For a creationist claim, the assertion that no new species have been seen to evolve takes some beating for its sheer denial of the readily available data. Now geneticists working at the Australian Centre for Ancient DNA at the University of Adelaide, have shown that even the Stone Age painters of the caves such as Lascaux Cave, France, captured one such event in their art. Their findings were published yesterday in Nature Communications.
|(a) Reproduction from Lascaux cave (France), from the Solutrean or early Magdalenian period (∼20,000 kya). |
(b) Reproduction from the Pergouset cave (France), from the Magdalenian period (<17,000 kya).
- The extinct auroch - the ancestor of the modern domestic cattle, with its long horns and relatively small haunches.
- The large-haunched small-horned steppe bison which was common across the Eurasian and North American grasslands (the North American buffalo).
- A third species with the steppe bison's heavy haunches and the auroch's long horns.
The team have now shown that this third type was derived from a stable hybrid between the auroch and the steppe bison and eventually became the European bison or wisent. In other words, what was captured in these cave paintings was the emergence of a new species which arose by hybridization. As the climate oscillated back and forth, this new species and the steppe bison changed places as the dominant bovine species in Europe.
The two living species of bison (European and American) are among the few terrestrial megafauna to have survived the late Pleistocene extinctions. Despite the extensive bovid fossil record in Eurasia, the evolutionary history of the European bison (or wisent, Bison bonasus) before the Holocene ( <11.7 thousand years ago (kya)) remains a mystery. We use complete ancient mitochondrial genomes and genome-wide nuclear DNA surveys to reveal that the wisent is the product of hybridization between the extinct steppe bison (Bison priscus) and ancestors of modern cattle (aurochs, Bos primigenius) before 120 kya, and contains up to 10% aurochs genomic ancestry. Although undetected within the fossil record, ancestors of the wisent have alternated ecological dominance with steppe bison in association with major environmental shifts since at least 55 kya. Early cave artists recorded distinct morphological forms consistent with these replacement events, around the Last Glacial Maximum (LGM, ∼21–18 kya).
Soubrier J., et al
Early cave art and ancient DNA record the origin of European bison.
Nature Communications, 2016; 7: 13158 DOI: 10.1038/ncomms13158
Copyright © 2016 The Authors, Nature Publishing Group.
Reprinted under Creative Commons Attribution 4.0 International License (CC BY 4.0)
The team analysed both mitochondrial and nuclear DNA recovered from a large number of bison bones carbon-dated to different periods and found many with a distinct genetic signal which suggested a third species existed. However, it was not until French cave painting experts were consulted that they discovered that not only were there the three types of cattle depicted but that their occurrance in art of known dates corresponded with the carbon-dated ages of the different genomes, and these in turn corresponded with changes in weather patterns.
This hybrid species is the ancestor of the European bison which went through a very narrow genetic bottleneck in the 1920, only narrowly avoiding extinction with a population of just 12 individuals.
So, our cave-painting ancestors captured this evidence of a new species arising by hybridization as well as the history of its struggle for dominance in Eurasia with the steppe bison as climate fluctuated, favouring first one species and then the other. The final survivor in this struggle being hybrid species. Isn't it beautiful how so many strands of evidence come together. We now have the evidence from genetics, from geology, from palaeontology, from the nuclear physics of carbon-dating, and now from the aesthetic appreciation of subtly different living species from our cave-painting ancestors, and they all converge on the emergence of a single new species by stable hybridization.
So, what we can now expect, if they don't simply avoid it altogether, is the traditional moving of the goal-posts as creationists change their claim from no new species to no new genuses.
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