Post by Ian Thomas on Jun 11, 2023 14:06:06 GMT 10
Megafauna extinctions.
Not a case of 'humans dunnit' after all.
Chain of causality goes like so:
Long term cooling -> declining rainfall within continents => forests -> savannah -> grasslands -> deserts.
The Sahara is only a few thousand years old. Getting bigger in fits n starts.
en.wikipedia.org/wiki/Sahara#History
Today's human populations are mono-crop specialists more than ever before in our history ... like the over-specialised megafauna of former times.
Not a case of 'humans dunnit' after all.
Lost giants: New study reveals the abundance decline of African megafauna.
Retrieved June 10, 2023, from
www.sciencedaily.com/releases/2023/06/230608195648.htm
The study confirms recent work arguing for the deep-time antiquity of African megafaunal losses and challenging the idea that the decline of African megafauna was primarily driven by human activities. While the spread of humans across the globe during the late Pleistocene and Holocene (the last ~100,000 years) coincided with major extinction of many large animals, the research supports the idea that megafaunal losses in Africa began much earlier, around 4 million years ago, and long before humans learned to engage in efficient hunting. Instead, the study highlights environmental factors, such as the long-term decrease in global temperatures and the expansion of tropical grasslands, as potential drivers of megafaunal extinctions.
Retrieved June 10, 2023, from
www.sciencedaily.com/releases/2023/06/230608195648.htm
The big surprise came when the researchers examined how size-abundance distributions changed over time. They discovered that earlier communities, older than ~4 million years ago, had a considerably higher number of large-sized individuals and a greater proportion of total biomass in larger size categories, than did younger communities. The high abundance of large individuals in these fossil African communities -- with some individual elephants reaching sizes over 10 tons -- is unparalleled in ecosystems today. Since that time, there has been a gradual loss of large-sized individuals from the fossil record, reflecting the long-term decline of late Pliocene and Pleistocene large mammal diversity, and resulting in the impoverished and 'miniaturized' communities we know today.
The study confirms recent work arguing for the deep-time antiquity of African megafaunal losses and challenging the idea that the decline of African megafauna was primarily driven by human activities. While the spread of humans across the globe during the late Pleistocene and Holocene (the last ~100,000 years) coincided with major extinction of many large animals, the research supports the idea that megafaunal losses in Africa began much earlier, around 4 million years ago, and long before humans learned to engage in efficient hunting. Instead, the study highlights environmental factors, such as the long-term decrease in global temperatures and the expansion of tropical grasslands, as potential drivers of megafaunal extinctions.
Chain of causality goes like so:
Long term cooling -> declining rainfall within continents => forests -> savannah -> grasslands -> deserts.
The Sahara is only a few thousand years old. Getting bigger in fits n starts.
en.wikipedia.org/wiki/Sahara#History
Today's human populations are mono-crop specialists more than ever before in our history ... like the over-specialised megafauna of former times.
Ominous? 
