Aryan Invasion/migration Theories & Debates -2

[acharya]

Darwin’s legacy

On February 12, 2009, most of the world will celebrate the 200th birth anniversary of a great scientist whose theory — based on incredibly laborious empirical observation and once-in-a-millennium insights — forever changed humankind’s perceptions of itself and of the natural world around. Next year will also mark the 150th anniversary of the publication of Charles Darwin’s great work On the origin of species by means of natural selecti on, or the preservation of favoured races in the struggle for life. The five years (December 27, 1831-October 2, 1836) the English naturalist spent on board H.M.S. Beagle in a round-the-world voyage gave him the opportunity to study and compare the fauna, flora, and geology of many distant lands. It led him to wonder about the diversity of life forms he found and why creatures occupying similar environments in places around the globe could be so vastly different. The idea that biological species were not immutable but were capable of change was in itself not new at the time. Darwin would have been familiar with the speculations of his own grandfather, Erasmus Darwin, and the French zoologist, Jean-Baptiste Lamarck. But within a couple of years following the Beagle voyage, Darwin was going much further. He was thinking about a common origin for all life on the planet when he sketched in his notebook a ‘tree of life,’ implying that all species had diversified from a common stalk.

However, Darwin was not the only one thinking along such lines. In 1858, he received a letter suggesting ideas remarkably like his own; it was from Alfred Russel Wallace, who was collecting biological specimens in south-east Asia. Papers putting forth both points of view were duly presented at a meeting of the Linnean Society of London. The Origin of Species (as Darwin’s 1859 magnum opus came to be titled in 1872, in the sixth edition) marshalled a vast body of evidence and presented his arguments in favour of evolution driven by a process of natural selection that allowed traits best suited to a particular environment to spread in a population. Evolution and a common origin for all life lie at the heart of biology. In an essay strikingly titled ‘nothing in biology makes sense except in the light of revolution,’ the geneticist and evolutionary biologist Theodosius Dobzhansky declared: “Without that light [biology] becomes a pile of sundry facts — some of them interesting or curious but making no meaningful picture as a whole.” The elucidation of the structure of DNA, the unravelling of the genetic code, and the ability to sequence the entire genome of even complex organisms have served only to lay bare the processes that produce life, which all living organisms share, and show how evolutionary pressures act on those processes. As though this were not enough, Darwin’s ideas have inspired, over the past century-and-a-half, “powerful images and insights in science, humanities and the arts,” as an essay in Nature reminds us.