If an approximately Earth-sized planet had a greater ocean-to-landmass ratio than Earth, and the minimum distance between continents was at least the width of the Atlantic (i.e. >3000 km), how could prehistoric humans settle all the continents? What level of technological development would be necessary to make ocean crossings of that length?

The largest landmass in this scenario is the size of Asia (~45 million sq km), and the other continents are no larger than North America (<25 million sq km).

I'm assuming that there were no convenient land bridges such as Bering Strait or the Timor Sea, but there are scattered archipelagos no larger than the Arctic Archipelago throughout the oceans.

EDIT I've started sketching out the map of this world, and shortest distances between adjacent continents looks to be about 3000 km, so I've revised the ocean crossings accordingly.

  • $\begingroup$ Any chance of an ice bridge between continents during an ice age? $\endgroup$ – Henry Taylor Jul 11 '17 at 3:06
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    $\begingroup$ They definitely could; evidence points to ancient polynesians using canoes to traverse the oceans. After all, they made it to places like Hawaii. I'm too lazy to find sources for this info though. $\endgroup$ – Phiteros Jul 11 '17 at 3:12
  • $\begingroup$ @HenryTaylor Possibly. The continents are fairly evenly distributed between the hemispheres (the largest is in the north), but the north pole is under a landmass slightly smaller than Greenland. $\endgroup$ – Robbie Jul 11 '17 at 3:23
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    $\begingroup$ For Polynesians travelling across oceans: en.wikipedia.org/wiki/Polynesian_navigation . With need and practice, apparently, you can navigate anything! $\endgroup$ – Layna Jul 11 '17 at 13:40
  • $\begingroup$ Michener's "Hawaii" is also a good background read for this, esp. the first few chapters. $\endgroup$ – papidave Jul 12 '17 at 16:15

The Polynesians get a lot of adulation for their ocean going Moana canoes. Yes, they got to Hawaii, Easter Island etc. But they were practically moderns. That was just a couple of thousand years ago.

The Australian aborigines got to Australia 70,000 years ago.
https://genographic.nationalgeographic.com/migration-to-australia/ This migration is amazing to consider because it implies that these ancients were seafarers on par with the Polynesians at an unimaginably distant time. To me this means considerable technological sophistication.

I think that other populations in the Pacific and Indian ocean are thought to be relics of this particular diaspora: the Andaman Islanders, the Negritoes in the Phillipines, some of the peoples of New Guinea.

In any case: stone age tech can get you across oceans.

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    $\begingroup$ I thought the prevailing wisdom was that Australian Aborigines walked across land bridges, and that the Timor Sea was a littoral region around 70,000 years ago? They seem to have come via Asia, and likely only embarked on short island-hopping trips rather than the several thousand kilometre journeys necessary in this scenario. (Clumsy phone typing messed up the first attempt at commenting) $\endgroup$ – Robbie Jul 11 '17 at 15:44
  • $\begingroup$ I think of a land bridge as something you walk across. The Wallace Line differentiating the fauna of New Guinea/Australia from that of Asia means that there must have been a reasonably substantial ocean barrier preventing animal transit. But: I did not notice the 12,000 km requirement in the OP. That would be a trip. $\endgroup$ – Willk Jul 11 '17 at 17:03

I think it depends on how far are the land masses from each other, what trees are available for rafts, and if there is enough pressure from other humans or predators to force them to the sea. There is also a need for a seafaring culture, like that of the Vikings, or Greeks.

Oceania was colonized by people who rode sea currents from South America (or so is the theory). To prove such theory, someone made a raft out of balsa wood and traveled for three months from Peru to Oceania islands. He also had 2 attempts to cross the Atlantic in a papyrus boat, the second being successful. The balsa raft in the first expedition was made with stone age technology. I don't remember where they were keeping their fresh water, though.

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    $\begingroup$ While Thor Heyerdahl idea of seafaring Americans is possible, if was later dispelled (see "Theory on Polynesian origins" in your link). It is now believed that Polynesia was settled from Asia/Australia. $\endgroup$ – Alexander Jul 11 '17 at 18:15
  • $\begingroup$ There is some evidence of contact between Polynesia and South America, even though the main route of colonisation was almost certainly from Asia. Sweet potatoes are native to the Americas but were widespread throughout Polynesia as a staple food by the time of European exploration. $\endgroup$ – Robbie Jul 12 '17 at 2:18
  • $\begingroup$ Oceania was not colonized from South America. This is not a generally accepted view. $\endgroup$ – kingledion Jul 12 '17 at 12:17

The prehistoric humans would have been locked to a single continent if it had not been for an unusual oceanic vegetation which evolved in the tropical regions. These human-edible plants grew out in vast floating fields like water hyacinth but thicker and closer knit together. Although they initially root in shallow water, they remain fixed to a specific location for only long enough to grow a few miles wide. Then the surface currents, which constantly push at the massive plant's sides, break its feeble roots free from the ocean shore, sending it out into deep water, where wind and wave can carry it to distant shores.

It was only a matter of time until foraging humans journeyed out onto the surface of one of the water plant during its shore-locked youth, then found themselves castaway on its floating island when the currents broke it free.

And like rats on the merchant ships of earth history, these prehistoric humans traveled to all the distant lands, leaving their prodigy everywhere in their wake.

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    $\begingroup$ Floating oceanic islands? Is it a work of fiction? $\endgroup$ – Alexander Jul 11 '17 at 18:22
  • $\begingroup$ @Alexander, absolutely fictional as far as I know. $\endgroup$ – Henry Taylor Jul 11 '17 at 18:30

It only depends on whether there are catchable fish in the ocean. There is plenty of evidence that very early humans (even non-humans, like Neandertal and Heidelbergensis (the predecessor of both Neandertal and Homo Sapiens)) knew how to tie nets and make flint knives and spears; and archaeologists have found carved animal bones that may have served as fish barbs (for spear points) and fish hooks from "prehistoric" (pre-technological) humans ten thousand years ago. Take a chunk of hard femur and use a rock or sharp flint to pare it into a shape you want. What else were you doing today anyway?

Fish alone, even raw, can supply enough protein and nutrients (eat the brains, eyeballs and organs) to keep humans alive for many years; no vegetables needed.

All you need next is seaworthy rafts and an ability to dive and swim; also in evidence from prehistoric times. See Thor Heyerdahls's Voyage of the Kon-Tiki, for example.

Also note that such rafts can be HUGE, the size of several football fields; and with pitch (waterproof tar widely used in prehistoric construction) and strong hair rope (animal or human hair), many smaller rafts can be made (say 10 yards square) and lashed together, making a resilient, flexible surface that is nearly impossible to overturn or sink. Especially if the inner material (I say inner because I presume it is covered by pitch) is reeds and wood that naturally floats; the platform may be swamped by a wave but will rise to the surface again anyway.

Such rafts can have shelter from the sun and precipitation built on board. Fresh water would be a distinct problem, but large skins full of fresh water are buoyant enough to be easily towed, and it is possible to capture rainfall in the ocean. Also water can be obtained through food metabolism (see here), basically fish blood has the same salinity as terrestrial blood, so does not create a salt-elimination problem for us.

Although I have never heard of any archaeological evidence of it, I think solar stills to distill seawater might be within the scope of prehistoric human technology, it isn't like they never saw water evaporate or condense. If nothing else, they could learn to follow the rain.

The answer is: Sea faring cultures could abound and live on the sea for years at a time, plenty of time to find other lands and colonize them, without any need for a terrestrial path, or any technology more advanced than what we have evidence for actually existing in prehistory.

Response to Comments about Raft Size

See The Benson Raft, as an example; circa 1906, a gigantic sea worthy cargo raft made of logs (tied together with chains not available to primitive people, but still, giant rafts of logs **can be ** seaworthy).

Here is an article on Pre-Columbian Rafts, made of bundled Reed and wood, often bamboo, these are tied together by hemp, and which mentions they were found as much as 36 feet long, with over 30 men, and 30 ton cargo capacity. Spanish explorers in the 1500's encountered them, and reported the rafts were almost unsinkable; because the were constructed so water just washed through them.

Note these particular rafts in South America only lasted six months to a year, but were not coated in pitch like early Egyptian rafts, which lasted for many years.

In my commentary response I discuss using timbers to make rafts, which I consider viable. Bamboo is another very popular alternative and seaworthy.

But rafts are not the only option: early sailing ships where constructed of timbers with pitch or tar for waterproofing, and iron or metal is never a necessity in wood-working. We have all heard of dove-tail joining; and woodworkers can create dozens of similar locking mechanisms to join wood by simple carving; I have seen an hourglass kind of join for joining boards edge to edge, for example.

The question isn't necessarily about the materials or the shape of the ship, just whether primitive humans could build something to live on the ocean for years. All oceans, if heated by a sun, will have convection patterns that circulate between continents. An ocean-going tribe caught in a storm might well find themselves on something like our Gulf Stream and transported to another continent, which they might choose to colonize, especially if they are the first intelligent species to set foot there, and don't want to risk trying to find their way home (Ocean streams are one-way streets, the one that brought you to point B won't take you back to Point A.)

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    $\begingroup$ Do you have any sources to back up the maximum size of a prehistoric raft? 50 square metres (~1 football field?) and up seems rather large, even if it was made from lots of smaller ones lashed together. $\endgroup$ – Robbie Jul 11 '17 at 14:40
  • $\begingroup$ A raft like that would be destroyed in 2 seconds by an ocean wave $\endgroup$ – Andrey Jul 11 '17 at 16:30
  • $\begingroup$ @Robbie I have read that, but I also have logic: There are trees 50 feet tall. by "prehistoric" I mean people just as capable of creative problem solving as modern humans, with at least stone tools, stone axes and hammers, strong ropes, levers, rollers. Such people built Stonehenge, the heaviest single stone there weighs about 45 tons and was somehow transported from the Marlborough Downs 18 miles away. Supposing 30 ft of tree can yield an 18x18 inch sq timber; we need 20 for a 30x30 ft raft. I think we'd figure out how to securely connect them on our very first try, even without any metal. $\endgroup$ – Amadeus-Reinstate-Monica Jul 11 '17 at 18:43

There are many animals (birds spring to mind, but you also have Turtles and Butterflies off the top of my mind) that use techniques to return to mating or birthing grounds for generations (the Monarch Butterfly is especially noted as the "flock" will never return to the same mating grounds in the life time of any individual). Humans being a pack hunting persistent predator relied on covering a lot of ground for a long time to wear down their prey (we're also the best animal for speed in an Ultra-marathon... a 100 mile race). Even among paleolithic man, a set of Wayfinding skills would quickly develop as we would be required to bring food back to feed the rest of the tribe. These same skills can easily be employed by humans on an ocean surface. Early man most likely quickly developed skills to identify the changes in the sky (shadows on the ground, in relation to a landmark of some kind can help determine direction... location of the stars at night might also be vital as night time hunting would be better for prey).

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