Friday, January 02, 2009

exercising body and mind, largely in vain

willi hennig

I've managed to do 15 kms on the exercise bike for three days in a row now, and my daily steps aren't bad, but my weight keeps increasing. Probably better to measure it weekly rather than daily. Starting to obsess over this, but I really look terrible. Some recent photos have shocked me to the core.

Monroe doctrine. Propounded in 1823 by the USA's 5th President, it was designed to impede any further encroachments on New World territory by European colonial powers - especially Spain. It was audacious for the time, as the USA was hardly then in a position to back up its hand off policy. Niall Ferguson mentions it in the context of Japan's Chinese adventurism of the thirties, in which there might've been a whiff of their proclaiming some sort of Asian Monroe doctrine against Western powers - but with much less likelihood of success. 

2009 is a big year science-wise. It's a big Darwin year of course [I think I've already mentioned that here] and I hope to continue to educate myself [and my many readers] on evolutionary matters throughout the year. Also, 2009 is the year of astronomy. Four hundred years ago, in 1609, Galileo reflected that a new invention, the telescope, could be refined and developed and pointed at the night sky. In so doing he explored for the first time the surface of the moon, observed that the so-called milky way was made of stars, and discovered those moons of Jupiter now called the Galilean moons. Modern astronomy was born.

So to today's topic in evolution: cladistics.
This is a massively complex topic in fact, so I'll just deal with it skimmingly. Cladistics is a taxonomic system based on evolutionary relationships between species. In recent years it has become the predominant taxonomic system. The term clade was first used by Julian Huxley in 1958, but the real 'architect' of the system was Willi Hennig, who began developing the system, which he called phylogenetic systematics, while a POW of the British at the end of WW2. 

The recent success of cladistics owes much to developments in biochemical analysis. The term clade is ancient Greek for branch, and cladograms are trees of connection between species and their common ancestor. The major difference between cladistics and the Linnaean [or neo-Linnaean] taxonomic approaches are that cladistics is strictly about phylogeny, rather than simply observed similarities between species. Cladistic branching can be enormously complex, so much so that the old classifications [family, order, phylum, etc], which suggest that a few fixed levels can be sufficient, has been rendered obsolete. Cladistics presents a more open classification, which can be filled out as more knowledge comes to light. This knowledge can be gleaned from the fossil record, but DNA/RNA sequencing has increased our knowledge of the relations between existing species considerably. 
A clade is also known as a monophyletic group. Other more inclusive groups are discouraged in cladistic classifications.
Finally, taxonomy is something of a ding-dong battleground, a bit like some branches of linguistics, so there are plenty of critics of cladistics out there. Also, there's a question about whether it will ever fully replace the Linnaean system on the popular, lay level.

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