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 ;

An Inordinate Fondness For Beetles

Asked what could be inferred about the Creator from a study of His works, British scientist and naturalist JBS Haldane replied:

“The Creator, if he existed, had an inordinate fondness for beetles”.

I have just re-read the delightful book Jayne Janetsky gave me in 1999 and learned again:

– Every fifth species of known animal in the world is a beetle;
– Beetles come in the most beautiful array of shapes and sizes and colours.

Absolutely fascinating! And right up my alley!

I show just three of the 350 000:

 

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The book has a few more!

Beetles fondness

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In a letter to the August 1992 issue of The Linnean, a friend of Haldane’s named Kenneth Kermack said that both he and his wife Doris remembered Haldane using the phrase “an inordinate fondness for beetles”:

I have checked my memory with Doris, who also knew Haldane well, and what he actually said was: “God has an inordinate fondness for beetles.” J.B.S.H. himself had an inordinate fondness for the statement: he repeated it frequently. More often than not it had the addition: “God has an inordinate fondness for stars and beetles.” . . .

Haldane was making a theological point: God is most likely to take trouble over reproducing his own image, and his 350,000 attempts at the perfect beetle contrast with his slipshod creation of man. When we meet the Almighty face to face he will resemble a beetle or a star, and not Dr. Carey [the Archbishop of Canterbury].

Rhinoceros beetle

The Venomous, Egg-Laying, Duck-billed Platypus

This odd Australian mammal looks like a duck wearing a fur coat. Many other descriptions could be – and have been – made. People from the northern hemisphere might say it looks like a beaver trick-or-treating with a clumsily stuck-on fake duck bill.

Famous also for laying eggs, the playtpus flummoxed clever men back in 1799 when the first dead and preserved one was brought to Europe. They confidently pronounced it a fake, made of several animals sewn together.

Mammal-like reptiles diverged from the lineage they shared with birds and reptiles about 280 million years ago. Around 80 million years later, the monotremes—or egg-laying mammals—split off from the mammalian lineage, says Rebecca Young, a biologist at the University of Texas at Austin. All that remains of that branch of the family tree is the platypus and four species of echidna.

This split happened before the evolution of the placenta, so in that sense they are somewhere between a lizard and a placental mammal retaining some reptilian and mammalian features, according to Young.

Although the platypus lays eggs, unlike a mammal, like a mammal it suckles its young on milk, but the platypus’ milk seeps through pores in its abdomen, not through teats as in all other mammals. Another incredible adaptation is how they forage for food. Platypuses close their eyes, ears, and noses underwater and find prey by sensing electric currents with their duck-like bills. These bottom feeders scoop up insects, larvae, shellfish, and worms in their bill along with bits of gravel and mud. Platypuses do not have teeth, so the bits of gravel help them to “chew” their meal.

They also very unusually for mammals, and more like their reptilian ancestors have venom! And their venom is located in a spur in the males’ heels—a unique method of delivery among venomous creatures. Platypus venom contains genes that resemble the venom genes of other animals, including snakes, starfish, and spiders. It’s real venom, with 83 toxins and is likely an example of convergent evolution, in which unrelated species evolve similar traits.

We will learn more about platypus evolution as time and research goes on. The elements of mutations and adaptations and randomness determine how we acquire things over time, and it’s fascinating to try and work out the puzzle, like scientific detectives.

platypus6

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Thanks Liz LangleyNational Geographic

Wes Warren of the Washington University School of Medicine in St. Louis led the 2008 study that found that the platypus has a “fascinating combination of reptilian and mammalian characters.”

Related: “Platypus Genome Reveals Secrets of Mammalian Evolution