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

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

Darwin Day

Charles Darwin was born 210 years ago today. He died aged 73 in 1882. One of the single most profound ideas ever to enter a human brain seeped into his around 1836 and stewed and bubbled there until in 1858 he was jolted into action and finally published his stunning insight.

No, NOT “the theory of evolution”! Evolution is not a theory, it’s an established scientific fact that happens around us all the time. Don’t listen to claptrap. Evolution is accepted and observed, and is the reason – just for one example – that we have a major problem with drug resistance. Germs evolve to be resistant to drugs. Daily.

No, the theory that evolution happens by natural selection; THAT’s the amazing thought that Darwin had. One hundred and sixty years later, despite the devious efforts of naysayers – and the earnest efforts of real scientists – all the evidence still points to Darwin’s idea being right. Discovery after discovery in the fields of biology, paleontology, geology, molecular biology, genetics, anthropology, and more – each one of which could potentially sabotage his theory – have instead reinforced it. The age of the earth, plate tectonics, fossils, common structures, the distribution of species, embryonic development, germ theory, DNA, etc. Each new discovery has been found to align with Darwin’s powerful theory – biological evolution by natural selection or “descent with modification,” the differential survival of organisms following their naturally occurring variation. His amazing insight, his ‘dangerous idea’, remains a good brief definition of the process to this day.

What Darwin discovered was that “all life is one”! An amazing thought. Who could ever have thought that one day when we became able to test the genes of plants and animals we’d discover that we shared some genes with chimps, yes – one of the reasons the bishop of London fought so hard against the idea when first announced in 1859 – but that we also share some of our genes with grass! NO-ONE would have predicted that. All life is one. Stunning.

As a student Darwin was a proper, normal person! He neglected his medical studies in Edinburgh, preferring to study natural history on interesting field trips, then when his wealthy medical doctor father sent him to Cambridge to study to become an Anglican parson, he preferred riding, shooting and beetle collecting! Only beer drinking seems to be missing from a well-balanced start in life.

Darwin’s room, Christ’s College

Then he took a gap year – five years, actually – and traveled:

Five years on the Beagle
The Beagle on the coast of South America

On his return from sailing around the world he threw himself into scientific work, experimentation, meticulous research and lots of thinking. But he couldn’t bring himself to publish his big insight. His wife Emma was very religious and they both were very aware of the stir his amazing insight would cause. After twenty years of this he was suddenly nudged into action when a younger man sent him a paper to publish which he felt was almost identical to his theory. He scrambled to action, and so it happened that his friends Lyell and Hooker arranged to have his and Alfred Russel Wallace’s papers read jointly to the Linnean Society on 1 July 1958. On the evening of 28 June, Darwin’s baby son died of scarlet fever after a week of severe illness, and he was too distraught to attend the presentation. Their joint paper On the Tendency of Species to form Varieties; and on the Perpetuation of Varieties and Species by Natural Means of Selection was read. What followed was . . nothing. Little attention was given to this announcement of their theory; the president of the Linnean Society made the now-notorious remark in May 1859 that the year 1858 “had not been marked by any revolutionary discoveries.”

In 1859 he finally published his amazing book On The Origin Of Species, ‘one long argument’ for the idea, hatching in his head since 1837, of the ‘common descent’ of all life.

Book Darwin Origin

His theory is simply stated in the introduction: As many more individuals of each species are born than can possibly survive; and as, consequently, there is a frequently recurring struggle for existence, it follows that any being, if it vary however slightly in any manner profitable to itself, under the complex and sometimes varying conditions of life, will have a better chance of surviving, and thus be naturally selected. From the strong principle of inheritance, any selected variety will tend to propagate its new and modified form.

At the end of the book he concluded that: There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.

A toast to an amazing man and his insight!

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Evolution was already old in 1859: Contrary to popular opinion, neither the term nor the idea of biological evolution began with Charles Darwin and his 1859 paper, On the Origin of Species by Means of Natural Selection. Many scholars from the ancient Greek philosophers on had inferred that similar species were descended from a common ancestor. The word “evolution” was widely used in English for all sorts of progressions from simpler beginnings from 1647 on. The term Darwin most often used to refer to biological evolution was “descent with modification,” which remains a good brief definition of the process today.

Darwin proposed that evolution could be explained by the differential survival of organisms following their naturally occurring variation—a process he termed “natural selection.” Offspring of organisms differ from one another and from their parents in ways that are heritable – that is, they can pass on the differences genetically to their own offspring.

See more evidence supporting biological evolution.

To this day the truly ignorant – just as the bishop of London did in 1859 – and the merely dishonest misrepresent Darwin’s theory
  • Yes, evolution is also a scientific theory, but not when used in a negative sense. If anyone says ‘it’s only a theory nya nya’, ignore them. If anyone says its a scientific theory matter-of-factly they’re right, but then those people will also immediately tell you it’s also a scientific fact. Read about that here.

Jerry Coyne wrote a lovely affirming letter to Charles Darwin on his 200th birthday, back in 2009. How Darwin would have loved reading it, and how it would have brought relief and peace of mind to a wonderful man who worried a lot!