How much land on Earth is inhabited?

Question: How much of the land on Earth is covered by humans?

Answer: Approximately 10%.

This question is an interesting one because, when my friend asked me the other day, I could tell her confidently that not only did science know the answer, science had multiple different ways to quantify that answer, but that I had absolutely no idea what it was.

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What is a Nut?

Question: What is a Nut?

Answer: In Botanical terms, a nut is a hard-shelled fruit, which does not open to release its seed. There are relatively few true nuts because dehiscent fruit (where the shell does split open) is far more common; true nuts include chestnuts, pecans and hazelnuts. Not all nuts are closely related to each other on the family tree of plants though – indehiscence has evolved multiple times as a strategy for seed dispersal.

However, the word nut is used to refer to a huge range of hard fruits and seeds, from legumes (e.g. peanuts) to drupes (e.g. coconuts and cashews).

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Why Does Sour Food Make us Cringe?

Question: Why Does Sour Food Make Us Cringe?

Answer: Turns out, not many people have directly looked at this – the scientific literature has relatively little to say on the topic of cringing at sour food. However, what it does say is this: the cringing facial expressions are part of a general ‘disgust’ response that we make towards unpleasant smells and tastes. Some aspects of the face we pull when we eat sour sweets or a particularly tart tangerine are also produced when we smell off milk or bite into a rotten apple. The disgust response is designed to stop us from eating poisonous or rotten food, and to communicate with others around us that the food is bad. It probably formed a key part of social foraging, enabling early humans to avoid bad food and share information within their social group.

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Which is slimier?

Q: Is a Slug Slimier than a Snail?

A: Land snails and slugs like the ones you get in your garden are members of the class Gastropoda, along with sea snails, sea slugs and limpets. However, they do not represent distinct branches of the evolutionary tree – slugs are just species of snail that have lost their shell. There are even some snails that have a reduced shell – halfway between slug and snail. So this makes it difficult to answer the question.

However, there are some good reasons why slugs (shell-less snails) might seem to be slimier than their shelled counterparts.

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Can Chickens Change Sex?

Not the most pervasive of suburban legends, granted, but it seems to keep popping up. It goes something like this…

Confused Farmer finds Hen is now Cock
The mature hen, Gertie, who had laid eggs the previous year, suddenly stopped, grew chin wattles and started to crow.

So, can chickens really change sex? – Short answer: NO

The Long Answer

There are a few different explanations for stories such as these, but the important point of all of them is that these apparent sex changes are merely superficial – the hen might be visually and behaviourally male, but she is still unable to fertilise another hen’s eggs. So why does the hen suddenly start crowing? Continue reading

Do Insects Sleep?

In my recent article in Experimentation magazine, I made the rather bold claim that all animals sleep in some way or another. This is certainly true for all mammals and probably all vertebrates, but do insects experience sleep, and how similar is their experience to ours?

In order to determine whether insects can be said to sleep, we first have to define exactly what we mean by sleep. Traditionally, sleep is defined as a “rapidly reversible state of immobility and greatly reduced sensory responsiveness” (Seigel, 2008). It is distinct from simply resting, where we are still conscious. It is also distinct from more permanent states of rest such as hibernation. Sleep in humans, and in mammals in general, is defined by specific patterns of electrical activity in the brain, but can the same patterns be found in insects?

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Is There Any Truth to Astrology?

While your daily horoscope may seem to have little bearing on your life, recent research suggests that the month of our birth may have more influence that we think. A number of studies have shown that month of birth has a small, but significant impact on the chance of developing schizophrenia, depression, alcoholism, anorexia and a variety of other psychological issues as adults. Your birth month could even affect your chances of being dyslexic.

The cause of this is believed to be cosmic, however the star in question is our own sun. Scientists claim that the amount of sun exposure during your mother’s pregnancy is the cause of the seasonal pattern. This is supported by the finding that the pattern is exactly reversed in the southern hemisphere compared to the north, where sun exposure peaks at the opposite time of year. Scientists are not yet certain of the cause of the connection between psychology and sun exposure during pregnancy, but a number of theories exist.

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