When choosing a favorite animal, creatures like elephants, pandas, and lions are often at the top of the list for their larger-than-life personas. Known as charismatic megafauna, these species are among the most researched and are
all characterized by their massive size (typically over 100 pounds) and public adoration that’s often used to garner support for the conservation movement — it’s no coincidence that the World Wildlife Fund chose a panda as its logo.
Today, megafauna stand out for their size and charm. However, during the Pleistocene Epoch and the last ice age, colossal species like the woolly mammoth, saber-toothed tiger, and ground sloth ruled the Earth.
Roaming the mammoth steppe — an Arctic grassland spanning from Eurasia to North America — these species shaped the environment into a highly productive landscape crucial to carbon sequestration and permafrost regulation.
Once the Earth’s most expansive biome, the mammoth steppe supported as much biodiversity as the modern African savanna, until a megafaunal extinction wiped out 65% of the world’s large mammals around 25,000 years ago.
Referred to as the Late Pleistocene extinctions, these annihilations were concentrated in Australia and the Americas. Their catalyst remains hotly contested among the scientific community, although it’s believed that climate change and early modern humans played a significant role.
With the era typified by rapid climatic changes and the proliferation of early hunter-gatherer societies like the Clovis people, most credit the extinction to either the glacial-interglacial transition or an early example of overhunting, though uncertainty lingers.
“The megafaunal extinction at the end of the ice age was the biggest extinction event to happen since an asteroid slammed into Earth and wiped out all the large dinosaurs,” Emily Lindsey, Ph.D., associate curator and excavation site director at La Brea Tar Pits and Museum, told the National History Museum of LA County. “The problem has been that nobody has been able to determine exactly when most of these big mammals actually disappeared because the fossil record is really spotty. It’s hard to say much about what caused an extinction if you don’t know when it happened.”
The Massive Mark of Missing Megafauna
With the disappearance of megafaunal species like the woolly mammoth, the mammoth steppe ecosystem has also been lost, leading to some unfavorable environmental changes. As the steppe ceased to be dominated by megaherbivores and their predators, much of it was transformed into forests, an ecosystem that only exacerbated the changing climate by absorbing high levels of sunlight.
Today, the absence of the woolly mammoth has been further amplified as permafrost temperatures continue to rise by 0.6 degrees Fahrenheit per decade, threatening the release of an estimated 1,500 gigatons of carbon — double what our atmosphere currently contains. Given their massive size, woolly mammoths, as with most megafauna, are considered keystone species characterized by a disproportionate impact on their ecosystems relative to their populations.
Losing these keystone species can trigger what’s known as a trophic cascade, which can impact an entire ecosystem down to the composition of its vegetation. The loss of megafaunal keystone species has resulted in a variety of documented trophic cascades, including in Tasmania, where the loss of the thylacine (also called the Tasmanian tiger) has led to issues like an increase in diseases, invasive species, and wildfires.
The thylacine — which went extinct in 1936 due to excessive hunting, habitat destruction, and introduced disease — was once the apex predator of Tasmania, ensuring that the biodiversity hot spot was filled with healthy populations of local prey and predator species alike.
Since the thylacine’s extinction almost 100 years ago, the Tasmanian ecosystem hasn’t quite been able to recover, with the now-reigning largest carnivore — the Tasmanian devil — suffering from a nearly 85% population decline since the 1990s due to the highly contagious and fatal Devil Facial Tumor Disease.
“The thylacine was the only apex predator in the Tasmanian ecosystem, so no other animal was able to fill its place once it was lost,” said Andrew Pask, the head of the Thylacine Integrated Genomic Restoration Research Laboratory at the University of Melbourne, to NPR. “We have seen the impacts of this in the Tasmanian devil population, which was nearly wiped out by a facial tumor disease.”
Megafauna’s Colossal Comeback
Given the massive impact that megafauna have on their ecosystems, some scientists have started to advocate for the rewilding of these species as a progressive form of conservation. While most of these megafauna species are lost remnants of the Pleistocene Epoch, the thylacine and woolly mammoth — with their distinctly abundant amounts of preserved DNA — have led to unique advancements in the de-extinction process.
Now, Colossal is paving the way for the return of the two species — along with the dodo — with a modern woolly mammoth expected as early as 2028.
While similar in likeness and ecological importance to their extinct counterparts, these de-extinct species will be a product of gene editing and genetic engineering, requiring intricate, cellular-level edits of the extinct animal’s closest living relatives, the Asian elephant and fat-tailed dunnart being the current counterparts to the woolly mammoth and thylacine.
Colossal has been working with Pask and scientists around the world to foster breakthroughs in de-extinction like the proliferation and sequencing of ancient specimens, the development of artificial wombs for mammals and marsupials, and the creation of elephant induced pluripotent stem cells capable of differentiating into any cell in the body.
With over 42,000 species currently in decline, including keystone megafauna like elephants, lions, and rhinos, we are working against the clock to develop solutions that safeguard endangered species and reverse the effects of extinction.
As we continue to edge closer to the return of extinct megafauna like the woolly mammoth and thylacine, the hope is not only for these species to return their ecosystems to their former productivity, but for the science to provide a conservation toolkit that ensures their modern counterparts don’t suffer the same fate.
“Now more than ever, we need to build technologies to save critically endangered species as well as build a de-extinction toolkit that we can leverage to bring back lost keystone species, should we need to. And hopefully we won’t need to, but the current trajectory doesn’t look as positive as one would hope,” CEO Ben Lamm told USA Today.
While megafauna are known for their ginormous impact on the past, with the push toward de-extinction, their impact on the future could be just as big.
