Among the most recent of many puzzle pieces to be painstakingly extracted from Abaco’s Sawmill Sink blue hole is described in a report recently published in the prestigious ‘Proceedings of the National Academies of Science’ (PNAS).
The authors’ charge that warmer climate and rising sea levels after the Pleistocene Ice Age (15,000 – 9,000 years ago) resulted in mass extinction in the Americas. However, they conclude that it was the introduction of a human presence in the islands that rapidly depleted the animal life and pose the largest threat going forward.
Of the 95 species identified and recovered from Abaco’s Sawmill Sink, 41% are no longer found here. As per the publications abstract, “The late Holocene arrival of people probably depleted more populations than the dramatic physical and biological changes associated with the Pleistocene–Holocene Transition.”
Pleistocene extinctions are a controversial bit of science. However, with the authors’ latest publication, the view is a little more cohesive. In fact, the significance of the team of scientists’ findings warranted international note – appearing in publications such as the “Washington Post,” “New York Times,” and others.
The fossils unearthed and studied from Sawmill Sink is the largest amount of ice-age vertebrates to be recovered from any Caribbean island. What makes this even more special is the unique isolation islands have and thus the more undisturbed fossils and ecosystems are.
Of the 95 vertebrates recovered, thirteen were fish, eleven were reptiles, sixty three were birds and eight were mammals. Among those that are now extinct: four reptiles (among them tortoise and crocodile species), thirty one birds and four mammals.
The bird extinctions are linked exclusively warming and moistening climate, coppice overtaking pine forests, rising sea levels and shrinking island area. The remaining twenty two extinctions are theorized to be directly related to the arrival of human populations.
With this, the paper’s authors claim human arrival to the islands played a more devastating impact than even the massive shrinking of land on Abaco (from ~17,000 square kilometers to under 1,200 square kilometers) and warming climate of the time.
“It looks like within no more than a century of humans arriving in the Bahamas, they wiped out the tortoise and the crocodile,” Dr. David Steadman (one author of the paper) said.
Beyond simply hunting, it is hypothesized that clearing already reduced land for growing crops was too much of a stressor for many of these ill-fated species.
The authors of the paper were: David W. Steadman, Nancy A. Albury, Brian Kakuk, Jim I. Mead, J. Angel Soto-Centeno, Hayley M. Singleton, and Janet Franklin.