The 10 greatest discoveries of zoology

A panel of judges at BBC Wildlife Magazine has named the greatest zoological discoveries of all time. Do you agree with their choices?

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Archaeopteryx shares some features with ancient reptiles and others with modern birds. Photograph: Jason Edwards/Getty Images/National Geographic RF

Mid-way through the 4th century BC the Greek philosopher Aristotle turned his great mind to the wildlife around him and documented the behaviour and characteristics of hundreds of species in nine books that together became The History of Animals.
The work is impressive for its sheer scope and ambition. In 130,000 words, the author divides and categorises animal life every which way: by basic physiology and anatomy; by habitat and mode of movement; by how and what these creatures ate. Humans are not excluded from examination, but are woven throughout the text, giving Aristotle the opportunity to compare and contrast the essence of other species with that of our own.
There are some gems. He observes that elephants do not sleep standing up, but do copulate in lonely places. How fish hear is frankly a mystery since they don't seem to have ears. In humans, baldness is declared a consequence of sexual passion, since no boy, woman or castrated man ever loses hair like an intact adult man. So the inferences and assertions are often flawed (even if they contain a kernel of truth), but then how well will our own understanding of nature hold up in another 2,000 years?
The History of Animals might well be considered the starting point for zoology, at least in a systematic sense. By tackling questions like those Aristotle posed, scientists have made great strides in understanding the animal kingdom, from the collective behaviour of ant colonies and the intricate dances of honeybees, to the great migrations of whales and co-dependence of one species on another.
But what are the greatest zoological discoveries of all time? At BBC Wildlife magazine, a panel of judges has been mulling over the question. Today, the results of their deliberations are published as the top 10 breakthroughs in zoology. The list in full is below, in descending order. How have they fared?

10) Tool use by chimps

In 1960, Jane Goodall discovered that chimps in Gombe Stream National Park in Tanzania stripped leaves from twigs and inserted them into termite mounts to fish for grubs. The discovery challenged anthropologists' description of humankind as "man the toolmaker".

9) Symbiosis in coral

What we call coral is the hard shells of animals called polyps. But these marine creatures would die were it not for a symbiotic relationship with photosynthesising algae called zooxanthellae. The algae take up residence inside the polyps, trading the products of photosynthesis for a safe haven.

8) How the giant squid hunts

The giant squid is the largest invertebrate on the planet, but lives at such inaccessible depths that little was known of its behaviour in the wild. In 2004, Japanese scientists Tsunemi Kubodera and Kyoichi Mori lowered a bait-laden video camera 900 metres under the sea and snapped around 50 images of the beast in action. The footage showed the squid lunging, tentacles first, out of the gloom.

7) Migration routes

Modern tagging techniques have provided researchers with detailed knowledge of where birds migrate to with the change of the seasons, but for thousands of years their whereabouts was shrouded in mystery. Outlandish speculations ranged from the birds hibernating at the bottom of ponds, flapping up to the moon, or simply staying put but morphing into new species.

6) Mendelian inheritance

It took the patience and perseverance of Gregor Mendel, a 19th century monk, to discover that traits were passed on from one generation to the next. Mendel, who grew thousands of pea plants and painstakingly observed their inherited characteristics, showed that each new generation received "elements" from both of its parents, and that some were recessive and others dominant, thereby laying the foundations of genetic inheritance.

5) Death of the dodo

The extinction of the dodo stands as the most striking example of the human impact on wildlife. The last of its kind were alive in the late 17th or early 18th century.

4) Hydrothermal vents

The discovery of marine creatures living around geothermally heated water that gushed from cracks in the seabed overturned the notion that sunlight sustained all life on Earth.

3) Photosynthesis

The process by which plants use sunlight to convert carbon dioxide and water into sugars and oxygen underpins most of life on Earth. It is hard to credit any one researcher with the discovery, though key findings were made by the Dutchman Jan Ingenhousz in 1779, who revealed the crucial role of sunlight in driving the process.

2) Microscopic life

The 17th century Dutch scientist Antonie Philips van Leeuwenhoek made some of the best microscopes of his time, using them to discover microorganisms, or "animalcules". His work led to dramatic re-evaluations of the causes of disease and improvements in hygiene.

1) Transitional species

The most impressive breakthough of all, according to the judges, was the discovery of the fossilised remains of Archaeopteryx, a creature that shares some features with ancient reptiles and others with modern birds. The transitional species – often misleadingly called a missing link – lived around 150 million years ago and had wings and feathers, but also claws, teeth and a long, bony tail. More than any other discovery, Archaeopteryx helped drive the idea of evolution into the public consciousness.