How Did Humans Contribute to the Megafauna Extinction Around 10,000 Years Ago? — Here’s What Researchers Found Out

Over 10,000 years ago, Earth was filled with huge and powerful creatures called the megafauna. They are generally accepted to be at least 45kg or 99lbs up to and beyond 1000kg or 2200lbs. It includes animals like woolly mammoths, woolly rhinoceros, saber-toothed cats, and dire wolves. However, a vast majority of them are extinct now.

This mass extinction happened around 10,000 years ago during the Late Pleistocene epoch, and even thousands of years before that. This event was primarily attributed to two significant factors, which are climate change and big game hunting. So, we already know that humans played a role, but just how big was their influence on the disappearances of the megafauna? Let’s dive deep into this question and explore the evidence that supports each idea.

Hunting Pressure: Humans as Big Game Hunters

One of the strongest ideas was that humans, both Homo sapiens and other hominins, may have hunted megafauna and reduced their population until they couldn’t reproduce fast enough to recover. Large animals like woolly mammoths and other mammals multiply slowly. This is because of a complex evolutionary adaptation and trade-offs that led to them having fewer numbers but longer lifespans.

Their large size protects them from predators, which also allowed for a longer developmental period and slowed aging. These are survival strategies that are more favorable in stable environments, but they are prone to greater risks when this very environment changes, such as by climate shifts or the arrival of a smart predatory species like humans.

In other words, the human hunters presented a new selective pressure that megafauna may not have been adapted to. Humans, especially Homo sapiens, were unlike any other predators that these large creatures were accustomed to. Instead, they were technologically smart, and hunts coordinatedly in greater numbers.

Most carnivorous animals, like big cats, may have been limited by physical constraints, but humans could target almost any size prey. So, the survival strategy that helped the megafauna survive for possibly millions of years became their critical weakness when an intelligent predator migrated to their natural habitats. Additionally, humans were not their only problem, as a new environmental shift was also underway.

Read more: ScienceDaily

Habitat Change and Climate as Supporting Factors

Did Humans wipe out Megafauna?

Humans played a very big role in the extinction of megafauna, but climate change may have contributed just as much, if not more. Earlier, it was mentioned that there are evolutionary trade-offs for the survival strategy of large animals. In stable environments, where there are a few predatory threats, it may be more evolutionary advantageous to become bigger with a long lifespan, slowed aging, and prolonged periods of growth.

However, if their habitat changed, the longer developmental period and typically fewer but larger offspring could become liabilities instead. The resources became more scarce, and the already small population of megafauna children could now be endangered. This may be just what happened during the Late Pleistocene epoch, where their numbers dwindled.

After the last ice age, around 10,000 years ago, ice sheets melted, and the overall landscape changed around the world. This could have created fragmented habitats of megafauna, which isolated their groups. A smaller population meant being more vulnerable to environmental and biological diseases due to a lack of genetic diversity. Then, in those small pockets of ecosystems, humans may have pushed various species into a state headed to extinction.

Regional Differences: Where Human Impact Was Strongest

Both humans and climate change affected and contributed to the megafauna mass extinctions thousands of years ago. However, it did not happen all at once, at the same time, and in the same places. Instead, in specific places where humans arrived later on, or where large animals coexisted with human hunters, the impact was different.

For example, in Africa, where Homo sapiens evolved and spent most of their time, some of the megafauna survived until today. It may be because they were able to adapt and coevolve with early humans, reducing the extinction rates of various species. Some survivors are African bush elephants and hippopotamuses, both of which co-existed with hominins for millions of years.

On the other hand, places where humans arrived later, like Australia and the Americas, suffered a sharp decline of megafauna species once the smarter hominins arrived. It may be because they have not had the chance to evolve and adapt to the predatory pressure that humans presented.

These regional patterns and differences are often key evidence that support the idea that the mass extinction of megafauna may be primarily driven by the arrival and spread of humans.

Read more: PubMed Central

Mechanisms and Models: How Humans Caused Collapse

WHAT KILLED THE MEGAFAUNA? | Mini Documentary

It is not enough to just say that megafauna were led to extinction because humans arrived and hunted them. These are creatures that may have existed for millions of years, so just how much hunting did the humans do to be able to cause their collapse? Here are some models and mechanisms that could explain what could have happened over 10,000 years ago.

First is the Blitzkrieg-like model or the rapid overkill hypothesis. Proposed by geoscientist Paul Martin, it suggests that humans arrived in megafauna’s habitats as smart and highly efficient predators. Early humans may have rapidly taken over and hunted enough numbers to make their recovery nearly impossible, since most are slow-reproducing species that did not have evolutionary adaptations to human hunters.

Another model could be the Sitzkrieg or a slow overkill mechanism. A hypothesis that suggests that the human hunting of megafauna did not immediately drive them to extinction. But rather, it took a slower and more prolonged period of predatory pressure. Early humans could have worn down the populations of megafauna species through repeated and persistent low-intensity hunting over a long time, until they became genetically and environmentally vulnerable to extinction.

There are a few other models for how human hunting may have pushed the megafauna’s population to decline. However, these two are the most significant, but even then, most scientists today have a multicausal view. It meant that they do not attribute the mass extinction to just any one reason, but instead a combination of factors, such as human hunting and climate change together.

Author's Final Thoughts

To answer the main title question, humans are believed to have contributed greatly to the extinction of megafauna around 10,000 years ago. However, they may also be just the last straw that pushes the already vulnerable and weakened population to the path of collapse. Climate change and other environmental factors may have also played just as big a role.

So, instead, scientists often have a multicausal view of what really happened thousands of years ago. All the different factors, may it be climate change, regional differences, habitat shifts, and human actions, could have caused the extinction of megafauna together at varying levels of impact.

The lessons that we could gain from this complex history, hopefully, should serve as a timeless reminder that our collective actions as a species, combined with environmental shifts, could forever reshape our world.

Read next: How Did Early Homo Sapiens Survive in Africa for Over 200,000 Years Before Spreading Worldwide? — Here’s What Scientists Found Out

References & Further Reading

Gill, J. L., Williams, J. W., Jackson, S. T., Lininger, K. B., & Robinson, G. S. (2009). Pleistocene megafaunal collapse, novel plant communities, and enhanced fire regimes in North America. Science. https://www.science.org/doi/10.1126/science.1179504

Nogués-Bravo, D., Rodríguez, J., Hortal, J., Batra, P., Araújo, M. B. (2008). Climate Change, Humans, and the Extinction of the Woolly Mammoth. PLoS Biology. https://doi.org/10.1371/journal.pbio.0060079

Malhi, Y., et al. (2016). Megafauna and ecosystem function from the Pleistocene to the Anthropocene. PNAS. https://www.pnas.org/doi/10.1073/pnas.1502540113

Abramson, G., Laguna, M. F., Kuperman, M. N., Monjeau, A., & Lanata, J. L. (2015). On the roles of hunting and habitat size on the extinction of megafauna. arXiv. https://arxiv.org/abs/1504.03202