Science underpins most of what we cover in BBC Wildlife. How do we know why, when and where animals migrate? Or how bats fly in the dark? Or when species are teetering on the brink of extinction? It's all down to science.
The simple fact that we know the chiffchaff, willow and wood warbler are three separate species is because someone – Gilbert White – bothered to study the birds and record his observations in the mid-18th century. While not a scientist in the modern sense of the word, White was preparing the ground for scientists to come.
- How a few pioneering Victorian women - and a fashion campaign - launched the RSPB, despite being written out of the society's history
- 10 women who changed the world: The pioneering female conservationists, from Jane Goodall to Sylvia Earle, who redefined our bond with nature
So we decided to celebrate the role science plays in what is known about wildlife, and have chosen what we think are the 10 greatest biological discoveries ever made.
10 greatest biological discoveries of all time
10 Chimps using tools
The discovery that our closest cousins use tools made us reconsider what it means to be human.
Dolphins carry sponges on their beaks to flush out fish from the seabed. Capuchin monkeys crack palm nuts with rocks, New Caledonian crows shape twigs to probe for insects in dead wood. A species of octopus has been observed transporting coconut shells for use as a lair, Yes, other animals – not just humans – make and use tools.
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But Jane Goodall's discovery, in 1960, that the chimps of Gombe Stream National Park inserted grass stems into termite mounds to fish out the termites, and stripped leaves from twigs to make tools for the same purpose, was the first of its kind and rocked the scientific world. As anthropologist Louis Leakey observed, since humans were defined as 'man the tool-maker', “Now we must redefine 'tool', redefine 'man', or accept chimpanzees as humans.”
Researchers have since shown that chimps also possess culture. For example, those in Ivory Coast's Tai Forest use tools differently to those in Gombe and pass their skills onto the next generation. "Indeed," said the primatologist Christophe Boesch, "once we observe how a chimpanzee behaves, we can identify where the animal lives."
Perhaps none of this should be surprising: though the line that gave rise to chimps and humans split about six million years ago, that's just 250,000 generations between you and a chimpanzee.
9 Symbiosis in coral
The revelation that coral is in a partnership with algae unlocked the secrets of a vital marine system
The subject of symbiosis sounds complicated, but it's worth persevering with and understanding, because it is probably responsible for the existence of all complex life forms – including us.
What exactly is it, though? The German mycologist Heinrich Anton de Bary first defined symbiosis in 1879 as "the living together of unlike organisms", yet this scarcely does justice to the sheer wondrousness of it all.
Take coral. Most people understand corals to be the hard shells of animals called polyps (which are in the same phylum of animals as jellyfish and sea anemones), and that's true, but the polyps would not survive without their symbiotic relationship with photosynthesising algae known as zooxanthellae (a relationship first described by the German zoologist Karl Brandt in 1881).
The zooxanthellae are ingested by, and live inside, the cells of the polyps, and here they share the fruits of their photosynthesis – so the polyps get supply of food, while the algae receive protection, in a mutually beneficial relationship.
If one organism is exploiting the other, however, then symbiosis becomes parasitism. Indeed, some researchers argue this is the true nature of the relationship seen the coral polyps and their algae.
8 How the giant squid hunts
Underwater photos of the monster solved a long-standing mystery
It's the world's largest invertebrate and the source of the myth of the kraken: a terrifying beast up to 18m long. This marine monster has eight arms, two grasping, lightning-quick tentacles, the biggest eyes of any known species and a giant parrot-like beak that carves up its prey alive before ripping off hunks of meat with an extraordinary, rasping radula.
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And yet very little is known about the giant squid (or its smaller but heavier cousin, the colossal squid). None had even been seen alive until scientists Tsunemi Kubodera and Kyoichi Mori captured a sequence of 50 shots about 900m below the surface of the sea off Japan's Chichijima Island in the North Pacific in September 2004.
What's more, the photos cleared up a long-standing debate about whether these beasts simply drifted through the ocean depths waiting for something tempting to turn up, or actively hunted down their dinner.
"Architeuthis appears to be a much more active predator than previously suspected, using its elongated feeding tentacles to strike and tangle prey," the researchers wrote, following the discovery. Probably best not to go diving too deep, then.
7 Where swallows go in winter
Locating the birds' destination put an end to over 2,000 years of speculation
For thousands of years, people have been fascinated by where birds disappear to and come from as the seasons change.
Some theories were eccentric (that they hibernated at the bottom of ponds), some even more far-fetched (that they flew to the moon) and some oddly credible (that they morphed into a different species – a redstart into a robin, for example). Many birds do look different in summer and winter, so there is some logic behind the last idea, at least.
In 1250, a monk called Caesarius of Heisterbach (who was prior of a Cistercian monastery in Germany) attached a note to a swallow's leg that read: "Oh swallow, where do you live in winter?" The following spring – it is said – the bird returned with a note saying, "In Asia, in the home of Petrus" (that is, in Israel).
Adopting a slightly more scientific approach, amateur naturalist John Masefield clipped a metal ring onto the leg of a female swallow in Staffordshire in 1911.
She was reportedly found in Natal, South Africa, on 23 December 1912. Today, we know that most British swallows overwinter in South Africa (particularly the east and north-east), but some also travel to other southern African countries such as Namibia, Botswana and Zimbabwe.
With modern technology, we are also able to track barnacle geese from Svalbard to the Solway Firth, bar-tailed godwits from Alaska to New Zealand, and red knot from the Canadian Arctic to Tierra del Fuego, but the beauty of Masefield's experiment is that it neatly demonstrated the value of bird ringing, which had been invented just 12 years earlier.
And bird ringing continues to be the cornerstone of much of our research into bird behaviour today.
6 Inherited characteristics
Mandel's monkish devotion to his pea plants led to the birth of a new science – genetics
The work of Gregor Mendel made possible some of the most pressing and controversial (or exciting, depending on your point of view) issues of the 21st century, from feeding the world with GM food to DNA finger-printing.
Mendel bred peas. Between 1856 and 1863, he cultivated some 29,000 plants and, by doing so, he was able to show that there were elements, which we now call genes, that were being passed from one generation to the next. He also demonstrated that, though the plants inherited two elements, one from each parent, only one was manifest in the descendant, giving us the concept of dominant and recessive genes.
Mendel's work was forgotten for over 30 years, until scientists at the start of the 20th century started performing almost exactly the same experiments. “There is no greater legend in the history of science than that of the experiments of Gregor Mendel,” declared the evolutionary biologist Jan Sapp in 1990. In 1961, the American scientist and writer Loren Eiseley wrote that he "rescued Darwinism itself from oblivion”.
5 Extinction of the dodo
The fate of this portly pigeon has come to symbolise the danger of overexploiting nature
The dodo is, without doubt, the most famous example of an extinction caused by humans. While there have certainly been many others – the passenger pigeon and Tasmanian tiger in the early 20th century, and the Yangtze river dolphin in the early 21st all spring to mind – this flightless relative of the pigeon has given its name to a well-worn phrase and is the symbol for the Durrell Wildlife Conservation Trust. Its portly frame embodies a stark warning to the world about what happens when we carry on regardless.
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No one knows for sure, but the dodo is likely to have become extinct from the island of Mauritius, to which it was endemic, some time between 1688 and 1715 (according to research published in Nature based on hunting reports). For more than 150 years after its disappearance, all that remained of this extraordinary bird were a single head and a couple of feet. By the beginning of the 19th century, some authorities had come to regard it as a mythological creature.
Then, in 1865, some railway workers unearthed some bones from a bog called the Mare aux Songes, and a civil engineer, suspecting they might belong to the dodo, contacted a Mauritian schoolmaster. “A Mr Clarke had Professor Owens’ book on the Dodo, so I took the bones to him, for comparison with the book plates,” he later wrote. These, and other bones subsequently pulled from the same bog, are today all in museums in Liverpool, York and Leeds.
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Noted ecologist Bill Sutherland, of the University of Cambridge, has said: “The extinction of the dodo was key in showing that there are limits exploitation.” So, now, we just have learn from it – and fast.
4 Hydrothermal vents
The discovery of deep-sea food-webs scotched the notion that all life depends on sunlight
That all life on Earth is essentially propagated by energy from the sun was taken as given until, in 1977, geologists working at depths of about 3,000m near the Galápagos Islands discovered extraordinary communities of 2m-long tube worms. They also found many other species new to science living near cracks in the seabed that were spewing out vast quantities of geothermally heated water.
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Subsequent research established that bacteria derive their energy by 'chemosynthesising' the minerals in the water, especially sulphur compounds, and that the gigantic tube worms, in turn, fulfil their nutritional requirements from the sugars produced by the bacteria.
To do this, they possess 'blood' that contains haemoglobin (like ours) to transport oxygen, hydrogen sulphide and carbon dioxide to the bacteria, which then break these down into sugars and sulphur.
Many of the bacteria, known as thermophiles, can live at temperatures as high as 80°C. But the world record is held by a hyperthermophile that can survive at 113°C, an environment that would destroy all known bacteria at the Earth's surface.
A variety of amphipods and copepods feed directly on the bacteria, forming the basis for a food-web comprising snails, shrimps, crabs, fish and octopuses.
3 Photosynthesis
The first description of how plants make food is among the great scientific breakthroughs
It is no accident that so many organisations have picked the colour green as a symbol of their environmentally sound values, because it is the basis for almost all living things (see hydrothermal vents, above, for one of the few exceptions).
It is the green chlorophyll within chloroplasts that enables plants to capture energy from the sun and use it to convert carbon dioxide and water into the complex organic compounds we call sugars and oxygen.
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- Photosynthesis: what it is, how it works and why it fuels life on earth
Who discovered photosynthesis is rather more difficult to pin down. A Flemish chemist, Jan Baptista van Helmont, carried out one significant experiment in the early 17th century, and, in about 1770, the English chemist Joseph Priestley found that a mint plant could "restore [the] air" in a glass jar that had a candle burning in it – in other words, that a plant produces oxygen.
But it is the Dutchman Jan IngenHousz who determined that light was necessary for photosynthesis and therefore generally regarded as the person who discovered it.
In 2007, the philosopher of science Geerdt Magiels observed in paper entitled ‘Dr Jan Ingenhousz or Why don't we know who discovered photosynthesis?' how his “name has been forgotten, his life and works lost in the midst of of time, [but] the tale of his scientific endeavour shows science in action.”
2 Microbes
Knowledge that minuscule organisms exist opened a new frontier in scientific research
Deep-sea hydrothermal vents are not the only communities of living things invisible to humans without the aid of technology. In the 17th century, no one could possibly have imagined that there were billions upon billions of tiny creatures living right under (and, in fact, on, and in) our noses. Then along came a rather unlikely zoological hero in the form of the Dutch cloth merchant Antonie van Leeuwenhoek.
Living in relative affluence in Delft, van Leeuwenhoek began grinding glass to make lenses and microscopes – though fairly crude, they were better than anybody else's. He was astonished to find countless, minuscule moving creatures – or ‘animalcules' as he called them – swimming in just a single drop of water.
“It was for me among all the marvels that I have discovered in nature,” he wrote, “All the creatures huddling and moving, but each having its own motion."
Clearly, the discovery of life at the microscopic scale changed everything. It paved the way for scientists to begin to understand the ways in which diseases are transmitted, and hence enabled basic standards of hygiene to be developed – arguably the single biggest contribution to the advances in human health made during the industrial era.
1 The missing link
Archaeopteryx was incontrovertible proof of the theory of evolution
If the theory of evolution, as proposed by Charles Darwin and Alfred Russel Wallace, is the greatest biological idea of all time, then surely the greatest zoological discovery must be the one that helped to embed that concept in the public consciousness.
There are numerous so-called 'missing links' – fossils that illustrate the concept of one species or group of animals evolving into another – but perhaps none as perfectly preserved and as perfectly ‘in between’ as the Archacopteryx fossils (and one feather) discovered in limestone deposits near Solnhofen, in southern Germany, between 1860 and 2007.
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Here was an animal with wings and feathers like a bird, but with teeth in its jaws, fingers and claws on its wings and a long, bony tail like a bipedal dinosaur – proof, indeed, that the terrible lizards did not go extinct 65 million years ago, but were able to evolve into an entirely new and equally successful group of animals.
The credit for describing Archacopteryv lithographica (from just a single feather) must go to the German palaeontologist Hermann von Meyer. But the first full skeleton was described in 1863 by the English scientist Richard Owen.
