Conflict with megafauna

Evolution and extinction are both natural phenomena, whose characters and chapters make the story of life on Earth interesting and intriguing.
The fossilised skeleton of a giant ground sloth on display at the North Carolina Museum of Natural Sciences
The fossilised skeleton of a giant ground sloth on display at the North Carolina Museum of Natural SciencesPhoto | Express

The Earth is 4.543 billion years old. In its primeval journey which is in continuation, the planet experienced immense cataclysmic changes in terms of climate, topography, physical features, and evolutionary patterns, giving rise to and extinguishing a mega plethora of species through the ages.

Evolution and extinction are both natural phenomena, whose characters and chapters make the story of life on Earth interesting and intriguing. However, while evolution, through the Darwinian principle of Natural Selection and adaptation, takes a naturally-timed course, extinction has accelerated artificially, owing to human intervention and practices. This occurrence is not recent, being under way since the time humans adopted a hunter-and-gatherer lifestyle.

In scientific terms, extinction is defined by the termination of a taxon (a group of one or more populations of an organism that form a unit) by the death of its last member. A taxon may become functionally extinct before the death of its last member, if it loses the capacity to reproduce and recover. Because a species’ potential range may be vast, determining the moment of absolute extinction is difficult, and is usually done retrospectively. This hindrance results in what is known as Lazarus taxa, where a species presumed extinct suddenly reappears, after a period of apparent absence.

However, the pace of unnatural factors, including pollution, deforestation, hunting/poaching, wildlife trade, encroachment of forests, unbridled urbanisation, and overexploitation by humans, are further fuelling unavoidable man-animal conflict, habitat fragmentation, and climate change, pushing several species towards extinction. Those on this path pass through several stages of risk, from being near-threatened to vulnerable, endangered, critically endangered, to going extinct.

The extinction or extermination of a species means the loss of its genetic heritage. Over 99% of all the species that once called the Earth home, translating to over five billion of them, are estimated to have gone extinct. These include the dinosaurs, which went extinct 65 million years ago, and many others that followed, and whose ultimate end came sooner, largely through competition with humans. While a range of taxons, including flora, died out, the fate of the megafauna is grim.

ECONOVO researchers have presented their conclusions in a review article in Cambridge Prisms: Extinction.

An important observation is that the previous, equally dramatic ice ages and interglacials over the past couple of million years did not cause a selective loss of megafauna. Especially at the beginning of the glacial periods, the new cold and dry conditions caused large-scale extinctions in some regions, such as trees in Europe. However, there were no selective extinctions of large animals.

“The large and very selective loss of megafauna over the last 50,000 years is unique over the past 66 million years. Previous periods of climate change did not lead to large, selective extinctions, which argues against a major role for climate in the megafauna extinctions,” says Prof Jens-Christian Svenning, who leads ECONOVO and is the lead author of the article.

Other recent extinct fauna

  • 1690: Dodo – Extinct from predation by introduced pigs and cats

  • 1768: Stellar’s sea cow – Extinct from hunting for fur and oil

  • 1870: Labrador duck – Extinct from human competition for mussels and other shellfish

  • 1900: Rocky mountain locust – Extinct from habitat conversion to farmland

  • 1914: Passenger pigeon - Extinct from a range of human activities

  • 1936: Thylacine – Extinct from hunting, habitat loss, and competition with dogs

  • 1952: Deepwater cisco fish – Extinct from competition and predation by introduced fishes

  • 1989: Golden toad – extinct from climate change or other impacts

Source: Smithsonian Institution

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