This is an astonishing find that reveals humans have been far more sophisticated and capable than we have thought. Due to the constant saturation by it's proximity to Kalambo Falls, Zambia, the wood was preserved in the absence of sufficient oxygen to sustain microorganisms, that would ordinarily rot wood in a few centuries, for hundreds of millennia.
IMG source - Ancient-origins.net
Homo erectus by 500kya had extended it's range to the entirety of the habitable old world, from S. Africa to the Caucasus, from Iberia to China, and, surprisingly, to the Philippines. The surprising thing about finding pre-sapiens humans in the Philippines is that there are extremely strong currents in the sea between the Philippines and the Asian continent, that has created a boundary for land mammals called the Wallace Line. Even strong swimmers like the Asian Elephant were unable to cross the Wallace Line to reach the islands, yet a new human species, H. luzonensis, was found to have colonized the island of Luzon by ~700kya.
This discovery caused a great deal of controversy, because it is very unlikely that humans could have reached the Philippines without blue water capable watercraft. A boat that can withstand the rigors of the sea is necessary, and lesser craft such as small rafts suitable for in shore waters simply wouldn't make the journey. However, earlier human species were claimed by some to be incapable of such construction, and no physical evidence of such construction had been found, until now. The polished plank from Gesher Ya'aqov is believed to be a stand alone artifact, not part of a structure. But the notched logs clearly show pre-sapiens humans were capable of building large and complex structures, meaning watercraft were not inconceivable either.
IMG source - https://www.nature.com/
Papers published in 2017 by Posth and 2020 by Petr show that H. denisova diverged from NEA (H. neanderthalensis) ~700kya. Then NEA and AMH (H. sapiens) diverged ~450kya [likely interbreeding with H. antecessor produced AMH, because only H. antecessor and H. sapiens of all hominids are known to have chins, Ed.]. Then by ~370kya interbreeding between NEA and AMH replaced NEA Y DNA (Y DNA is passed from fathers to sons. Only males have Y DNA) throughout their range. Subsequent to that, by ~270kya AMH mtDNA replaced NEA mtDNA across it's range. This is extremely significant, because mtDNA is passed only from mothers to their offspring (while mtDNA comes only from the mother, both males and females have mtDNA). For AMH mtDNA to replace NEA mtDNA, AMH females would have to completely replace NEA females across the entire range, and not just for quickies but to successfully rear children to adulthood.
This establishes that AMH did not arise in Africa, because NEA never lived in Africa. AMH females had to live with NEA males to replace NEA mtDNA, so at least female AMH were living across the entire NEA range. However, I find the idea that all NEA males would travel to Africa to kidnap AMH females and bring them back to Europe utterly preposterous. AMH populations were inhabiting the same range as NEA, or range contiguous with it across Eurasia, if but further south. There are other finds that further deprecate the hypothesis humans evolved in Africa.
Hominines arose in Eurasia and migrated to Africa according to the fossil evidence we have now. Anadoluvius turkae has recently been described to have lived in Anatolia 8.7 million years ago. After that Ouranopithecus and Graecopithecus lived in Greece and the Balkans 7.2mya.
H. erectus is now thought to have arisen in the Caucasus, not Africa.
Very large Homo fossils have been found near Harbin, China, dated to ~150kya.
Indeed, these fossils from long before the Out of Africa theory proposes AMH emerged from Africa show derived traits that are present in Asian populations today, demonstrating that they were ancestral to present AMH populations. We have very few known Denisovan fossils, but there are claims that H. denisova averaged more than 7 ft tall. Given there is no DNA evidence from H. longi, I strongly suspect that their great size and location in the heart of where we think H. denisova ranged, suggest H. longi are in fact H. denisova, or AMH/denisova hybrids. E. Asian AMH populations do carry DNA from H. denisova today, and Philippine Negritos, Papuan, and Australian Aboriginal populations have as much as 6% Denisovan admixture (from the Oceanic Denisovan population, which is different than the Siberian Denisovan people).
The Out of Africa theory is based only on mathematical calculations of the rate of evolutionary changes in mtDNA, and the remarkable homology of AMH mtDNA today, which led Alan C. Wilson and Rebecca L. Cann to suggest 'Eve' came from Africa ~75kya. However, 73kya was one of the most cataclysmic events that has occurred since humans arose, the eruption of Mt. Toba in Indonesia. This eruption was so violent that it buried S. Asia west of Indonesia under ~6M of ash, making the are uninhabitable. It would have taken a lot longer than 2k years for the area to recover enough to make it more attractive than Africa, which was largely unaffected by the catastrophe.
Numerous researchers have noted that it was much more likely that AMH living in the Levant and S. Asia fled the destruction into Africa, a refugium. The L, M, and N haplotypes the OoA theory supposes to have arisen in that small African region and spread from are better explained as arising across Eurasia, and then ending up in Africa as a result of flight from the Toba devastation. The OoA theory was proposed before aDNA (ancient DNA) was able to be measured, so there is now much genetic evidence, such as Petr and Posth, and much else, that completely contradicts the evolution of AMH in Africa, and while I am eager for more evidence of these matters, from what is available now, there is no basis for claiming AMH arose in Africa. Overall I am left with the impression from all the interbreeding humans have been shown to do that AMH evolved as a breeding complex across Eurasia rather than a species very constrained in it's features.
Here's a podcast from Bruce R. Fenton, who proposes the Into Africa theory.
So H. erectus was capable of building ocean faring watercraft and timber framed structures before AMH even evolved, at the extreme reaches of it's range in Africa to the west, and the Philippines to the East, thousands of miles apart. This suggests it is almost certain the capability was expressed across that entire expanse, by H. erectus. Denisovans, NEA, and AMH are more intellectually advanced than H. erectus, so all human species on Earth since ~2mya, when H. erectus is known to have arisen, have been capable of building timber framed structures, and ocean going watercraft. That is astounding!
It is very difficult to find artists' representations of people before the Bronze Age living in structures, wearing anything but hides flung over their shoulders, or perhaps tied with a cord at the waist, or using tools capable of boat building and building construction. It is very obvious that people capable of building houses would have measuring tools. Knotted string, notched or painted measuring sticks, plumb bobs, and a square are about the minimum requirements for residential construction. I know, because I am a carpenter.
This kind of tool use completely breaks the image of a brute with a cape of tanned hide for formal attire. It is also obvious that Siberian Denisovans and NEA at the northern limits of their range must have had tailored clothes to survive extremely cold conditions at the margins of the glaciers that were present for most of the time they lived in N. Siberia and N. Europe. They may well have had far better adaptations to cold weather than AMH, but they did not have adaptations nominal to enable them to survive and do useful work without well fitting parkas, pants, and boots. They didn't have thick layers of fat or fur like other mammals adapted to winters in Arctic conditions, where temperatures can plunge to -40C and stay there for weeks at a time. If you have ever experienced temperatures in that range, you will know that exposed skin freezes in seconds, and nothing about the remains and DNA we have of either Denisova or NEA suggests they had any adaptations that would have prevented them from suffering such harm from those temperatures, and they lived in habitat that sustained such winter temperatures.
This is something I have understood for some time, but apparently isn't understood by National Geographic or any artists that produce images of our human ancestors and cousins for scientific publications. I have never seen a Neanderthal depicted in tailored clothes that wasn't a comic. It has been possible to think that NEA, Denisova, and H. erectus never had a tent, a hut, or a boat, from the archaeological evidence we haven't found, until now. Finding just two members from a timber framed structure built almost half a million years ago changes everything. These people had to have had those things, their lives would have depended on their parkas, pants, and boots in glacial winters, but we have never found any of those clothes, or tools to make them, like needles, older than ~50kya. If they could make timber framed houses, they could sure stitch up a pair of pants or a parka, so it is impossible they didn't have them. We haven't found any yet because clothes, wood, and string rot pretty quickly.
Were there ever actually any cavemen at all?
I hope this information sparks your imagination and you find it as exciting as I do.