ExtinctZoo - When The Sahara Was A Jungle

Episode Date: August 23, 2026

Only a few thousand years ago, the Sahara wasn’t a desert at all—it was a green paradise filled with lakes, rivers, vegetation, wildlife, and people.

Two and five Canadians will hear the words, you have cancer. That's why every step and dollar raised matters. On September 19th, join thousands in Toronto for the Princess Margaret Cancer Foundation Walk. Challenge yourself, friends, and family to walk 21 kilometers in support of life-saving research. Together, we can carry the fire and help create a world free from the fear of cancer. Register today at pmcfwalk.ca.ca. This episode is brought to you by Accenture. When your advertising operations fall out of sync, everything else follows.

Spotify and Accenture are working together to reinvent the rhythm of ad sales, using automation, analytics, and smarter workflows to simplify campaign delivery and access better data across the business. The result? Less time spent on operations, more time connecting brands with the moments and fandoms that matter most. Learn more at Accenture.com slash Spotify. The largest hot desert on the planet today is by far Africa-Sahara, an immense desolate region that encompasses the size roughly equivalent to the entire United States.

Now, it's largely composed of barren rocky plateaus, gravel plains, sand seas, and massive dunes that can rival the height of skyscrapers, with just less than 1% of this entire region being made up of green areas or water, which understandably makes survival here kind of a long shot. And that's before factor in the brutal sandstorms, the scorching heat during the day, and then surprisingly cold nights, which during the winter can drop well below freezing. And unsurprisingly, because of all these hardships, not a lot of people can survive here, with the desert being home to just between 2 and 4 million people, which may sound like a lot at first, but given just how vast this desert is, that equates to less than one person per square mile.

So for perspective, over 90 times less than the USA's density. And it's not just humans that are sparse, here. Wild animals are a dime a dozen as well. And if you take a look at any biodiversity map, you'll notice that the Sahara is just about the biggest and most extreme place for a lack of diversity. So all in all, it's not a place for the faint of heart. And it's because of this harshness that the Sahara's past is almost unbelievable, as while you may not know it, this desert had a secret past life, so to speak, and not so long ago at that too. As only a few thousand years ago, it wasn't just less of a harsh area, but practically a full-fledged paradise.

being green, of all things, with expansive vegetation, lakes, rivers, and an abundance of life calling the Sahara home. And this brief period of respite in its history is nowadays referred to as the African humid period. The first time researchers started to get a whiff that the Sahara may have been harboring a lush past was back in the 1800s, after European expeditioners noted the strange discovery of petroglyphs, ancient carved images deep inside the desert in places such as Merzuk, the depicted scenes of settlements and plentiful life, in spite of the place now being, of course, a very desolate wasteland. And more such finds were ultimately made going into the 1900s, including a very peculiar piece of art discovered in the Libyan portion of the desert

that showed numerous savannah-bound animals that do not exist in the area now, or anywhere close by, for that matter. And so all of this led to a green Sahar concept being coined as early as the 1930s, but it wasn't until the late 20th century that more conclusive evidence of a greener Sahara, Sahara finally came to light, after researchers found signs that numerous large lakes and rivers had existed within the Sahara not that long ago, and which had obviously subsequently dried up. And based on the age of these ancient waterways and the Petroglyphs located, the current hypothesis is that the lost Sahara that used to exist had formed the very tail end of late Pleistocene, and existed from about 14,600 years ago to as recently as 5,000 years ago, which therefore means that while

the first civilizations were being built, the Sahara was still green. What is pretty interesting though is that before this period of abundance began, the Sahara was largely like it is now, as during the last glacial maximum, the region was extremely dry and was somehow even more harsh than the present, being more arid and dusty, leading to a larger range that extended 500 miles or 800 kilometers further south than a dozen the present, which therefore means that nearly all of the Sahel was consumed by the desert as well. Now, this extremeness of the Sahara during the last glacial maximum is thought to have been a result of the Ice Age weakening monsoons in West Africa, while then the large breakup of certain icebergs also coincided with spikes in aridity as well, due to them cooling sea temps and therefore impacting global weather patterns, including those that affect the Sahara. Ultimately, this series of misfortune events led to very little living in the region of the time, where there being almost no evidence for human habitation.

While then in places like the Akaku's Mountains, the evidence we do have for human presence only comes from much earlier, about 70,000 years ago, which therefore implies that because the last glacial maximum, numerous groups of people were forced to abandon, the region, traveling further north to the Mediterranean coast or fertile havens like the Nile Valley. In fact, this time was so severe that even most of Africa's Great Lakes dried up at this point, which in turn caused local extinctions that devastated the desert's marine and terrestrial biodiversity. Yet, like everything, where there is a put, There is then ultimately a pole, and for the Sahara, this would come by the weakening of

the last glacial maximum, which had already lost some of its oomph by 17,000 years ago, largely thanks the changes in the Earth's orbit. And on top of slightly reheating the planet, the changes brought by the last glacial maximum winding down also led to many weather systems changing positions, including the westerlies, which might have brought about the first relief to the Sahara, namely the more northern and mountainous parts of the desert, where there being clear evidence of lakes forming in elevated terrains, which led to the creation of small sheltered oasis in what was otherwise a sea of death.

Or should I say desert of death. Yet with that said, while the first signs of relief were limited, and despite the fact that the Sahara had been absurdly dry for a very extended amount of time, it wouldn't need to wait that long to be absolutely showered. As only some 1,500-2,000 years after this, a massive human period sprung up upon the continent, almost instantly affecting not just the Sahara, but the entire landmass. The current hypothesis being that a reduction in the ice age's intensity led to the monsoon season rapidly strengthening, leading to increased moisture all around. And this would eventually turn into a feedback loop.

If more moisture created more vegetation and water sources, which then on their own, blocked and locked down dust, while then also reducing albedo, and thus resulting in the monsoon strengthening again. And this led to fast-paced changes for the entire Sahara, with some areas like Egypt starting to receive tens of times more rain on an annual basis, while then in general, the Sahara, the Sahara was now roughly receiving eight times the amount of precipitation that it currently does. But, of course, this still would have depended on exactly where in the Sahara you were. But no matter the case, what is certain is that this sudden flood of water impacted virtually the entire desert. And over the course of about a thousand years, it's believed that the desert underwent a radical glow-up, if you will. Kind of that one kid, you know, who went from Scronny to Super Jack over one summer vacation. And amongst the earliest changes seen, where the dried-up lakes and river,

rivers of the Sahara refilling, while then also many new ones were created as well. The ground itself also changed with the southern forest starting to move upwards, and new plants led to soil formation and reduced desertification. And not long after, the Sahara Desert had been transformed into the Sahara non-desert, or the Green Sahara Oasis, with the vast majority of it now being composed of vegetation and countless bodies of water, with very little places actually remaining a true desert biome. Now, some like to imagine this lost Sahara as a place that would have mirrored the Amazon rainforest. But in reality, it wouldn't have been anything like the South American jungle.

And in fact, scientists have even said that there really is no good modern region to compare it to. So, in other words, this was basically a one-of-a-kind place unlike anything else on Earth now. But to help paint a picture, based on certain models, we do think that large parts of the Sahara transformed it to mostly open savannas with a diverse variety of shrubs and trees, while even mountainous areas also developed their own savannah-like conditions. Meanwhile, mangroves around the coast of the Sahara took shape and expanded, while swamps, rainforest, wetlands, and jungle-like conditions, became mainly widespread around rivers and lakes, with the scenery in these parts likely being closest to what you may see in Central Africa today. Understandably, this influx of flora and more habitable environments led to an absolute population explosion amongst animals, with troves of species making their way into this new Sahara, spreading out across pretty much the entirety of it. A lot of this new life were animals you can still see in modern Africa, only they were now in places that you normally wouldn't associate them with,

with countries as far north as Libya, possessing petroglyphs that clearly depict giraffes, elephants, wildcats, lions, and leopards. All of which, by the way, are a void from the country nowadays. And it's not such Libya that is such petroglyphs reflecting a lush paradise. As so far, major petroglyph discoveries have been made in at least six countries showing similar conditions at the time of the humid period. On top of that, remains of these actual animals have also been found, and based off of them and other known artworks in the Sahara, it seems that it wasn't just a few brave animals here or there that decided to venture into this new territory. Instead, with there being, massive herds of all walks of life coming to live here, namely though in the savannah-like areas. While then

in the forest of the Green Sahara, you would have seen an extensive amount of birds, bovids, rhinos, and elephants. And though, like I said, many animals that called the Green Sahara home are still alive, there were indeed a few that are now relics of the past, having got extinct. And this included the smaller North African elephant, the Bubol Hartebeast, giant orox, and the buffalo Sincerus Antikas, which was known for its large two-toned body and absurdly long horns. Additionally, at the same time, the Sahar was also full of animals that remain, but are far more critically endangered, such as the cemeter oryx,

who had once thrived and been exceedingly abundant in this green paradise. And so, because of this and, well, obviously the vastly different scenery, walking across the Sahara during the humid period would have been quite the trip and a far cry from the same trip taken today. With pretty much one of the only similarities being the heat. If don't be mistaken, the green Sahara was blistering hot as well, despite being wetter, with it likely only having been a smidge cooler thanks to vegetation and standing water that increased evapot transpiration. However, the one thing that would have made a very big difference in reality was the physical coverage the vegetation provided. And of course, the fact that you had a lot of water sources to choose from for a drink or just to cool down in.

Two and five Canadians will hear the words, you have cancer. That's why every step and dollar raised matters. On September 19th, join thousands in Toronto for the Princess Margaret Cancer Foundation walk. Challenge yourself, friends, and family to walk 21 kilometers in support of life-saving research. Together, we can carry the fire and help create a world free from the fear of cancer. Register today at pmcf walk.ca.ca.

And speaking of water, the green Sahara might as well have been nicknamed the Blue Sahara instead. As during this humid period, it wasn't only the vegetation that was impressive, but also the rivers, lakes, and bodies of water themselves, with many of them reaching their maximum extent in these days. And this included, by the way,

the famed Nile River that increased in size until, was between two to three times its current size, receiving more than four times the annual precipitation, and leading to a much wider river that submerged wide swathes of land, including a large majority of the Nile Valley. And throughout the course of this humid period, the Nile would also experience frequent massive flood events, ones that were so extreme that they would make anything in modern times look arguably laughable, with the river's water level surging more than twice the level seen in Nile floods right before the construction of the Oswald Dam, whose construction led to essentially

the stoppage of the river from flooding anymore. Because of how volatile and voracious the ancient Nile floods were, it is often referred to as the wild Nile period. And during this phase in the river's history, much of Egypt would have been impacted by these flooding events. And it was in fact so bad at times that large swathes of land surrounding the river were simply inhospitable to permanent human populations, leading to this otherwise fertile area being left essentially untouched. Yet, when looking at the bigger picture, it was clear that this expanded Nile did mean a lot more opportunity for life, as it created more diverse and farther-reaching environments compared to the present one, leading to an abundance of aquatic remains being attributed to it, including numerous

species of catfish, now perches, mollusks, toads, turtles, tilapia, clams, and a much more healthy population now crocs that virtually inhabited every part of the river, opposed to now with a range being far more limited. And though it has never been corroborated by evidence, it is also highly likely during this time that bull sharks could have ventured into the area as well. Now, around the Nile itself, life is plenty too, with large groups of gazelle, hippos, rhinos, buffaloes, hyenas, wildebeest, zebras, elephants, and more calling it home. So in other words, it was a lot like the Serengeti from a fauna aspect, but just much more crazy and chaotic. And even birds might have shifted their migration patterns in response to the Nile's pure bulk. However, even with all of this said, not even the Nile was the Sahara's crowning body of water in this age.

No, instead it was a lake that still exists today, but back then was on a whole other level. And this is Lake Chad, a freshwater lake which serves as a junction for Nigeria, Niger, Chad, and Cameroon. It is one of the continents, larger lakes, yet at the time it was far, far bigger, being should I say, a Mega Chad lake. Get it, Lake Chad, Mega Chad. And I mean this, by the way, literally, as during this part of its history, it was actually known as the Mega Chad Lake, the largest in the planet at the time. At its maximum extent, the megachad might have been 620 miles long and 370 miles wide, submerging the entire Baudelae Depression and covering up to 8% of the entire Sahara,

meaning it had roughly the same surface area as the Caspian Sea. In fact, its sheer size was so grand that the climate in the region was even being influenced by its presence alone, lowering precipitation as he moved more inwards to the center, while then along its edges and surrounding areas, rainfall would have been magnified. Yet, despite stretching out farther than the eye could see, this Paleo Lake was surprisingly shallow, having a maximum depth of around 600 feet or 182 meters, which obviously isn't anything to scoff at, but it still makes it shaller than all but one of the great lakes, like Erie, despite having a greater surface area than all of them combined.

This said, it was still deep enough for plenty of life, which likely mirrored the fauna scene in the Nile. Although organisms here, primarily the aquatic ones, possibly grew to larger sizes given the deeper water. While then there is also evidence that bodies of waters with deeper waters, in other words, lakes, served as more permanent locations for herds of terrestrial animals during the Green Sahara. So at the very least, we know that going here would be a safari like no other. But it wouldn't be all that foreign or exotic, as one animal amongst the crowd was a very familiar one. And I'm talking about us. Just like other animals, our species, repopulated the Sahara as well, once I'm wasted up.

And boy oh boy, did we repopulate it, with a region turning into an extremely important hub for many different cultures. Now, it's unknown exactly where the first humans in the Green Sahara came from, but it's believed that they started showing up about a thousand years after the humid period started, and from there a kind quickly increased, with groups spreading out across the entire region, inhabiting a wide range of environments from mountain ranges like the Akakus Mountains to the shores of ancient paleo lakes and megalakes that once littered the lands. And just as the range was diverse across different groups, so were their homes, with many cultures utilizing caves and rock shelters,

while others built more human structures, let's say, typically along the water's edge. And as a result of the sheer widespreadness of people in this time, it's actually the Sahara that holds the highest density of petroglyphs and rock paintings on the entire planet, with each certainly giving us a unique window into what the Green Sahara was truly like. What's also fascinating is that many of the areas known to have been inhabited by humans seems to have been inhabited. for exceedingly long times, with some places even showing signs of residency lasting for thousands of years. An large part of this had to do with the stable water sources that were obviously of utmost importance to numerous, if not all, groups, with many relying heavily on fishery and the

overall resources that lakes and rivers provided, leading to some of the culture of the Green Sahara, in fact being referred to as aquilithic, just given their reliance. And with living by them, humans were able to experience such an abundance that some groups even left signs of recreational and leisurely activities in the archaeological record. So, quite a strong sign that life in the Green Sahara could be very good. The transformation of desert into a boundful land also allowed the people of the Sahara to make substantial progress from a technological standpoint as well. As along with hunting large animals in the typical fashion, we also see that people began

to acquire food through domesticating cattle, goats, and sheep, with a practice becoming widely popular about 7,000 years ago in the Sahara, which then also led to a second and even more pronounced population boom. It was around this time, the scientists additionally believe that cultures progressed from the middle stone age to the late Stone Age, showing refined blade technology, more complex art, and a gradual shift to permanent settlements that relied on farming. And among the many discoveries that have come out of the region, the Green Sahara was also seemingly responsible for some of the oldest cemeteries and ships made by people, which is kind

of obvious that they're made by people and, well, not aliens, but you give my point. and this is yet another indication of how all people were doing here. So, in more ways than one, this was the golden age of the Sahara. Yet, like all golden ages, it too eventually had to come to an end, as so is evidently clear by the massive desert that now lies there. But this does then beg the question of, how does something so lush, green, and expansive transform back into a desolate area so quickly? Well, similar to why the Sahara was brutal long ago and why it became green, it seems again

that the answer has to do with climate change. As about 5,500 years ago, the world's orbit changed once again, and the globe saw cooler temperatures arise, leading to the monsoon's weakening once more. And as a result, the Sahar started to dry up almost scarily fast, as within a very short time, vegetation started to wither and die, and those oh so precious lakes started to shrivel up once again. Now, some researchers believe that this great dying would have occurred from north to south, and that if you had lived in the south, you may have been protected from its effects for an additional couple thousand years or so. But wherever you were, the aridity still came eventually. And as the greenery and lakes vanished, the impacts of this event were only magnified,

as wind erosion increased, and so did dust production. This especially included the area around the now shrinking Megachad Lake, in the Bodele Basin, which slowly went from blue to a giant pit of dust, which is now also, by the way, the largest single source of dust for the entire planet. And you can bet that while the desert we know of today, slowly, or rather quickly consumed more and more of this paradise, that the region once again experienced devastating local extinctions. Well, then our kind was also greatly impacted as well, with there being a clear shift from abundant, frequent permanent settlements to very few ones, and an increased number of mobile cultures as well. And within as little as 500 years, we had gone from this,

basically what you see before you today. It was really that quick. Now, it's definitely sad that the Green Sahara is no more, but you may have noticed by this point that the region seems to go through phases, and as such it turns out that we might not have to wait that long, geologically speaking, that is, for the Green Sahara to be reborn once again, as orbital projections indicate that they can turn back into this lush paradise in as little as 10,000 years. On top of that, the erudification event might not have been all that bad either, as it did lead to other developments for humanity, the big one possibly being ancient Egypt. Specifically, as life deep in the Sahara became more impossible due to aridity, people had to adapt and move to more fertile spots,

including one spot that during the Green Sahara had been essentially inaccessible. And yes, I'm talking about again, the Nile Valley. At this point, the Nile dried quite a bit and trunk, revealing a valley that was very fertile and still offered a great water source. And so this led to a surge of people come into this area seeking salvation and ultimately helps set the stage for unified Egypt, with upper and lower Egypt completing unification right around this time, about 3,000 BC. So, who knows, maybe if the Green Sahara never ended, we would have never had pharaohs or any of those cool shows on the History Channel. Thanks for watching, and until next time, on Extinct Zoo.

Two and five Canadians will hear the words you have cancer. That's why every step and dollar raised matters. September 19th, join thousands in Toronto for the Princess Margaret Cancer Foundation Walk. Challenge yourself, friends, and family to walk 21 kilometers in support of life-saving research. Together, we can carry the fire and help create a world free from the fear of cancer. Register today at pmcfwalk.ca.ca.ca.