Friday, November 17, 2017

Comment on "A parsimonious neutral model suggests Neanderthal replacement was determined by migration and random species drift"

Note: This comment was originally posted on the article's Nature Communications site on Nov. 10, 2017.  

As strong supporters of open, reproducible science, we are happy to see that Kolodny and Feldman replicated our research, published six years ago, and obtained results very similar to ours—results that they, like us, referred to as a “neutral model” for apparent Neanderthal extinction.

To obtain their results, Kolodny and Feldman use a protocol that parallels our 2011 paper, using both an analytical panmixia model and a spatially explicit model as we did. However, our modeling experiments also showed that given demographic imbalances between semi-isolated Neanderthal populations and more widespread 'modern' human populations, migration (very difficult to demonstrate empirically in the paleoanthropological record) is not necessary to eliminate Neanderthals as a morphologically recognizable group. It can be accomplished by gene flow and demic expansion alone, probably triggered by ecological responses to the onset of glacial conditions that can be identified empirically.

A subsequent paper in 2012 further explored the impact of fitness differences and also demonstrated that culturally mediated mating taboos have minimal to no biocultural impacts on these processes in the long-term. Both our papers predicted low-level introgression of Neanderthal genes into the modern human genome on the basis of the modeling work.

Although our 2011 paper was published in the well-known journal Human Ecology, Kolodny and Feldman seem to have missed it, so we provide the citation here.

Barton, C. M., Riel-Salvatore, J., Anderies, J. M. & Popescu, G. Modeling human ecodynamics and biocultural interactions in the Late Pleistocene of western Eurasia. Human Ecology 39, 705–725 (2011).

The authors did cite our 2012 paper but not in reference to our methods, results, or conclusions. We provide the citation here for those who are interested in this work.

Barton, C. M. & Riel-Salvatore, J. Agents of change: modeling biocultural evolution in Upper Pleistocene western Eurasia. Advances in Complex Systems 15, 1150003-1-1150003–24 (2012).

A subsequent paper, also in Human Ecology, discusses additional dimensions of the modeling environment.

Barton, C. M. & Riel-Salvatore, J. Perception, Interaction, and Extinction: a Reply to Premo. Human Ecology 40, 797–801 (2012).

We have published the code of the models used in all three papers in the NSF supported Model Library of the Network for Computational Modeling in Social and Ecological Sciences (CoMSES Net). This code is freely accessible for downloading and use.

Barton, C Michael (2011). Hominin Ecodynamics v.1. CoMSES Computational Model Library.

Barton, C Michael (2012). Hominin Ecodynamics v.2. CoMSES Computational Model Library.

Barton, C. Michael (2012). Hominin Ecodynamics v.1.1 (update for perception and interaction). CoMSES Computational Model Library.

C. Michael Barton, Arizona State University
Julien Riel-Salvatore, Université de Montréal
J Marty Anderies, Arizona State University
Gabriel M Popescu, University of Bucharest

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