Adrian Lister: the Eurasian extinctions have a particularly good record. I don’t feel we have adequate data, even in Europe, to solve the megafauna/climate debate.
Felisa Smith: we are mixing apples and oranges. There is a background extinction rate. The Pleistocene extinctions in northern Eurasia are not that different from background rates, but elsewhere they are way above background rates
Kate Lyons: the extinctions were highly size biased. These extinctions would not have happened without the addition of humans to the system.
Todd Surovell: spatial distribution of elephant kill sites and decline globally can only be explained by humans
Blaire Van Valkenburgh: what is lacking in our models is thinking about the importance of the biotic interactions that are going on.
David Nogues-Bravo: Extinction events were rarely caused by a single driver. Debates about climate vs humans may not be useful.
Jens-Chrstian Svenning: we should exploit the repeated climate changes of the whole Quaternary. From that perspective it is even more striking that we have such a size bias in the recent extinction but little plant extinctions. We don’t expect large bodied animal species to be the most sensitive to climate change because they have ranges and are relatively mobile.
Felisa Smith: large body size does not make species prone to extinction in the fossil record. We only see this in the late Pleistocene extinctions. And we see it in recent marine extinctions. We have to be careful to infer the past from highly modified ecosystems of today
Frans Vera: many megafauna became extinct or effectively extinct in Eurasia in the last few centuries. We can look at modern animals to know what happened in the past.
Tony Stuart: There is a tendency for North Americans to play down northern Eurasia, but the extinctions there were significant. They were not just background extinction rates. The super-mega mammals go out as they did elsewhere in the world.
Felisa Smith: we need to be careful about cherry-picking taxa.
Todd Surovell: I don’t see Eurasia as anomalous. Hominids and megafauna occupied in different parts of the continent. Before the LGM little evidence of humans in high Arctic, but abundant megafauna. Like to see more explicit hypothesis testing as to what is affected.
Adrian Lister: From our data and the pattern of staggered extinction, we can predict based on distinct ecology of species (e.g. Mammoth was grassland species, giant deer was forest edge species). Don’t expect range of species of different ecologies to all go extinct at the same climate signal.
In N America, if we find all species disappear at the same time then we could be convinced of human drivers of extinction, but we don’t have the data.
John Terborgh: Several interesting cases of refugia where megafaunal species persisted into Holocene (elephants in Mediterranean, giant sloths in Caribbean etc). They survive until humans show up on the islands.
Abby Swann: there has been a lack of discussion about the uncertainty in climate modelling of past climate conditions.
David Nogues-Bravo: one way to get at climate uncertainty is through using multiple climate models.
Tony Stuart: very few people doubt that extinctions on islands re caused by humans.
Adrian Lister: no-one has really shown a clear mechanism as to why African species persisted within humans
Todd Surovell: in archaeology Pleistocene overkill is very controversial. He is happy to be in good company here.
Kate Lyons/Blaire Van Valkenburgh: in Africa we have been looking at the wrong timescale. There is evidence of major extinctions around 2-2.5 million years ago around emerging of Homo erectus. Much of Africa’s megafaunal extinctions happened then. Early carnivores would have been quite disturbed by early hominids.
Felisa Smith: Shame Paul Martin is no longer with us. He would have loved this meeting.
Melissa Pardi: in order to test the climate hypothesis we are looking at the long time. We need to look into the deeper past.
Josh Donlan: how important is attribution of Pleistocene extinction to moving forward? Do we need evidence that humans played a major role in order to move forward with rewilding etc., or is it irrelevant.
Kate Lyons: it depends on what is going to motivate people to change policy. Some think that human-caused extinctions mean we’re powerful agents of change and can fix it; others feel hopeless.
Adrian Lister: justifying for rewilding has to be made on basis of the ecological situation now, not on Pleistocene arguments
Frans Vera: disagree, we can learn from the past overkill
Adrian Lister: We can see the importance of synergy of forces, how climate and human drivers can interact.
Maan Barua: naive to consider modern human drivers as equivalent to Pleistocene human drivers
Adam Wolf; Ancient food webs are important. How much do we understand them.
Felisa Smith: we are mixing apples and oranges. There is a background extinction rate. The Pleistocene extinctions in northern Eurasia are not that different from background rates, but elsewhere they are way above background rates
Kate Lyons: the extinctions were highly size biased. These extinctions would not have happened without the addition of humans to the system.
Todd Surovell: spatial distribution of elephant kill sites and decline globally can only be explained by humans
Blaire Van Valkenburgh: what is lacking in our models is thinking about the importance of the biotic interactions that are going on.
David Nogues-Bravo: Extinction events were rarely caused by a single driver. Debates about climate vs humans may not be useful.
Jens-Chrstian Svenning: we should exploit the repeated climate changes of the whole Quaternary. From that perspective it is even more striking that we have such a size bias in the recent extinction but little plant extinctions. We don’t expect large bodied animal species to be the most sensitive to climate change because they have ranges and are relatively mobile.
Felisa Smith: large body size does not make species prone to extinction in the fossil record. We only see this in the late Pleistocene extinctions. And we see it in recent marine extinctions. We have to be careful to infer the past from highly modified ecosystems of today
Frans Vera: many megafauna became extinct or effectively extinct in Eurasia in the last few centuries. We can look at modern animals to know what happened in the past.
Tony Stuart: There is a tendency for North Americans to play down northern Eurasia, but the extinctions there were significant. They were not just background extinction rates. The super-mega mammals go out as they did elsewhere in the world.
Felisa Smith: we need to be careful about cherry-picking taxa.
Todd Surovell: I don’t see Eurasia as anomalous. Hominids and megafauna occupied in different parts of the continent. Before the LGM little evidence of humans in high Arctic, but abundant megafauna. Like to see more explicit hypothesis testing as to what is affected.
Adrian Lister: From our data and the pattern of staggered extinction, we can predict based on distinct ecology of species (e.g. Mammoth was grassland species, giant deer was forest edge species). Don’t expect range of species of different ecologies to all go extinct at the same climate signal.
In N America, if we find all species disappear at the same time then we could be convinced of human drivers of extinction, but we don’t have the data.
John Terborgh: Several interesting cases of refugia where megafaunal species persisted into Holocene (elephants in Mediterranean, giant sloths in Caribbean etc). They survive until humans show up on the islands.
Abby Swann: there has been a lack of discussion about the uncertainty in climate modelling of past climate conditions.
David Nogues-Bravo: one way to get at climate uncertainty is through using multiple climate models.
Tony Stuart: very few people doubt that extinctions on islands re caused by humans.
Adrian Lister: no-one has really shown a clear mechanism as to why African species persisted within humans
Todd Surovell: in archaeology Pleistocene overkill is very controversial. He is happy to be in good company here.
Kate Lyons/Blaire Van Valkenburgh: in Africa we have been looking at the wrong timescale. There is evidence of major extinctions around 2-2.5 million years ago around emerging of Homo erectus. Much of Africa’s megafaunal extinctions happened then. Early carnivores would have been quite disturbed by early hominids.
Felisa Smith: Shame Paul Martin is no longer with us. He would have loved this meeting.
Melissa Pardi: in order to test the climate hypothesis we are looking at the long time. We need to look into the deeper past.
Josh Donlan: how important is attribution of Pleistocene extinction to moving forward? Do we need evidence that humans played a major role in order to move forward with rewilding etc., or is it irrelevant.
Kate Lyons: it depends on what is going to motivate people to change policy. Some think that human-caused extinctions mean we’re powerful agents of change and can fix it; others feel hopeless.
Adrian Lister: justifying for rewilding has to be made on basis of the ecological situation now, not on Pleistocene arguments
Frans Vera: disagree, we can learn from the past overkill
Adrian Lister: We can see the importance of synergy of forces, how climate and human drivers can interact.
Maan Barua: naive to consider modern human drivers as equivalent to Pleistocene human drivers
Adam Wolf; Ancient food webs are important. How much do we understand them.