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Archive for November, 2012

Giving The Far Future The Blues

When writers build worlds, we [are supposed to] give at least a passing thought to water supplies and waste management, and all the handy physical infrastructures that support our characters. We also [are supposed to] spare a thought for social infrastructures like bureaucracies, economies, families, and so on. It’s usually possible to gloss over most of these things – much exposition can be safely left to the readers’ assumptions – and when that’s impossible, it’s usually still wise to attend primarily to the details of the setting that lend context and veracity to the plot.

That said, there is a tendency to retreat the setting to the background to such a degree that characters merely strut their half-hour upon a stage; a practice that leaves many stories reading like the pilot episodes of failed sitcoms.

Then again, there is an equally unfortunate habit – particularly in epic fiction – of elevating the setting to the point that it upstages the players. In examples of this, readers must follow puppets along the three-hour tour demanded by too-formidable scenery.

In stories with depth, there is an interplay between agents and their environment. This repartee is best carried out in the middle ground: Yes, there is political intrigue on our generation ship, and yes our happenstance main character must expose the villainous parties before Voting Day, but what about the music? What earworms has she been enjoying or suffering, lately? What’s the current musical controversy? What’s losing traction on the playlists? Musical divergences reflect broader social shifts, and signs of the times tend to be broadcast in popular music. Generally speaking, party music is big while the populace is happy with the course their ship is on. But if everyone’s singing the blues? Expect change.

Nuancing the middle ground – the field of play between foreground and background – is the technical equivalent of granting that even futuristic cities (and generation ships) must include alleys and graymarkets in their design to function believably. For the writers among us who particularly enjoy devilling with the details, this layering approach to story-building may sound like child’s play. For everyone else, it may seem like a shortcut, a hack, or a magic trick. Better yet: Music to their ears.

Room Needed on the Ark

Startling StoriesImagine in the not-so-distant future an asteroid is on a direct course to hit the Earth. It’s large enough to destroy most life as we know it. NASA, the European Space Agency and China’s National Space Administration are scrambling to launch teams that will attempt to deflect the asteroid, but there is no guarantee that they will be successful.

Meanwhile a team of scrappy and resourceful aerospace engineers and biologists put into motion a plan meant to rescue at least a few species – including humans – from extinction. A spacecraft that will carry genetic material, along with live plants and animals, is readied for launch.

The hope is that after escaping the cataclysmic effects of the asteroid strike, the space ark would travel long enough for the Earth’s dust to settle (literally) so that the ship could return and restore life on our planet. Or perhaps the ship would continue on to a distant solar system, and the life it carries would be used to start a new settlement on a habitable planet.

This would obviously be a technically complex operation that would require substantial advance planning. One of the big tasks for the biologists on the team would be to decide how the genetic material and live travelers on the space ark would be selected and collected.

An obvious source of genetic material would be gene banks that collect and store samples of a wide range of genetic material. Such repositories exist today. The Millenium Seed Bank Partnership, for example, is an international project meant to save seeds from wild plants around the world. There are a number of other more agriculture-focused gene banks around the world that preserve seeds from a variety of crops.

Animal genetic material is a bit more difficult to archive than plant seeds. Projects like the US Department of Agriculture’s national Animal Germplasm Program primarily focuses on collecting and storing semen and eggs, not embryos.

There is also a current push to sequence the genomes of as many different species as possible. Perhaps in the future will have the technology to start from a raw DNA sequence to create a living breathing animal. There have been recent proposals to use DNA sequences along with reproductive cloning technology to restore wild animal populations on the verge of extinction.

But whether an “archived” animal is grown from germ plasm or from a synthesized DNA sequence, there still must be at least one female for the fetuses to grow in. Not a simple proposition.

But it would not be enough for our space ark to carry a male and female of each species. There must be a minimum number of genetically distinct individuals to allow a population to survive and thrive.  Conservation biologists estimate that such a “minimum viable population” would require anywhere from a hundred to several thousand members to survive at least a century. The lower estimates usually assume that there would be minimal environmental changes and human intervention to keep the population going.

Even with human intervention a lack of genetic diversity in a population puts it at serious risk for being completely destroyed by disease or unexpected environmental changes. That’s already a problem today. Disease outbreaks have put agricultural “monocultures” of some crops (like the Cavendish banana) at risk of extinction.

If samples from many individuals of a species are required for genetic diversity, our hypothetical space ark might not have enough space to carry every known species. So how would a biologist decide which critters are most important to save? That turns out to be a complicated question.

Restoring – or creating – a stable ecosystem needs to have a wide variety of different species from microbes to large vertebrates and algae to trees. The exact needs would depend on the local climate, soil and atmospheric conditions, among other factors. So far, we humans haven’t been very successful in creating an ecosystem from scratch. And the less that’s known about the environment where the ecosystem is going to be established, the longer the list of potentially necessary species.

So for the space ark scenario to work, it would not only need to carry a variety of species, but a variety of individuals in each species. And that is, of course, in addition to the humans – not just an Adam and Eve, but a large mixed group of people with enough genetic variation to start a healthy human colony. Throw in the complex social and political considerations in selecting who gets rescued and the population would probably have to number in the thousands.

Our hypothetical space ark would have to be huge to carry them all!

The space ark scenario is admittedly pretty implausible, at least with present-day technology. Even so, I think it’s worth seriously considering how it might be done. That’s not just because catastrophe is always a possibility, but because I’d like to think that some day self-sufficient extraterrestrial colonies will be a reality. We need to start thinking about how we might do that now so that the genetic material can be saved and reproductive technologies can be developed before they become a necessity.

But there are many questions that need to be considered:

If we are going to collect and archive seeds and animal germ plasm and genomic DNA sequences should the focus be on agricultural species? or should we cast our species net as far and wide as possible?

Should we seriously consider setting up a gene bank on the Moon, just in case something terrible happens to the Earth? or would it be better to have our archives closer at hand so that they can be more easily maintained and added to? How much redundancy should there be between different seed and germ plasm repositories?

Or should we focus more of our resources on developing synthetic biology techniques, in the hope that they will eventually become advanced enough so that collections of physical specimens will become unnecessary?

And if Earthly life is destroyed, would it be worth trying to restore Earth’s ecosystems or better to start over elsewhere among the stars?

What do you all think?

Technical Reading 

Blackburn HD “Genebank development for the conservation of livestock genetic resources in the United States of America” Livestock Science 120:196-203 (2009) (pdf)

Holt WV et al “Wildlife conservation and reproductive cloning” Reproduction 127:317-324 (2004) (text)

Traill LW et al “Minimum viable population size” a meta-analysis of 30 years of published estimates” Biological Conservation 139:159-166 (2007) (pdf)

Shaffer ML “Minimum Population Sizes for species Conservation” BioScience 31(2):131-134 (1981) (pdf)

Zhu et al “Genetic diversity and disease control in rice” Nature 406:718-722 (2000) doi:10.1038/35021046 (text)

 

On holiday

SiMF is taking a very short break.

Miss the science? Consider writing for us.

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We are not interested in reviews or non-science topics, nor are we currently soliciting fiction.

To apply, please email sarah.goslee at gmail dot com with a brief description of your qualifications and why you’re interested in SiMF, and either a link to relevant online articles you’ve written or a sample of your work that would be appropriate for SiMF.

Watching the Weather

Hurricane Sandy was hugely destructive, but it could have been even worse. Imagine what would have happened if we didn’t have good data allowing us to know in advance where and when the storm would hit. No evacuations, no specific preparations, no warning.

Instead, we have a network of satellites and other systems that allow us to keep a close eye on the weather, and models that let us predict the future with a remarkable degree of accuracy.

Some of those satellites produce stunning images, like this NASA GOES-13 composite. The NASA archive page has more images, and some fascinating videos.

NASA Satellites See Sandy Expand as Storm Intensifies

Or what about this wind map?

The wind map uses near real-time wind data to create these beautiful graphics, and was very popular on twitter during the hurricane.

Then there’s NASA’s TRMM, or Tropical Rainfall Measuring Mission: a satellite that can track rainfall.

TRMM data were used to make this three-dimensional composite.

I think if I were establishing an outpost on a new planet, weather satellites would be very high on my list.