The Water-Crossers

Science Magazine

One interesting and puzzling question is when and how humans  developed the ability to make ocean crossings.  Although much of the Indonesian archipelago turns into a peninsula during the glacial peaks (Sundaland), it’s never possible to walk to Sahul (Australia/New Guinea). I don’t think it was ever quite possible to walk to the main Philippine islands, either. Palawan had a land connection with Borneo at times of extreme glaciation, but the last time that happened was something like four hundred thousand years ago, well before modern humans.

Homo erectus had a limited ability to cross these water barriers, as far as we can tell. They seem to have managed to get to Flores (judging from old tools and of course  hobbits) , which meant that they had to make two short sea crossings, Bali to Lombok and then Lombok to Flores. Apparently some kind of tool-maker reached Timor as well, and some other islands of Wallacea.  But none managed to get all the way to Sahul – if they had, they would have spread widely and left plenty of very old stone tools, which have not been found.

Modern humans were better at crossing water barriers: they made it to Sahul and the Philippines. The two colonizing populations were evidently related – you can see this in some of the remaining Philippine Negritos, like the Mamanwa, that also have that characteristic Denisovan admixture. These people went on to colonize the Solomon Islands about 40,000 years ago, but  didn’t go further: after the Solomons  you have to cross 200 miles of open ocean to go further, and that didn’t happen until the Polynesians arrived, relatively recently.

This is hard to square with the fact modern humans apparently couldn’t manage to settle Cyprus and some other Mediterranean islands ( judging by the late survival of their odd fauna, such as 3-foot elephants)  until just a few thousand years ago, but that’s what it looks like.

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78 Responses to The Water-Crossers

  1. j says:

    Also the Andamanese crossed the ocean, and they had no Denisova ancestors. Maybe the Neanderthal and their half-breed descendants (we?) hated saltwater.

    • Rick says:

      But does anyone have a good idea when the Andaman islanders actually first arrived at their present location? Certainly they are genetically distant from South Indians, but that doesn’t mean they arrived in the islands 30,000 years ago.

      I think a related population also reached Australia about 4,000 years ago.

  2. john leah says:

    Homo erectus in Australia? J.P. White, Australian Archeology; 65, December, 2007

  3. dearieme says:

    Maybe populations were so small that everything turns on whether they ever had a member with the right sort of genius meeting the right opportunity. Maybe “me build raft” didn’t come along all that often.

    “modern humans apparently couldn’t manage to settle Cyprus and some other Mediterranean islands … until just a few thousand years ago”: now now, is this just you singing your old song that nobody else thought Levantines were especially clever?

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  5. BB753 says:

    Maybe unadmixed modern humans were dumber or less adventurous than populations with huge amounts of Denisovan or Neanderthal genes. Maybe “modern” humans were less advanced cognitively in certain areas compared to “archaic” Eurasian hominids. Perhaps fresh out of Africa humans ( as in 20, 000 years) were simply not that bright. Just speculating.

  6. Matt says: – This (via wiki) reckons that Crete was visited, as an island, 130,000 years ago.

    Earliest human remains on Sardinia 18,000 YBP supposedly.

    • Fourth doorman of the apocalypse says:

      I don’t know what the shallowest part of the path from the land around the Med to Sardinia is, but doesn’t that time frame correspond to the last ice age (or close to it) so it would seem conceivable that they walked there.

  7. Rick says:

    I think that Cuba was not connected to the mainland when it was first populated ~7,000 years ago.

  8. Fourth doorman of the apocalypse says:

    I would imagine that more complex feats of technology develop out of simpler beginning. That is, I would expect metallurgy to develop in cultures that already have a sophisticated ceramics technology.

    In a similar way, developing the ability to bridge shortish distances over the sea (say, 10 miles) would likely develop out of an already established coastal fishing or etc technologies? Or at least river craft …

    Maybe I am wrong on both counts.

  9. Patrick Boyle says:

    Maybe the water crossing by early man in the South East Asian area and not in the Mediterranean is just what you would expect if the these crossing were not purposeful but accidental.

    In the Boxing Day tsunami of 2004 hundreds of thousands of people were swept away – some inland and others out to sea. Presumably similar tsunamis have been experienced in that part of the world every couple hundred years or so for millennia. That might have happened to erectus grade populations.

    A single storm might sweep away a man who clung to a log across open ocean but even if he made it to shore he would leave no descendants. But a Boxing Day sized event might transport a small population which could gain a foothold on a distant shore. It would be hard to prove of course but it seems possible in that part of the world.

    • Steve Sailer says:

      Interesting idea. This part of Southeast Asia has lots of tsunamis (e.g., Krakatoa), while the Mediterranean has a more moderate number.

      Has anybody counted how many survivors in 2004 wound up on different islands? Of course, the population density is likely several orders of magnitude higher today. But maybe more people got rescued out at sea a few days later, while a few of them might have eventually washed up on distant islands without naval and air rescue patrols.

    • dearieme says:

      Seconded: it’s an interesting conjecture.

    • Labayu says:

      There was a guy who survived 8 days on some tree branches and was rescued 100 nautical miles from where he was swept out. Over the course of the first few days he saw a lot of other people alive in the water. They were headed the wrong direction to end up on land, but if they had been headed in another direction, several people could have ended up on land near each other.

      • Bob says:

        From the article:

        ” In an interview with the Telegraph from his home in Kuala Lumpur, Rizal, now 30, said that when he was swept up by the water on the morning of December 26 2004, he thought the world was ending. But then he realised he had not drowned and that “nobody is coming to rescue me”. He recalled his grandfather’s instructions on how to make twine from tree bark and began to assemble his raft. ”

        Chalk one up for nurture over nature!

        • jamesd127 says:

          I think we can reasonably assume that the average homo erectus, unlike the average modern urbanite, could make string from tree bark, so, finding himself at sea with some random tree branches, would be able to assemble a raft.

  10. Greying Wanderer says:

    Apparently a back-migration from SE Asia is a thing so crossing the Wallace line could be a sign that something happened down there which increased brain power and that increased brain power was both the reason for crossing the line and the back-migration.

    What might have lead to an increase in brain power – maybe all that coastline led to a very large effective population along the coasts creating the opportunity for adaptation and more brains meant out of reach island came in reach creating the motive?

    If so the brains might increase to the SE until there were no more islands and then back-migrate all the way to Cyprus.

  11. Hokie says:

    My guess is that gradient of edible fish has something to do with it. If if there are more fish further from shore, lots of reasons for people to take risk of clinging to log to go fishing. Then more chance for boat designs to be realized. If there are fewer fish further from shore, more reasons to fish more intensively on shoreline, so less chances for new boat designs to be realized.

    What are the fish density gradients like in Indonesia vs Mediterranean? My guess should be really easy to falsify.

    • Fourth doorman of the apocalypse says:

      That is an interesting thought. Shades of Jared Diamond’s claims about geography determining destiny.

      Pretty much all of the interesting regions in the map above lie between 10 degrees North and 10 degrees South of the Equator, while pretty much all of the Mediterranean is north of 32 degrees North of the Equator.

      Maybe that means something.

      • Asher says:

        yeah, did not realize that. very interesting.

        Also, Jared Diamond. Ewww

        • John Hostetler says:

          Diamond’s main problem is simply the gene scotoma he shares with fellow more-calor-than-luminaries Boas, Montagu-Ehrenberg, Gould and Lewontin. Amend it to ‘geography determines genes determine destiny’ and he’s approximately correct.

      • Patrick Boyle says:

        Jared Diamond’s claims about geography determining destiny.

        That’s not very surprising. Diamond is a geographer.

    • Asher says:

      Interesting. Still you’d have to infer that fish population patterns haven’t changed over the past several thousand years.

      • Fourth doorman of the apocalypse says:

        Except that I would expect fish population patterns to differ between the Equator and the Tropic of Cancer and for patterns to remain stable in the same geographic region.

        • Fourth doorman of the apocalypse says:

          and for patterns to remain stable in the same geographic region.

          Until there were enough people to overfish the region, but by then their sea-faring technology would be good enough to fish further afield.

    • Rick says:

      But then why would no other people make it to Australia for more than 40,000 years? If they were fishing and developing boats that whole time?

      There must have been something different about the culture of the first modern people that made it out there. Like an early version of the Polynesians.

      I don’t think the accident theory is reasonable, because there would have to have been several massive accidents happening quickly in series.

      • Fourth doorman of the apocalypse says:

        The Java/Sunda trench runs along Lydecker’s line between Irian Jaya and the rest of Indonesia.

        That trench is deep (7,000 M it seems), and even at the sea levels of the last glacial the distance between New Guinea (Irian Jaya) and the land masses of Indonesia would approach 100 km by the look of things.

      • dearieme says:

        “But then why would no other people make it to Australia for more than 40,000 years? If they were fishing and developing boats that whole time?” They did; there seem to have been Indonesian pearl fishermen who visited. I’d bet that there may have been Polynesians who touched on the Queensland coast too. But settling an already occupied territory where the inhabitants already know the lie of the land is not always easy. After all, it needed the mass die-off of Red Indians under infectious assault to make settling N America easy. A small party of Vikings from Greenland was never going to manage it.

        • Rick says:

          “They did; there seem to have been Indonesian pearl fishermen who visited. I’d bet that there may have been Polynesians who touched on the Queensland coast too.”

          Of course. And that is exactly what I meant by saying no one else showed up for 40,000 years.

          Some people must have brought dingos, likely the people distantly related to the Andaman Islanders that left a genetic trace in Australia.

          Also, it looks like the whole population was originally twice as high in Denisovan ancestry, but that was later diluted.

          • dearieme says:

            There is a pretty continuous population stretching from PNG across the islands in the Torres Straits, and down to the tip of Queensland. As for nobody arriving in 40k years: maybe it’s not Politically Correct to admit that not all Abo ancestry is that old. Or maybe the ancestors of the present Abos ate the people who had first settled. Who knows?

          • With the thoughts you'd be thinkin says:

            The Lake Mungo remains imply that the current Aboriginals are not the original people who settled Australia. Perhaps the Tasmanian Aborignals were a relic population.

            • jamesd127 says:

              Tasmanian type aboriginals (Mungo type) existed outside Tasmania to modern times, largely in the colder and wetter parts of Australia. They remained a separate and distinct “race” from the “mainland” aboriginals, which suggests that crossbreeds were rare and subfertile. They became extinct on the mainland as in Tasmania, possibly as a result of sex with white males, which was effectively non reproductive sex, and because their lands were more attractive to whites.

              Tasmanian aboriginals became extinct, and left no known mixed breed descendents. All tasmanian “descendents” with documented ancestry are descended from an aboriginal that was very clearly mainland type.

          • Anonymous says:

            Can you provide any reading material on the Mungo type aboriginals from Tsmania and Australia? They were so distinct as to not have viable children with modern humans, while neanerthald and denisovans could? This is extremely interesting I would love to read aboit this.

    • John Hostetler says:

      A key issue the specialists debate seems to be the origin of hook and line fishing, especially for scombrids (tuna, mackerel and bonitos). This group does have a lot more tropical representatives than Mediterranean, but if even the Mediterranean mackerel and the Atlantic bonito (the binomial – Sarda sarda – will appeal to all Westhunt fans) were as numerous in Mediterranean waters back then as they were in recent times, they should have been sufficiently enticing.

  12. jamesd127 says:

    During the recent ice age, south east asia/indonesia formed a peninsula off eurasia. Assume someone out to sea on crude flotation devices spearfishing, or on simple rafts fishing. Storm rises, blowing them eastwards. He or she will hit land, unoccupied by humans. So, feeling lonely, walks steadily along the coast, northwards or southwards. If there are two people in that land, and they both stick near the coast, will probably find each other.

  13. Rick says:

    The main problem I have with the tsunami hypothesis is the lack of most other placental mammals. The only placental land mammals to have reached Australia and New Guinea prior to 5,000 years ago were bats and rats, and both look like they arrived several millions of years ago, and as very small populsevera that expanded rapidly into new families.

    Not even one small group of monkeys, or apes , or squirrels, or mice ever got swept out to sea on a big log and ended up there in many millions of years. Yet, virtually no time after modern humans arrived on the scene in Southeast Asia, they made it over there. And then no one else shows up for more than 40,000 years.

    Also, although the mtDNA and Y haplogroups look like there was a small founding population, it certainly was not as small as you would expect from random stranded tsunami survivors.

    • dearieme says:

      Good point. The level of debate here can be impressive.

    • ChrisA says:

      Any placental mammal that did get to Australia by accident on a tsunami would have to find other members of it species while surviving in a pretty different environment. In addition how would the placental mammal survive without fresh water for several days or weeks in a row in the hot sun? Or find other members of its species?

      Most likely the original Australian settlers were people in a boat near shore which was hit by a tropical storm of some kind and driven far offshore. Dugout canoes are very ancient technologies. The thing about boats and canoes is that they can carry more than one person, rather than just one individual. Drinking water would be collectible from rain water if they didn’t already have supplies. Floating towns are very common in Indonesia even today, people build their houses on stilts in shallow water. In a highly mountainous region where a ground trip would take months boats are a good way to get around the place. You see small boats filled with families moving from town to town, trading or looking for work. The difference versus Cyprus is that in the Med the boats would have had male only crews as they would be out fishing, not travelling from town to town with their families.

      As to why there was seemingly only one migration event into Australia, I would guess that once man had established himself on Australia with it’s unique environment, then future shipwreckers would be “easy meat” in both senses of the phrase to the established people.

      • Rick says:

        The first part of this is what the whole post was about. That the first people of the region could (and did) make boats good enough to travel hundreds of kilometers on the open ocean. That is not a given. It does not seem that this was common until much more recently.

        As for the natives keeping away others (and vice verse), that just can’t be true. Before the Polynesians populated most of them, the islands of the Pacific and Indian Oceans were free of humans. Even Madagascar and New Zealand, which are huge and not that far out from populated areas.

        • dearieme says:

          Isn’t your Polynesian argument the wrong way round? I had earlier suggested that it would be hard for Polynesians to settle in the face of opposition from Abos. I was implying that it was easy, by comparison, for them to settle unpopulated islands.

          P.S. NZ was an enormous distance from areas populated with excellent navigators. It’s not even terribly close to Oz, whose people were not. Madagascar being unpopulated takes more explaining especially by people who believe the ancient fanciful tale of the circumnavigation of Africa by Phoenicians.

          • Rick says:

            I was saying, that if the polynesians found it so easy to populate hundreds of unpopulated islands, then clearly no body else since the first Australians figured out how to cross long stretches of ocean.

            Otherwise those islands would not have been unpopulated when the polynesians arrived
            That’s what I said from the start.

            I’m not sure what you disagree with.

  14. dave chamberlin says:

    It has been conjectured (I have no idea of the actual number) that it took a minimal population of a couple hundred people to prevent serious problems resulting from inbreeding. The last post on inbreeding explained in part why humans would be more prone to inbreeding problems via serious hits on intelligence. Small founding populations subject to many generations of inbreeding might hang on but would prove absolutely no competition to the later arrival of humans that were not at all dumbed down by inbreeeding. Boatloads of people whom survived a storm only to be washed ashore on an uninhabited island or continent might survive just fine via beachcombing at their new home but it is likely a small group would be doomed to both inbreeding and the subsequent loss of key skills required to compete with later less inbred arrivals.

    I have repeatedly read the opinions of Cochran, Khan, and others that no way, no how, were there humans in the Americas before 20,000 years ago. If there had been here they would have left extensive stone tools and there would be telltale give aways of the earliest arrivals in the DNA of present day populations. These are very powerful arguments that I can’t argue with. However I would not exclude the possibility of small populations of survivors from shipwrecks to have made it to the Americas and other uninhabited islands. They may have survived and reproduced, hanging on with a backwards primitive culture much like the Tasmanians did after sea rise left them isolated on the island of Tasmania. It is kind of a moot point from our point of view since they left no trace, but still I would not be so completely closed minded to the possibility of humans making to the Americas before they were supposed to be here.

    • Boris Bartlog says:

      Inbreeding does eventually sort itself out, if the population can survive the effects (and expand to sufficient size) for long enough. In practice this seems to not happen for humans, since the effects are quite severe and at least within historical times the competition from other human groups is significant. But any group that reached sufficient size, and didn’t practice cousin marriage or the like, would gradually purge the genetic load.

  15. Four-door swings near it. The people of Papua NG were way smarter than us. Jared Diamond says so. Cyprus, pah!

  16. EoT says:

    I’ve always found it really odd that Asians didn’t overrun Australia before the Europeans made it there. I assume there were some contacts between Aborigines and East/Southeast Asians before European contact but it makes you wonder why it never turned into full-scale colonization. It seems to have been ripe for the taking, for a really long time.

    • dearieme says:

      I take it that Australia wasn’t terribly attractive until Captain Cook discovered the good bit on the E coast. After all Dutchmen had explored much of the west and north coast without making any attempt to settle it. Why would they? There was nobody to trade with, there were no spices or other attractive exotic products, only a small corner in the far SW was useful for agriculture, and it was all absurdly distant from the markets Dutch farmers might want to supply. Most of those objections are even stronger for Tasmania, which the Dutch also discovered. Probably the British were simply the first to appreciate the E coast’s usefulness as a prison-cum-reformatory. After all, they had just lost the ability to use N America for that purpose. And there was always the Rule of Thumb: don’t let the French bag it.

      If Polynesians had touched on the E coast, they’d have found it already occupied by people who had stone weapons (which is more than many Polynesians had), and were numerous enough to see off a boatload of strangers who didn’t know the territory.

    • dearieme says:


      In 2012, the results of large-scale genotyping has indicated that Aboriginal Australians, the indigenous peoples of New Guinea and the Mamanwa, an indigenous people of the southern Philippines are closely related, having diverged from a common origin approximately 36,000 years ago. The same studies show that Aboriginal genomes consist of up to 11% Indian DNA which is uniformly spread through Northern Australia, indicating a substantial gene flow between Indian populations and Northern Australia occurred around 4,230 years ago. Changes in tool technology, food processing and the Dingo appear in the archaeological record around this time, suggesting there may have been migration from India.

      Direct from India is possible but seems unlikely: I wonder whether an Indian volkerwanderung left traces across Indonesia.

      • syon says:

        Cochran speculated about that a while back:

        New genetic analysis indicates that Australian Aboriginals, at least those in the northern part of Australia, picked up about 11% of their ancestry from India, relatively recently – about 140 generations ago. 4000-5000 years, depending on generation length.

        Lots of interesting things happened in Australia around that time. Previously Australia had a Middle Stone Age technology, no better than the Neanderthal toolkit. But around that time, microlithic stone tools showed up, along with new food processing techniques and the dingo. Very few dingos – they’re genetically similar, very much so. There might have been a single pregnant bitch. Population density went up by something like a factor of five. Altogether, the transition is similar to what happened when anatomically modern humans replaced Neanderthals in Europe.

        Let assume that this new analysis is correct. How could this have happened? There was never any significant colony -archeologically, it would stand out like a sore thumb. India had all kinds of useful technology that never made it to Australia, above all agriculture.

        So the problem is this: what historical process ends up contributing some key technology and 11% of the genome, while failing to transmit the vast majority of available culture and technology?

        Here’s a scenario. A ship from some Indian civilization about 4000 years ago [maybe Indus] loses its way and ends up crashing on the shore of Arnhem Land. Like most ships, its crew is all male. They survive the landing, and end up warring with a local tribe. Eventually, they kill off most of the men and annex the sobbing women. The new tribe has 5x higher carrying capacity, essentially due to better technology, and they’re militarily superior as well – better weapons and tactics. They expand and expand, picking up more and more old Australian genes as they do so. Not as an empire – they’re too simple for that – but the tribes that descend from them keep winning. They speak the ancestor of the Macro-Pama-Nyungan languages, which originates as a mix between their old-Dravidian language (from the men) and some local Australian tongue (from the women).

        In the post-Columbian world, there have been events that could have gone this way, but the players always ran into Europeans again before anything really interesting had time to happen.

        One funny thing about this scenario: the sailors lose almost all of their civilization, and probably thought they were descending into savagery. On the other hand, the locals probably thought of the castaways as incredibly advanced, magicians or gods. They were both right.

    • dearieme says:

      More WKPD:

      “With the end of the ice-age, strong rains returned until the wet season in the north collapsed around 5,500 years ago bringing with it a mega-drought which lasted 1,500 years. The return of reliable rains around 4,000 years BP gave Australia its current climate.

      There has been a long history of contact between Papuan peoples of the Western Province, Torres Strait Islanders and the Aboriginal people in Cape York. The introduction of the dingo, possibly as early as 3500 BCE, showed that contact with South East Asian peoples continued, as the closest genetic connection to the dingo seems to be the wild dogs of Thailand. This contact was not just one way, as the presence of kangaroo ticks on these dogs demonstrates. Dingoes began and evolved in Asia. The earliest known dingo-like fossils are from Ban Chiang in north-east Thailand (dated at 5500 years BP) and from north Vietnam (5000 years BP). According to skull morphology, these fossils occupy a place between Asian wolves (prime candidates were the pale footed (or Indian) wolf Canis lupus pallipes and the Arabian wolf Canis lupus Arabs) and modern dingoes in Australia and Thailand.”

      What happened to the dingos between Thailand and Oz: exterminated? Eaten?

      Anyway there’s four roughly congruent lines of enquiry that give you modest Asian immigration at roughly 4k BP: weather, dingos and human DNA.

      One other perhaps relevant point: I remember (vaguely) that there was a serious attempt to grow rice in Far North Australia in the last few decades: it flopped. Maybe there were earlier attempts that also flopped?

      P.S. WKPD: In the late 3rd millennium BC, there was a rapid expansion of rice cultivation into mainland Southeast Asia and westwards across India and Nepal.

      • Fourth doorman of the apocalypse says:


        blockquote>One other perhaps relevant point: I remember (vaguely) that there was a serious attempt to grow rice in Far North Australia in the last few decades: it flopped. Maybe there were earlier attempts that also flopped?

        There have been at least two that I am aware of.

        When I was a kid they tried to grow rice at Humpty Doo just south of Darwin. Didn’t work. They also tried to grow it at Broome in WA, I believe.

        The problem seems to have been poisons in the soil like Manganese and pests like insects and geese.

      • Garvan says:

        I think the wikipedia is misleading regarding Dingos in Thailand.

        There are no native wolf species in SE Asia, and the first domesticated dogs arrived from China with the migration of Austroasiatic farmers. There are feral packs of dogs in NE Thailand (Thai Buddhists don’t like killing strays) with are genetically related to Dingos, but this is not the same thing.

        The two native dog like species are the Asian Golden Jackal and the Dhole, neither of which is in the wolf family, although the Jackal’s can interbreed with dogs.

        If you need references on the spread of agriculture and domestic animals to Thailand I recommend Charles Higham and Rachanie Thosarat “Early Thailand from Prehistory to Sukhothai”. For mammals Boonsong Lekagul’s “Mammols of Thailand” is old but still the most comprehensive reference I have.


  17. Cattle Guard says:

    So, near the Wallace line, is there also a Gromit line?

  18. Andy says:

    What about the Negritos of the Andaman islands (the Jarawas, the North Sentinelese)? How they got there when there was never a land bridge? And the Sentinelese don’t even have boats today.

    • Boris Bartlog says:

      Technological regression. They lost the tools, skills, and knowledge to build boats.

      • Fourth doorman of the apocalypse says:

        Perhaps it is the case that if you do not have to compete with outsiders coming into your territory you slowly devolve in technology.

        • Fourth doorman of the apocalypse says:

          More specifically, perhaps when entering a new environment free of humans and other big risks, the costs associated with giving birth to smart people outweigh the benefits if life is easy for the rest. Thus the fraction of smart people declines and with it the ability to maintain any sophisticated technology.

  19. j says:

    If the peopling of islands is a function of fish density or fishing as a livelihood, that would explain why Cyprus was not discovered but recently. The whole Eastern Mediterranean is a “saltwater desert”, with no fisheries that could be exploited by pre-historic fishermen.

    • ChrisA says:

      Also could be due to “cultural” preferences for the fishermen in the Mediterranean. Fishing boats are invariably only male. So any Med fishing boat that was wrecked on Cyprus would not leave any long term traces.

  20. Fourth doorman of the apocalypse says:

    Present sea levels submerge the Pleistocene Molengraaf River System – three vast submerged river systems that drained much of Sundaland during the last glacial maximum 18,000 to 20,000 years ago.[6] Generally, the paleo-rivers are extensions of present-day river systems and may be interpreted to follow topographic lows in a down-slope direction. During the driest of the Pleistocene era the catchments forming west Borneo and the majority of Sumatra emptied through the Great Sunda River which arose between Belitung Island and Borneo flowing north east between the North and South Natuna Islands.


    Where there are vast river system and humans watercraft might develop.

  21. BurplesonAFB says:

    Is that biome map accurate for 15k years ago? Had the desertification progressed that far in the outback?

  22. jamesd127 says:

    That the Eastern Mediterranean is a salt water desert resolves the problem. Fish attract fishermen, fishermen head off to new lands, either as a result of storm or deliberate intent.

    Even if all you have is a crude raft made out of random forest debris, that and a net or a fishing line can get you places.

  23. Don says:

    What are the odds that a group goes from gracile to robust? I thought it went the other direction unless there was interbreeding.

  24. John Hostetler says:

    Apparently humans have been on Cyprus for about 12,000 years, so what intrigues me is this: it looks like Paleolithic humans developed the ability to cross 50-100 km stretches of salt water about 40,000 years ago, arrived in Sundaland and the Philippines that way, and then barely if ever, did anything like that again, anywhere in the world, until the Neolithic Revolution. Not even in the Indonesian archipelago where, glaciation or no glaciation, 100 km hops can get you across both Wallace and Lydekker lines.

    Was there something about the then-fresh Denisovan input into their genes that helped them c 40,000 years ago? Something that then receded on both sides of the lines?

    Is this what you’re getting at Greg?

    • John Hostetler says:

      Sorry, not Sundaland. Sahul.

      • Fourth doorman of the apocalypse says:

        Maybe Cochran’s boiling off theory applies here. After a while perhaps the genes that predispose some people to adventurism were lost to the population.

    • Fourth doorman of the apocalypse says:

      Was there something about the then-fresh Denisovan input into their genes that helped them c 40,000 years ago? Something that then receded on both sides of the lines?

      On the Australian side of the Lydekker line you can understand why they didn’t do much interesting except fill a large continent. They had a lot of space to fill and at time and in some places (like Lake Mungo based on the claimed height of one of the individuals found there) life was reasonably easy, until things became very dry.

      On the other side, perhaps they became too busy dealing with rising sea levels (after about 18,000 years ago.)

      All speculation, of course.

  25. Omegaman says:

    I’m aware that it is taboo to mention Thor Hyerdahl’s name on sites devoted to anthropology but one part of his life’s work was to drive home the point which armchair anthropologists missed and that is that one must look at the oceanic currents to understand the ocean-crossing capabilities of earlier men. A common example. A boat that shoves off from the north African Atlantic coast will be carried by currents across the Atlantic to the Islands of the Carribean. Many deliberate and accidental crossings attest to this fact. The oceans are not merely large passive lakes. The continents are connected by the great Oceanic Gyres and these Gyres are veritable rivers (e.g. the Gulf Stream) that flow one to three knots and will carry even a passive raft across the ocean. One of you could research (and earn a PhD?) by creating a computer model of the currents that prevailed during the time of maximum glaciation/low water. They may have been favorable to a crossing that is not probable today.

  26. The most obvious evidence that there was never a land bridge between Asia & Australia / New Guinea is the fact that there are no placental mammals here (with a few exceptions) is that we aren’t dealing with the “Kakadu tiger” or the “Oodlawirra Elephant” in Australia. I’ve always suspected that you could easily see smoke from fires on the mainland from, say, Timor & some adventurous souls, or those totally p’d off with their parents & “the establishment” just lashed some logs together and sailed off into the sunrise.

    One thing that fascinates me is that citrus fruit probably originate in Australia (the genetic variation in native citrus is far greater than any found anywhere else). So, who took the first finger lime from Australia, took it to China & hey presto!! made oranges & lemons? & don’t get me started on sugar cane & bananas …

  27. waterman says:

    What can you find if people live on the shore and sealevel rises 100 meter.
    How many times are those coral-islands re colonised after tsunami’s ?
    Interesting , the citrus fruit thing.
    There has been a high papua-culture 12.000 ya .
    They were good with boats and trees.

  28. waterman says:

    “These people went on to colonize the Solomon Islands about 40,000 years ago, but didn’t go further: after the Solomons you have to cross 200 miles of open ocean to go further, and that didn’t happen until the Polynesians arrived, relatively recently.”
    I don’t think that is true.
    About 15.000 ya the waterlevel start rising more than the coral could grow.
    So the area that is called now Polynesia just vanished in a very short time , and came back 10.000 years , or more later.

  29. Pingback: Remnants at the fringes theory and the Ainu | evolutionistx

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