Xref: utzoo sci.astro:4144 sci.space:11538 sci.space.shuttle:3186 Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!ucbvax!agate!web-2c.berkeley.edu!c60a-1hb From: c60a-1hb@web-2c.berkeley.edu (The Daimyo) Newsgroups: sci.astro,sci.space,sci.space.shuttle Subject: Re: Asteroids and Dinosaurs (was Re: asteroid almost hits earth) Message-ID: <24656@agate.BERKELEY.EDU> Date: 20 May 89 22:52:07 GMT References: <256@ringwood.Morgan.COM> <3200009@hpindda.HP.COM> <1212@irisa.UUCP> <40171@bbn.COM> <1493@optilink.UUCP> <40227@bbn.COM> Sender: usenet@agate.BERKELEY.EDU Organization: University of California, Berkeley Lines: 86 In article <40227@bbn.COM> ncramer@labs-n.bbn.com (Nichael Cramer) writes: >In article <1493@optilink.UUCP> cramer@optilink.UUCP (Clayton Cramer) writes: >>In article <40171@bbn.COM>, ncramer@bbn.com (Nichael Cramer) writes: >># #Does anyone knows others example of strange disappearance ? >># >># I don't remember the numbers (in species/yr) offhand, but I've read >># arguements (e.g. by S J Gould) that claim that we are *now* in the midst of >># the one of greatest (if not in fact _the_ greatest) of mass extinctions of >># all time. >># >># If I recall right, the numbers work out to ~1 species/100,000 increase in >># human population. >> >>I've read that the current rate of extinction is about 15 species/century -- >>which is clearly far lower than ~1 species/100,000 increase in human >>population. > >I checked my source for the above after I got home last night, and he was >claiming a loss of 10,000 species/yr but he didn't cite any sources. This >does sound very high. But on the other hand, it seems equally difficult to >believe we've only lost 13-14 species in all of the 20th century. (I've >also seen figures in the 1-10/yr range.) > >Do you (or anyone else) have specific references for what the actual value >of this rate is? There is a theory that was proposed by the late Dr. Luis Alvarez and Dr. Richard Muller on the topic of mass extinctions. In the geological record there is evidence of mass extinctions at regular intervals thru out earth's history. These extinctions occurred (don't quote me on this, I'm doing it by memory) I think every 300 million years, at a almost frightening regular interval. The extinctions of the dinosaurs was one and about 300 million years later, the extinction of pre-historic mammals another. Before then, the geological record shows extinction after extinction at roughly 300 million year intervals. The theory proposed states that our Sun may have a companion star. For years, astronomers and astrophysicists had assumed that our sun was different from the rest of the stars in the universe in that it was not part of a binary system. This theory states that our sun may have a companion star that at its closest point to the earth (it still looks like a normal star from a telescope at its closest point) crosses thru the comet belt with enough gravitational disturbance to knock about a 300,000 (I think) or so comets out of the cloud into the inner solar system. The odds worked out that one would hit the earth. For more information consult the book "Nemesis: the Death Star" by Dr. Richard Muller. Extinctions on the smaller scale, aka caused by man, continue on this planet in several key places : 1South America 2Africa ...etc. the list goes on. The destruction of the Amazon to make farm land is by far one of the fastest destruction of both animal and plant species in the world. The uniqueness of the Amazon enviroment is such that the plant and animal species that live there cannot be found anywhere in the world. In fact in a recent shuttle picture, the Amazon area was nothing but smoke as the forest is being burned down. In Africa, the desert grows. Man's own folly is to blame for that disaster as well. The interference of well meaning foreigners to help the people has led to the destruction of thousands of acres of land. The digging of wells in areas with lush vegetation was not only not productive but is the direct cause of the growing deserts. Herd animals, wild life, and man flock for miles around just to get to this plentiful source of water. In their rampage, the vegetation is stripped, trees are cut down and tender vegetation trampled. What's left in a matter of months is a wasteland, a addition to already expanding desert. Destruction of trees has had a direct impact on the ecosystem in Africa. In areas where there are trees it rains. In areas where there were trees not long ago, it will rain for a few years more. In areas where trees were cut down a long time ago, there is desert. The ecosystem is destroyed the moment the native habitat is destroyed, and the weather adjusts accordingly. The famine in Africa will continue, probably and sadly, forever, unless the the ecosystem is restored. In the United States, coal burning plants have destroyed forest land on the Eastern Sea Board and all over Eastern Canada. Lakes have so much acid content in them that the water is poisonous. In Europe, a similar situation exists in Germany, where a huge portion of forest land has been labeled as doomed from the acid rain. In Chicago, the marble off the buildings is being dissolved by the acid rain, of which sulfuric acid is a member. When the habitats go, so do the life forms that live within them. Hopefully something can be done to stop this. Soon I hope. Albert Sze-Wei Wang ------------------------------ The Daimyo | c60a-1hb@widow.berkeley.edu | ------------------------------