The Empty Pampas: epitome of a biogeographical mystery, part 3
...continued from https://www.inaturalist.org/journal/milewski/55191-the-empty-pampas-epitome-of-a-biogeographical-mystery-part-2#
This brings us to the question of why the indigenous people of the pampas failed to adopt a pastoral economy, which would have restored at least one relatively large herbivore to the ecosystem.
This aspect of the mystery hinges on the camelids, on which the following points are worth noting.
Firstly, the camelids seem to be the only component of the ungulate fauna of body mass exceeding 50 kg in the pampas which survived the megafaunal extinction (file:///C:/Users/Antoni%20Milewski/Downloads/CASSINI_MUOZ_MERINO-2016-EvolutionaryhistoryofSAartiodactyls.pdf).
Secondly, both of the extant wild species are native to Buenos Aires Province. Although the vicuna (Vicugna vicugna) is currently restricted to the Andes, it is associated with poorly-drained grassland rather than high altitudes per se, and was formerly at home in what is now the Empty Pampas. For its part, the guanaco has survived in this province up to the present day, but only in a small range of rocky hills, the Sierra de la Ventana; there is no evidence of its presence on the vast, well-watered plain itself even at the time of European arrival.
And thirdly, both of the wild species of camelids referred to have been selectively bred by indigenous people (albeit in the Andes) to the point of the creation of new, purely domestic, species.
What this resolves to is a simplified question: why did the pastoral culture of the Incans not spread to the pampas on the back of the llama (Lama glama) and the alpaca (Vicugna pacos)?
What happened instead is that the people of the pampas continued to lack domestic animals with the possible exception of the dog.
They ate mainly rodents, of which the pampas is the opposite of empty, with at least five genera abundant enough to provide staple food. And their culture was accordingly as simple as those of hunter-gatherers elsewhere on Earth, differing mainly in being based on the smallest of game.
After the Spanish left the pampas in the early 1500's to try their luck northwards, the few individuals of Equus caballus and Bos taurus which they had abandoned to the wilds found the grassland so favourable that they soon overran the entire pampas as feral animals.
This ungulate resource drew the people of the Andean foothills eastward, usurping the land of the hunter-gatherers.
The newcomers soon re-invented an equestrian, beef-eating way of life with no lessons from Europeans - whom they violently excluded from most of the pampas for more than two centuries before the gauchos eventually prevailed.
The extreme success of ungulates on this productive plain, from 1600 to 1825, paralleled the history of the prairies in North America, in which the bison (Bison bison) was exploited on horseback by indigenous people.
The fact that in the pampas it was not only the horse but also the cattle that had to be introduced only underscores the mystery of the Empty Pampas in the first place.
But for the twist in the tale - and the possible solution to the mystery - let us return to the humble rodents, the mainstay of the people who inhabited Buenos Aires Province for most of the Holocene.
For it may be the productivity of such small, fecund mammals which gives us a clue to the truest nature of an extremely fertile ecosystem.
To be continued in https://www.inaturalist.org/journal/milewski/55214-the-empty-pampas-epitome-of-a-biogeographical-mystery-part-4#...
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