0:03 Bears are nature's vacuum cleaners.
0:04 Though they're part of the same
0:06 carnivore order as wolves and big cats,
0:08 they have one of the most varied diets
0:10 of any animal group, eating everything
0:12 the natural world can provide. From
0:14 berries and fungi to meat, fish, and
0:17 even insects. It's part of what has made
0:18 bears such a successful and widespread
0:21 group, with the brown bear in particular
0:23 once roaming across the entire northern hemisphere.
0:24 hemisphere.
0:27 This makes the panda with its vegan diet
0:30 of bamboo seem very odd indeed. These
0:32 black and white beasts don't fit the
0:34 bear blueprint to the point that
0:35 scientists didn't initially think they
0:38 could be bears at all. Pandas were first
0:40 discovered by a French missionary in
0:42 1869. And though originally described as
0:45 Ursus Melanucas or black and white bear,
0:48 they were soon ousted from the Ursa and
0:50 placed in a separate family alongside
0:52 the red panda which also lives in China
0:54 and has converged on many of the same
0:57 adaptations like large bamboo mers and a
1:00 bony pseudo thumb for gripping their
1:02 favorite snack.
1:04 Modern molecular methods eventually put
1:06 an end to a century of debate. DNA
1:08 demonstrates that pandas are indeed true
1:10 bears and red pandas more closely
1:13 related to raccoons and weasels. But
1:15 their diet remains a distracting puzzle.
1:17 By adapting to eat the hard woody stalks
1:19 of bamboo, [music] pandas have found a
1:22 food source that won't run away. But
1:24 because pandas are carnivora and lack
1:26 the robust guts and cellulose degrading
1:27 gut bacteria of more established
1:29 herbivores, it's also a food source that
1:31 they struggle to digest.
1:33 This means in order to survive on
1:35 bamboo, the panda has to stuff itself
1:38 for 15 hours a day and spend most of the
1:40 rest of its time asleep. A bit like the
1:43 koala with its toxic eucalyptus habit,
1:45 it's had to adopt a low calorie
1:47 lifestyle, conserving energy whenever possible.
1:49 possible.
1:51 This addiction to bamboo, combined with
1:53 a legendary reputation for refusing to
1:56 reproduce, has given the panda a very
1:58 bad name. You don't have to look far to
2:00 find advocates calling for their
2:02 extinction. If the lazy pandas can't be
2:04 bothered to continue their own species,
2:06 why should we intervene? The argument goes.
2:08 goes.
2:10 But if pandas are so bad at existing,
2:11 then how did they evolve in the first
2:13 place? How could natural selection shape
2:16 a creature to be totally inept? Let's
2:18 dive into panda evolution and find out
2:20 exactly what we're missing.
2:22 The story of the panda starts 19 million
2:24 years ago when it split off from the
2:26 most recent common ancestor of the
2:29 bears. Pandas were the first to diverge,
2:30 making them the equally distant cousins
2:33 of all other living bear species. The
2:35 early history of the panda tribe is
2:37 shrouded in mystery. And it's not until
2:38 11 million years ago [music] in the
2:41 midst of the Mayene that we find our
2:44 oldest known panda relative, Cretzotos.
2:46 Instead of China, Cretzotos lived in
2:48 Western Europe, which had a warm
2:51 tropical climate in this period. It was
2:53 much smaller than modern pandas. In
2:54 fact, it was even smaller than the sun
2:56 bear, the most petite modern bear
3:00 species. Like most small bears, Crestos
3:02 was probably a good climber, and the
3:04 scientists who named it think it mostly
3:06 fed on plants and would scramble up
3:08 trees to escape the large amphisanid
3:09 bear dogs that were the dominant
3:12 predators of the age. Yet, the animals
3:14 teeth, which along with its jaw is about
3:15 all that's actually been found of
3:17 quartos, show that they had a much
3:19 broader diet than their descendants. A
3:20 recent study shows that grooves and wear
3:22 on the teeth of this species are more
3:24 comparable to omnivorous black and brown
3:26 bears than to pandas.
3:28 It's hard to pin down exactly what an
3:30 omnivorous bear ate, though, especially
3:32 from just a handful of fossils because
3:34 the same species can have vastly
3:36 different diets between regions across
3:38 seasons and over extended periods of
3:41 time. For instance, over the last 100
3:43 years, brown bears on the Japanese
3:46 island of Hkaido have gone from eating
3:49 60% meat to less than 10% meat. This is
3:51 because the Hkaido wolf was driven
3:53 extinct, and the bears would get most of
3:55 their meat by musling in and stealing
3:56 deer carcasses from the more fleeted
3:59 predators. Without the wolves to catch
4:01 their deer for them, the brown bears now
4:04 mainly live off fruit and herbs. That's
4:05 just one example that show how this
4:06 animal group can adapt to what's
4:09 available in its habitat. It's likely
4:11 the panda's ancestors could pull off the
4:13 same trick, becoming more vegetarian
4:15 when prey was in short supply, perhaps
4:17 as a way to avoid competition with other
4:19 species. If this way of life was
4:21 sustained long term, they would
4:24 gradually start to adapt for herbivy.
4:26 Pandas stuck it out in Europe for a long
4:28 time with the last known species,
4:31 Agratos Nicolivi, living up to 5 million
4:34 years ago. It was a planteater, but it
4:35 didn't have strong enough teeth to crush
4:37 the woody stalks of bamboo and probably
4:40 ate much softer vegetation.
4:42 Long before the pandas died out in the
4:44 west, they had already made the move to
4:45 China, and this is where their bamboo
4:48 eating seems to have got started. Elotos
4:51 lived 8 million years ago in China and
4:54 Southeast Asia. Like a modern panda, its
4:56 teeth were covered in complex grooves,
4:57 which could mash through tough plant
4:59 fibers, working a bit like a meat tenderizer.
5:01 tenderizer.
5:02 But we have more than just teeth to talk
5:04 about now with the first appearance in
5:06 the fossil record of the panda's strange
5:09 sixth digit, its makeshift thumb. This
5:11 thumb is actually a massively expanded
5:14 wristbone, the radio sesimoid, which
5:16 works like a pinser, helping pandas grip
5:18 bamboo tightly while their jaws go to
5:20 work. When you need to eat 100 lb of
5:22 bamboo a day, anything that makes the
5:23 process more efficient becomes an
5:26 invaluable survival tool.
5:28 Islo Arthus actually had a larger grip
5:30 than modern pandas and over time the
5:32 fake thumb grew shorter and more hook
5:33 shaped. [music] Scientists think this
5:35 was to prevent it protruding too much
5:37 and to present a flatter surface to the
5:40 ground allowing modern pandas to keep a
5:41 strong grip while not hampering their
5:43 ability to walk.
5:45 The red panda also has the bamboo
5:47 grasping pseudo thumb. And while it's
5:50 initially bamboozled, it's now held up
5:51 as an amazing example of conversion
5:54 evolution. The two species both came to
5:55 eat bamboo, so they evolved the same
5:58 tool. But that may not be the whole
6:01 story. While the red panda's wristbone
6:02 thumb definitely grew large to help the
6:04 animal hold stalks, scientists now think
6:07 it was originally used for locomotion.
6:08 The fossil record shows red pandas had
6:10 this feature before they became bamboo
6:12 eaters. So, it probably developed to
6:14 help them grip slender branches, much
6:17 like us apes and our opposable thumbs.
6:19 In the panda with its patchy fossil
6:22 record, the origins are less clear. But
6:23 because the spectacled bear also has a
6:25 small pseudo thumb and this was the
6:27 second bear species to split off from
6:29 the common ancestor, some scientists
6:31 think this digit was an original feature
6:33 of the Ursid family, one that was then
6:36 lost in the Ursa bears. With the bears
6:38 large body sizes, they wouldn't have
6:39 been nimly scampering across thin
6:41 branches. So their thumbs probably did
6:43 develop for manipulating food, [music]
6:45 but for grasping plants that weren't bamboo.
6:46 bamboo.
6:49 One last wrinkle, some distantly related
6:51 carnivorans like the palm civet engineet
6:54 also have large radial sesimoids. So
6:55 it's just about within the realm of
6:57 possibility that this was actually an
6:58 ancient climate adaptation of the very
7:01 earliest tree dwelling carnivorance from
7:02 60 million years ago. One that was then
7:04 lost in many species to allow for faster
7:07 movement on the ground. But for whatever
7:10 its origins, the isoartis thumb size
7:12 combined with its strong teeth suggest
7:14 that by now pandas had bamboo on their
7:16 menus. But we have to jump forward in
7:17 time to see the first appearance of
7:19 another trademark feature, their mighty
7:23 jaws. Yes, you heard that right. Pandas
7:25 have very powerful mouths with one of
7:27 the strongest bites of any bear species.
7:29 A panda's massive head may make it look
7:31 sweet, but its purpose is to allow room
7:34 for large jaw and cheek muscles, which
7:37 it uses for some serious chewing. Pandas
7:39 have highly reinforced skulls to
7:41 withstand the forces their awesome jaws
7:43 throw out. Their skulls are stronger
7:45 than polar bears, which mainly eat the
7:47 soft, nutrient-rich blubber of seals and
7:50 don't crunch on bone.
7:52 While they may look harmless, panda
7:53 strong bites make them dangerous when
7:55 provoked. And there are many cases of
7:56 pandas attacking people who
8:07 Over a span of four years, one panda
8:10 called Goooo in Beijing Zoo hospitalized
8:11 three visitors foolish enough to enter
8:13 his enclosure. [music] Each time
8:15 treating the intruder's legs like big
8:17 pink bamboo stalks to be chomped on. In
8:20 one of these attacks, Goo bit through to
8:22 the bone and Zustaf had to use tools to
8:25 pry its jaws open.
8:26 We start to get really good skull
8:28 remains from about 2 million years ago
8:31 with the species is microa considered
8:33 close enough to the modern pandas to be
8:35 part of the same genus. Its skull shape
8:37 is very similar shown that this aspect
8:38 has stayed largely the same since at
8:41 least the late plyioene. It was a
8:43 smaller animal though only about 2/3 the
8:47 size of a modern panda at 1 m in length.
8:49 Entering the plea scene we meet the
8:51 imposing isupola bacon which was very
8:54 similar to modern pandas only larger. It
8:56 seems these bears tried out a couple of
8:57 different sizes before landing on one
9:00 that was just right. Now, we followed
9:01 the pandas from their European origins
9:03 to their current form, but we still
9:05 haven't solved the mystery of when they
9:07 became bamboo only feeders. It seems the
9:09 foundations for holding and chewing
9:11 bamboo were laid millions of years ago.
9:12 But one study which examined chemical
9:15 isotopes in ancient panda teeth found
9:16 they had more varied herbivorous diets
9:19 as recently as 5,000 years ago. So
9:21 perhaps the switch was more recent.
9:23 Scientists have worked out how pandas
9:25 survive on bamboo despite their simple
9:27 stomachs and short guts. Though by
9:28 looking at what pandas eat on the
9:30 nutrient level, we figured out they're
9:31 getting roughly as much of their energy
9:34 from protein as hyperinivous animals
9:36 like wolves and cats. They do this by
9:39 being selective, prioritizing different
9:40 types of bamboo and different parts of
9:42 the plant throughout the year, migrating
9:44 between different altitudes in their
9:45 mountain habitats to follow the
9:47 proteinrich young shoots.
9:50 So, the question why pandas eat bamboo
9:52 may be starting with a false assumption
9:53 that there's something wrong with
9:56 bamboo. While they're less active than
9:57 other bears as a result of their diet,
9:59 pandas can get the energy and nutrition
10:01 they need from bamboo alone. And the
10:03 plant is abundant and grows incredibly
10:06 fast. And because no other animal, not
10:07 even the red panda, [music] can tackle
10:09 their tough stocks the way giant pandas
10:11 can, they avoid competing for their
10:12 dinner. [music]
10:14 It's true they have to eat for long
10:16 periods to get enough food, but that's
10:18 true of many planteating species,
10:19 especially large animals like gorillas,
10:21 giraffes, elephants, and [snorts]
10:24 pandas. It's not a unique weakness. I
10:26 also found a study from 2025 that
10:28 suggest another utterly bizarre
10:30 possibility that bamboo may actually
10:33 want to be eaten. Chinese researchers
10:35 took blood from pandas and found 57
10:36 different microarnas, which come from
10:39 bamboo in the animals bloodstream.
10:41 [music] These microRNAs do all sorts of
10:43 things. Regulating genes by stopping
10:45 particular proteins from being produced.
10:47 But some of the bamboo ones the
10:49 scientists found in pandas affect
10:51 dopamine metabolism [music] and the
10:52 processes through which smells are
10:54 converted into a signal in the brain.
10:56 The idea here is that material from
10:58 bamboo has hopped over to pandas and is
11:00 making bamboo smell better, taste
11:03 better, and feel good to eat. It's
11:05 completely unbelievable and I can't find
11:06 anyone else really talking about it. So,
11:07 it feels like this might have been a
11:09 strange fever dream, but no, here it is
11:12 in a proper scientific paper. Here's the
11:15 theory it was based on from 2023. Weird,
11:18 weird, and wacky sci-fi type stuff. It
11:19 would be interesting to consider an
11:21 alternative history for the panda.
11:23 Imagine a spec evo project exploring a
11:25 sister species to these bears. one that
11:27 not only maintained an omnivorous diet
11:29 but actually became more carnivorous
11:31 over time eventually giving rise to a
11:33 hunter killer panda that terrorized the
11:34 plains of some other continent say North
11:37 America okay now stop imagining it
11:40 because all of that actually happened
11:41 [music] after the pandas split from the
11:43 rest of the bear lineage they split
11:46 again we follow the branch of Isa podini
11:48 because that's the one that gave rise to
11:51 the pandas but the agaran went in a very
11:53 different direction the earliest known
11:56 species the omnivorous And Dartos lived
11:58 11 million years ago just like Cretzotos.
11:59 Cretzotos.
12:01 But while that bear is walking the path
12:03 towards herbivy, indoss is its twisted
12:06 mirror image, meat became a steadily
12:08 more important part of its diet.
12:10 These renegade path pandas would
12:12 culminate in the late measene with the
12:14 huracan genus. Sometimes described with
12:16 the epic name storm bear, [music] this
12:18 apex predator had a massive skull and
12:20 strong canines for shearing through
12:23 flesh and bone. It also had long limbs.
12:25 Rather than opportunistic hunters like
12:27 black and brown bears, Huracan would
12:29 chase down its prey like a lion, using
12:31 its immense bulk to bring down anything
12:33 it could catch. Huracan was very
12:35 successful and survived in North America
12:37 until about 4 million years ago. The
12:39 cause of its extinction is not exactly
12:41 clear, but what is clear is that on the
12:43 other side of the world, the pandas with
12:45 their plant-based diets were soldiering
12:47 on. So, we've established that bamboo is
12:49 not so bad, but what about their lack of
12:51 interest in the opposite sex? Surely
12:54 that can't be a good survival trait.
12:55 Well, it turns out this is just panda
12:59 slander. It's more or less a myth. The
13:00 idea that pandas are sex shy has been
13:03 around since at least the 1940s when the
13:05 first specimens in American zoos sparked
13:06 headlines like this one from Life
13:08 magazine. But this was hardly fair,
13:10 unbiased treatment from the press
13:11 because it turned out the animals they
13:13 were trying to make were both male.
13:15 Another high-profile example was London
13:17 Zoo's famous Chi-Chi. Once star of a
13:20 children's TV show, and now still in the
13:21 spotlight, but looking rather less
13:23 lively at the Natural History Museum,
13:26 Chi-Chi was handed by keepers. As a
13:28 result, the panda sexually imprinted on
13:30 the wrong species. This deviant
13:32 preferred humans to other bears. With
13:34 famous failures like this one, it's not
13:36 hard to see why the reproduction rumors
13:38 stuck. [music] Pandas are very hard to
13:40 breed in captivity. Obviously, that
13:42 makes conservation efforts tricky, but
13:44 it's true for thousands of other animals
13:47 from cheetahs to leafy sea dragons and
13:49 even other bear species like sun bears.
13:51 It's also true that female pandas are
13:53 only fertile for a few days a year, but
13:55 that's again also true for elephants,
13:58 moose, and brown bears. It's a strategy
13:59 that ensures offspring are born at the
14:01 right time of year, [music] and in the
14:04 wild, it doesn't present a problem. In
14:05 short, there's nothing especially
14:07 unusual about pandas mating habits.
14:09 Their population has shrunk not because
14:12 of a design flaw, but because of habitat
14:14 destruction, which has restricted their
14:15 range to a small band of mountainous
14:17 terrain in central China.
14:19 The pandas population collapse maps onto
14:21 the rise of agriculture in our own
14:23 ancient history, as well as the
14:26 increased deforestation in recent years.
14:27 Panda numbers have recovered recently
14:31 from 1,100 to 1,900, and as a result,
14:33 they've become a symbol of conservation.
14:35 But the fact is, rather than graciously
14:36 rescuing the pandas from their own
14:38 design flaws, we're the villains that
14:40 put them on the brink in the first
14:42 place. Evolutionary, the pandas were
