Ancient humans used plants to build sturdy seafaring boats over 40,000 years ago

Ancient humans living across Southeast Asian islands over 40,000 years ago were not drifting on rafts, waiting on currents and luck to decide their path. They were building seaworthy boats and fishing the open ocean using fiber and tools built with plants.

Stone tools and animal bones from the Philippines, Indonesia, and Timor-Leste point to deliberate voyages over deep water.

The work centers on Wallacea, a stretch of islands between Asia and Australia with channels that demand purposeful crossings seasonally.

Building tools and boats with plants

Traceology, the study of microscopic tool wear and residues, links many artifacts to the processing of tough plants for ropes and bindings.

The study noted that identifying boat-building materials through direct or indirect evidence is essential for understanding how people once moved across and between islands.

Those traces show scraping, polishing, and edge rounding tied to fiber extraction from bark and leaves. The repeated patterns point to planned tasks rather than one-off, opportunistic use.

In the Philippines, fish bones from Bubog I and Bubog II, coastal cave sites on Mindoro Island, and Bilat Cave document fishing traditions spanning at least 30,000 years. That long record suggests flexible strategies that changed with coasts, reefs, and tidal channels.

Use-wear, tiny damage accrued during real-world tasks, helps separate tools used on wood from those used on softer plant fibers. The patterns match tasks needed to twist cords, caulk seams, and lash outriggers.

Evidence from the deep

Jerimalai Cave in East Timor preserves a vivid piece of the picture, including open-ocean fish and very early shell hooks in littered layers.

A study reported remains of various pelagic and other fish species that point to advanced deep-sea fishing skills.

Pelagic, living in the open ocean far from shore, fish such as tuna and shark do not patrol shallow bays. Catching them points to boats, strong lines, durable hooks, and confident navigation in blue water.

Hooks made from shell at Jerimalai are the earliest definite fishhooks yet found, archaeologically. Their presence fits wider signs that lines and nets were part of everyday gear across Island Southeast Asia.

Deep-sea species appear alongside near-shore catches in site layers, revealing mixed strategies guided by seasons and habitat changes. That blend reflects people who understood currents, feeding grounds, and risk on the water.

Rethinking early boats

A common idea holds that early crossings rode the currents on bamboo rafts. Experimental projects have tested that picture with mixed and often discouraging results in strong flow.

A 2025 team built a cedar dugout with replica tools, then paddled from Taiwan to Yonaguni over 140 miles in roughly 45 hours. Their bamboo and reed rafts failed repeated trials against the Kuroshio current.  

Dugout canoe, a boat carved from a single log, works without complex joints but needs heavy woodworking and large timbers.

Wallacea toolkits around 40,000 years ago were dominated by small flakes, not adzes suited to hollowing trunks.

That is why Fuentes and colleagues emphasize plant-based boats built from multiple parts lashed by strong cordage. Fibers twist into ropes that bind planks, outrigger booms, ribs, and frames for balanced travel.

Why this matters

The pattern matters for more than craft history or bragging rights about who did what first. It signals planning, seasonal knowledge of fish runs, and social know-how to build, crew, and maintain vessels safely.

These skills echo in later migrations across large archipelagos, where planning, memory of routes, and hand-built gear made long voyages possible.

The Austronesian expansion that began about 4,000 years ago spread people and languages across the Pacific and Indian Oceans.

Behavioral modernity, the capability for complex, symbolic, and planned actions, shows up in rope making, hull assembly, and coordinated fishing.

It also appears in long-distance exchange and shared seafaring traditions between neighboring islands.

Island Southeast Asia sits at the meeting point of major currents, monsoon winds, and diverse coasts. That geography rewarded navigators who tracked seasonal shifts and tuned voyages to safer windows.

Context in a bigger world

A paper reports that researchers have found early direct evidence for fiber technology in Europe. A tiny three-ply cord from Abri du Maras in France dates between 41,000 and 52,000 years.

That find shows fibercraft was available to ancient peoples in more than one region. It also underscores how rare such objects are when plants and wood usually vanish from cave deposits over time.

Southeast Asia’s record relies heavily on stone clues and fish bones, which survive far better in the tropics. That makes the consistent tool traces for fiber extraction especially persuasive when viewed across many sites and layers.

Comparing regions is not a scoreboard because preservation varies by climate and cave chemistry. Tropical heat and microbes erase fibers quickly, so indirect clues carry more weight in Island Southeast Asia.

Where the evidence fits

Boatbuilding with stitched seams and plant lashings can be done with simple cutting, scraping, and smoothing tools.

That approach reduces reliance on heavy adzes, metal fasteners, or large trees, and it fits resource constraints on small, forested islands.

Outrigger, a float attached to a hull for stability, makes narrow boats safer in choppy seas. Lashings allow quick repairs, so a crew can tighten joints, replace booms, and keep moving even after hard landings.

Fiber technologies supported fishing as well as travel in these islands, linking harbors, fishing grounds, and camps with dependable ropes and knots. Strong ropes control anchors, handle sail rigs or paddles, and haul heavy nets during short, intense runs when schools pass close.

In stitched boats, every seam must be kept tight against pounding surf and daily swell. Waterproofing with sticky plant resins, plus regular re-lashing, kept joints reliable during long coastal runs.

Plants, stones, and boat tools

Lithic, stone made or shaped by humans, tools dominate late Pleistocene kits in Wallacea. Flake edges can slice bark, split stems, and abrade rough spots without leaving large wooden chips behind.

Microscopic residue studies reveal plant fragments adhering to edges where they were gripped or cut. When paired with patterned wear, those residues strengthen the case for fiber work tied to ropes and bindings.

Variation across sites shows people adjusted techniques to local plants, tides, and shorelines. That flexibility is a hallmark of skilled mariners who work with moving water and irregular coasts.

Controlled experiments can recreate edge rounding and polish by scraping fresh, wet fibers in measured bouts. Matching those trace sets to cave tools helps translate microscopic marks into clear actions and time on task.

Studying ancient plant-built boats

Archaeologists are cautious with claims based on what is missing rather than what is present. Wood and plant fibers rot in tropical caves, leaving us to read stone tools, fish bones, and residues with care.

That is why the call for experiments is so useful and timely, turning careful hypotheses into tested models with measurable performance at sea.

Building boats, testing cordage, and sailing controlled routes can connect artifacts to real performance and navigational choices at sea.

New work will try controlled fiber extraction with the same stone tools seen in caves. Teams will test rope strength, knot types, and seam lashing under wet, salty conditions that mimic long trips.

A clearer view of early seafaring will not rank cultures like a scoreboard or contest. It will show how people solved hard problems with local materials and careful observation over many generations.

The study is published in the Journal of Archaeological Science.

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