Ancient bones — how old?

22 01 2021

Radiocarbon (14C) dating was developed by Nobel-Prize winning chemist Willard Libby, and has become the predominant method to build chronologies of ancient populations and species using the Quaternary fossil record. I have just published a research paper about 14C dating of fossil bone reviewing the four standard chemical pretreatments of bone collagen to avoid sample contamination and generate accurate fossil ages: gelatinization, ultrafiltration, XAD purification and hydroxyproline isolation. Hydroxyproline isolation is perceived as the most accurate pretreatment in a questionnaire survey completed by 132 experts from 25 countries, but remains costly, time-consuming and not widely available. I argue that (1) innovation is urgently required to develop affordable analytical chemistry to date low-mass samples of collagen amino acids, (2) those developments should be overseen by a certification agency, and (3) 14C users should be more conceptually involved in how (much) 14C chemistry determines dating accuracy. Across the board, scientific controversies like the timing of Quaternary extinctions need not be fuelled by inaccurate chronological data.

Megafauna bones from the Quaternary fossil record. Top: excavation of a partial skeleton of a short-faced kangaroo Procoptodon browneorum at Tight Entrance Cave (Western Australia) [1]: these bones are close to the limit of radiocarbon (14C) dating in a geological context 43000 to 49000 years old. Middle: metacarpal of the extinct horse Hippidion cf. devillei from Casa del Diablo (Peru) 14C dated at 11980 ± 100 years before present (BP) (CAMS-175039) following XAD purification of collagen gelatin [2]. Bottom: collection of skeletal remains of (mostly) red deer Cervus elaphus from El Cierro Cave (Spain) 14C dated at 15520 ± 75 years BP on ultrafiltered gelatin (OxA-27869 and OxA-27870 average) [3].

Scientists have widely been interested in the present and future state of biodiversity. Ecologists (the main audience of this blog) have also looked into the past with pioneering investigations addressing the composition of ancient forests and the origins of agriculture in layers of fossil pollen accumulated in lake sediments [4]. But it took us decades to see the fossil record as a useful tool (combining biological, geochemical and molecular techniques) to answer basic ecological questions. Some of those questions are critical for conserving today’s biodiversity [5, 6]: for example, when did human impacts on ecosystems become global or what extinct species have best tolerated past environmental change and what that means to modern species? [7].

The study of (pre)historic biological events relies one way or another on our ability to time when a certain animal, human, or plant occurred and what environmental conditions they experienced, and relies on concepts borrowed from archaeology (past human activity), palaeontology (fossils), palaeocology (species responses to past environments), and geochronology (age of fossils and/or their geological context). Among the range of chronological methods available to date biological and cultural samples [8], radiocarbon (14C) dating has become the most important for dating bones aged modern to late Quaternary (last ~ 50,000 years). Hereafter, ‘bone’ comprises antler, bone, ivory and teeth. 14C dating of bones is appealing at least for four reasons: 

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Worried about Earth’s future? Well, the outlook is worse than even scientists can grasp

14 01 2021

Daniel Mariuz/AAP

Corey J. A. Bradshaw, Flinders University; Daniel T. Blumstein, University of California, Los Angeles, and Paul Ehrlich, Stanford University

Anyone with even a passing interest in the global environment knows all is not well. But just how bad is the situation? Our new paper shows the outlook for life on Earth is more dire than is generally understood.

The research published today reviews more than 150 studies to produce a stark summary of the state of the natural world. We outline the likely future trends in biodiversity decline, mass extinction, climate disruption and planetary toxification. We clarify the gravity of the human predicament and provide a timely snapshot of the crises that must be addressed now.

The problems, all tied to human consumption and population growth, will almost certainly worsen over coming decades. The damage will be felt for centuries and threatens the survival of all species, including our own.

Our paper was authored by 17 leading scientists, including those from Flinders University, Stanford University and the University of California, Los Angeles. Our message might not be popular, and indeed is frightening. But scientists must be candid and accurate if humanity is to understand the enormity of the challenges we face.

Girl in breathing mask attached ot plant in container

Humanity must come to terms with the future we and future generations face. Shutterstock

Getting to grips with the problem

First, we reviewed the extent to which experts grasp the scale of the threats to the biosphere and its lifeforms, including humanity. Alarmingly, the research shows future environmental conditions will be far more dangerous than experts currently believe. Read the rest of this entry »

Time for a ‘cold shower’ about our ability to avoid a ghastly future

13 01 2021

I wish it need not have happened in my time,” said Frodo. “So do I,’ said Gandalf, “and so do all who live to see such times. But that is not for them to decide. All we have to decide is what to do with the time that is given us.”

Frodo Baggins and Gandalf, The Fellowship of the Ring

Today, 16 high-profile scientists and I published what I describe as a ‘cold shower’ about society’s capacity to avoid a ghastly future of warfare, disease, inequality, persecution, extinction, and suffering.

And it goes way beyond just the plight of biodiversity.

No one who knows me well would mistake me for an optimist, try as I might to use my colleagues’ and my research for good. Instead, I like to describe myself as a ‘realist’. However, this latest paper has made even my gloomier past outputs look downright hopeful.

And before being accused of sensationalism, let me make one thing abundantly clear — I sincerely hope that what we describe in this paper does not come to pass. Not even I am that masochistic.

I am also supportive of every attempt to make the world a better place, to sing about our successes, regroup effectively from our failures, and maintain hope in spite of evidence to the contrary.

But failing to acknowledge the magnitude and the gravity of the problems facing us is not just naïve, it is positively dangerous and potentially fatal.

It is this reason alone that prompted us to write our new paper “Underestimating the challenges of
avoiding a ghastly future
” just published in the new journal, Frontiers in Conservation Science.

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Cartoon guide to biodiversity loss LXIV

7 01 2021

As the pandemic rages globally, and the fragility of the American political system goes on full display, I give you the first set of biodiversity cartoons for 2021. See full stock of previous ‘Cartoon guide to biodiversity loss’ compendia here.

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