Our planet is home to the most beautiful, wonderful, mesmerising mix of biology. There are currently over eight million species of animals and almost four hundred thousand species of plants. Yes – that many! And the numbers are increasing every day. All the complexity and diversity of life is so breathtaking it is difficult for one to imagine how so many organisms came about. The majority of us rarely stop to think about how wonderful and strange life actually is. Every so often we are treated to a new Attenborough documentary which gives us an insight into the weird and wonderful, usually at close range in high definition.
One of my favourite animals is an unusual looking sea creature with eight tentacles and no skeleton. Through observation and learning it can distinguish shapes and colours, navigate through mazes, and use items (such as coconut shells) as tools to enhance its chances of survival. If you haven’t guessed it yet, I am referring to the octopus.
And the flamboyancy does not stop there. Some octopuses can accurately mimic the colour and texture of seaweed or rock in order to camouflage from predators (when viewing this in action the disappearing effect is phenomenal) whereas some will instead squirt a thick cloud of black ink. Interestingly, all octopuses have nine brains and three hearts which pump blue coloured blood. My choice of favourite animal may seem bizarre (especially when in competition with the cuteness of pandas or the intelligence of dolphins), but they are quite the underdog when it comes to the world’s coolest organisms.
This is just one example of how extraordinary life actually is on our planet. Further examples may include the Venus flytrap - a carnivorous bug-eating plant with jaw like leaves that snap and trap prey, the electric eel - pumping out six hundred watts of electricity as a hunting mechanism, and the giraffe - with a height of up to twenty feet and running speeds of up to thirty miles per hour. Life on our planet certainly is remarkable, and has intrigued humankind for generations. The question was only natural for us to ask – where did all this life come from?
It wasn’t actually until the eighteenth century until someone began grouping biology into an ordered classification system. His name was Carolus Linneaus - a naturalist, and today we still use his classification system as it easily allows us to group organisms. Starting with the broadest, the groups are as follows: domain, kingdom, phylum, class, order, family, genus, and species. This taxonomy helps us break down the complexity of life into groups and helps identify differences and similarities. There are odd occasions when an animal cannot be classified with certainty (in which we use the term sub-species). A good example of this is the Australian dingo, in which there is still debate on its ancestry roots. However, most animals have consecutively been grouped; an organism in which one can interbreed with another tends to be the general definition of what a species is.
Now the people of the eighteenth century were prominently theistic, and were at ease with the idea that god had created all life on earth. But this became a perplexing puzzle for many scientists. Why would god have created so many similar yet distinct species? It became apparent in 1796 that some species had actually become extinct. The naturalist George Cuvier proved this when discovering the fossils of a mammoth and publicised his idea that some species were no longer in existence. So at the turn of the eighteenth century, our understanding of the earth and fossils started changing. Meanwhile, some of the first geologists (such as James Hutton and Charles Lyell) contributed significantly to our understanding of the earth’s age. The several layers of sedimentary rock which were being discovered beneath the earth’s surface were proving that the earth had to be much older than the Bible’s claim of six thousand years. It also became apparent that the earth had experienced a series of catastrophes, with new fossilised species appearing each time a catastrophe took place. Today, sophisticated techniques measuring the internal radioactivity of the earth means we can accurately pin-point the age of the earth to four and a half billion years. Back then, the very first methods of geological enquiry were proving the same thing.
During this time, Cuvier was still studying the bones of fossilised animals and comparing them with living ones. It was becoming obvious that animals had changed over time. The French naturalist Jean-Baptiste Lamarck in Philosophie Zoologique (1809) argued for an early theory of evolution, through the transmutation of living organisms. His scientific theory was actually incorrect, but just the very idea was enough to cause controversy. In Britain, natural theology was hugely influential. The common explanation of diversity was a Great Chain of Being – with simple life forms at the bottom, humans in the middle, and god at the top. There was no place for evolution in Victorian society, but all that was soon to change.
Charles Darwin and the Theory of Evolution
The British ten-pound note currently holds a picture of Charles Darwin, an English naturalist. But why out of all the contributors to society is Darwin entitled the prosperous honour of appearing on our currency? Because Darwin is credited for solving the riddle of why there are so many varied species on the planet. Through his book The Origin of Species (1859), Darwin presented the idea that life evolved through generations of species over millions of years through a process called natural selection. It was a key breakthrough in understanding the diversity of life and was the birth of biology as we know it today.
A brief definition of natural selection is as follows - every organism produces offspring, variations in the offspring make some individuals more likely to survive, these variations will be passed onto future generations, thus in the long run (millions of years) animals will continually change, branching off into new species as they evolve and separate. A common way to describe this process is by using the example of frogs in a pond. If those frogs with slightly longer legs are able to escape more successfully from predators, it becomes inevitable that over time those frogs with longer legs will flourish. Eventually the feature of long legs becomes so exaggerated the species changes and evolves into something different. Of course, evolution is a complex area of study and there is much more to it than just natural selection. Other factors play a significant role, including genetic drift and mutation. But to explain the many facets of evolution would take much more than an article. What is important here is that Darwin had a strong mechanism for evolution, and it suggested that life had evolved without any supernatural commodity.
Charles Darwin (1809-1882)
Darwin's original sketch on evolution
Soon after Darwin’s death, more discoveries were made in the fields of palaeontology, biogeography, and geology, all adding to the overwhelming evidence that evolution is a factual part of history. In Julian Huxley’s Evolution: The Modern Synthesis (1942), a framework was set in place which broadly defined the scientific theory of evolution which is still used even today. Shortly after this, advancements in genetics and the discovery of DNA confirmed what was expected – that all living things are undisputedly related, and this includes us. The chimpanzee shares an astonishing 99% of our genes.
Although it is grounded within the scientific community as fact, evolution has sparked much controversy. One of the main concerns is that evolution removes an assumed sort of special status in humanity. On the surface, we seem to be comfortable with being acknowledged as animals, even though the thought of the fish being a relative is profoundly hilarious. But deep down evolution has changed the way we view ourselves and the world around us.
Knowing its implications, Darwin had been relatively quiet on the topic of human evolution in The Origin of Species (1859). He later decided to address the issue in The Descent of Man (1871) and was explicit in that “the same conclusion may be extended to man…enabling him to invent and use language, to make weapons, tools, and traps”. And Darwin was right. From the moment our ancestors became bi-pedal, they would have been able to make and use tools for hunting, increasing their chances of survival. And as intelligence increased, sophisticated civilisations would gradually form and develop language, writing systems, agriculture, medicine, and so on.
A great deal of evidence for human evolution comes from anthropology and the thousands of bones that have been discovered in the last hundred years. It is estimated that our primates evolved shortly after the dinosaurs became extinct sixty-five million years ago. Genetic evidence tells us that our genus (Homo sapiens) evolved around two hundred thousand years ago, and we are the last surviving. Therefore humans have not spontaneously appeared in the timeline of evolutionary history; it has been a long, gradual process.
Of course the Victorian world did not respond well to human evolution, for it threatened the notion that humans were uniquely moulded in the eyes of god. There was a mass of negative responses after Darwin’s publication, even from scientists. Martin Meredith’s Born in Africa (2011) describes the feeling at the time: "The implications of Darwin’s theory were profound. It opened up the possibility of a world without purpose, or direction, or long-term goal, a world that seemed to be no more than a product of chance. It stripped humankind of its unique status and was seen to undermine Victorian respect for hierarchy and social order. Above all, it threatened the very foundations of Christian belief and morality".
Evolution was an ostracised concept, and Darwin was subsequently mocked, ridiculed, and even had his life threatened. Unfortunately, over a hundred years later, the debate on whether evolution is a fact still continues.
Evolution as Fact
It is important at this point to discuss in more detail what I mean when I say that evolution is a fact, as this is where many people get confused. And the reason for this is because within the scientific community, a theory is not just an idea, but an explanation which accounts for a number of provable facts. And it is a fact within science that living species have evolved through a process called evolution. Further conclusive empirical evidence continues to confirm that evolution happened, and the mainstream scientific community today undoubtedly accept evolution as a true and accurate account of our varied biology. There have been disagreements between scientists about some of the minor details (notably between Stephen Jay Gould and Richard Dawkins), but generally the framework for evolution has remained the same since the Modern Evolutionary Synthesis.
So now we have established that the theory of evolution is a fact, the question arises – what does this imply for humans? Is our purpose simply in life to survive and reproduce as evolution teaches? Or has consciousness, self-awareness, and intelligence developed for a more specific reason? I leave that for the reader to ponder. Although we are not sure why we are here, we can be certain on how we arrived.