An Interview with Andy Knoll
Part I: Biodiversity and Astrobiology
Interview with Andrew Knoll, professor of evolutionary biology at Harvard University (original video with the NASA Astrobiology Institute)
What is the biotic crisis?
|Norman Myers, a conservation biologist at UC Berkeley, believes that scientists can predict how evolutionary processes will play out in the future.
Image Credit: Jane Scherr
We live in a moment in Earth's history where, uniquely in the history of our planet, one species has become responsible for the entire biosphere. There's no question that what happens to all of biology over the foreseeable future depends on conscious decisions made by humans. Our population has been growing and we've been expanding our use of resources over the past hundred to two hundred years without a whole lot of thought for the other residents of the planet. That brings us to a moment in biological history where there's a real threat to whole classes of organisms. Many organisms live in environments that are being decimated, and large mammals need large areas of range. Decisions that we humans make over the next two or three decades will determine what biology will look like for millions of years.
That's why I got involved in this topic with Norman Myers, a conservation biologist. He thought we had to ask about the most likely scenarios for what evolution might be like in the future. And by that we don't mean the standard response to that question - we don't think we can pinpoint what a giraffe might look like in a million years; that's not a predictable thing. But what we can predict is how evolutionary processes will play out: when, for example, population sizes are small and fragmented, or when we have homogenization of biotas based on immigrations of people bringing plants, animals, and microorganisms with them. Only by understanding evolutionary processes, the evolutionary present, and something of the evolutionary past can we, as scientists, give wise counsel to those who will be making the policy decisions in the future.
Why is it important to maintain biological diversity?
I think maintenance of diversity is important for the functioning of ecosystems. There's increasing work that suggests ecosystems as regional landscapes are more likely to be resistant to perturbations if diversity is high. So diversity for it's own sake may be a buffering system for biota. Certainly the components of that diversity - the individual plant and animal species - are important to the maintenance of a world we're comfortable in, whether or not they're important in any abstract sense to the future of evolution.
|"Only by understanding evolutionary processes, the evolutionary present, and something of the evolutionary past can we, as scientists, give wise counsel to those who will be making the policy decisions in the future." -Andrew Knoll
Image Credit: querysoft.es
Life will persist. I don't see anything coming up that is likely to destroy all life on this planet. For the first eighty percent of the history of this planet, life did quite well with only microorganisms. In that sense, all plants and animals are intricate and unnecessary ornaments in the operation of a biosphere. Nonetheless, that's very cold comfort. Our food and fiber, our sense of landscape and aesthetics, and increasingly the genes that might be used in pharmaceuticals come largely from the plants and animals that form our landscape.
Are there intrinsic limits on diversity, and how does the human presence or "intervention" factor in?
It's not clear that there are intrinsic limits on diversity, although there may be limits on the diversity of individual types of organisms. If we look, for example, at animals that live in the ocean, fairly sedentary and passive animals reached a peak diversity about four hundred million years ago. Whereas other animals with more active physiologies have diversified almost linearly over that past four hundred million years. The overall diversity of animals in the ocean is much higher today than it was in the past, but only certain components of the animals have expanded.
I don't think there's an intrinsic limit on diversity. Diversity acts as a flywheel because the way organisms interact with each other creates new opportunities. As long as we have this system, where evolution on one branch of the tree begets a response on another branch of the tree, I don't see a world that tops out on diversity. But then again, that's a world without human intervention. In a world with humans as a principal part of communities, maybe we have topped out, who knows.
What does all this have to do with Astrobiology?
The astrobiological component is that everything we know about life in the universe comes from life on Earth. In a sense, putting current diversity at peril for those who would like to understand biology as a planetary phenomenon is like burning a library. It will be hard for us to fully understand the history and properties of life on Earth on an impoverished planet. Until or unless we find evidence of life anywhere else, that's a serious issue.
As we think about extending human purview beyond Earth, we also need to think about what effects we might have on other planets in the solar system. There may well come a day when humans colonize Mars. How should we think about our stewardship for Mars? I'm not sure I know the answer to that, but I think the answer in some way has to be bound up with our sense of respectability at handling our own planet.
One of the keystones of astrobiology is asking the question 'what is our future as a species?' - which I think in the language of NASA is interpreted as some sort of planetary manifest destiny. I think many of the questions of our future as a species are going to be answered right here, and not on Mars.
Related Web Pages
Biodiversity interview with Andrew Knoll, professor of evolutionary biology at Harvard University (original video)
Astrobiology at Harvard:
NAI Lead Team Details-Harvard
World Map of Biodiversity