- A suite of studies recently published in the Proceedings of the National Academy of Sciences examine human interactions in the tropical environment from the Late Pleistocene to the Holocene and what’s now known as the Anthropocene.
- According to the editors of the volume, tropical forests are the most threatened terrestrial settings after the polar ice caps.
- Many of the studies found that humans have been living in the tropics and using its resources for millennia, impacting local ecosystems and biodiversity.
- The studies challenge the concept of the Anthropocene as a defining moment in history in which humans became a force that shaped nature.
Ostrich-shaped but elephant-sized, a species known as the elephant bird once roamed Madagascar’s tropical forests. But close to a thousand years ago, these giant birds slipped into extinction. Now all that remains of elephant birds are their fossilized skeletons and shards of their hard-shelled eggs. While experts are still debating the exact reason for their disappearance, humans most likely played a role.
The disappearance of elephant birds in Madagascar is just one example of how humans modified the composition of tropical forests well before the advent of the so-called Anthropocene, the proposed epoch defined by human modification such as large-scale land clearing, pollution, and biodiversity loss.
Generally, the tropics tend to be overlooked as sites of human activity, say the editors of a recently published volume in Proceedings of the National Academy of Sciences (PNAS). Instead, these regions tend to be viewed as “blanks” on the map, partly because the tropics have previously been viewed as inhospitable places for human beings. The nine studies in the volume challenge this view by showing that humans not only lived in tropical habitats, but used their resources — and as a result, humanity had a substantial impact on tropical biodiversity, landscape structure, and even climate. The studies also challenge the concept of the Anthropocene, which has become popular yet controversial.
Patrick Roberts, an archaeologist at the Max Planck Institute for the Science of Human History in Germany and lead editor of the volume, says that looking at the wide breadth of history of human interactions with tropical forests can help us understand how to deal with today’s environmental issues.
“By 2050, over half of the world’s human population is going to live in the tropics, and they’re inevitably going to be relying on tropical forests for resources,” Roberts told Mongabay in a Zoom interview. “While there’s a lot of emphasis on replanting trees or keeping pristine reserves, there are issues with both of those policies that probably aren’t going to deal with the whole situation. So we have to understand how humans can live with tropical forests in a kind of more sustainable and interactive way as well.”
The past can give us clues about what we can do, he said.
‘More pressing than ever’
In the introduction to the PNAS feature, Roberts and his two co-editors state that the nine articles in the volume address at least one of a trio of questions: when did pre-industrial human societies occupy and impact tropical forests; how can we understand pre-industrial human land management in different parts of the tropics and their ecological and Earth system feedbacks; and how can the knowledge of anthropogenic impacts on tropical forests — ranging from humanity’s initial arrival in the tropics to the present day — help us plan for a better future?
“The diverse authors, topics, regions, and timescales covered in this volume are designed not only to address these themes, but also to encourage intersection between them, leading to a vibrant, interdisciplinary, and multivocal product,” the editors state in the collection. “Given that tropical forests are the most threatened terrestrial settings after the polar ice-caps, the integration of multidisciplinary datasets, and the use of the past to contribute to the present and future of the battle for human sustainability, is more pressing than ever.”
One study, which received widespread coverage on international news outlets, including The New York Times, was led by Pennsylvania State University’s Kristina Douglass. When analyzing the microstructural features of cassowary eggs, Douglass and her colleagues found that humans may have been hatching and rearing these large, flightless birds as early as the Late Pleistocene, which rewrites a narrative of the human relationship with tropical megafauna. Instead of merely killing them, humans helped raise them. Cassowaries continue to exist today in Australia and Southeast Asia. They’re known to be one of the most dangerous birds to humans, which makes their past relationship with humans even more remarkable.
Research by Zhuo Zheng and 12 co-authors, including Roberts himself, examined how early rice agriculture in China and Southeast Asia indelibly altered local ecosystems by driving out the Chinese water pine (Glyptostrobus pensilis) from the landscape.
A team of researchers led by Northumbria University Newcastle’s Neil Duncan co-authored a paper that argued that pre-Columbian people of the Amazon changed the hydrological conditions of the local climate through the use of hydraulic engineering and fire.
Another study, led by Indigenous researcher Michael-Shawn Fletcher, examines more than 50 case studies from tropical ecosystems in Southeast Asia, the Pacific, Australia and South America to show how Indigenous peoples have “valued, used, and shaped ‘high-value’ biodiverse landscapes for millennia.” They argue that the European concept of protecting the pristine “wilderness” from human destruction is flawed, and that Indigenous and community land areas need to be legally recognized to enable “socially just, empowering, and sustainable conservation across scale.” The study also challenges the concept of the Anthropocene since it suggests that preserving or restoring land to “wilderness” will be the “antidote” to the human-induced crisis we currently find ourselves in.
Do we need to redefine the ‘Anthropocene’?
The views proposed by Fletcher and his colleagues are supported by other experts, including Lisa Kelley, a critical physical geographer at the University of Colorado.
Kelley, who was not involved in this PNAS volume, says the study led by Fletcher shines a much-needed light on the myth of “wilderness,” a topic she says has resurged “under the guise of the ‘Anthropocene’ and the catastrophic thinking characteristic of it.” She adds that Western thought tends to view nature, and particularly tropical nature, as only holding value when it can be strictly protected against human use, or deliberately used for yields and profits.
“These politics have long been used to dismantle Indigenous and local communities’ sovereignty over lands and waters, including at present through the sale and leasing of Indigenous and local lands to corporate entities for industrialized resource extraction,” Kelley told Mongabay in an email, “and through conservation approaches which extend power over the protection of ‘high-value’ conservation areas to many of these same entities through public-private partnerships.”
Study collection lead author Roberts agrees there’s an issue with the concept of the Anthropocene, especially since the majority of planetary destruction stems from Western practices such as the colonization of land.
“The problem with the Anthropocene … is that the Anthropocene implies that all humans are responsible for it, and that we’re all in it together,” Roberts said. “But what the last 500 years show is that a lot of these impacts are actually the product of colonialism, and more recently industrialism and then capitalism. In Europe, we’ve burned the vast majority of fossil fuels. Same [as] in North America. How can we then say to people in the tropics: stop burning fossil fuels?”
Jan Zalasiewicz, a geologist at the University of Leicester and member of the Anthropocene Working Group, who was not involved in the PNAS volume, says he doesn’t think the Anthropocene needs to be redefined, at least in terms of it being considered a geological time unit.
In a paper he co-authored, the Anthropocene is identified as starting in the 1950s, although this idea is debated.
“This long, diffuse history [of human influence on the terrestrial environment] — the roots of the Anthropocene — contrasts markedly with the marked, globally synchronous onset of major changes to the Earth System that represents the change to an Anthropocene state as understood geologically and in Earth System science, sharply distinct from that of the Holocene,” Zalasiewicz told Mongabay in an email.
However, he says the PNAS volume provides a “useful set of papers” that contribute to the study of human interactions with the environment dating back to Late Pleistocene times and extending into the Holocene epoch. The studies also show how Indigenous peoples managed to live on Earth without inflicting the same level of destruction as seen today, he said.
“They show the great variability of these anthropogenic influences in time and space,” Zalasiewicz said. “A striking feature common to several of these studies is that many Indigenous peoples could co-exist sustainably with their local environment for thousands of years, and with little perturbation of the major parameters of the Earth System such as climate and sea level.”
Citations:
Douglass, K., Gaffney, D., Feo, T. J., Bulathsinhala, P., Mack, A. L., Spitzer, M., & Summerhayes, G. R. (2021). Late Pleistocene/Early Holocene sites in the montane forests of New Guinea yield early record of cassowary hunting and egg harvesting. Proceedings of the National Academy of Sciences, 118(40), e2100117118. doi:10.1073/pnas.2100117118
Duncan, N. A., Loughlin, N. J., Walker, J. H., Hocking, E. P., & Whitney, B. S. (2021). Pre-Columbian fire management and control of climate-driven floodwaters over 3,500 years in southwestern Amazonia. Proceedings of the National Academy of Sciences, 118(40), e2022206118. doi:10.1073/pnas.2022206118
Fletcher, M., Hamilton, R., Dressler, W., & Palmer, L. (2021). Indigenous knowledge and the shackles of wilderness. Proceedings of the National Academy of Sciences, 118(40), e2022218118. doi:10.1073/pnas.2022218118
Roberts, P., Hamilton, R., & Piperno, D. R. (2021). Tropical forests as key sites of the “Anthropocene”: Past and present perspectives. Proceedings of the National Academy of Sciences, 118(40), e2109243118. doi:10.1073/pnas.2109243118
Syvitski, J., Waters, C. N., Day, J., Milliman, J. D., Summerhayes, C., Steffen, W., … Williams, M. (2020). Extraordinary human energy consumption and resultant geological impacts beginning around 1950 CE initiated the proposed Anthropocene epoch. Communications Earth & Environment, 1(1). doi:10.1038/s43247-020-00029-y
Zheng, Z., Ma, T., Roberts, P., Li, Z., Yue, Y., Peng, H., … Saito, Y. (2021). Anthropogenic impacts on late Holocene land-cover change and floristic biodiversity loss in tropical southeastern Asia. Proceedings of the National Academy of Sciences, 118(40), e2022210118. doi:10.1073/pnas.2022210118
Banner image caption: A Kichwa villager cuts down small trees using a machete, while her husband uses a chainsaw nearby. They are clearing an area to sow corn to feed their livestock near the Napo River, Orellana, Ecuador. Image by Tomas Munita/CIFOR (CC BY-NC-ND 2.0)
Elizabeth Claire Alberts is a staff writer for Mongabay. Follow her on Twitter @ECAlberts.
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