Dr. David Gwynn

So, the timing issue doesn't work, the kill site issue, not enough, right? We also know what extinctions might look like in terms of the kill site record. And let me explain. Humans have been hunting bison for 12,000, 13,000 years. And they've been hunting them in sometimes large numbers.

So, the timing issue doesn't work, the kill site issue, not enough, right? We also know what extinctions might look like in terms of the kill site record. And let me explain. Humans have been hunting bison for 12,000, 13,000 years. And they've been hunting them in sometimes large numbers.

So, the timing issue doesn't work, the kill site issue, not enough, right? We also know what extinctions might look like in terms of the kill site record. And let me explain. Humans have been hunting bison for 12,000, 13,000 years. And they've been hunting them in sometimes large numbers.

There are sites in Colorado that are 10,000 years old for which we have 190 bison that got stampeded into an arroyo and died a horrible death. I mean, you've got skeletons that are on their backs and they were clearly riding around, but they were then piled on by three or four other layers of bison. It must have been a terrible way to go.

There are sites in Colorado that are 10,000 years old for which we have 190 bison that got stampeded into an arroyo and died a horrible death. I mean, you've got skeletons that are on their backs and they were clearly riding around, but they were then piled on by three or four other layers of bison. It must have been a terrible way to go.

There are sites in Colorado that are 10,000 years old for which we have 190 bison that got stampeded into an arroyo and died a horrible death. I mean, you've got skeletons that are on their backs and they were clearly riding around, but they were then piled on by three or four other layers of bison. It must have been a terrible way to go.

There's a site in southeastern Wyoming, it's a sinkhole where an estimated 10,000 or more bison were stampeded into the sinkhole repeatedly over several centuries. And yet, after all that intensive hunting, bison are still around. So here we have a record of

There's a site in southeastern Wyoming, it's a sinkhole where an estimated 10,000 or more bison were stampeded into the sinkhole repeatedly over several centuries. And yet, after all that intensive hunting, bison are still around. So here we have a record of

There's a site in southeastern Wyoming, it's a sinkhole where an estimated 10,000 or more bison were stampeded into the sinkhole repeatedly over several centuries. And yet, after all that intensive hunting, bison are still around. So here we have a record of

heavy-duty almost, I hesitate to use the term industrial scale, but heavy-duty hunting of a species for 12,000 years, but it didn't go extinct. And yet people claim that these 38 genera of animals for which we have only 16 sites giving us evidence that they were hunting went extinct and they call that or they blame that on humans, that seems kind of unlikely.

heavy-duty almost, I hesitate to use the term industrial scale, but heavy-duty hunting of a species for 12,000 years, but it didn't go extinct. And yet people claim that these 38 genera of animals for which we have only 16 sites giving us evidence that they were hunting went extinct and they call that or they blame that on humans, that seems kind of unlikely.

heavy-duty almost, I hesitate to use the term industrial scale, but heavy-duty hunting of a species for 12,000 years, but it didn't go extinct. And yet people claim that these 38 genera of animals for which we have only 16 sites giving us evidence that they were hunting went extinct and they call that or they blame that on humans, that seems kind of unlikely.

Lots of stuff is happening at the end of the Pleistocene. We've got an increase in the amount of incoming solar radiation, a rapid rise in atmospheric CO2. We've got warmer climates. Patterns of seasonality are changing. So we're getting, in some areas... which had been sort of relatively mild winters, relatively mild summers. We're now getting really, really cold winters, really hot summers.

Lots of stuff is happening at the end of the Pleistocene. We've got an increase in the amount of incoming solar radiation, a rapid rise in atmospheric CO2. We've got warmer climates. Patterns of seasonality are changing. So we're getting, in some areas... which had been sort of relatively mild winters, relatively mild summers. We're now getting really, really cold winters, really hot summers.

Lots of stuff is happening at the end of the Pleistocene. We've got an increase in the amount of incoming solar radiation, a rapid rise in atmospheric CO2. We've got warmer climates. Patterns of seasonality are changing. So we're getting, in some areas... which had been sort of relatively mild winters, relatively mild summers. We're now getting really, really cold winters, really hot summers.

We're changing moisture regimes. Ecosystems that had been in place for literally thousands of years are fragmenting because in response to these changes in the climate, species are going off in different directions depending on their ecological tolerances and their thresholds, right? You've got feedback effects because when megafaunal populations die off, they're no longer clearing out

We're changing moisture regimes. Ecosystems that had been in place for literally thousands of years are fragmenting because in response to these changes in the climate, species are going off in different directions depending on their ecological tolerances and their thresholds, right? You've got feedback effects because when megafaunal populations die off, they're no longer clearing out

We're changing moisture regimes. Ecosystems that had been in place for literally thousands of years are fragmenting because in response to these changes in the climate, species are going off in different directions depending on their ecological tolerances and their thresholds, right? You've got feedback effects because when megafaunal populations die off, they're no longer clearing out

certain types of vegetation from an environment. So you've got changing habitats, you've got changing competitive relationships. So lots of different things are happening in the environment. The real tough question is how do you link that to the processes that would have led to the extinction of these animals.

certain types of vegetation from an environment. So you've got changing habitats, you've got changing competitive relationships. So lots of different things are happening in the environment. The real tough question is how do you link that to the processes that would have led to the extinction of these animals.