Martha: The Last Passenger Pigeon

The passenger pigeon used to be the most numerous bird on Earth. Then, in less than a century, it was driven to extinction at the hands of humans. This month marks the 100th anniversary of Martha, the last passenger pigeon’s death.

There used to be billions of passenger pigeons. Literally. And that’s passenger pigeons, not carrier pigeons by the way, which are still alive and well today. When Europeans arrived in North America, there were between 3 and 5 billion passenger pigeons there. The passenger pigeon, Ectopistes migratorius, were highly sociable, living in huge colonies with up to 100 nests in a single tree. Continue reading

The Curious Case of Turritopsis

The Immortal Jellyfish

The idea of ageing backwards might seem like the kind of far-fetched tale that only the likes of Brad Pitt could sell, but for some of our distant, under-water cousins, it’s just a really bad day. A few unusual jellyfish species have evolved the ability to completely rearrange the cells in their bodies and return to an earlier life stage. They use this curious talent to deal with times of stress; if adult jellyfish (medusa) find themselves in unfavourable conditions, they can simple revert to their juvenile form and wait it out until things improve. Scientists believe this may enable them to endure poor environments and ultimately spread across the globe into regions other jellyfish cannot reach.

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Biological Linguistics:
The Difference Between Chimps and Monkeys

Chimpanzees and Monkeys

Non-scientists often make mistakes when talking about science. This is understandable. I’m sure I make mistakes when I talk about politics! But there is one mistake, one seemingly inconsequential error, that I find completely intolerable. The error I am referring to is the routine use of ‘ape’ ‘chimpanzee’ and ‘monkey’ as interchangeable terms for the same entity.

The word chimpanzee refers exclusively to members of a single genus; Pan. This genus contains two species; the common chimpanzee (Pan troglodytes) – what most people think of when they imagine a chimpanzee, and which have been famously humanised in television shows for decades – and the bonobo chimpanzee (Pan paniscus) which is found only in the Demoncratic Republic of Congo.

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What a Way to Make a Living

Nine to five. The whole western world seems to based around this simple concept. And perhaps for many people this seems to work just fine. If you’re a morning person, the nine to five regime works perfectly with your natural biological rhythms. But what if you’re an evening person? Research has shown a real genetic distinction between morning and evening people, and this distinction affects not just your preferred sleep-wake cycle, but daily body temperature rhythms, and variation in concentration and attention span.

Estimates suggest that just 15% of the population are true morning people, with about 25% being true night owls. The rest of the population is intermediate. If such a small fraction of the population is completely suited to a nine to five schedule, then why has this time frame become the standard? And does this mean that 85% of the population are not working to their full potential, simply because they are being forced into an unnatural work rhythm?

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Ice Science

The Hows and Whys of Glaciers

If you have ever been fortunate enough to see a glacier up close, it is hard not to be struck by the sheer scale of this huge ice formation. How can something so enormous have formed, and how is it possible for these huge structures to move? There are numerous examples world wide of the effect that glaciers can have on the landscape as they move, grow and retract, carving new shapes out of solid rock. But how can ice alone be responsible for such dramatic changes?

Glaciers form in areas where snowfall exceeds melting, and so snow is present on the ground year-round. As new snow falls it covers and compresses previous layers, transforming snow into ice; the weight of new snow causes older layers to re-crystalise. Over time these ice crystals grow larger, and in ancient glaciers the crystals can grow to several inches in length. Freshly created glacial ice is white, but as it becomes more compact over time it takes on a deep blue tinge. It is the high density and extreme weight of glacial ice which is responsible for its extreme terrain-shaping capabilities.

Glacial movement is caused by the sheer weight of the glacial ice, which causes stress on the ice sheet. Glaciers usually form into an accumulation area, where snowfall is high, and an ablation area, where most melting and evaporation occurs. When these two processes are in equilibrium, the glacier is balanced. Changes in snowfall or melting will cause the glacier to either advance or retreat, which is why glaciers are so vulnerable to climatic changes. But exactly how is solid ice capable of ‘flow’ similar to liquid water? The answer to this comes from a quirk in the chemistry of water. For most substances, as pressure increases, melting point decreases, causing them to become more stable. This is not the case for ice; the melting point of water decreases as pressure increases. The high pressures exerted on ice at the base of a glacier, combined with heat released from the earth itself causes this ice to melt. Small quantities of liquid water at the base of the glacier allow it to slide over the land.

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Glacial movement causes the development of huge crevasses in the ice sheet, as well as grinding up rock and soil underneath the glacier. Debris can be carried huge distances by the movement of the glacier. Dark bands of debris in the ice, known as moraines, are evidence of this transport. While glacial movement typically occurs slowly, over periods of hundreds or thousands of years, in some cases movement can be much faster. The Kutiah glacier in Pakistan holds the record for the fastest recorded glacial movement, advancing 12km in just 3 months during one glacial surge!

At present, around 10% of land area (15,000,000 km2) on Earth is covered by glacial ice, containing about 75% of the world’s fresh water. Almost all of this ice is contained within huge ice sheets in the polar regions, however glaciers are found on every continent except Australia. The ice sheets in the polar regions are particularly ancient, and the antarctic ice sheet has persisted for at least 40 million years.

As well as shaping landscapes, glaciers have a significant impact on human populations. Annual glacial melt is a significant source of fresh water for people (as well as plants and animals) in extremely harsh environments, and provides fresh water for around one third of the worlds population.

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