Tree of Life has branched out over its 150 years
The ‘‘Tree of Life’’ is 150 years old this year. Charles Darwin often wrote about a ‘‘tree of life’’ when explaining his theory of evolution, but it remained just a mental picture with him.
However, the picture took root in the imagination of Darwin’s biggest fan in Germany, the young Ernst Haeckel. In 1866 he turned Darwin’s vision into a picture of an old tree.
‘‘Haeckel’s Tree’’ was an intellectual tour-de-force, depicting everything known about biology through Darwin’s evolutionary eyes.
On a single page, Haeckel showed us how all animal life had a common ancestor in the distant past, how all animals are related to each other through intermediary forms of life, how animals evolved greater complexity over time, how closely or distantly they are genetically related to each other and how Man emerged as the ultimate product of evolution.
Haeckel’s Tree hung on many a classroom or laboratory wall and featured in innumerable textbooks and encyclopaedias throughout the 20th century.
With the exception of the United States, most people in the Western world are comfortable with Haeckel’s Tree of Life. But many Asian and North African governments, bureaucracies and religions censor open discussion on evolution.
Some influential mullahs preach that Darwin is an unclean, atheistic infidel who challenges the veracity of the Koran, turns Muslims into animals, insults Muhammad and erodes Muslim spiritual and moral beliefs.
Evolution is taught in Pakistani, Iranian and Egyptian high schools but human evolution is excluded from most courses.
The topic is banned altogether in Saudi Arabian and Sudanese schools, and when Isis captured the Syrian town of Mosul in 2014, rules were written to ban the teaching of evolution there.
Only 8 per cent of Malaysian and 10 per cent of Egyptians believe in evolution and, surprisingly, only 30 per cent of Americans.
Most Americans think God put mankind on Earth within the last 10,000 years, many believing that we shared the planet with dinosaurs.
Haeckel’s Tree has been updated a thousand ways since his day. The biggest changes have been made at the base of the tree, where improved microscopes and the DNA revolution have revealed a microbial world unknown to Haeckel – the viral, the bacterial, the Archaean and the Chromistan kingdoms. Many biologists think it is misleading to rank one animal higher than any other so, in true democratic fashion, they represent evolution in a circle with the animals arranged like spokes in a wheel.
Who are we to put on top of the tree?
In the 1930s, a pipe-smoking Englishman in a tweed jacket often featured on the topmost branch. More recently I have seen trees with Ronald Reagan, Queen Elizabeth and Kim Kardashian as the ultimate manifestations of evolution.
The Tree of Life once featured in The Simpsons. There, sponges evolved into folk singers, warthogs into bosses and leeches into televangelists.
Haeckel depended on comparative anatomy and fossils to develop his tree.
Today, DNA studies have given us X-ray eyes to put accurate dates on every fork and twig of his gnarled old stammbaum.