Visit Your Local PBS Station PBS Home PBS Home Programs A-Z TV Schedules Watch Video Donate Shop PBS Search PBS
    
Click to return to the Evolution Home Page
darwin change extinction survival sex humans religion
mass extinction    
   
roundtable:a modern mass extinction Watch Show 3:
"Extinction!" on PBS
Check local listings
select a question from below
First, a general question. Are we now in a mass extinction, and if so, why does it matter?
Some Web visitors wrote to say they have heard it said, especially of tropical and marine organisms, that we are losing species before we even know of them. And the question is, if we haven't discovered a species yet, how do we know that we've lost it?
Would Darwin support the Federal Endangered Species Act? Millions of dollars are spent by corporations and government for habitat conservation plans, recovery plans, etc., for species that seem doomed for extinction. Is this a wise use of money? Why or why not?
If extinction and mass extinctions are a natural part of Earth's history, should we really be concerned about our effects on endangered species? Are we trying to fight something that's inevitable anyway and that is much larger than us, as a single species ourselves?
I'm concerned with the loss of genetic diversity because it affects food supply, drug discoveries, and the stability of ecosystems on which we depend. And yet, I'm very skeptical of the theory of evolution as it now stands. How does the theory of evolution -- or we could also say that as evolutionary thought -- explain and predict what's going on with the current cycle of extinction, better than if we had to just rely on what we can observe? In other words, what context and what value does evolutionary thought provide to this discussion that we're having?
Several other questions relate to this: Loss of biodiversity, water and air pollution, and the greenhouse effect are all impacting the biosphere, and if these are indeed combining to produce a mass extinction, do you think our species will survive it? Peter's already said that he thinks yes. How about some other perspectives?
Let's move onto some more specific questions. Why do bigger species go extinct faster than smaller ones?
Do you feel that extinctions of large Ice Age mammals had any human causes?
Another Web user wrote: I know there is a gene databank under construction right now. Could this be used as a modern Noah's Ark for the future?
We'll wrap up with a different kind of question. There was one that came from a younger visitor to the Web site who asked, What can kids do to help save the rain forest and animals?
   

 

Q: If extinction and mass extinctions are a natural part of Earth's history, should we really be concerned about our effects on endangered species? Are we trying to fight something that's inevitable anyway and that is much larger than us, as a single species ourselves?
Panelist Responses: < back to intro page
Tundi Agardi
It's a very big question, obviously a very deep question, and one that we could spend hours and hours, I think, debating as individuals, and talking about the role of ethics, both in science and, obviously, environmental protection and species protection. And I don't really want to go into the ethical argument. But, we have a situation where we are the only species, in the history of the world, that has engineered single-handedly the extinction of large numbers of organisms.

I think that carries with it a kind of special responsibility. We need to evaluate our role in the world and the fact that we do have choices, and we have the option to stop the current rate of extinction with measures that will prevent habitat loss, and with regulations and rules that will provide species the kind of safety net that the Endangered Species Act provides.

So we have to ask ourselves the question, Do we have a special responsibility given that we are the only species that we know about, in any kind of history of life, that has engineered these mass extinctions? And that's a question that I think we have to ponder as individuals and as societies, and I think we have to recognize the choice is ours to make -- that we either continue along the trajectory which most people feel is a probable one, or we make some choices to get us off that track.

Again, I would say that I don't think people are concerned so much about the absolute number of species out there. And also even though I'm the only bona fide professional environmentalist on the panel, I want to strike a moderate tone in saying that I don't think that there is really any "original condition." That I don't think any of us are striving for the pristine Eden, where humans don't have any impact and where we think we would know what the species were and how many were out there and how they interacted.

I think there is no original condition. There's a constantly changing environment with a constantly changing set of species that interact with one another. But I think what we are trying to strive for is to prevent irreversible changes to the biosphere, because we don't really understand the consequences of any irreversible impact, whether it's species lost, which is of course the ultimate irreversible change, or whether it's the loss of a unique habitat, or whether it's in fact loss of genetic diversity and the loss of a unique population. We don't understand the consequences.

So, in light of our limited understanding, I think we all strive for making sure that we don't make irreversible mistakes in the future, and I think that's what our special role may be in the future. We have played a very large role in structuring the modern world, and I think we have to now look at what we've done, and look at the future, and try and find ways that we don't end up harming ourselves as a species, and harming the rest of the biosphere irreversibly, by kind of keeping up with the same behavior and the same kind of situations that have created the extinction crisis so far.
Daniel Simberloff
I guess I adamantly refuse to comment on the question. I mean, my area of expertise as a scientist is what is happening and why it's happening and, to some extent, what the consequences may be. But the question is about should it be happening and should we care, and that's really a question of ethics or psychology. I just don't have any expertise in the area.
Peter Ward
I agree with Dan. This is why I'm withholding comments here.
  related web activities  
   
Deep Time
Explore 4 billion years of life on Earth.
 
 
What Killed the Dinosaurs?
Find clues to one of life's great mysteries.
 
 
The Evolving Enemy
Experts discuss how we can stop deadly, drug-resistant microbes.
 
   
  related topics  
   
  Why Evolution Matters  
   
  Deep Time/History of Life  
   
  Evidence for Evolution  
 
 
         
 
Source Credits      
 
Videos Web Activities Site Guide About the Project FAQ Glossary Site Map Feedback Help Shop