Do humans always wipe out the big animals, or can they sometimes coexist? Evidence from Madagascar.

Scientists generally accept the theory that once humans arrive at an isolated landscape, they quickly destroy the big animals there.

Some call it the blitzkrieg hypothesis. But there's new evidence that, at a minimum, raises questions about this theory.

(Image: Bones with tool cut marks of the Madagascar Aepyornis, the giant elephant bird. Credit:  V. Pérez, Science Advances, 5:9 (2018))

In the Hawaiian Islands, the big flightless ducks that have been called moa nalo were in the islands when the first Polynesians arrived, but were gone soon thereafter. Smithsonian researcher Storrs Olson reported that the moa nalo—which represents a class of extinct big birds—disappeared during the early human occupation of the Islands.

Fossils of numerous such species are "contemporaneous with Polynesian culture. The loss of species of birds appears to be due to predation and destruction of lowland habitats by humans before the arrival of Europeans," Olson wrote. 

In New Zealand, the class of giant moa birds (Dinornis sp.) also disappeared with the arrival of the humans. New Zealand Geographic has a piece on that loss. 

In Madagascar, the arrival of humans has been linked to the loss of the giant elephant birds, Aepyornis maximus and other species.

But recently, researchers in Madagascar found Aepyornis bones more than 10,000 years old with human tool marks on them. Until now, humans were not believed to have been in Madagascar until 2,500 years ago or at most 4,000 years ago. Some came from Polynesian origin societies to the east and some from Africa to the west.

And Aepyornis are believed to only have gone extinct in the last couple of thousand years.

So, 10,500 years ago?

"Our evidence for anthropogenic perimortem modification of directly dated bones represents the earliest indication of humans in Madagascar, predating all other archaeological and genetic evidence by >6000 years and changing our understanding of the history of human colonization of Madagascar," write the authors of this paper, Early Holocene humanpresence in Madagascar evidenced by exploitation of avian megafauna. 

An article in Science reviews the issue. 

In it, paleoecologist David Burney says it's a big deal: The findings"fly in the face of all that we thought we knew about human arrival in Madagascar." Burney has worked extensively with the Kaua`i-based National Tropical Botanical Garden, and has also done considerable work in Madagascar.

If humans were there that early, why didn’t they earlier wipe out the big birds and big mammals as the theory suggests they do? And if humans were there that early, why haven't archaeologists found evidence of the human presence?

For now, two theories arise.

1) It was perhaps a small, temporary human presence—maybe a visiting group of people that killed and ate some creatures and then left, or died out.

2) Maybe they haven't found evidence because they haven’t been looking for archaeological sites that early.

That said, scientists for four decades have understood that when humans arrive, they conduct a "blitzkrieg" that wipes out many big animals. Is it possible that in Madagascar, humans were able to coexist, to survive for thousands of years without wiping out megafauna?

Depending on what researcghers uncover next, it is at least possible.

Well, and then there's the question of how humans were voyaging across oceans as early as 10,500 years ago. That's more than 5,000 years before Polynesians began plying the Pacific in their voyaging canoes.

© Jan TenBruggencate 2018