Tuesday, June 7, 2016

Pristine landscapes are perhaps long gone

The exhibition of increasingly intensive and complex niche construction behaviors through time is a key feature of human evolution, culminating in the advanced capacity for ecosystem engineering exhibited by Homo sapiens. A crucial outcome of such behaviors has been the dramatic reshaping of the global biosphere, a transformation whose early origins are increasingly apparent from cumulative archaeological and paleoecological datasets.

A new study is taking a new look at how the world's landscapes have been shaped by repeated human activity over many thousands of years. An exhaustive review of archaeological data from the last 30 years  reveals a pattern of significant, long-term, human influence on the distribution of species across all of the earth's major occupied continents and islands. It draws on new datasets using ancient DNA, stable isotopes, and microfossils, as well as the application of new statistical and computational methods.

The authors argue that it is wrong to assume that societies before the Industrial Revolution had little effect on the environment or diversity of species. They show that many living species of plants, trees and animals that thrive today are those that were favoured by our ancestors. Furthermore, large-scale extinctions started thousands of years ago due to over-hunting or change of land use by humans

One of the take home messages of the study is that pristine landscapes likely do not exist anywhere in the world today and, in most cases, have not existed for at least several thousand years. Consequently, the colleagues conclude that in light of their findings and other evidence of long-term anthropogenic change, we need to be more pragmatic in our conservation efforts rather than aiming for perhaps impossible natural states. I am sure that view will spark further discussions about what constitutes a natural state and and how far back in time we want to go to determine our efforts for restoration, conservation, invasive species eradication and so on. The main message of the paper is nicely summarized by the lead author:

Cumulative archaeological data clearly demonstrates that humans are more than capable of reshaping and dramatically transforming ecosystems. Now the question is what kind of ecosystems we will create for the future. Will they support the wellbeing of our own and other species or will they provide a context for further large-scale extinctions and irreversible climate change?

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