Эртний хүмүүсийн хийж бүтээх чадварын талаарх ойлголтыг өөрчлөхүйц хамгийн эртний модон бүтээцийг Каламбо голын эрэг дээрээс илрүүлсэн байна.
Ливерпүүлийн их сургуулийн профессор Ларри Бархамаар ахлуулсан судлаачдын баг Замби болон Танзани улсын хил дээрх Каламбо хүрхрээний орчмоос 476,000 жилийн настай хоёр модыг олжээ. Эдгээр модыг чулуун зэвсэг ашиглан ховил гарган нэгтгэж, тогтвортой бүтэц үүсгэсэн нь тогтоогдсон байна. Энэхүү олдвор нь хүн төрөлхтний өвөг дээдэс байгаль орчноо өөрчлөн, зориудаар бүтээн байгуулалт хийх чадвартай байсныг харуулж буй чухал нотолгоо юм.
Нүүрстөрөгчийн шинжилгээний аргаар хэт эртний олдворын насыг тогтоох боломжгүй байсан тул судлаачид тухайн хэсгийн элсний эрдсийн давхаргыг гэрлийн аргаар (luminescence dating) шинжилжээ. Үр дүнд нь тус байгууламж нь ойролцоогоор 476,000 жилийн настай болохыг тогтоосон бөгөөд энэ нь өмнө нь олдож байсан хамгийн эртний модон бүтээцээс даруй олон зуун мянган жилээр илүү эртнийх юм. Тус газраас мөн чулуун зэвсгээр хэлбэржүүлсэн шаантаг болон ухах саваа зэрэг бусад модон эдлэлүүд олдсон байна.
Судлаачид энэхүү байгууламжийг голын эрэг дээрх үерлэдэг бүсэд сууц барих эсвэл явган зам гаргах зорилгоор ашиглаж байсан байж магадгүй гэж таамаглаж байна. Тухайн бүс нутагт усны түвшин өндөр байсан нь модыг агаар болон ялзралаас хамгаалж, ийм урт хугацаанд хадгалагдах боломжийг бүрдүүлжээ.
Одоогоор уг байгууламжийг бүтээгчдийн яс болон биологийн үлдэгдэл олдоогүй байгаа тул хэн болох нь тодорхойгүй байна. Судлаачид үүнийг Homo heidelbergensis эсвэл Homo erectus төрлийн хүмүүс бүтээсэн байх магадлалтай гэж үзэж байгаа юм. Олдворыг Их Британид сэргээн засварлаж, улмаар Замби улсын Ливингстоны музейд шилжүүлэн хадгалахаар төлөвлөжээ.
Дэлгэрэнгүйг эх сурвалжаас харах
↓Эх сурвалжийг нээх ↓
Nearly half a million years ago, before the earliest known fossils of our own species, someone on a riverbank in Zambia took a stone tool to a log and cut a notch into it. Then they fitted a second trunk through the gap.
The two logs are still there, locked in place. Sediment around them dates to at least 476,000 years ago, making them the oldest known wooden structure ever found.
No bones of the builders have been found at the site.
A Joint Cut With Stone Tools
The logs lay in waterlogged sand on the Kalambo River, upstream of Kalambo Falls, a 235-meter (770-foot) waterfall on the border between Zambia and Tanzania. A team led by Larry Barham of the University of Liverpool uncovered them in 2019 and described the find in the journal Nature.
The upper log is a piece of bushwillow (Combretum zeyheri) about 1.4 meters (4.6 feet) long, with tapered ends. It rests on a larger tree trunk at a 75-degree angle. Where the two meet, the upper log carries a U-shaped notch 13.2 centimeters long and 11.4 centimeters wide, cut across its grain.
Under magnification, the notch shows chopping and scraping marks left by stone tools. The researchers interpret it as intentional, made by scraping and adzing to join the two logs into a single construction. The trunk underneath was also shaped. “This arrangement prevents the overlying log from moving side to side, giving stability to the structure,” Barham told Reuters.
“This is a disruptive discovery,” Barham told Scientific American. “I never would have thought that pre-Homo sapiens would have had the capacity to plan something like this.”
Dating the Sand Around the Wood
Radiocarbon dating cannot reach that far back: the wood samples all came out older than 50,000 years, the method’s limit. So the team dated the sand instead, using luminescence dating, which measures when mineral grains were last exposed to sunlight.
Study co-author Geoff Duller of Aberystwyth University and his colleagues analyzed 16 sand samples. The deepest layers, holding the logs, gave a mean age of 476,000 years, with a margin of about 23,000 years. That figure is conservative: correcting for a known signal loss in the feldspar grains would push it to about 554,000 years.
Before this find, the oldest known wooden structure was only about 9,000 years old, Barham told AFP. The oldest known wooden artifact of any kind remains a fragment of polished plank from Gesher Benot Ya’aqov, in Israel, more than 780,000 years old.
A Wedge, a Digging Stick and a Cut Log
The same riverbank yielded four other modified wooden objects, including a wedge and a digging stick. One was a section of tree trunk with stepped chop marks at both ends. In experiments, the team reproduced those marks by chopping fresh elm with a quartzite cleaver mounted in a wooden handle.
Wood rarely survives this long. Here, a permanently high water table kept the logs soaked and sealed from oxygen. Researchers had already recovered wood from the site in the 1950s and 1960s, including a 165-centimeter log with a similar groove, but they could not show it had been shaped by hand or date it precisely.
“It’s an important window into what these humans were capable of,” Annemieke Milks, an archaeologist at the University of Reading who was not involved in the study, told the Associated Press.
A Platform Above a Wet Floodplain
The study links the logs to a long period of forest cover in the Kalambo basin, between about 470,000 and 274,000 years ago. Life on a periodically flooded riverbank would have been easier with a raised platform, a walkway or a foundation for shelters, the researchers write.
The structure also points to a key technical idea: combining two or more parts into one construction. The authors see it as a forerunner of hafting, the practice of fixing stone tools onto handles.
“The finds from Kalambo Falls indicate that these hominins, like Homo sapiens, had the capacity to alter their surroundings, creating a built environment,” Barham told Reuters.
The Builders Remain Unidentified
Without human remains at the site, the builders’ identity is open. Barham suspects Homo heidelbergensis, a human relative known from about 700,000 to 200,000 years ago, whose fossils have been found elsewhere in Zambia. He told Scientific American that Homo erectus is another candidate.
“We like to think that anything complex and clever has got to be us, which is kind of arrogant,” he said.
The logs are being conserved at the York Archaeological Trust, in the UK, before their return to Zambia, where they will be kept at the Livingstone Museum.
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