Elephant Birds Never Forget

Reference: Hansford, J., P.C. Wright, A. Rasoamiaramanana, V.R. Pérez, L.R. Godfrey, D. Errickson, T. Thompson, S.T. Turvey. 2018. Early Holocene human presence in Madagascar evidenced by exploitation of avian megafauna. Science Advances. DOI: 10.1126/sciadv.aat6925

Background

Madagascar is an island nation in the Indian Ocean and a biodiversity hotspot – most of the 25,000 wildlife species that live there do not exist anywhere else in the world. At the beginning of the Holocene (our current period of geological time – see figure 2), this island was populated with “megafauna”. These were huge animals like giant lemurs, some of which were as large as modern gorillas and weighed up to 350 pounds. All of Madagascar’s megafauna are now extinct, but until recently, no one understood if humans had played a role in their extinction, due to a lack of data regarding when the first human presence was on the island.

Figure 1. Where in the world is Madagascar? Source: http://www.pasttime.org/2013/06/episode-1-field-guide-finding-fossils-in-madagascar/

 

Let’s dig up some evidence!

Archaeologists around the world have used the remains of prehistoric wild animals to estimate the timing of human contact with an area. This is done by determining the age of bones that have evidence of human modification, such as marks from butchering. In the last decade, similar techniques in archaeological research have already led to several extensions (from 1500 to 4000 years ago) to the date when humans first arrived on Madagascar.

Figure 2. A visualization of geological time periods, where Ma = Millions of years Ago. We’re currently in the Holocene! Source: http://www.oldearth.org/curriculum/geology/images/timescale.jpg

The Christmas River archaeological site was a wetland ecosystem in the early Holocene, and has many well-preserved samples of now-extinct animals. Previously, however, no tools or other human artifacts have been revealed. This study describes several examples of recently collected bone pieces of Aepyornis maximus, the elephant bird, that show marks consistent with human modification. The elephant bird bones were analyzed and estimated to be between 10,500 and 10,700 years old, over 6,000 years older than previous estimates of the first human-animal contact on Madagascar.

 

Why is this important?

Archaeologists and biologists alike want to understand the timing of the first arrival of humans on Madagascar because that will help define ecological “baselines”, or how the island functioned before humans. These baselines, in turn, can inform modern conservation practices.

Studies like these will also help researchers understand how humans interacted with prehistoric animals. For example, this article compares the story of the New Zealand moa, another prehistoric bird, to Madagascar’s elephant bird. The moa was estimated to be extinct approximately 150 years after the arrival of Polynesians in New Zealand. It is extremely interesting that humans on another island appear to have been able to coexist with a similar large bird for potentially thousands of years.

Figure 3. The Ratite group of birds are all flightless (note the size of the elephant bird and the moa). Source: https://teara.govt.nz/en/interactive/11361/ratite-birds

The diverse wildlife of Madagascar continues to be threatened by ever-expanding human activity to this day. By expanding the timeline of human occupation, this archaeological study has revealed a previously unrecognized period of potential human-animal interactions in Madagascar. This will hopefully aid in the future conservation of this fascinating island and its wild inhabitants.

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Maddie Halloran

Maddie Halloran

I am a second year master's student at Humboldt State University in the Fisheries Biology Department. I'm interested in human impacts on the environment and conservation. When I'm not counting fish you can probably find me outside on an adventure or eating ice cream on my porch.

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