An analysis of butchered animal bones suggests humans had somehow ventured to Madagascar by at least 10,000 years ago, which is 6,000 years earlier than previous evidence suggested. This means humans likely played a key role in the extinction of the island’s large animals.
Humans lived on Madagascar during the early Holocene, according to new research published today in Science Advances. The evidence for this claim comes in the form of butchery and cut marks found on the bones of a single elephant bird (Aepyornis maximus) specimen. The remains of this now-extinct flightless bird, which resembled an ostrich, were found at the Christmas River site in southern Madagascar. Back during the Holocene, this area was a wetland ecosystem, featuring such animals as giant lemurs, hippos, giant tortoises, crocodiles, and, as the new study suggests, humans.
Artist’s depiction of an Elephant bird skeleton. Illustration: Alain Rasolo, Wildlife Artist, Madagascar
Madagascar, the world’s fourth largest island, is located around 1,070 miles (1,730 kilometres) east of Mozambique, Africa. Today, the island is home to a diverse but relatively tiny array of animals, as any fan of the 2005 DreamWorks film can attest. During the Holocene, however, Madagascar was home to a bunch of oversized animals, including the giant lemurs and elephant birds. These creatures are now extinct, and scientists have suspected that climate change had something to do with their demise.
Humans were considered an unlikely cause of these extinctions. Prior to this new work, the oldest evidence of human activity on Madagascar came in the form of 2,500-year-old cut marks on giant lemur bones, and a batch of 4,000-year-old tools found in the northern part of the island. The discovery of butchered elephant bird bones, directly dated to 10,000 years ago, now places humans in Madagascar 6,000 years earlier than previously thought — a finding which subsequently suggests humans may very well have played an active role in the extinction of Madagascar’s megafauna.
James Hansford, a PhD student at the Zoological Society of London and the lead author of the new study, documented several human-made “modifications” on the elephant bird bones, including five grooves on its lower leg bone that appear to have been made by a single bladed stone tool.
“Tool use on fresh bones leaves unmistakable patterns, as knives cut across the surface of the bones when cutting away flesh or as large tools chop down to cut ligaments and tendons to break apart limbs,” Hansford told Gizmodo. “The tool marks presented in the paper are consistent with experimental work using stone tools on large bones leaving ragged V-shaped grooves, and their position and orientation point to butchery practices. As there is no cracking extending further away from the tool marks and that the colouration within the grooves matches the outer surface, we know these were made near the time of death. No natural erosion process could have made these marks.”
Elephant bird bones showing cut marks. Image: V. R. Pérez, University of Massachusetts Amherst. Hansford et al., Sci. Adv. 2018.
To date the bones, Hansford and his colleagues extracted collagen from the bones, which was then analysed at two separate Accelerated Mass Spectrometry Radiocarbon dating facilities, producing a date range between 10,721 to 10,511 years.
“The ages observed from both facilities were similar, which is strong evidence in itself, but to further improve their accuracy they were then calibrated and combined to give the age we report in the paper,” added Hansford.
Scientists commonly study tool marks on animals to understand when humans arrived at certain geographical locations, which subsequently allows scientists to study the global impact made by humans on animals and ecosystems through time.
“Before this study, humans were thought to have arrived in Madagascar just 3,000 to 4,000 years ago, although this has been a source of debate within the scientific community for some time,” said Hansford. “Extending human history in Madagascar to at least the end of the Ice Age drives a radical paradigm shift in understanding human migration and global impact. I hope that this opens up the field of early Holocene archaeology in Madagascar, and that the scientific community can learn about who these people were.”
As to how these humans made it all the way to Madagascar, the researchers have no idea. It’s possible they constructed boats, but the archaeological evidence doesn’t support this assertion. Another possibility is that a group of humans were swept away by a tsunami that struck Africa’s east coast, sending them all the way to Madagascar. But this is just speculation; “we know almost nothing about the identity of the people that hunted and butchered these giant birds,” said Hansford.
That said, Hansford’s analysis is offering some new insights into how these elephant birds were hunted. Depression fractures on the bird’s legs look like “hobbling” marks, meaning the human hunters knocked the bird to the ground by hitting it very hard in the legs, prior to inflicting the killing blow.
Thomas Ingicco, an assistant professor in the Archaeological Studies Programme at the University of the Philippines, said he likes the new study but would have preferred to see more photographs of the butchery marks, including some close-up images made with a microscope.
“Some of the marks seem convincing while some others are less,” Ingicco told Gizmodo. “The percussion marks — described in the text as ‘depression fractures’ — might very well be human made, but a detail on the cancellous bone [the spongy part of the bone], whether it is crushed or not, would have been helpful.”
Ingicco says this finding makes sense from a genetic perspective. The presence of Bantu people (i.e. sub-Saharan Africans) in Madagascar prior to the arrival of Austronesian-speaking people to the island some 2,000 years ago (they sailed on boats from southeast Asia), is consistent with genetic evidence. “This study is the archaeological evidence one would have been waiting for,” said Ingicco.
“There is an ongoing debate over the reasons for the extinction of the megafauna from Madagascar,” added Ingicco. “This study shows humans were present several centuries before the extinction of this megafauna.”
Hansford said his new paper is “an incredibly important archaeological record,” but it presents more questions than it answers about post-Ice Age Madagascar. Trouble is, the island has been poorly studied by archaeologists.
“I hope it sparks new and exciting investigations into Madagascar’s past,” he said. [Science Advances]
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