The ‘Tree of Life’

Back in 350 BCE, Aristotle regarded the essence of species as fixed and unchanging. He wrote his Historia Animalia, grouping animals according to their similarities of looks, actions or dwelling place: animals with blood and animals without, animals that live on water or on land, etc. Aristotle grouped his animals hierarchically from ‘lowest’ to ‘highest’, with, of course, himself – or us, the human species – on top! This view was pretty much unchallenged for the next two thousand years.

Hold on! How Eurocentric! The earliest pharmacopoeia was written by Shen Nung, Emperor of China around 3000 BCE. Known as the father of Chinese medicine, he is said to have tasted hundreds of herbs to test their medicinal value. His ‘Divine Husbandman’s Materia Medica’ included 365 medicines derived from minerals, plants, and animals.

Then around 1500 BCE medicinal plants were illustrated on wall paintings in Egypt. In one of the oldest papyrus rolls, Ebers Papyrus, plants are included as medicines for different diseases. They have local names such as “celery of the hill country” and “celery of the delta”.

OK, now we’ve shown it was Asia, then Africa, let’s go back to Europe and Aristotle . . One of his disciples or students, the philosopher and naturalist Theophrastus, classified plants into three categories: herbs, shrubs and trees. He classified local specimens as well as specimens sent to him by Alexander the Great, collected during his expeditions to Asia and elsewhere in Europe.

Then in Europe came, in no accurate order – and probably missing out many! – an Italian, Cesalpino (1519-1603), a Swiss, Bauhin (1560-1620), who described about six thousand species and gave them names based on their ‘natural affinities,’ grouping them into genus and species. He was thus the first scientist to use binomial nomenclature in classification of species. By the time the Swede Carl Linnaeus (1707-1778) was born, there were many systems of botanical classification in use, with new plants constantly being discovered and named. He became famous for ‘sorting things out!’ His book Systema Naturae is regarded as the start of modern nomenclature.

The more people classified things, the more they realised they were related. And so came the first ‘Tree of Life’ (that I could find – there are sure to be more, earlier, better):

Hitchcock 1840

Not only is MAN on top, he gets – we get – a crown and cross. Palm trees get the plant crown. Then came Haeckel’s Pedigree of Man, still with animals and plants separate, even though this is a real tree!

Haeckel 1879

Most of the subsequent line of naturalists, zoologists, botanists and herbalists worked on classifying, describing and naming. The first departure from this approach was probably by Frenchman de Lamarck (1744–1829), who launched an evolutionary theory including inheritance of acquired characters, named ‘Lamarckism.’ Others, like Erasmus Darwin, who, like most people looking into classification accepted that evolution happened, but HOW it happened was not known. He – the elder Darwin, Charles’ grandfather – proposed his evolutionary theory that ‘all warm-blooded animals have arisen from one living filament.’

The next big step in evolutionary theory was when in 1858 in London Charles Darwin and Alfred Russel Wallace proposed that evolution proceeded ‘by natural selection’. This theory of Darwin’s and Wallace’s changed EVERYTHING.

Huge jump here: When DNA and genes and genomes were discovered and worked out, everything changed again. No longer did one have to painstakingly study an animal’s anatomy and habits to classify it, its DNA classified it accurately even if you looked on in astonishment and thought ‘can’t be!’ If the DNA says they’re related (or not) they they’re related – or not.

So our 1969 school Tree of Life below was still intent on showing how single-cell animals were low down and we were high up. But at least we were starting to learn we weren’t the crown of a tall tree. But at least we were separate from plants and fungi! Well . . .

1969 tree of life

But the more we know, the more we know. And we now know it’s us and fungi. Get used to it, us and fungi.

So next time you scoff a plate of mushrooms, feel a bit guilty. And when you see a live mushroom growing, say ‘Howzit Cousin.’ And get used to it.

See bottom right the little word opisthokonta? That’s us.

Us opisthokonts


Thanks Dave’s Garden ; Vision Learning ; wikipedia ; Science News ; EDIT ;

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