Why Can't Mules Have Babies?

Animals of different species rarely get it on, and when they do, they rarely produce offspring. But even rarer than the ligers, zonkeys, camas, and beefalo of the world are hybrid animals capable of making babies of their own.

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LEARN MORE
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To learn more about this topic, start your googling with these keywords:
- Hybrid organisms: The offspring of two animals or plants of different breeds, varieties, species or genera.
- Mitosis: A process of cell division that produces copies of the original cell.
- Meiosis: A process of cell dividion that produces new daughter cells with half the chromosome number of the original cell.
- Sex cell, or gamete: a cell that fuses with another cell during fertilization (conception) in organisms that sexually reproduce.
- Hemiclonal transmission: The rare occurence in which only maternal DNA gets passed along during the creation of sex cells.

Species featured in this video:
- Mule, is the offspring of a male donkey (jack) and a female horse (mare)
- Liger, is a hybrid cross between a male lion (Panthera leo) and a female tiger (Panthera tigris)
- Zonkey, is the offspring of a zebra and a donkey. Zebra hybrids are generally known as zebroids
- Beefalo, also known as cattalo, is the offspring of a domestic cattle (Bos taurus) and an American buffalo (Bison bison)
- Cama, is the offspring of a male dromedary camel and a female llama.

CREDITS
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Script Writer: David Goldenberg
Script Editor: Emily Elert
Video Illustrator: Chad Geran
Video Director: Emily Elert
Video Narrator: Emily Elert
With Contributions From: Henry Reich, Alex Reich, Kate Yoshida, Ever Salazar, Omkar Bhagat, Peter Reich, Rachel Becker
Music by: Nathaniel Schroeder

OTHER CREDITS
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Liger Hercules - Ed Quinn

Zonkey - Flickr user Leogirly4life

Beefalo - Noah's Ark Animal
Sanctuary

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OUR LINKS
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REFERENCES
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Millon, L. (2016). Personal Communication.

Antczak, D. (2016). Personal Communication.

[Stormprobe]

Pigs occasionally fly, when they get caught in a tornado.

[Patolagos]

"When the chicken has teeth"
T-rex: Let me introduce myself

[SomeGuy-lrms]

When “Pigs Fly”
Me an intellectual “When the Queen of England Dies”









This comment did not age well.

[zoltankiss]

That chicken looked like he came from alabama

[jmhinnen]

That's a pretty good explanation for mule sterility, and I'll add to that:

Mules also have an odd number of chromosomes. You see, a horse has 64 chromosomes, while donkeys have 62. That leaves mules in the middle with 63. Because it's an odd number, it can't split evenly for sexual reproduction. The video kinda touched on that with the "different deck of cards" analogy. :)

Also on that note, the total number of recorded cases of a female mule giving birth within the past 500 years have been 60. Let that sink in: 60 in 500 years, versus millions of mules within that same time span. That's why it's just easier to say that mules are sterile, without having to explained just how miraculously rare it is for a molly (the word for a female mule) to be fertile.

[Angelofthursday]

Big cat hybrids are strange because all male hybrids are sterile, while females are fertile (though they have cubs pretty infrequently). I've personally always wondered if it were possible for the descendent of a big cat hybrid of a liger for example to have perfectly normal lion descendants, and how many generations it would take before the male descendants of said hybrid to regain fertility, or if they would at all. Like how many generations would it take for that one tiger ancestor to just not matter in the bigger genetic picture.

[darkbobblackpants]

1:35 my new threat of choice is “I will turn your bones into kidneys”

[marybandy]

Whoever came up with the name "Beefalo" for the cow and buffalo hybrid deserves a prize

[crissy]

FINALLY an actual explanation instead of 'Just accept it you'll never need that in an exam'

[colk]

“When fish climb trees”
Mudskippers: am I a joke to you?

[lagumlemoni]

"When the chickens have teeth"

Geese: 👁👁

[mikewilliams]

Aristotle: "All mules are sterile. This is a mule's offspring. Therefore this creature is a flying pig."

[planetcarbs]

Her: Pigs will never fly
Waddles the pig: Gets taken by a pterodactyl

[swedhgemoni]

Very well done, I've never seen such a simplified version of such a complex topic.

[Nightcoffee]

I need to point out that geneticists actually activated chicken-teeth at one point.

[KvaGram]

So... if a female mule were to produce a foal with a horse, it would end up being a horse?

[jorgelotr]

The weirdest of all are beefaloes, which not only can reproduce despite their parents having very different numbers of chromosomes of wildly different sizes, they manage to keep genetic material from BOTH parents in their offspring.

[chris]

I haven't thought about it recently, bit I have wondered about it on and off for years. Thanks, Minute Earth!

[briantran]

So your telling me....




A spiderman can really exist?

[victorvvc]

"When the frog grows hair" we say in my country