tim@ism780c.UUCP (03/25/87)
Note: I have redirected followups to sci.misc, since this has little to do directly with misc.kids anymore. A fun thing to do is to pick some population limit, and see how long it would take to reach it. Let's assume a 1% annual growth rate. The last time I checked ( which was quite a while ago, the growth rate was higher than this. I have no idea what it is now. ) Let's start with a fairly low limit: the entire surface of Earth, including the oceans, packed with people to a density of one person per square foot. This would take about 1400 years. Let's go a bit farther. The entir volume of the Earth replaced with people. This would take less than 2800 years. Let's get really silly now. How long until we have so many people that the amount of space occupied by people is expanding at the speed of light? About 11,000 years. Does anyone want to argue that this is not an upper bound on human population? Another interesting one to calculate is how long it would take to fill the galaxy, assuming each star has a few planets that we can make into habitable places. It is on the order of 4000 years. Note that without faster than light travel, this won't work. It seems pretty clear that we can't maintain a 1% population growth rate forever. It will have to be slowed down. The only question is how. The death rate can be increased, or the birth rate can be decreased, or both. Any comments? Anyone see any holes in this analysis? -- Tim Smith Welcome to Wackyland uucp: sdcrdcf!ism780!tim "It can happen here" Compuserve: 72257,3706 Pop: 100 nuts and a squirrel Delphi or GEnie: mnementh
howard@cpocd2.UUCP (03/26/87)
Please followup to sci.bio as this has gotten away from a kids subject. In article <1866@k.cc.purdue.edu> ahe@k.cc.purdue.edu.UUCP (Bill Wolfe) writes: >In article <513@cpocd2.UUCP> howard@cpocd2.UUCP (Howard A. Landman) writes: >>You mean like in Ethiopia? > > Actually, there is more than enough to go around; it's just a > question of distribution. Look at all the grain stacked up in > Midwestern silos, the overproduction which is driving food prices > down to where the farmers are going bust, etc.... > > The problem is that the Ethiopian economy cannot generate the required > cash, and this in turn has a political/cultural basis. Unfortunately, when transportation/storage/distribution of food costs much more than the food itself, the only reasonable solution is to have each bioregion be more-or-less self-sufficient. Only recently has it even been possible for a society to eat more than it grows, and only extremely wealthy states with high population densities, where food is a small part of the economy, have been able to make it work. Ethiopia will not be in this class for many, many years. >>WHEN we get off this planet onto other worlds, the genetic heritage >>of each and every living organism on this planet may suddenly become >>IMMENSELY valuable. How do we know that some obscure species of >>Tibetan lichen won't hold the key to colonizing Mars, for example, >>by being able to survive low pressures and temperatures? The answer >>is, we don't. We haven't got the FOGGIEST notion of what secrets and >>surprises lay hidden in the "library" that current life holds in each >>cell. It's a bad time to be "burning books", just as we begin to be >>able to read them. > > We will soon be able to WRITE them. If by "soon" you mean "within the next several hundred years", then I might agree. What we can "write" now are the equivalent of the single-syllable babbling of a 10-month-old baby. A few dozen codons at a time. Do you have any idea how much genetic material there is in a single cell of a large organism? Would you believe 50-100 times as many base-pairs as there are letters in a complete set of Encyclopedia Brittanica? Now, to represent an entire species, you need 2 or 3 or 4 orders of magnitude more than that, because genetic diversity is important to allow a species to adapt. Then to represent all the species we now know is another 6 or 7 orders of magnitude on top of that. We know how to make tiny genes. We know how to cut medium-sized genes from an organism and paste them into E. Coli. We have a complete genetic code for a handful of viruses, mostly VERY small ones like PhiX174 (about one paragraph worth). All *WONDERFUL* stuff, but just the tip of the tip of the tip of the iceberg. When genetic engineering gets 1,000 times better than it is now, we will be able to design totally new single-celled organisms. 1,000,000 times better than now for multicelled organisms. 1,000,000,000 times better for complete new species with adequate diversity to eveolve on their own. And about 1,000,000,000,000,000 times better and we will be able to design complete planetary ecosystems. Perhaps we should try not to destroy our own until then. > I see no need to preserve > obscure species when we will soon be able to create our own, > to predefined specifications. You're not looking hard enough. One reason: In order to figure out how they work, so we know what to specify and how to design something that meets those specifications. We could easily spend a few hundred years doing small modifications to existing organisms and trading genes around to figure out what they do, and cataloguing the results. It's odd to call that "soon". >>I'll bet dinosaurs would have considered cockroaches "lower", but >>look who's still here. > > This may change as we gain the ability to conduct unprecedented > biological warfare along with the ability to design and implement > DNA systems. I seriously doubt that they will survive a massively > parallel attack on every system (respiratory, reproductive, immune, > circulatory, digestive, etc.) with brand-new microorganisms specifically > designed to seek out and destroy the targeted genetic structure. > > Cockroaches are a recursive problem, and they require a recursive > solution. (Actually, parallel recursive solutions for good measure) The problem is multifold. First, if we kill 99.999% of all cockroaches, the remainder can still breed and will likely be more immune to the attack just launched. So you need to get them ALL at once. Second, even if you did that there is a niche that cockroaches fill that would be left empty. Organisms from neighboring niches would evolve into it (tiny mice? large ants?) and the only real effect would be to simplify the ecosystem and hence make it less stable (remember that the Geckos that ate the cockroaches would starve, too). There's no logical end to that approach other than killing all other animals on the planet besides man. >>We are easily capable of annihilating ourselves. > > But you can be quite certain that we will not. You presumably > refer to nuclear weapons; they are VERY, VERY tightly controlled. Tightly. That's why a new country joins the nuclear fraternity every few years. Can you say "proliferation"? What do you think will happen when two minor nuclear powers go to war, and one starts losing *REALLY* *BADLY*? I can hope that we will not; but no one can be certain. Then let's consider the biological warfare that our new technology makes possible. If you can tailor a microbial attack on cockroaches, how about one on, say, Caucasian Homo sapiens that leaves Oriental Homo sapiens unscathed? According to you, it will soon be easy! And everyone can play! Of course, we could simply render the earth unfit to support ourselves. It's so painless until the final collapse. And blithely wasting species is still the social norm. :-( -- Howard A. Landman ...!intelca!mipos3!cpocd2!howard