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Sea levels rise and fall in response to complex planetary drivers, including shifts in polar ice caps, land masses, and other factors. Understanding these processes is crucial for studying prehistory in deep time, including human migration from Sundaland to Sahul and the movement of people around the globe. In this episode, Justin Dix breaks down what drives sea level change, how scientists reconstruct past sea levels, and how these fluctuations have shaped human history.

Key People

Justin Dix

Key Places

Bonaparte Gulf

Key Concepts

Gravity Earth Model (aka the lumpy potato)

Further Reading

Anthony Fogg, Justin Dix, Helen Farr. Late Pleistocene Palaeo Environment Reconstruction from 3D Seismic data, NW Australia.The ACROSS project - Australasian Research: Origins of Seafaring to Sahul. Authorea. January 06, 2020.

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In this episode, we speak with Before Us co-host Helen Farr about her European Research Council project, Australasian Colonisation Research: Origins of Seafaring to Sahul—or simply, ACROSS. This ambitious project dives into oceanographic, geoscience, archaeological, and archaeogenetic data to figure out when and how people first made the journey to Sahul, what routes they might’ve taken, and just how long they were stuck in a boat. Spoiler: it wasn’t a weekend trip. These early voyages don’t just tell us about getting to Sahul—they also help us understand the bigger picture of how modern humans spread around the world. Think of it as the original travel blog...but with fewer selfies and more science.

Key People

Helen Farr

Key Places

Bonaparte Gulf

Key Projects

ACROSS Project

Further Reading

Anthony Fogg, Justin Dix, Helen Farr. Late Pleistocene Palaeo Environment Reconstruction from 3D Seismic data, NW Australia.The ACROSS project - Australasian Research: Origins of Seafaring to Sahul. Authorea. January 06, 2020.

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The rapid dispersal of modern humans across Wallacea to modern day Australia not only required boat technology for long-distance sea travel, but also knowledge about deep-sea fishing. In this episode, we talk to Sue O’Connor about the different routes that people may have taken across Wallacea in the Pleistocene and how the different kinds of islands on those routes may have influenced maritime resource use and the earliest evidence of pelagic fishing.

Key People

Susan O'Connor - Australian National University

Key Sites / Concepts

Asitau Kuru / Jerimalai

O'Connor, Sue, Ono, Rintaro, and Clarkson, Chris. Pelagic Fishing at 42,000 Years Before the Present and the Maritime Skills of Modern Humans.Science334,1117-1121(2011).DOI:10.1126/science.1207703

Kisar

O’Connor, S., Mahirta, Kealy, S., Boulanger, C., Maloney, T., Hawkins, S., … Louys, J. (2018). Kisar and the Archaeology of Small Islands in the Wallacean Archipelago. The Journal of Island and Coastal Archaeology, 14(2), 198–225. https://doi.org/10.1080/15564894.2018.1443171

Laili

O’Connor, Sue, Ceri Shipton, and Shimona Kealy. "The southern route to Sahul: modern human dispersal and adaptation in the pleistocene." The Prehistory of Human Migration-Human Expansion, Resource Use, and Mortuary Practice in Maritime Asia. IntechOpen, 2023.

Shipton, C., Morley, M.W., Kealy, S. et al. Abrupt onset of intensive human occupation 44,000 years ago on the threshold of Sahul. Nat Commun 15, 4193 (2024). https://doi.org/10.1038/s41467-024-48395-x

Maritime Networks

O’Connor, S., Kealy, S., Reepmeyer, C., Samper Carro, S. C., & Shipton, C. (2022). Terminal Pleistocene emergence of maritime interaction networks across Wallacea. World Archaeology, 54(2), 244–263. https://doi.org/10.1080/00438243.2023.2172072

Pleistocene female burial with fish hooks

O’Connor S, Mahirta, Samper Carro SC, et al. Fishing in life and death: Pleistocene fish-hooks from a burial context on Alor Island, Indonesia. Antiquity. 2017;91(360):1451-1468. doi:10.15184/aqy.2017.186

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In this special bonus episode, Erich answers some of the fantastic questions that we've received from listeners around the world. If you want to send us your own questions about anything you've heard on Before Us, or just comment in general, please hit the "send us a text" button above every episode description. We would love to hear from you!

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The discovery of Homo floresiensis and Homo luzonensis in SE Asia raises big questions about what happened to some early populations of migrants. Here, John McNabb, explains how these discoveries re-shape our understanding of human evolution and human migrations, but also what the world was like when modern humans began to expand out of Africa. It may have been much more crowded than previously thought!

Key Site

Liang Bua

Mata menge

Dmanisi

Key People

John McNabb (Mac)

Mike Morewood

Key Hominids

Homo floresiensis

Homo luzonensis

Homo erectus

Denisovan

More Reading

Brumm, A., van den Bergh, G., Storey, M. et al. Age and context of the oldest known hominin fossils from Flores. Nature 534, 249–253 (2016). https://doi.org/10.1038/nature17663

Baab, K. L. (2012) Homo floresiensis: Making Sense of the Small-Bodied Hominin Fossils from Flores . Nature Education Knowledge 3(9):4

Détroit, F., Mijares, A.S., Corny, J. et al. A new species of Homo from the Late Pleistocene of the Philippines. Nature 568, 181–186 (2019). https://doi.org/10.1038/s41586-019-1067-9

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Why did humans migrate out of Africa? This question has long puzzled archaeologists. Were they driven by unknown pressures, drawn by opportunities, or was it something else entirely? Best-selling author and researcher Clive Gamble explores how curiosity may have fueled the human expansion out of Africa and how the development of the concept of 'containers' was crucial for technological innovations, such as boats.

Key People

Clive Gamble

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Sea levels have risen and fallen repeatedly over the last 2 million years. During low sea levels, large tracts of land were exposed along coastlines around the world, creating new habitats for plants, animals, and people to inhabit and new routes for people to move around the world. Now, many of these places are underwater, but evidence of these ancient landscapes, and the people who occupied them, still exists. In this episode we chat with Geoff Bailey and Hayley Cawthra about the challenges of working in coastal environments and reconstructing their submerged stories.

Key People

Geoff Bailey

Hayley Cawthra

Additional resources

2021. Bailey G, Cawthra HC. The significance of sea-level change and ancient submerged landscapes in human dispersal and development: A geoarchaeological perspective. Oceanologia

2020 Cawthra, Hayley C., et al. "Migration of Pleistocene shorelines across the Palaeo-Agulhas Plain: Evidence from dated sub-bottom profiles and archaeological shellfish assemblages." Quaternary Science Reviews 235: 106107.

2022. Hill J, et al. Sea-level change, palaeotidal modelling and hominin dispersals: The case of the southern Red Sea. Quaternary Science Reviews

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Around 170,000 years ago people living in sea caves on South Africa’s south coast were repeatedly collecting and eating shellfish from the nearby coastline. It marked an important behavioral shift from the occasional collection of aquatic resources to systematic relying on aquatic resources for survival. In this episode, travel to the UNESCO World Heritage Site of Pinnacle Point in South Africa to talk with Curtis Marean, one of the foremost experts on the origins and development of coastal foraging, about how the transition from opportunistic to systematic coastal foraging may have occurred and the unexpected impact that the shift to a true coastal adaptation may have had on the development of social cooperation.

Key People

Curtis Marean

Key Places

Pinnacle Point

UNESCO

Marean, Curtis W. 2016, The transition to foraging for dense and predictable resources and its impact on the evolution of modern humansPhil. Trans. R. Soc. B37120150239http://doi.org/10.1098/rstb.2015.0239

Marean, Curtis W. 2014. "The origins and significance of coastal resource use in Africa and Western Eurasia." Journal of Human Evolution 77: 17-40.

Marean, C., Bar-Matthews, M., Bernatchez, J. et al. Early human use of marine resources and pigment in South Africa during the Middle Pleistocene. Nature 449, 905–908 (2007). https://doi.org/10.1038/nature06204