Entries tagged with “extinction”.

DodoWe have an endangered species list identifying organisms that are about to wink out of existence like the dodo and the passenger pigeon. Some of these should are listed because they are emotionally important to humans – like the bald eagle and the koala bear. Some folks bemoan the protection of the snail darter and the northern spotted owl when it interferes with an economic activity.

These lists are of limited value because they include only the organisms we know exist. The organisms we know of represent only a tiny fraction of those in the world, and hence only a tiny few of those in danger of extinction, so putting a few on a list from those few we know might make us feel better, but it is really myopic.

There is a good case for preserving biodiversity in all ecologies, as each organism fills an important place in the system. Arguments are made that minor players in an area (such as low populations of a specific creature) are not important because they don’t seriously effect the balance of the ecology. On a day to day basis, these organisms seem insignificant – the proportion of the photosynthesis, grazing, predation, parasitism, etc. in the ecology is just not significant enough to make a difference.

Recent research in the Census of Marine Microbes, part of the project Census of Marine Life, done by Mitchell Sogin at the Marine Biological Laboratory at Woods Hole, shows that in each sample of the microscopic life from a submarine ecology station there are always a few dominant microbe species in each sample but thousands more species that are present, but rare. Each ecological sampling point or station has an entirely new suite of rare microbes. (more…)

Since the discovery in the 1920s that all types of radiation can cause gene mutations, scientists have wondered what role high energy cosmic rays might play in human evolution. Yet it was an idea destined never to find favour among geneticists, who could determine no hard evidence that the background flux of cosmic rays might have had any noticeable effect on human cell mutation.

All this is about to change, as an examination of ice cores extracted from sites in Antarctica and Greenland provides new information on the level of cosmic rays reaching Earth in past ages.

When so-called “primary” cosmic rays hit the upper atmosphere they generally break up to produce a plethora of “secondary” particles that form isotopes, which fall to Earth and are preserved each year in layers of ice. One such isotope is beryllium 10, found within the ice cores, which provides clear evidence that on three occasions over the past 100,000 years � around (more…)