Humans and The Megafauna Extinctions: A 50,000-Year Cautionary Tale

Around 50,000 years ago, two-thirds of the world’s megafauna became extinct. It wasn't just Wooly mamoths and Sabre-toothed tigers that disappeared. In Australia, 2,500kg Diprotodons the size of cars, towering Genyornis birds, and the fearsome Thylacoleo marsupial lion all vanished. We lost 90 per cent of our megafauna. Cassowaries, Emus, Crocodiles and Red kangaroos are just relics of what was once here.

So what caused this extinction wave? Analysis published by Cambridge University from eight scientists last year provides a stark answer: humans played the main role.

While climatic changes had an impact, it was people that pushed the late-Quaternary megafauna to extinction. And today, as we ride an even bigger extinction wave in the Anthropocene, this history holds some critical lessons.

So What Happened to the Megafauna?

The Cambridge paper systematically examined megafauna extinctions across the world during the late Quaternary period - about 50,000 years ago. It revealed a global pattern of loss driven primarily by human activity. From the America’s to Eurasia and Australia, the arrival and rise of humans coincided with collapsing populations of large animals.

While exact timings and causes varied by region, the interplay of human pressures and environmental changes created conditions for collapse of these species. Early humans targeted megafauna as a convenient food source. In the Americas, animals like mammoths and giant sloths faced relentless hunting pressure. And in Australia, similar overhunting most likely contributed to extinction of the Diprotodon and other large marsupials. Fire and other tools used by humans altered landscapes and disrupted ecosystems worldwide. In Eurasia, for example, forest clearing reduced habitats for mammoths and giant deer. Rapid climatic shifts added pressure to populations already stressed by humans. But this was secondary to human impacts.

Extinction of megafauna was a global phenomenon, with humans at the centre.

Parallels to Today

The same drivers of extinction - overexploitation, habitat destruction, and climate change - threaten biodiversity today. Just as the arrival and rise of humans marked the end for megafauna, industrialisation and unsustainable practices today are pushing modern species to the brink. From industrial-scale fishing to poaching, we’re emptying oceans, forests and savannahs at alarming rates. Land clearing for grazing, agriculture, mining, and urban expansion is fragmenting habitats and displacing countless species. And just as the megafauna faced ecological stress from aridification, today’s species are confronting a rapidly warming planet that is altering their habitats, and disrupting food webs and breeding cycles.

Lessons and Recommendations

The megafauna extinctions reminds us that our choices and actions have far-reaching consequences. They also offer three critical lessons for today:

1. Protect Keystone Species: Megafauna once played key roles in maintaining ecosystems - dispersing seeds, cycling nutrients, and shaping vegetation. Losing modern keystone species like elephants, cassowaries or whales could trigger cascading effects similar to those seen in ancient ecosystems. Conservation efforts must prioritise these species.

2. Restore and Protect Habitats: Previous modification of landscapes by humans was much less significant than today’s huge and unchecked land clearing. That's why safeguarding ecosystems and restoring degraded habitats must be central to conservation strategies. For Australia, Indigenous land management practices - such as cultural burning - should guide our approaches to land use.

3. Halt Climate Change: While climate wasn’t the primary driver of megafauna extinctions, it exacerbated the pressures they faced. Today, addressing climate change is non-negotiable for the survival of all species, including humans. The climate change we are experiencing is the most dramatic that has occured for at least 125,000 years. Urgently transitioning to renewable energy, protecting carbon sinks, and ending fossil fuel extraction are thus crucial.

The megafauna’s extinction is more than just history - it’s a cautionary tale. Our current impacts as humans on biodiversity and the climate are unprecedented. In the Anthropocene, over one million species are currently at risk of extinction, and scientists estimate that tens of thousands have already been lost. But this time we have the tools and knowledge to change course. We owe it to our planet, and ourselves, to rewrite the ending.

My aim in writing this blog is not to assign blame for past extinctions, but to highlight that unchecked human pressures, especially when coupled with climate change, are perilous for ecosystems and species, including we humans. The interplay of megafauna extinction drivers offers a critical lesson: while challenges of adaptation and coexistence are not new, they are now more urgent than ever. Our ancestors faced and navigated complex ecological pressures, and their stories can inspire us to find better ways to live and look after our planet.

What do you think about humanity’s role in the destruction of Nature and how we can learn from the past and turn the tide? Share your thoughts below and subscribe to my blog to stay updated on solutions for conservation and climate action.

Image from The late-Quaternary megafauna extinctions: Patterns, causes, ecological consequences and implications for ecosystem management in the Anthropocene.