.com/arti....cle/10.1007/s10914-0
https://eurekamag.com/research..../020/408/020408865.p
https://www.tandfonline.com/doi/abs/10.1671/2429b
https://link.springer.com/arti....cle/10.1007/s10914-0
https://link.springer.com/arti....cle/10.1007/s10914-0
https://link.springer.com/arti....cle/10.1007/s10914-0
https://www.ncbi.nlm.nih.gov/p....mc/articles/PMC39732
http://www.bioone.org/doi/abs/....10.1671/0272-4634(20
https://academic.oup.com/zooli....nnean/article/140/2/
https://link.springer.com/arti....cle/10.1007/s10914-0
https://www.ncbi.nlm.nih.gov/pubmed/25861559
https://peerj.com/articles/5600/
https://www.tandfonline.com/do....i/abs/10.1671/0272-4
https://www.researchgate.net/p....ublication/233548931

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Paleontologists have been studying and drawing totally different conclusions about the fossil LH PV18 for almost a decade. Is it just one of many specimens of a theropod called Tarbosaurus bataar or is it an entirely different theropod named Raptorex kriegsteini? In order to answer this question, you have to understand the many ways in which we can--and can’t--determine the age of a fossil.

Thanks to Gregory S. Paul for allowing us to use his illustrations in this video. Check out his website here: http://gspauldino.com/

And thanks as always to Nobu Tamura for allowing us to use his wonderful paleoart: http://spinops.blogspot.com/

Produced in collaboration with PBS Digital Studios: http://youtube.com/pbsdigitalstudios

Super special thanks to the following Patreon patrons for helping make Eons possible:
Katie Fichtner, Aldo Espinosa Zúñiga, Anthony Callaghan, Marcus Lejon, Anel Salas, Robert Arévalo, Robert Hill, Kelby Reid, Todd Dittman, Betsy Radley, Svetlana Pylaeva, Colin Sylvester, Philip Slingerland, John Vanek, Jose Garcia, Noah offitzer, Eric Vonk, Tony Wamsley, Henrik Peteri, Jonathan Wright, Wilco Verweij, Jon Monteiro, James Bording, Brad Nicholls, Miles Chaston, Michael McClellan, Elysha Nygård, Jeff Graham, Maria Humphrey, Nathan Paskett, Connor Jensen, Sapjes, Daisuke Goto, Hubert Rady, Yuntao Zhou, Gregory Kintz, Tyson Cleary, Chandler Bass, Maly Lor, Joao Ascensao, Tsee Lee, Sarah Fritts, Ruben Winter, Ron Harvey Jr, Joshua Mitchell, Johnny Li, Jacob Gerke, Brandon Burke, Alex Yan

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Want to follow Eons elsewhere on the internet?
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References:
https://www.radiocarbon.com/ab....out-carbon-dating.ht
https://www.nature.com/articles/srep20252
https://www.researchgate.net/p....ublication/288175395
https://onlinelibrary.wiley.co....m/doi/abs/10.1111/j.
https://link.springer.com/article/10.1360/02tb9031
https://www.sciencedirect.com/....science/article/pii/
https://journals.plos.org/plos....one/article?id=10.13
http://science.sciencemag.org/content/326/5951/418
https://www.jstor.org/stable/3515101

Viewers like you help make PBS (Thank you

You can check out Google's Science Journal app at https://makingscience.withgoog....le.com/science-journ

We traveled to Bozeman, Montana to meet with Dr. Ellen-Thérèse Lamm who explores ancient life by studying it at the cellular level. Kallie and Dr. Lamm discuss how she does this, and what she’s learned by putting dinosaur bones under a microscope.

Check out the Museum of the Rockies - Paleohistology Lab website: https://www.morhistologylab.org/

Produced in collaboration with PBS Digital Studios: http://youtube.com/pbsdigitalstudios

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As more and more fossil ancestors have been found, our genus has become more and more inclusive, incorporating more members that look less like us, Homo sapiens. By getting to know these other hominins--the ones who came before us--we can start to answer some big questions about what it essentially means to be human.

Thanks as always to Nobu Tamura for allowing us to use his wonderful paleoart: http://spinops.blogspot.com/

Thanks to Julio Lacerda and Studio 252mya for the hominin illustrations. You can find more of Julio's work here: https://252mya.com/gallery/julio-lacerda

Produced in collaboration with PBS Digital Studios: http://youtube.com/pbsdigitalstudios

Super special thanks to the following Patreon patrons for helping make Eons possible:

Katie Fichtner, Anthony Callaghan, Renzo Caimi Ordenes, John Vanek, Neil H. Gray, Marilyn Wolmart, Esmeralda Rupp-Spangle, Gregory Donovan, Ehit Dinesh Agarwal, الخليفي سلطان , Gabriel Cortez, Marcus Lejon, Robert Arévalo, Robert Hill, Kelby Reid, Todd Dittman, Betsy Radley, PS, Colin Sylvester, Philip Slingerland, Jose Garcia, Eric Vonk, Tony Wamsley, Henrik Peteri, Jonathan Wright, Jon Monteiro, James Bording, Brad Nicholls, Miles Chaston, Michael McClellan, Jeff Graham, Maria Humphrey, Nathan Paskett, Connor Jensen, Daisuke Goto, Hubert Rady, Yuntao Zhou, Gregory Kintz, Tyson Cleary, Chandler Bass, Maly Lor, Joao Ascensao, Tsee Lee, Sarah Fritts, Ruben Winter, Ron Harvey Jr, Jacob Gerke, Alex Yan

If you'd like to support the channel, head over to http://patreon.com/eons and pledge for some cool rewards!

Want to follow Eons elsewhere on the internet?
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References:
http://humanorigins.si.edu/evi....dence/human-fossils/
http://humanorigins.si.edu/evi....dence/human-fossils/
http://humanorigins.si.edu/evi....dence/human-fossils/
http://humanorigins.si.edu/evi....dence/human-fossils/
http://humanorigins.si.edu/evi....dence/human-fossils/
http://humanorigins.si.edu/evi....dence/human-fossils/
http://humanorigins.si.edu/evi....dence/behavior/footp
http://humanorigins.si.edu/evi....dence/human-fossils/
https://australianmuseum.net.a....u/learn/science/huma
https://www.earthmagazine.org/....article/redefining-h
https://medium.com/@johnhawks/....the-plot-to-kill-hom
Antón, S. C., Potts, R., & Aiello, L. C. (2014). Evolution of early Homo: an integrated biological perspective. Science, 345(6192), 1236828.
Gibbons, A. (2015). Deep roots for the genus Homo.
Haile-Selassie, Y., Latimer, B. M., Alene, M., Deino, A. L., Gibert, L., Melillo, S. M., ... & Lovejoy, C. O. (2010). An early Australopithecus afarensis postcranium from Woranso-Mille, Ethiopia. Proceedings of the National Academy of Sciences, 107(27), 12121-12126.
Leakey, L. S., Tobias, P. V., & Napier, J. R. (1964). A new species of the genus Homo from Olduvai Gorge.
Schwartz, J. H., & Tattersall, I. (2015). Defining the genus Homo. Science, 349(6251), 931-932.
Susman, R. L. (1994). Fossil evidence for early hominid tool use. Science, 265(5178), 1570-1573.
Villmoare, B., Kimbel, W. H., Seyoum, C., Campisano, C. J., DiMaggio, E. N., Rowan, J., ... & Reed, K. E. (2015). Early Homo at 2.8 Ma from Ledi-Geraru, Afar, Ethiopia. Science, 347(6228), 1352-1355.
Wood, B. (1992). Origin and evolution of the genus Homo. Nature, 355(6363), 783.
Wood, B. (1999). 'Homo rudolfensis' Alexeev, 1986-fact or phantom?. Journal of human evolution, 36(1), 115.
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Wood, B., & Collard, M. (1999). The human genus. Science, 284(5411), 65-71.

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I'm sure you've heard of Pavlov's Bell (and I'm not talking about the Aimee Mann song), but what was Ivan Pavlov up to, exactly? And how are our brains trained? And what is a "Skinner Box"? All those questions and more are answered in today's Crash Course Psychology, in which Hank talks about some of the aspects of learning.

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Table of Contents

Associative Learning 01:33:17
Behaviorist Theory 04:32:05
Classical and Operant Conditioning 03:47:01
Positive and Negative Reinforcement 07:18:22
Reinforcement Scheduling 09:32:02

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What exactly is Consciousness? Well... that's kind of a gray area. In this episode of Crash Course Psychology, Hank gives you the basic ideas of what Consciousness is, how our attention works, and why we shouldn't text and drive... ever... no, really, NEVER!
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Table of Contents

Defining Consciousness 00:00:00
Neuroimaging 02:16:01
Dual Processing 03:45:18
Selective Attention 04:22:16
Selective Inattention 05:46:21
Change Blindness 06:12:08
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Continuing our look at Nuclear Chemistry, Hank takes this episode to talk about Fusion and Fission. What they mean, how they work, their positives, negatives, and dangers. Plus, E=mc2, Mass Defect, and Applications of Fission and Fusion in the real world!

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Table of Contents

E=mc2
Mass Defect
Fission vs. Fusion
Applications in the Real World

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Hank gives us a tour of the most important table ever, including the life story of the obsessive man who championed it, Dmitri Mendeleev. The periodic table of elements is a concise, information-dense catalog of all of the different sorts of atoms in the universe, and it has a wealth of information to tell us if we can learn to read it.

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Table of Contents
Dmitri Mendeleev - 0:45
Mendeleev's Organization of the Periodic Table - 2:31
Relationships in the Periodic Table - 5:03
Why Mendeleev Stood Out from his Colleagues - 7:09
How the Periodic Table Could be Improved - 8:28

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How did we get here? Well, in terms of Atomic Chemistry, Hank takes us on a tour of the folks that were part of the long chain of other folks who helped us get to these deeper understandings of the world. From Leucippus to Heisenberg to you - yes, YOU - the story of Atomic Chemistry is all wibbly-wobbly... and amazing.

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Table of Contents

Leucippus, Democritus & Atomic Theory 0:09
Discharge Tubes 1:52
Ernest Rutherford & The Nucleus 4:22
Chemistry = Math 7:22
Niels Bohr Model 5:32
Heisenburg & Quantum Theory 6:35
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Dihydrogen monoxide (better know as water) is the key to nearly everything. It falls from the sky, makes up 60% of our bodies, and just about every chemical process related to life takes place with it or in it. Without it, none of the chemical reactions that keep us alive would happen - none of the reactions that sustain any life form on earth would happen - and the majority of inorganic chemical reactions that shape the surface of the earth would not happen either. Every one of us uses water for all kinds of chemistry every day - our body chemistry, our food chemistry and our laundry chemistry all take place in water.
In today's Crash Course Chemistry, we use Hank's actual dirty laundry (ew) to learn about some of the properties of water that make it so special - it's polarity and dielectric property; how electrolytes can be used to classify solutions; and we discover how to calculate a solution's molarity as well as how to dilute a solution using the dilution equation.

Table of Contents
Polarity 02:40
Dielectric Property 04:13
Electrolytes 04:29
Molarity 08:46
Dilution 10:56

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In this episode of Crash Course, Hank introduces you to the complex history and terminology of Anatomy & Physiology.

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Table of Contents:

Anatomy: The Structure of Parts 2:34
Physiology: How Parts Function 3:50
Complementarity of Structure & Function 4:09
Hierarchy of Organization 4:20
Directional Terms 7:27

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