Ice age Animal Extinctions in Tropical America

[faslan]

what were the causes for Ice age animals( large herbivores ) or animals extinct 15000-5000 years ago in tropical America ??

 

i learned North american mega fauna extinct because of global warming,a meteoroid impact BP 13000 years ago,and human impact also Eurasian ice age animals died out because of warming. climate warming probably gave the large mammals heat strokes

 

but how could End of Ice age affect Tropical megafuna because they were already adapted to hot environment, human hunted them for food but it's impossible to accept human were the cause of extinction

[Anthony Morris]

Humans are probably the main reason most large animals died out in South America. Climate change probably helped but humans not only hunted these animals but altered the habitat and possibly introduced diseases that these animals could not counter. The extinction was not likely to have just one cause.

[tantalus]

I think ice age and tropical as word choices are misleading.

 

The theories for the wave of extinction during your stated period are climate change, human arrival and hunting, disease (linked to human arrival), comet impact, or some combination. Also discussed is ecosystem shift due to key singular extinctions that also may have altered fire regimes.

 

Interesting over the last couple of years, the clovis first theory (that the clovis people first settled the americas) has finally been put to bed. That theory dominated the field for decades and nobody has a wining theory to replace in at the moment. We know now that there were people pre-clovis, from where, when, how many, where they big game hunters?, is yet to be established. This has potential to significantly alter conclusions on the megafaunal extinctions.

 

Personally, I favour human arrival as the significant factor. Maybe I just have a bias for correlation. The timing is very good, and the existence of pre-clovis, on first thought, seems to strengthen the case, and weaken the argument human populations couldnt have grown fast enough, with the clovis first theory. However, it has been argued (through mathematical modelling) that the clovis people could have hunted at the necessary levels to bring about the extinction wave in the time period required. There were not too late or too few to do the deed.

 

Also, Interesting new paper.

 

http://www.pnas.org/content/113/4/886.full.pdf?sid=78082c56-76a7-46a1-8248-a0c6d1760c4e

However this focuses on the clovis people, despite the fact we know of pre-clovis (the paper mentions this). But it can't be ignored that clovis arrival, migration and technology may still be the key cause, even with the presence of pre-clovis humans. The paper attempts to establish a geographical pattern of extinction through time that could only fit the clovis theory. It is suggestive, although I would question the idea that extinctions will neatly occur in space and time to fit any theory. If such kind of evidence is found, great, but its absence doesn't necessarily destroy a theory imo.

 

I also like human hunting as a cause when you look at megafaunal extinctions globally over last 100,000 years, where they were occurred rapidly, they seems to coincide with human arrival (with previous isolation), Americas, Australia, New Zealand , Madagascar, less so and further back in history for the Old World. To expect perfect fits and neat patterns of extinction doesn't fit with reality, so I feel some of the criticism are unreasonable when one finally needs to draw conclusions, or hedge bets, whatever of the process.

 

Other suggestive evidence is large species surviving on islands when extinctions where occurring on the americas. The eventual extinctions correlated with the later arrival of humans.

 

Of course the clear pattern of extinctions of large species over small ones is suggestive of hunting as a major factor.

Edited March 27, 2016 by tantalus