4 ms·

"The Amazon" and some of the other habitats you mention, all very different in their ecologies (and especially their relationship to fire), have had very comple

by Kaijo 3y ago

"The Amazon" and some of the other habitats you mention, all very different in their ecologies (and especially their relationship to fire), have had very complex histories, but their co-history with humans must be seen as a recent history in relation to the evolutionary history of their core community structures and the tens of millions of species of which they are composed. Of course once we first arrived in South America, only about 20,000 years ago, we had quite profound impacts on the Amazon's species composition and distribution, but... that's a mere 20,000 years ago, and essentially all the species we see in today's Amazon were already there, just configured differently. Before that, there was certainly a highly biodiverse and to all intents modern Amazon pre-dating humans by millions of years, one in which, if we could go back, we could still find regions plainly characteristic of every major present-day Amazonian ecotype, minus humans. This applies even more so to the much more ancient central African and southeast Asian rainforests in which there are also some areas with no clear record of inhabitation. I have done fieldwork in such areas and am fine with the characterization that they present a "more pristine" state of ecological affairs, as would most biologists focusing on tropical forest ecology rather than anthropology. To claim all these habitats are intrinsically human-oriented ecosystems that have always been as dependent on us as we on them is myopic. That's a view of how things have to be going forwards. But to them we're a recent development.

culi 3y ago
Thanks for the comment. Would love to hear more about what kind of fieldwork you've done > Of course once we first arrived in South America, only about 20,000 years ago, we had quite profound impacts on the Amazon's species composition and distribution, but... that's a mere 20,000 years ago Consider the fact that only just 12,000 years ago the Amazon transitioned from mostly grasslands to the full-fledged continent-wide jungle it is today. Or that the last African humid period ended just 6,000 years ago during which the Sahara was covered with wetlands, grasses, trees, etc. A LOT can change in just a few thousand years > Before that, there was certainly a highly biodiverse and to all intents modern Amazon pre-dating humans by millions of years Sure, if we're talking on the scale of millions of years we can include a jungled Arctic which also ended 50 millions ago (around the same age as the Amazon). I did not intend to argue humans were necessary to biodiversity or even to the Amazon's development. Rather just that they clearly left a major impact. From that first paper I linked: > We found that half of the arboreal species (2,253) are useful to humans, which represents 84% of the estimated individuals in Amazonian forests. Useful species have mean populations sizes six times larger than non-useful species, and their abundance is related with the probability of usefulness. Incipiently domesticated species are the most abundant Of course naturally people will often use the most abundant species (the paper addresses that as well), but it's hard to deny that the millions of native Homo sapiens acted as a keystone species. The recent advances in Lidar technologies especially have revealed an Amazonian landscape and soil distribution that's been deeply shaped by human inhabitation. > if we could go back, we could still find regions plainly characteristic of every major present-day Amazonian ecotype, minus humans This seems like an incredibly hard claim to back up but I would be absolutely delighted to read through any papers or books on the topic if you have them on hand > This applies even more so to the much more ancient central African and southeast Asian rainforests in which there are also some areas with no clear record of inhabitation Yes, apologies if I seemed to imply that every corner of earth was shaped by humans. This is certainly not true. I did not mention the landscapes you brought up, but I stand by the claim that there is plenty of evidence that the 3 case studies I brought up are heavily shaped by human culture despite often being portrayed as "untouched" environments > But to them we're a recent development. I completely agree with this statement but go back to my first point (and I even made the point without bringing up climate change!)
- UncleEntity 3y ago
  > Consider the fact that only just 12,000 years ago the Amazon transitioned from mostly grasslands to the full-fledged continent-wide jungle it is today. Google says the Amazon rainforest is 10 million years old.
  - culi 3y ago
    well I suppose it depends what you define as the starting point but it's generally recognized it began in the Eocene epoch (55.8 million years to 33.9 million years ago) Not sure how that's relevant to the sentence you quoted though. The Amazon rainforest has been largely savanna type ecosystems at various points in its history. Including quite recently (like 12kya)
  - djbusby 3y ago
    Wikipedia shows 55 million, but this article https://www.scientificamerican.com/article/amazon-rainforest-is-much-younger-than-commonly-believed/ https://www.scientificamerican.com/article/amazon-rainforest... reads at 2000 years old. These are orders of magnitude different. Maybe they are using different definition or sub-regions.
    - scythe 3y ago
      The article also says: >The arrival of European diseases after Columbus crossed the Atlantic in 1492 may also have hastened the growth of forests by killing indigenous people farming the region, the scientists wrote in the U.S. journal Proceedings of the National Academy of Sciences (PNAS). It would be very lucky for humans to be so devastating[1] to the natural environment everywhere except the Amazon and yet have been excellent stewards of the natural environment within the Amazon. Such assumptions smack of the "noble savage" mythology. 1: https://en.wikipedia.org/wiki/Quaternary_extinction_event https://en.wikipedia.org/wiki/Quaternary_extinction_event
      - rob74 3y ago
        I think humans were more devastating to the environment elsewhere (e.g. in Europe) simply because there were more humans there. Also, tropical rainforests are not really comparable to forests in temperate regions. So my theory is that the faster-growing forest and the lower population density protected the rainforest of South America (and also equatorial Africa) until the 20th century.
pvaldes 3y ago
> To claim all these habitats are intrinsically human-oriented ecosystems that have always been as dependent on us as we on them is myopic. But is a convenient myth, as a justification to chop it. Animals also spread seeds and nuts.

by Kaijo 3y ago

culi 3y ago

Thanks for the comment. Would love to hear more about what kind of fieldwork you've done > Of course once we first arrived in South America, only about 20,000 years ago, we had quite profound impacts on the Amazon's species composition and distribution, but... that's a mere 20,000 years ago Consider the fact that only just 12,000 years ago the Amazon transitioned from mostly grasslands to the full-fledged continent-wide jungle it is today. Or that the last African humid period ended just 6,000 years ago during which the Sahara was covered with wetlands, grasses, trees, etc. A LOT can change in just a few thousand years > Before that, there was certainly a highly biodiverse and to all intents modern Amazon pre-dating humans by millions of years Sure, if we're talking on the scale of millions of years we can include a jungled Arctic which also ended 50 millions ago (around the same age as the Amazon). I did not intend to argue humans were necessary to biodiversity or even to the Amazon's development. Rather just that they clearly left a major impact. From that first paper I linked: > We found that half of the arboreal species (2,253) are useful to humans, which represents 84% of the estimated individuals in Amazonian forests. Useful species have mean populations sizes six times larger than non-useful species, and their abundance is related with the probability of usefulness. Incipiently domesticated species are the most abundant Of course naturally people will often use the most abundant species (the paper addresses that as well), but it's hard to deny that the millions of native Homo sapiens acted as a keystone species. The recent advances in Lidar technologies especially have revealed an Amazonian landscape and soil distribution that's been deeply shaped by human inhabitation. > if we could go back, we could still find regions plainly characteristic of every major present-day Amazonian ecotype, minus humans This seems like an incredibly hard claim to back up but I would be absolutely delighted to read through any papers or books on the topic if you have them on hand > This applies even more so to the much more ancient central African and southeast Asian rainforests in which there are also some areas with no clear record of inhabitation Yes, apologies if I seemed to imply that every corner of earth was shaped by humans. This is certainly not true. I did not mention the landscapes you brought up, but I stand by the claim that there is plenty of evidence that the 3 case studies I brought up are heavily shaped by human culture despite often being portrayed as "untouched" environments > But to them we're a recent development. I completely agree with this statement but go back to my first point (and I even made the point without bringing up climate change!)

UncleEntity 3y ago
> Consider the fact that only just 12,000 years ago the Amazon transitioned from mostly grasslands to the full-fledged continent-wide jungle it is today. Google says the Amazon rainforest is 10 million years old.
- culi 3y ago
  well I suppose it depends what you define as the starting point but it's generally recognized it began in the Eocene epoch (55.8 million years to 33.9 million years ago) Not sure how that's relevant to the sentence you quoted though. The Amazon rainforest has been largely savanna type ecosystems at various points in its history. Including quite recently (like 12kya)
- djbusby 3y ago
  Wikipedia shows 55 million, but this article https://www.scientificamerican.com/article/amazon-rainforest-is-much-younger-than-commonly-believed/ https://www.scientificamerican.com/article/amazon-rainforest... reads at 2000 years old. These are orders of magnitude different. Maybe they are using different definition or sub-regions.
  - scythe 3y ago
    The article also says: >The arrival of European diseases after Columbus crossed the Atlantic in 1492 may also have hastened the growth of forests by killing indigenous people farming the region, the scientists wrote in the U.S. journal Proceedings of the National Academy of Sciences (PNAS). It would be very lucky for humans to be so devastating[1] to the natural environment everywhere except the Amazon and yet have been excellent stewards of the natural environment within the Amazon. Such assumptions smack of the "noble savage" mythology. 1: https://en.wikipedia.org/wiki/Quaternary_extinction_event https://en.wikipedia.org/wiki/Quaternary_extinction_event
    - rob74 3y ago
      I think humans were more devastating to the environment elsewhere (e.g. in Europe) simply because there were more humans there. Also, tropical rainforests are not really comparable to forests in temperate regions. So my theory is that the faster-growing forest and the lower population density protected the rainforest of South America (and also equatorial Africa) until the 20th century.

pvaldes 3y ago

> To claim all these habitats are intrinsically human-oriented ecosystems that have always been as dependent on us as we on them is myopic. But is a convenient myth, as a justification to chop it. Animals also spread seeds and nuts.