How Did Humans Cross Vast Seas Nearly 50,000 Years Ago to Arrive on Distant Islands and New Continents? — Here’s What Still Baffles Scientists

Around 70,000 to 50,000 years ago, the modern human species, Homo sapiens, was believed to have first successfully migrated out of Africa. They spread through the Middle East, Europe, and Asia; however, fossil records show that around this time, they also reached isolated and distant islands.

To do that, they had to cross the open and vast seas. Unfortunately, there were no signs left as to what they could have possibly used. But this in itself is a clue because it likely meant that they used materials that would not have lasted thousands of years. So, what exactly did early humans use to be able to manage such a big journey that changed the world we are living in today? Let’s explore what scientists have discovered about these ancient sea voyages and what still remains mysterious.

Where and When Did These Sea Crossings Happen?

Researchers believe that humans reached the landmass of Sahul about 50,000 years ago. This area pertains to Australia and New Guinea. However, to be able to get there, the early humans needed to cross the open seas from South East Asia through islands like Timor and Wallacea. These are sea voyages that extend up to 100 kilometers.

There are also some clues in other islands and archipelagos, like Mololo Cave in West Papua, Indonesia, that state Homo sapiens may have already arrived there around 55,000 years ago. These findings suggest that humans could have moved island to island before finally reaching Sahul.

Read more: Phys.org

What Tech and Skills Did They Probably Use?

Are We Missing an Ancient Sea-Faring Culture?

To make these multiple crossings, early humans needed to master certain tools and technology. First, they had to create some form of a boat, even if it was just a raft. Scientists think these simple boats could just be made from a collection of logs, bamboo, or mats. To bind and secure them together, early humans may have used plant fibers to create a rope.

Their ability to create even just a simple raft showcases their mastery of stone tools. Homo sapiens most likely used them to cut plants and wood, create ropes, bind materials, and craft a seaworthy vessel.

Navigation of these rough seas is not just random or by luck. Researchers believe that humans were able to see the islands from the coastlines. They are also probably aware of the natural wind and current patterns. The stars and the sun are their compass. Overall, this journey highlighted some of their unique traits as a species, which include their intelligence, ingenuity, and deep understanding of the natural world.

What Makes Some Journeys Really Baffling?

Since there were no actual vessels that were preserved and discovered from around that time, 50,000 years ago, experts relied on circumstantial evidence and even real-life simulations to understand how early humans crafted their seafaring vessels and how they survived the journey.

The colonization of Sahul, or Australia and New Guinea, is one of the most remarkable feats of the modern human species. It is simply because of the extreme difficulty of the sea voyage. The estimated sea crossings could reach 4 to 7 days, depending on the sea level and the distance to the next islands.

This meant that early humans had to carry fresh water and food, cross the open seas without getting seasickness, dying of sun exposure, and running out of resources. They needed good timing and planning to make sure the seas and the winds were navigable. Their journey also took multiple crossings of open waters, from island to island, of up to 100 kilometers.

Another puzzle was whether the sea crossings are accidental or intentional. Did they aim to get to a specific island, or did they just accidentally drift on floating debris while looking for food and other resources?

The evidence, like ocean drift modeling, suggests they were intentional. It is because reaching the landmass of Sahul was highly improbable by accidental drifting. They might not have had any sails back then, so another challenge was propulsion, which would have relied on paddling using sticks, their own hands, or wood.

These ancient sea crossings remain a significant source of debate and research because of how immensely difficult the journey is and the lack of direct evidence to support any claims.

While scientists rely on climate, ocean, and environmental modeling and analysis, the substantial difference between the conditions of the past and the present environments could mean that the results of the studies just offer insights and not direct proof.

Read more: NATURE | Australian Museum

Why These Crossings Were So Important

Crossing the Sea Like a Stone-Age Person: Scientists Recreate Epic Voyage

These ancient sea crossings changed human history and evolution in ways we usually take for granted. But reaching new lands and environments means humans were forced to adapt and change to survive. It contributed greatly to our genetic diversity and drove further innovation.

This single achievement marked humanity’s transition from terrestrial migration into the truly global expansion that extends beyond the seas. The people who crossed continents and the ones who crossed the waters to settle in islands developed slightly different features, languages, and cultures over time.

Since these sea voyages were more likely intentional, they have resulted in a technological leap that extended the use of stone tools beyond just hunting and gathering resources. This whole journey was not just an impressive feat of survival, but it was also an outstanding display of human ingenuity and determination.

Author's Final Thoughts

The modern human species crossed the seas around 50,000 years ago; however, there may have been other hominins that were already present in those islands before our ancestors even got there. So, these ideas just beg more questions, like did they also cross the seas using simple rafts, were they intentional, and how much of their journey was planned?

More research and debates would have to be done to find out the exact truth. However, one thing is for sure: the early human species were much more resourceful, daring, courageous, determined, and ingenious than we ever realized.

Read next: Why Did Ancient Tiny Human Species Homo Floresiensis, “The Hobbits”, Evolve to Be Just Over 3 Feet Tall? — Here’s the Evolutionary Theory

References & Further Reading

Clarkson, C., Jacobs, Z., Marwick, B., et al. (2017). Human occupation of northern Australia by 65,000 years ago. Nature. https://www.nature.com/articles/nature22968

Allen, J., & O’Connell, J. F. (2020). A different paradigm for the initial colonisation of Sahul. Archaeology in Oceania. https://www.researchgate.net/publication/338662872_A_different_paradigm_for_the_initial_colonisation_of_Sahul

Bird, M. I., et al. (2019). Early human settlement of Sahul was not an accident. Scientific Reports. https://www.nature.com/articles/s41598-019-42946-9

Bradshaw, C. J. A., Crabtree, S. A., White, D. A., et al. (2023). Directionally supervised cellular automaton for the initial arrival across Sahul. Quaternary Science Reviews. https://researchnow.flinders.edu.au/files/64928417/Bradshaw_Directionally_P2023.pdf

Kealy, J., O’Connell, J. F., Clarkson, C., et al. (2018). Least-cost pathway models indicate northern human dispersal from Sunda to Sahul. Journal of Human Evolution. https://os.pennds.org/archaeobib_filestore/pdf_articles/JHE/2018_125_Kealyetal.pdf

Davidson, I. (2010). The Colonization of Australia and Its Adjacent Islands: Why Geography Still Matters. Proceedings of the Royal Society B. https://www.journals.uchicago.edu/doi/full/10.1086/650694