The Truth of Elephant Evolution - With Chris Packham

[00:00:00]Elephants, the largest animals to walk on land today, are fascinating creatures. These enormous mammals have captured the human imagination for as long as we've lived alongside them.

[00:00:11]These great intelligent beasts with massive specialized teeth projecting from their faces, and noses modified into muscular prehensile appendages almost seem like madeup creatures when you describe them. How on earth could such marvelously strange animals ever evolve? The story of elephant evolution is an ancient one, stretching back over 60 million years of our planet's past.

[00:00:35]Just three species of elephants exist today, the last vestage of a bygone dynasty, as hundreds of prehistoric species once lived and thrived across almost every continent on our planet.

[00:00:47]From the woolly mammoths, icons of the last ice age, to the utterly bizarre Platyelladon with their spoon-shaped jaws, elephants have had one of the wildest evolutionary journeys in the entire Animal Kingdom. The story of elephant evolution is also the focus of a brand new series airing on BBC 2 and available now on BBC i Player, Evolution, hosted by esteemed naturalist and TV presenter Chris Pacham. This series explores the evolutionary history of five iconic modern animals from their origins deep in the Paleozoic and tracing the key turning points that ultimately led to the creatures we see today. Recently, Doug and I had the chance to talk to Chris and executive producer Rob Littlele about their new series, particularly regarding elephant evolution, which is the focus of the first episode.

[00:01:36]>> You know, what we see in in the natural world today is a snapshot. 99% of all the species that have ever lived on the earth have already gone. We're left with probably less than 1% living today.

[00:01:48]There was a whole fauna of provisidians out there um that were prospering in in in one way or or another. And and and the only others that sort tend to make the charts are things like mammoth and and maybe mastadon and things like that.

[00:02:01]And that's because they're they're tied into our you know prehistoric uh history. So yeah, from from our point of view, I think that's another one of the key messages. It's not from N to elephant. There's been a lot of diversifying a lot of things that tried and worked and then failed ultimately.

[00:02:18]And of course, as we say in the program, when it came to the end of that group of animals, we were intrinsically involved in in in their demise. Basically, we hunted them and ate them. Be sure to stick around to the end of the video to see some more of our discussion with Chris and Rob as we talk about the future of elephant evolution and the issues of mammoth deextinction. So, join me and Chris Packham as we explore the truth about elephant evolution. The earliest stages of elephant evolution are surprisingly well documented in the fossil record. A number of very ancient representatives of the elephant order, technically known as Probacidia, have been discovered, allowing paleontologists to piece together a pretty good picture of where and when these animals evolved. Probacidians are members of the super order Afrotheria, which includes hierraxes, sea cows, tenrex, arvarks, and others. All of which appear to have had their origins in Africa at a time when the land mass was an island continent separated from Eurasia. Within Afrotheria, Probacidians are classified as part of the group known as Teytheria, which also contains the sea cows and a couple of extinct lineages. So, the closest living relatives to the elephants are actually manatees and the dong. The oldest example of a probacidian that we found so far is a species called Erietherum.

[00:03:41]This animal lived about 60 million years ago during the late Paleocene epoch and was discovered in Morocco. The fossilized jaws and teeth of erreium are remarkable for the way they display very primitive or basal features similar to those of other basal tethers yet also hint at the specialized anatomy that would become characteristic of later probacidian teeth. namely the transverse ridges running from one side to the other of the mers which makes elephant teeth highly efficient at grinding.

[00:04:12]Additionally, the eyes of erreium would have been positioned far forward on the skull, a typical feature of probacidians. However, it would not yet have possessed a proboscus.

[00:04:22]Erithetherium was a very small animal, only about the size of a rat at just 20 cm tall at the shoulder or around 8 in.

[00:04:31]So the elephants had humble beginnings.

[00:04:34]Nevertheless, the indications of their future success are there in Ertherum's teeth. The next oldest probacidian we know of is phosphorum. Also based on fossils found in Morocco, but dating to a few million years later during the early eosene epoch some 56 million years ago. Phosphotherum again lacked a trunk, but had eyes placed far forward on the skull and possessed more developed transverse ridges on the moler teeth when compared with erreum.

[00:05:02]Phospheretherum was probably quite a generalist browser, consuming lots of tough vegetation such as leaves and potentially had a semi-aquatic lifestyle. This was again a very small animal compared to the elephants we're familiar with about the size of a cat just 30 cm tall at the shoulder around 12 in. Morocco continues to be the go-to place for learning about early probesidian evolution as the next oldest member of the lineage found so far was also uncovered here from the same geological basin as phospheretherum.

[00:05:35]This was a species called Douethetherum which lived an estimated 53 million years ago. Douethetherum had fully formed transverse ridges across its mers, a condition called loofphodonty.

[00:05:48]This species is only known from jaw and tooth fossils, but it was already significantly larger than the more basal propbacidians, likely reaching about a meter tall at the shoulder or about 3.3 ft. So, it was around the size of a modern tape and potentially resembled one too. Also hailing from North Africa are the even younger species Numiditherum known from 51 million-year-old fossils found in Algeria and Barrytherum from Egypt and Libya which existed between 37 and 33 million years ago. While Numiditherum stood about a meter tall at the shoulder, Barrytherum was the first of the giant probacidians. These beasts grew up to 2 m high at the shoulder and probably weighed more than two tons.

[00:06:33]With their high foreheads and the beginnings of a trunk in the form of a short proboscus, they would have looked rather strange, kind of like halfbaked elephants. They also possessed the transverse crests on the mers typical of later probacidians and had large upper second incizers, hinting at the early development of tusks. Some close relatives of Numiditherum and Barrytherum are also known from African fossils dating from about 38 to 34 million years ago. These include arcanothereum found in Libya and Omanthetherum perhaps not surprisingly found in Oman. Though both were smaller than Barrytherum, they nevertheless provide more data on the evolution of probacidian dentition as both possessed specialized lower in sizes that may illuminate the ancestral condition for some later species of probacidians that possessed ever growing lower tusks such as the dinoars and certain early elephantapforms which we'll come to in a bit. For a while there was a mysterious gap in probacidian evolution during the eosene epoch. a hiatus lasting some 13 million years during which no probacidian fossils were uncovered.

[00:07:42]Before this gap, there were the very early species we've talked about erreum, phosphorreium, douetherium, and numidithetherreium. Then 13 million years with nothing followed by barrier, omantherum, and arcanothereum. This was the case until 2019 when another significant discovery in elephant evolution was made. a single upper mer uncovered in Sagal which dates from right in the middle of this hiatus. This tooth was used as the basis to name a new species Salumia as it was argued to be distinct enough from other early probacidians and might represent a basal member of the elephantform lineage. So it's potentially closer to modern elephants than any of the other probacidians we've discussed so far. A second new species from within the eosene hiatus was then described in 2021. Dagbatitherum from Togo in West Africa. Again, it's only known from a single mer, but it shows many of the characteristic features of the elephantform lineage. This led to its classification as a stem elephant, extending the known fossil record of the suborder by some 10 million years and placing the origin of the group at a much earlier time than previously thought. Now, it's important to note here that although it might seem at first that many of the species I've mentioned could be viewed as rungs on a ladder of progression with each one becoming progressively more elephantlike, that's not how evolution works. It's not a linear progression of one species evolving directly into the next one. Instead, it's a series of branching events. And each of these species is just a representative of one branch of the probacidian story with every one of them being adapted for their certain way of life and environment. It's also important to remember that although the early fossil record of Probacidians is certainly pretty good compared to many other lineages of organisms, it's far from complete and these fossils are only fragmentaryary glimpses at the various branching lineages that once existed. A perfect example of this sort of side branching is the wonderfully weird mirtherum. While the elephantform suborder originated during the eosene epoch, there were other more basal branches of the probacidian dynasty that had diverged at earlier stages and were doing their own thing during the late eosene to early algosene epochs.

[00:10:04]Miratherum lived in North Africa between about 38 and 34 million years ago and was another pretty oddlooking animal to put it nicely. Standing about 0.7 m tall at the shoulder, about 2.3 feet, but with a body length of almost 3 m or about 10 ft. It was a very tubular-shaped creature with a barrel-like body and stout limbs. It also would have possessed a proboscus, probably one that resembled a modern tape ears, and it had short tusks on its upper jaws, as well as quite spadeshaped lower front in sizes. Miratherum was also probably semi-aquatic, consuming soft vegetation that grew in freshwater environments. So, it essentially lived a bit like a hippo, but was an ancient elephant relative. The first major split within the probacidians occurred when the family dinoaday diverged from the lineage leading to the elephantforms.

[00:10:58]This divergence likely occurred during the eosene epoch more than 40 million years ago. The dinothes were seriously impressive beasts. Dinotherum, the youngest and largest of the genre in the family, includes several species that grew much larger than any modern elephant, with the largest estimates putting them at shoulder heights exceeding 4 m or over 13 ft and up to 12 tons in body mass. For context, the largest bull African elephant on record reached 3.96 m at the shoulder and weighed 10.4 tons. The dinoars were pretty similar in general body proportions to modern elephants and had fully developed trunks, but possessed much longer legs and lacked tusks on the upper jaws. Instead, they had paired backwards curving lower tusks, presumably used to hook branches and pull vegetation down. The evolution of the dinoars began in Africa where all probacidians originated with a genus called chiltherum. This was already a sizable animal, though much smaller than its younger relatives, and is known from approximately 27 million-year-old teeth found in Ethiopia. Next came Prodinotherum, a genus represented by several species that existed between about 20 1/2 million years ago and around 15 12. These animals have been found in Africa as well as Europe and Asia and were already getting pretty enormous with the largest estimates putting their shoulder height at 2.78 m about 9.1 ft and a mass of 4.3 tons.

[00:12:31]Eventually prodium disappeared and dinothereum arrived on the scene to replace it again. Dinotherium was widespread, found in Africa and across Eurasia and survived until 1.5 million years ago when the expansion of grasslands likely drove the lineage to extinction. So, the dinoars represent their own distinct lineage that branched from the ancestors of the modern elephants tens of millions of years ago.

[00:12:57]But let's now head back to the base of the elephantform suborder to catch up with where modern probacidians came from. A series of basil elephantforms have been uncovered at localities across northern Africa, including the well-known Fionomia from Egypt, which lived between about 37 and 30 million years ago, and Paleom Mastadon, also found in the same region of Egypt in rock sequences dating to between 34 and 27 million years ago. These animals were both fairly large compared to most of the more ancient African probacidians, with Fionomia standing about 1.7 m tall at the shoulder, 5.6 6 ft and Paleom Masttodon reaching 2.2 m or about 7.2 ft. Both species likely had trunks slightly longer than those of Miratherum. And their teeth were also rather fascinating. Paleomadon appears to have possessed short tusks in its upper and lower jaws with the lower ones placed very close together. Fomia also had upper and lower tusks with the lower teeth modified into flattened spatula-like structures. Studies of tooth wear on Fomia fossils have revealed that these probacidians were largely terrestrial animals and did not spend much time feeding on aquatic vegetation like miratherium. Instead, they probably inhabited woodlands and had diets that included leaves, twigs, and fruit. In 2006, another basil elephantform was discovered and hailed as a missing link that helped to resolve the origins of the modern probacidian lineage. This was Eratrium, a species uncovered in Eratria in northeast Africa and known from a partial jaw.

[00:14:33]Excitingly, this 27 million-year-old species is the oldest known probidian of its kind to have what is known as horizontal tooth displacement, a typical feature of modern elephants, in which replacement teeth grow at the back of the jaw and gradually push the older worn teeth forward in a sort of conveyor belt system. Within the elephantform lineage, the group known as the elephantorphs then appeared. The elephants appear to have rapidly split into two distinct branches. Elephantida, which includes the modern elephant lineages, plus various others, and the family mammoth, which contains the masttodons. This split must have occurred sometime before about 27 million years ago as the oldest example of the Mammuday family has been discovered in rocks dating to this time in Kenya where a species named Losokodon was found. Following their origins in Africa, the mammothids dispersed into Europe and Asia during the early Meiosene some 18 million years ago, seemingly across an ancient connection between Eurasia and Afroarabia known as the Githerreum land bridge. The mammoth genus Zygolofon includes at least six valid species. The oldest of which has been found in Africa, while younger species have been found at localities across Eurasia. One of these species was potentially the direct ancestor of the genus Mammoth, which includes the famous American mastadon. Zygalophodon would have been a wonderfully strange probacidian to see in the flesh. While these animals possessed the long trunks we're familiar with on modern elephants, many of them had upper tusks that were recurved downwards. Some also had very long fused lower jaws that featured lengthened forward-facing lower incizers projecting from the ends. There is some recent research suggesting that these long fused lower jaws and the presence of lower incizers might be sexually dimorphic, perhaps occurring only in males. There are also zygopodon fossils with short tuskless lower jaws that have historically been named as different species, but may in fact represent females. The evolutionary relationships among the various zygopodon species and related mammids are still the subject of much debate and revision at this time.

[00:16:47]The first known evidence of mammothids entering North America dates to about 16.5 million years ago as a fragmentaryary cheek tooth probably belonging to a zygopodon species has been discovered in Nevada. More complete remains of a species called Zygolofon Provis have also been uncovered from numerous younger sites across North America and it's widely thought that this is the species that mammoth evolved from. At least six different species of mammoth are currently considered valid, including the famous mammoth americanum, the American mastadon, which ranged from as far north as Alaska to as far south as Honduras and lived from about 4.7 million years ago until just 11,000 years ago. The American mastadon was a pretty huge species with males on average exceeding the shoulder height and body mass of Asian elephants and African forest elephants. Though male African bush elephants still tend to be a little taller. The head shape of mastadons was notably different from the highded shape of modern elephants being much flatter and gently sloping upwards.

[00:17:52]They possess long upper tusks and on occasion some males have been found with very short lower tusks too. Although it was thought for a long time that the American mastadon was the only mammothed species living in North America during the plea scene, in 2019 a second species was revealed, the Pacific mastadon, mammoth pacificum, which is known from fossils concentrated along the western coast of North America, but also from some remains further east. This species had narrower teeth and was smaller in overall size, but was also more robustly built than its relative. Mammothids differ in general from the elephant proportions we're more familiar with as they possess comparatively much more robust limb bones while their bodies are slightly longer and their chests deeper which explains why they had such immense body masses when compared to modern elephants of similar shoulder heights.

[00:18:44]Their teeth are different too possessing mers that display a condition known as being zygodont. This essentially means that they have patterns in which the paired cusps have joined together to form sharp ridges. This distinctive anatomy was in fact what inspired the creation of the name Masttodon to begin with when in the early 1800s the famous French naturalist Gor Kuvier devised this moniker which translates from ancient Greek as nippletoothoth as he observed that there was a rather striking resemblance between the shapes of these structures. Thanks for that one. The American mastadons seem to have inhabited more forested regions and fed on leaves and pine cones according to fossil stomach contents. Unlike the generally open plane grazing habits of the mammoths they coexisted with.

[00:19:31]Another truly remarkable example of a mammoth we simply must mention is mammoth borsai. The genus name is in quotation marks here because its relationship to other mammothids is still being investigated and it should most likely be classified as a distinct genus. Borson's mastadon was a truly terrifying giant being far larger than the American mastadon with males likely reaching shoulder heights of over 4 m more than 13 ft. And it appears to have been the heaviest probacidian to ever live. Not only that, its tusks are simply ridiculous. These insane teeth have been documented reaching more than 5 m in total length, about 16.5 ft. That would have been an insane animal to see alive. Fossils of Borson's masttodon have been found across Europe and possibly also in Asia. And this was the last mammoth to inhabit Eurasia, dying out some 2.5 million years ago and leaving just the North American lineages. Okay, so back to the other elephants. Now diverging from the mammothids was the group elephantida which underwent significant diversification between the end of the iligosine epoch and the start of the meiosin epoch giving rise to several lineages. The classification of this part of elephant evolution is again a little messy so bear with me here. Three distinct early diverging lineages of elephantidans are known. The family kiralophodonted, the family and the gumpers. The kiralofodontids originated in Africa where the oldest species kiralofodon kisumuensis was discovered in 18 to 15 million-year-old rocks in Kenya. Not long after their origin other species of kirolofodontids appear in the fossil records of Pakistan and China indicating that they had dispersed from Africa by about 17 million years ago. Kiralofodontids also reached southern Europe turning up in the fossil record of Greece. But it's thought that due to their preference for grass-feeding and open environments, they never made it to the more forested regions of Western and Northern Europe.

[00:21:36]Interestingly, some recent research has found support for the idea that the Kiralophodonted even migrated into the New World as a reassessment of a species called Nathabelladon from the Meosene of North America revealed it was likely a member of this lineage rather than belonging to a different group as had previously been thought.

[00:21:55]Kirillophodonted would have looked somewhat similar to modern elephants overall, but differed in several key respects. Their skulls were again much flatter and quite narrow, and although their lower jaws didn't possess any tusks, they were still very elongate.

[00:22:10]Recent research has even suggested that they may have wielded caratinous cutting plates at the ends of these long lower jaws, as they had long slits along the sides of the jaws. Presumably, these cutting plates were used to process twigs and branches. The Kiralophodonteds had all died out by the end of the Meioscene epoch, with the last known species going extinct some 5.3 million years ago. The related family, Amabella, was even more diverse, and members of this lineage took the specialization of the elongate lower jaws to a bizarre extreme. The most well-known member of the group is the genus Plattyon, which contains a number of different species.

[00:22:50]Platty Belelladon epitomizes the informal name often given to this lineage, the shovel tuskers, as these wonderfully weird-l lookinging beasts wield lengthened lower jaws with spatulate-shaped tips and flattened broad tusks jutting out from the ends.

[00:23:05]They literally had shovels for jaws. The precise function of these odd-looking jaws has long been a subject of speculation. And although it was once commonly thought that they may have been used like giant spoons to scoop out aquatic plants from the water, more recent work based on analyzing microware patterns on their tusks has concluded that these were rather versatile tools with different species of amabella utilizing them in different ways, ranging from cutting up vegetation to stripping bark and possibly in certain cases digging for food. The amabelladonteds first appear in the fossil records during the early meioscene and seem to have died out at the very start of the following plyiosene epoch around 4.9 million years ago. The amabella again probably originated in Africa but soon dispersed across Eurasia where most of their diversification occurred sometime in the middleene. The amabella also entered North America. This leads us to the third lineage of elephantidans, the problem child of probacidian taxonomy, the gumpaththes. Very simply, the reason this group of probacidians has proven to be rather difficult is because it includes the species from which the modern elephant lineage probably evolved. And so in phoggenetic terms, it is a paraphilletic grouping. This basically means that in the way we traditionally apply the name GI, it excludes some of the descendant groups that should technically be included within it. Namely, the family elephant which contains today's elephants.

[00:24:38]Additionally, the Amabelladonteds and Kiralophodonteds are sometimes also included as giers depending on the study. Anyway, the non-elephanted gumpers were nevertheless a fascinating bunch. These were the only probacidians ever to enter South America, surviving there and in North America until relatively recently, dying out only about 13 to 12,000 years ago. The first Gtheas appeared some 28 million years ago in East Africa with the genus Getherum. This genus is also a bit of a taxonomic mess as it contains numerous different named species, many of which will probably end up being renamed as separate things at some point. By about 18 million years ago, various Githerum species had dispersed from Africa across Eurasia. These older forms possessed quite elongated and narrow lower jaws and wielded a total of four tusks, two upper and two lower, with the upper ones gently curving downwards. Similar to the mastadons, the gumpers tended to have slightly different body proportions than modern elephants with more robust limbs and more elongate bodies. By approximately 15 million years ago, one of the more derived Githerreum species had crossed over into North America where numerous further species have been uncovered from younger rocks along with different Gaia genre that potentially evolved from Githerum including Megabelladon, Ringtherreum, Stegomaston, and others. Eventually, these American lineages would enter South America when the land bridge formed between continents during the great American biotic interchange with the oldest confidently dated South American gumir being about 2.5 million years old. Two generers are currently recognized. Kuvieronius which is also found in North America and so seems to have been the genus that traversed the continents and not mastadon which is thought to have evolved from kuvieronius during the pleaene epoch. These later American geers tended to have much shorter lower jaws than the older species and some species reduced the lower tusks while the upper tusks became much longer ending up looking a lot like modern elephants. These short-jawed species presumably relied much more on their trunks to obtain food rather than specialized lower jaws. While the gums survived until very recent times in the Americas, the last animal generally considered a typical Gaththeere to live in Eurasia died out approximately 800,000 years ago when the final species of syomaston disappeared. Syomaston appears to have been another descendant of one of the many Githerreum species and interestingly seems to have independently evolved short lower jaws mirroring the evolution of such anatomy in the American giers. Numerous Syomdon species have been recognized and are found across China and several other countries from somewhere within the many gither species that roamed across Eurasia and represented the dominant probacidians of the middleene. Yet another lineage arose, the so-called tetraofphodont githes. These animals seem to have derived from something very similar to a species called gumparreium steinheimens, a rather huge animal that inhabited Germany between about 12.5 to 9.5 million years ago. The tetraofodont githes are characterized by the number of enamel ridges they have on their mers, which differs from the trilophodont githerum, its American descendants, sinomastedon, and others.

[00:28:12]The tetraofphodons gonthes include the genus tetralophodon, a particularly important taxon as it's thought to potentially be the direct ancestor of the modern elephant lineage. Tetraofodon is known from Eurasia and Africa with the oldest fossils dating to about 13 million years ago in Europe where these browsers inhabited forest environments.

[00:28:33]Not long after tetralophodon then dispersed into Africa where it's thought these animals subsequently gave rise to the very first members of elephantiday.

[00:28:42]Tetraofodon possessed the ancestral gumpir condition of elongate lower jaws and lower tusks though these varied greatly in shape among species. In addition to probably giving rise to the first elephantids, tetralophodon also seems to have been ancestral to another fascinating side branch of probacidians, the short jaws genus, Anankus, which originated in Asia some 8.5 million years ago before dispersing to Europe and then entering Africa approximately 7 million years ago. Anankus was therefore a very widespread taxon represented by numerous species with diverse feeding strategies. The last species of an ankus to go extinct survived in Europe until about 1.7 million years ago where it's known to have coexisted with mammoth species. Now before we continue with the subsequent diversification of the elephant family, believe it or not, there's still one more family derived from the gumpers that we must mention.

[00:29:37]This is Stegodon today, which contains two genre, Stegalofodon and Stegodon.

[00:29:43]Stegalopodon first appears in the fossil record between 18 and 17 million years ago in East Asia. And it's thought that this genus eventually gave rise to Stegodon, which might have originated as early as 11 to 8 million years ago in Asia and was definitely present by at least 7 million years ago in Africa.

[00:30:01]With between 18 and 22 species of Stegodon recognized, depending on who you ask, this was a very diverse genus that ranged significantly in size. Only one instance of Stegodon has been reported from Europe so far, but they were incredibly successful across much of Asia, possibly surviving until as recently as 20,000 years ago in China.

[00:30:23]Stegodon would have looked a lot like modern elephants with very tall skulls, short lower jaws lacking tusks, and long curving upper tusks. On the Asian mainland, certain Stegodon species achieved some truly colossal dimensions, such as Stegodon Zadanski from China, which has been estimated as standing about 3.9 m tall at the shoulder, about 12.8 ft, and with a body mass of 12.7 tons. So, taller and heavier than the largest African elephant on record.

[00:30:53]However, rather amazingly, various species of Stegodon also underwent significant shrinking in size across their evolution. Incredibly, on at least eight different occasions, populations of giant Stegodon species ended up on islands across East Asia, including Japan, Flores, Luzon, Silhouazi, Java, and others. And here they each underwent a decrease in overall body size. the result of a well-studied evolutionary phenomenon known as insular dwarfism.

[00:31:23]This occurs when a population of once large-bodied animals adapt to an isolated island environment with more restricted resources, therefore becoming smaller over time. The most famous of these dwarf Stegodon is the species Stegodon Florenis which includes a couple of subspecies as these tiny probidians would have coexisted with the enigmatic homo floresiansis the so-called hobbit humans that inhabited Flores until about 50,000 years ago.

[00:31:50]However, rather remarkably, Stegodon Florenis wasn't even the first dwarf Stegodon to inhabit Flores. From about 1 million to 900,000 years ago, an even smaller species called Stegodon Sondari lived here, but it seems to have been wiped out by catastrophic volcanic activity. Stegodon Florencis then reached the island after Sundari disappeared, potentially crossing over from Java. Now, we can head back to trace the ancestry of the modern elephant lineage once again, as we finally come to Elephantday. The earliest widely accepted elephanted we know of is the genus Stegotetraeladon.

[00:32:27]A rather spectacular elephant possessing two pairs of very long upper and lower tusks. In fact, Stegotetraeladon may have had the longest lower tusks of any probacidian we've found so far.

[00:32:40]Seemingly descending from something like an AfroAbian species of tetralophodon, stego tetrabelladon first shows up in the fossil record of the Arabian Peninsula in rocks dating to between 8 and 6 million years ago. Several species have been recognized and are known from fossils ranging across northern and eastern Africa as well as the Arabian Peninsula. Additionally, there's also a record of stegoeton in southern Italy in a region that was biogeographically connected to North Africa during the Meiosene. Stego tetrabelladon could grow impressively massive with estimated shoulder heights approaching 4 m and body masses of up to 12 tons and with their four very long straight tusks this would have been an awesome animal to see alive. The last stegoeton fossils date to about 4.2 million years ago and the relationship between this genus and the other elephantids is still unclear. Some have hypothesized that they may represent the direct ancestors of the elephant subf family, but it's also possible that they simply shared a yet to be discovered common ancestor with elephantines. Either way, the first elephantines appear in the fossil record not long after the earliest stegoeton species. Prime elephus lived in central and east Africa between 7.4 4 and about 4 million years ago and again possessed two pairs of tusks although the lower tusks were much smaller than the upper ones. Selenthereum and stego dyeladon are other extinct elephant genre that inhabited Africa from about 7 to 4 million years ago diversifying as part of the meioscene to plyioscene elephant radiation. This particular African radiation of the elephant subf family also gave rise to the lineages that would eventually become the modern elephant genre. Loxodonta and Elephus.

[00:34:29]Loxodonta today includes the African bush elephant, Lockxodonta Africana, and the African forest elephant. Loxodonta cyclotus, which is on average slightly smaller than the bush elephant, has more rounded ears and has straighter, thinner tusks, as well as numerous other differences. Elephus contains just one surviving species, the Asian elephant, Elephus Maximus. Despite being the only surviving elephant species and therefore the ones we're most familiar with as humans, the African elephants and the Asian elephant actually diverged a very long time ago with the Asian elephant being more closely related to the mammoths than to the African species.

[00:35:08]The oldest fossils of loxodonta date to between about 7 and 6 million years ago and belonged to a species named loxodontto kukai that inhabited east and south Africa. The species loxodontto exoptata may have been a descendant of kukai which in turn is often considered to be the ancestor of loxodonta africana. The modern forest elephant diverged from the bush elephant between about 2.6 and 5.6 million years ago according to genetic studies. Though there's evidence that hybridization between the two species continued after their divergence in regions where they coexisted. A couple of giant loxodont species have also been recognized.

[00:35:49]Loxxodonta adora from Kenya and Ethiopia and Loxodonta Atlantica. Both of which appear to have been larger than the modern bush elephant but died out in the plea scene. Paleoloxxodon is another close relative of loxodonta. And this extinct genus is one of the most impressive of all probacidian groups since certain species were quite possibly the largest elephants to ever evolve. and as some have argued are even in the running for the title of largest land mammal to ever live. Paleoloxidon first originated in Africa between approximately 2.4 and 1.8 million years ago, depending on how we define the Paleolox genus, something that's been heavily debated in the past. One of the oldest species was Paleoloxidon Reki, an enormous form already larger than modern African elephants, which roamed across Africa and at some point about 800,000 years ago migrated out of the continent.

[00:36:44]These Paleoloxidon migrants subsequently diversified across Eurasia into a multitude of species, though again the precise relationships of these various Paleolox members have proven rather difficult to fully untangle.

[00:36:58]Interestingly, genetic evidence has also shown that paleoloxidon appears to have been the product of several hybridization events with evidence of gene flow from the ancestor of loxodonta, then more later on from African forest elephants and then also some genetic contribution from mammoths.

[00:37:16]In Europe, the gigantic paleoloxxodon antiquas appeared, commonly called the straight tusked elephant. Some of the largest size estimates for these behemoths suggest they could reach shoulder heights of up to 4.4 m and weigh up to 17 tons, absolutely towering over today's elephants. As this species survived until only about 30,000 years ago, they would have interacted with ancient human species. And indeed there are several sites known across Europe preserving straight tusked elephant fossils with signs of human butchery likely inflicted by homohybagensis and neanderals. In Asia, another truly enormous Paleolox species arose about 800,000 years ago. Paleoloxxodon nomadicus. This species has been estimated to have shoulder heights approaching 4.4 m. But there's also a more speculative size estimate that's been made based on a very fragmentaryary femur which suggests this particular individual was 5.2 m tall at the shoulder. If true, Paleolox Nomaticus may have rivaled the biggest paraceter in size, potentially making this the largest land mammal ever. However, again, I must stress that this estimate is based on a very fragmentaryary bone.

[00:38:33]At the opposite end of the scale, a species of Paleolox has also managed to claim the title of the smallest known elephant. Like all those Stegodon species that made their way onto islands and gave rise to dwarfed descendants, numerous dwarf species of Paleolox have been named from Greek islands as well as Cyprus, Sicily, and Malta. These tiny island inhabitants likely all descend from mainland populations of Paleolox Antiquas that became isolated here. The very smallest of these insula dwarfs has been referred to the species paleoloxxodon falconery, though the exact classification is up for discussion, and males of this species are estimated to have stood just under a meter tall at the shoulder, about 3.2 ft. The last surviving paleoloxidon is thought to have died out only 3,500 years ago, according to some preliminary dating estimates of the dwarf species Paleoloxidon Tyensis from the Greek island of Tylos. However, these dates do need to be confirmed by future research.

[00:39:32]Another lineage of elephantids originated in Africa about 6.2 million years ago, the mammoths. Among the most iconic of all prehistoric animals, the mammoths are all classified within the genus mammoth. The earliest recognized species was mammoth subplanifrons, which inhabited East and South Africa from about 6.2 to 3.8 million years ago.

[00:39:55]Between 3.5 and 3.2 2 million years ago, the lineage dispersed from Africa and rapidly spread across Eurasia, reaching all corners of the land mass and giving rise to multiple species as certain lineages adapted to colder climates. The patterns of mammoth evolution across Eurasia have been studied extensively and it's understood that a population of a species called mammoth meridianales which appeared 2.5 million years ago in Eurasia diverged from other populations to give rise to mammoth trogoni commonly known as the stepmamoth. This divergence is estimated to have occurred 1.7 million years ago in East Asia following which the step mammoths spread out across Eurasia. Between 1.5 and 1.3 million years ago, mammoth trogoni entered North America via the bearing landsbridge where it appears to have subsequently given rise to the enormous Colombian mammoth mammoth columbi. Back over in Eurasia, a population of mammoth trogoni in Siberia formed the basis of another new species, which appeared on the scene some 400,000 years ago, the woolly mammoth, mammoth primogenius.

[00:41:07]These ice age superstars seem to have replaced all the step mammoths in Eurasia by about 200,000 years ago, spelling the end for the stepmammoth.

[00:41:16]And they'd also entered North America sometime before 200,000 years ago as well. Since we have so much genetic data from woolly mammoths, we now know a great deal about their evolution, various hybridization events, and their adaptations to the different regions of the world they inhabited. However, there's so much to talk about that it really could be its own video, and maybe I'll make that one day. Once again, several species of dwarf mammoths ended up evolving on islands. And one of these was the Sardinian mammoth, mammoth lamari, which survived until just 40,000 years ago. And research suggests it may have descended directly from a population of step mammoths. Other dwarf mammoth species include the cretton dwarf mammoth, probably a descendant of mammoth meridianis, the Californiaifornian channel island dwarf mammoths, which derived from mainland Colombian mammoths, and of course, the famous last mammoths to ever live, the dwarfed woolly mammoths of Wrangler Island in the Arctic, where the species subsisted until just 4,000 years ago. As I mentioned, a close relative of the mammoths, the genus Elephus, also originated in Africa. Though the oldest fossils attributable to this genus date to between 5 and 4.2 million years ago, elephus presumably diverged from the mammoths by about 6.2 million years ago when the first mammoth species in Africa appeared. Between 3.6 and 3.2 million years ago, fossils belonging to elephus turn up on the Indian subcontinent belonging to a species called elephus planifrons. Around 2.6 6 million years ago. Also on the subcontinent, the massive elephus appeared, which some have suggested may represent the ancestor of the modern Asian elephant. Another now extinct elephus species might also have derived from this one, a species somewhat confusingly called elephusindrindicus, which inhabited Java until approximately 130,000 years ago. A few other elephus species have also been described, but the sole surviving elephus species, elephus maximus, probably originated in the late plea scene about 250,000 years ago and gave rise to at least three, potentially four different named subspecies. The Indian elephant, Sri Lankan elephant, the Sumatran elephant, and the Bornean elephant, which appears to be genetically distinct, but has yet to be officially named as a recognized subspecies. Finally, for the sake of completion, I must also mention that there are currently two more genre of extinct elephantines recognized.

[00:43:51]Fanagoroxidon, known from a 2 million-year-old skull in Russia, and Stegoxidon, represented by a couple of dwarfed species found in Indonesia, which died out around 800,000 years ago.

[00:44:03]Currently, the precise relationships of these species to other elephants are not fully resolved, though they're likely more closely related to Elephice than to Loxodonta, and their existence shows just how diverse this sole surviving lineage of Probacidians once was. So, that brings us to the current state of elephant evolution, and what an incredible journey it's been. It's also rather remarkable to think that for as long as our own species has been evolving. We've been coexisting with and hunting these magnificent beasts with multiple different lineages of probacidians living across the prehistoric world until surprisingly recent times. I was curious about whether Chris Packham and executive producer Rob Little thought this long period of coexistence and almost mythologizing of these incredible animals might have something to do with why humans are so fascinated by elephants. Do you think there's a case to be made for the reason the humans find elephants so fascinating? Partly being because of our almost shared relationship with them. Wherever humans were in the world, there were various other species of now extinct probacidians. I I think that humans tend to gravitate to animals which are social because we are uh longived and maybe slow to reach maturity with long periods of gestation and investment in parental care cuz those are the some of the sort of fundamental things that we really value and then if you add on top of that the ability to you know communicate let's not say that elephants are using a language but I think that might come um and maybe AI will open that capacity to to to for us to out to understand that maybe animals like dolphins and elephants are using language. Then then our base level those are some of the most important things that we value about ourselves. Some of the things that many people define us as humans. And then finally you put on top that you know that uh elephants are uh basically have the ability to recognize and know themselves as individuals and then know others as individuals in terms of shaping their you know capacity as a social species. And that's something that for a long time we thought was purely human. And then the last question is of course how much do we attribute elephants to have the capacity to be conscious and and I think there on there there is that borderline and whether you do it with a scientific basis or not people will project those characteristics onto an animal like an elephant. So they might imagine that it has a consciousness and ultimately that's one of the things that really does define us as a species. So I think that yes there's there's the interaction with them but I mean we were we were killing and eating them most of the time and then of course we've we we've trained them never fully domesticated but Hannibal took them over the Alps and they were used as war animals for a long time or beast of burden in other parts of the world. there's been a long-term, you know, relationship with them. But I do think it's projections of our own ideas of humanity on them which carry that through >> and and capt and and the captivating nature of size as well. I mean, they're obviously not the biggest animal ever to walk the planet, but they are the biggest animal that can walk the planet at the moment. and and that if you ever stand near an elephant or sit in a vehicle near an elephant, uh they look like they're amling around going but one stride, you know, it can take you 15 m or something like that. And so that just a whole different, you know, whole different, you know, thing that scale brings uh in a creature. I think I I certainly find that very >> presence, isn't it? They got they've got a real presence. I I think >> we also asked Chris and Rob about what it was that made them choose to focus on elephants as a sort of poster child for an extraordinary evolutionary journey.

[00:47:46]>> Why choose the elephant for the first episode? What is it about the elephant that you think makes it such like a fascinating example of evolution?

[00:47:54]>> Well, we have to hang a narrative that's going to engage our audience. And what we've got to do is take something which can be quite, you know, complex and make it comprehensible for that audience. And so access and engagement is is really important. So we chose iconic animals to head up each one of our programs, one of five five programs. Um but through that we've used that the you know that animal as a means of exploring its origin if you like. As Rob said, we've essentially it's the biography of that animal in terms of its evolution. And this allows us to choose its key points in its evolution. um we can jump through time, which we'll necessarily need to do in in in 50 minutes of of TV. Um and and and and show people in the case of the elephant, you know, the surprising changes that took place millions of years ago without which we couldn't have an elephant today. So, let's be clear, it's not all about elephants. We bring in lots of other species, uh contemporary and of course, extinct using CGI to to to illustrate those as well.

[00:48:58]>> I mean, people love elephants. They absolutely love elephants and and they're deeply familiar to us, aren't they? But then just stop and look at an elephant and isn't it one of the oddest things that you you you know you can see and actually of course it isn't because nature's full of things as odd or even odder than the elephant. But there is a lovely I think um dichotomy between our absolute familiarity and joy as well as when you step back and go oh actually hang on how did that all come to be?

[00:49:27]>> Yeah. You take trunks for granted don't you? Because you've always seen an elephant. You saw a cartoon of one, you know, before you could read basically.

[00:49:35]And it had a trunk and those massive ears and it was a vast animal processing enormous quantities of vegetation through its very very you know uh complicated gut. But you did you ever think what's that trunk? Where did that trunk come from? How did you you don't go from nothing to a trunk you know something has has shaped the process to shape that animal today. So I think you're right. Not taking it for granted is is a great a great way of looking at it.

[00:50:00]>> Elephant evolution has therefore been an astonishing 60 million-year long process. But what about the future evolution of this group? Will they have a chance to continue evolving now that they're reduced to such low diversity?

[00:50:14]Or will the human age be the end for them? We asked Chris and Rob what they thought. I'm curious about what you think uh the future of elephant evolution might look like. Do you think they are going to survive the human age?

[00:50:27]considering there's only three species left compares their past diversity and how can we ensure that they do survive >> well do they need to I mean that is a key point isn't it you know if we go back to the fact that the internal combustion engine and AI are going to shape and have been shaping you know the the planet and what's going to happen to it I think we have to ask the question do they need to survive given that we've already said that 99% of the species that have ever lived on earth have gone I mean if resources aren't available um because everything's packed everything you know is living in that space and it's pointing those resources then evolution won't function. So extinction is a really important part of it. The embarrassing thing is the way that we are driving extinction at the moment.

[00:51:06]And you know I refuse to call it a mass extinction event because it's down to us. For me it's a mass extermination event. We are destroying consciously destroying life and we have an alternative. So ultimately I would like to see elephants surviving in this point in the earth's evolution. um because essentially they haven't been elephants, you know, they've been that amongst that fauna of proposians before and and and maybe it would be nice if they had somewhere else to go. But the one thing that we can always go back to if we really want to be brutal when it comes to biologist is that whatever we do to this planet, life will prosper. life's tenacity will push through and it will be every bit as beautiful, diverse, dynamic, harmonious and as exciting as it is and was and and will be in the future. So yeah, I mean I I like elephants. I hate the idea of us driving to consciously driving them to extinction. Ultimately there'll be something else. It won't have a long trunk, but it will do the it will fill whatever niche is available at that time that the elephants have left vacant.

[00:52:09]Well, building on from that, I I'm very curious uh about what you think about uh de-extinction efforts, particularly focused on mammoths and things. Do you think it's a worthwhile use of resources?

[00:52:22]>> Well, okay, this is a this is where I'm really conflicted because, you know, I don't like the term, but let's just use it because you people might be familiar with it. Blue sky science basically. um you know, do we need to invest that much effort, time, money, resources, skill, energy, and endeavor in bringing something back when we've got three species which we are driving to extinction. Um so I I love the idea of needing to know. That's what makes us what we are. We need to know. That's why we're interested in what happens on the other side of the the universe. That's what makes us interested in, you know, what's happened to shape life at the moment. It's that irrepressible curiosity and a need to know that shapes humanity. Without that, we wouldn't have come up with great music and great art or anything else whatsoever. But we are in the midst of the most dire crisis for not just our species but life on Earth.

[00:53:16]And so I would, you know, if you were to say make a choice, I'd say yeah, put it on hold. That's all I would say. I'd love to know. I'd love to see a mammoth deextinction, you know, all of that stuff. But at this point in time, I'd put all of the resources into sorting out the shambles that we find ourselves in until we perhaps we're in a position where we can allow ourselves the luxury of that. And I would say exactly the same about going to Mars and everything else. Of course, we should be going to Mars. Of course, we should be stretching and pushing all of those envelopes. But at this point, there's not much there's not much left in the envelope. And so, we really need to be looking after it.

[00:53:50]Otherwise, there'll be no trips to Mars and there won't be any elephants and then then there won't be any eggs to produce mammoths. So I think it's about rationalizing that at this at this point in time. So yes, it's exciting. No, don't do it. Let's focus on looking after what we've got.

[00:54:05]>> Yeah. And I think just picking up on that actually is it's is though it's hard to you know think about how the best way to limit scientific endeavor because you don't know what you know you you've nodded to this which is who knows what would come from researching that.

[00:54:19]We don't know. There's huge amounts we just do not know about how reproduction works in mamalian species, how you know how wombs and and embryos and gestation works. That kind of knowledge and that kind of understanding that might need to go into into pursuing that goal of deextinction, whether the goal itself is is is, you know, worthwhile or not might might turn up all sorts of interesting science that could prove to be, you know, very useful and profound. But but yeah, so it's quite hard. I always find it quite hard to know how you should choose which bits of science should be done or not done.

[00:54:54]>> Yeah. But if I had all the money that they'd spent on SER to spend on conservation, >> but then I want to know what they've discovered every time I pick up new scientists, you know. So, well, you can't have it both ways, can you? So, if you could resources abundant, Earth's in a good place, um, bring back a a prehistoric prep, which one would you choose to see?

[00:55:19]>> Well, I' I' I'd go for the one which I have a, you know, we have a a broader understanding of. So, rather than go for one of the weird, you know, small elephants or anything like that, then I'd go for mammoth, I guess, basically, cuz we've got artistic representations of this. You know what I think about mammoth? It's a bit like megalodon and all those sorts of things, you know. Um I I feel I've been robbed by by, you know, by a few thousand years of seeing a remarkable animal. We just missed them. I you know, still a sea cal. Okay.

[00:55:47]It's a bit closer than so a great orc.

[00:55:49]But just on the brink, wasn't it? When you can I've been to the caves. When you go to the cave and you look at it and you see that they've been drawn by someone who looked like, thought like, acted like, smelled like me, and they've been drawing a mammoth there. I feel I've been robbed of an animal, so I'd choose mammoth.

[00:56:06]>> I'm going to go for the the the the hero in our story, the the proposian with the slightly longer nose that kicks off this, you know, this this sort of uh uh you know, internal arms race of teeth and nose and, you know, getting down to ground cuz just to see just to really see that creature that just is the the start of what is probably one of the most extraordinary what do we is it limb? What do we call the nose? I don't know. articulated, you know, uh, probosis. There we are. Yeah.

[00:56:36]>> Brilliant. Yeah. Very good answers, I think. Yeah.

[00:56:39]>> Yeah. Fabulous stuff. Thank you very much.

[00:56:41]>> Thank you.

[00:56:42]>> No problems.

[00:56:42]>> Mammoth.

[00:56:44]>> Mammoth.

[00:56:45]>> Well, there we have it. An overview of the complete evolution of the probacidians. Truly one of the most spectacular evolutionary journeys experienced by any group of animals on Earth. My hope is that this video will be able to give people a better appreciation for our modern and threatened elephant species, as learning about their extinct relatives really puts into perspective just how vulnerable they are at this point in time. I also hope that this video is useful as a way to better understand how distantly related certain extinct Probacidian lineages really are. For example, although we always hear about mastadons and mammoths, and many people probably assume they must have been close relatives, these are two entirely distinct branches in the great elephant family tree. I know I've definitely developed a much better picture of probesidian relationships after researching this video and an appreciation for how incredible it is that so many disparate lineages coexisted with one another at various points in time. So, I hope it helps others, too. Do be sure to watch Evolution with Chris Pacham which airs on BBC 2 and is also available to watch on BBC i Player. It's a tremendously fascinating series looking at the extraordinary evolutionary transformations that have occurred over deep time to result in the amazing biodiversity we see on the planet today.

[00:58:04]In addition to the evolution of elephants as seen in the first episode, it also explores dolphin, bat, horse, and ostrich evolution. So, there's lots more to learn about. Thank you again very much to the BBC for inviting us to do this interview and I hope you enjoyed watching.