This website uses cookies to provide a rich user experience. Please consult our Cookie Policy to learn about what cookies this website uses, or to control the cookies you receive. You need do nothing if you are happy to receive cookies.
Look and Learn History Picture Library License images from £2.99 Pay by PayPal for images for immediate download Member of British Association of Picture Libraries and Agencies (BAPLA)

Subject: ‘Biology’

All of these articles and images are available for licensing: click on an image to see further details and licensing options; contact us about licensing textual content.

Charles Darwin gave his name to a great Australian city

Posted in Animals, Australia, Biology, Birds, Historical articles, History, Nature on Tuesday, 31 July 2012

This edited article about Darwin in Australia originally appeared in Look and Learn issue number 757 published on 17th July 1976.

Charles Darwin, picture, image, illustration

Charles Darwin on the Galapagos Islands by Andrew Howat

It was on Christmas Day, 1974 that a hurricane named Tracy hit the northern coast of Australia and virtually wiped out the 27 square mile city of Darwin, chief port and administrative centre of the Northern Territory. The rest of the world was shocked at the extent of the damage, although most people had to reach for a map in order to discover exactly where Darwin was.

Gone were the 1930s when it had been well known as the goal of daring round-the-world flyers, even though the name was familiar. Probably, people surmised, it had been named after Charles Darwin. But had the great British naturalist ever been as far afield as Australia? The doubts were not surprising, for few associated photographs of a bearded 80 year old with the young man of 22 who had made one of the most significant voyages of all time. This was a voyage to the New World in 1831.

With the help of an artist, Darwin’s task was to record and obtain specimens of the plant and animal life of the countries visited, and for the next five years he worked with enthusiasm as the Beagle, on which he was travelling, slowly made her way along the coasts of South America and onwards to lands that were still mentioned very hazily in even the best geography books. Tahiti, the Maldives, Keeling Island, Tasmania, New Zealand, Australia, Darwin saw them all, and as he noted, collected and catalogued his specimens a new and extraordinary conviction began to form in his mind.

It had begun to grow after his visit to the Galapagos Islands, where he had light-heartedly ridden on the back of a giant tortoise and faithfully logged its speed as 4 miles per day. The islands abounded in a number of different types of finch, each specially equipped by nature for a particular task. On one island the birds had strong beaks for cracking the local nuts, on another they had small beaks for catching insects. There were woodpecker-like finches, and fruit-eating finches and even one that dug grubs from holes with a cactus spine. It seemed to Darwin reasonable to suppose that they had evolved, and adapted their shape over the centuries in order to suit their surroundings.

Read the rest of this article »

Migrating birds use the sun and stars to navigate their miraculous journeys

Posted in Biology, Birds, Nature, Wildlife on Wednesday, 27 June 2012

This edited article about bird migration originally appeared in Look and Learn issue number 741 published on 27 March 1976.

Migrating swallows, picture, image, illustration

Migrating swallows by A Oxenham

The radar operator stared in horror at the screen in front of him. The ‘blips’, or echoes of light on the radar, indicated a vast number of enemy planes heading straight for Britain, possibly on a massive bombing raid!

An air-raid warning was immediately given, and thousands of war-time Britons muttered unkind things about the Germans before hurrying to their shelters or into the Underground stations.

Yet no bombs fell that night, no aircraft were picked up by the probing searchlights, and before long, the “all-clear” siren filled the air with its welcome wail.

These false alarms happened many times before it was realised that the mysterious aircraft were in fact birds.

Since then, radar has provided much valuable information about the heights birds fly at, their course and their speed, adding to our knowledge about the annual movement of birds that takes place every year without fail and which has been taking place every year since man has been around to observe it.

But although we know where the birds go and we know why they go, we still do not fully understand how they are able to find their way hundreds, even thousands, of miles across strange lands and seas until they reach their destination. And we certainly do not know how the birds recognise this destination when they reach it.

Take the swallows, for instance. During the spring and summer we see them wheeling and darting above our houses and fields, ever on the look-out for insects. But as autumn approaches, they turn their faces south.

Over the Channel they head, right across France, throughout the length of Italy and over the Mediterranean. Still they travel on, down the Nile into the heart of Africa until they reach the very southern tip, Cape Town.

But as the sun begins to gather strength in Britain, as the first buds begin to appear on the trees, the swallows make the return journey, often going back to the very same farm, the very same barn, where they had nested the previous year.

Read the rest of this article »

A full suit of human skin is heavier than the liver

Posted in Biology, Science on Wednesday, 20 June 2012

This edited article about human skin originally appeared in Look and Learn issue number 734 published on 7 February 1976.

Mosquito bite, picture, image, illustration

Skin is perpetually renewed but its protective surface can easily be broken, as in the case of a mosquito bite. Picture by R B Davis

In spite of the skin’s tissue-like thinness, it is the largest and heaviest organ of the human body. The skin of a fully-grown person covers an area of over 3,000 square inches and has a total weight of nearly four pounds. That is more than the liver weighs.

Every square inch of your skin contains hundreds of nerve endings, several feet of blood vessels, many thousands of cells and hundreds of sweat glands. The thickness of the skin varies from 1/6th of an inch to 1/250th of an inch. It is thickest on those parts of the body which are subject to the most “wear”, such as the soles of the hands and feet.

There are two layers of skin, the epidermis or top layer and the dermis, which lies immediately under the epidermis. The epidermis is the skin that flakes or peels off when you get sunburned.

When a piece of the epidermis is examined under a powerful microscope, it is seen to be made up of rows of flattened cells piled upon one another like the bricks in a wall. The outer layer of these cells, which make up the surface of the skin, are constantly dying and being worn away. And as fast as they are worn away they are replaced by new cells pushed up from below.

It is because of the continual renewal of the skin’s worn-out cells that a healthy skin looks clean and fresh over a period of years. Skin that has been damaged or destroyed by minor bruises, cuts or burns is soon replaced. Often the replacement is so perfect that no scar remains.

Read the rest of this article »

The Mammoth remains the most iconic animal of the Ice Age

Posted in Animals, Biology, Nature, Prehistory on Wednesday, 6 June 2012

This edited article about the mammoth originally appeared in Look and Learn issue number 718 published on 18 October 1975.

Ice Age mammoths, picture, image, illustration

Mammoths lived in the Ice Age which explains why the remains of some of them have been perfectly preserved, by Angus McBride

The mammoth was an animal well suited to the Ice Age in which it lived. It had a shaggy coat of reddish-black hair and a thick layer of fat under the skin to protect it from the cold. Complete mammoths have been found in the frozen wastes of Siberia and Alaska – still wearing the remnants of their hairy coats. The contents of the beasts’ stomachs were also intact, giving scientists evidence of their diet.

Some distant ancestors of our familiar wild animals

Posted in Animals, Biology, Nature, Prehistory, Wildlife on Wednesday, 6 June 2012

This edited article about evolution originally appeared in Look and Learn issue number 718 published on 18 October 1975.

Mastodon Americanus, picture, image, illustration

Mastodon Americanus and the Dire Wolf

An amphicyon was an early bear-dog and was about the same size as a modern bear. Although much larger in appearance it was more like a modern dog.

Early camels seem to have varied considerably both in size and shape.

The poebrotherium is the earliest known forerunner of the modern camel. It was about the size of a present-day sheep but its neck and limbs were as long in proportion to its body as those of a modern camel. The feet had two toes and the formation of the teeth definitely resemble those of a camel.

The largest ancestor of the modern camel was almost certainly the gigantocamelus which lived in North America about a million years ago. The nostrils of this camel were not so flattened as they are today and the foot-pads were less developed.

The bison antiquus or bison occidentalis was a huge beast: its horns sometimes measured as long as six feet (1.8 m.) from tip to tip and a fully-grown bull weighed about 2,250 lb. (1,023 kg.).

This animal was an ancestor of the extinct wild ox of Europe known as aurochs. The aurochs stood about six feet (1.8 m.) tall at the shoulder and was probably black in colour. European domestic cattle are directly descended from the aurochs and by remove from the bison antiquus.

The mastodon was a forerunner of the modern elephant and, in fact, was very like it in appearance, although slightly longer. It also had differently-shaped teeth and a rather flat top to its head. But its trunk was the same as its modern descendant and it was roughly the same height.

The earliest known ancestor of the horse was the eohippus, often called the ‘dawn horse’, which was no larger than a rabbit. It had four toes on the fore feet and three on the hind feet.

A later evolution of the horse, and one which looked fairly like the horses we know today, was the merychippus. Its teeth, however, were slightly different in formation and the feet were of a different shape from those of the modern horse.

Scaly pangolins and transparent lepitodora – some of nature’s oddities

Posted in Animals, Biology, Insects, Nature, Oddities, Wildlife on Wednesday, 9 May 2012

This edited article about strange creatures originally appeared in Look and Learn issue number 702 published on 28 June 1975.

Pangolin, picture, image, illustration

Pangolin

In the world of nature, there are many very strange creatures, both in appearance and behaviour. Some have adapted themselves to living in very extraordinary situations. For instance, some exist in the hot water springs in New Zealand, and in pools of oil and in deep caves where no light ever enters and these, in course of time, have become completely blind.

One of the oddest of all mammals is the Pangolin. Looking more like a reptile, with hard scales, instead of hair, it feeds chiefly on ants and termites and has a tongue nearly a foot (304.8000 mm.) long. When alarmed, it rolls up into a ball rather like a hedgehog.

The Kiwi is a native of New Zealand. About the size of a large hen, its wings are only 2 inches (50.800 mm.) long, so it cannot fly. Most birds have a very poor sense of smell, but the kiwi, with nostrils near the tip of its bill, has such a good sense of smell that it tracks its prey, consisting of worms and insects, mainly by smell. Its egg is enormous in relation to its size.

The reptile and amphibian species contain some of the most extraordinary creatures. The Basilisk, about 2 feet long, looks like a miniature dragon and is also remarkable because it can run at a great speed on the surface of water; but when it tires and the pace slackens, it sinks until only its head is above water and it has to swim.

Read the rest of this article »

Human longevity is unremarkable compared with tortoises’

Posted in Animals, Biology, Nature, Plants, Wildlife on Friday, 4 May 2012

This edited article about longevity in nature originally appeared in Look and Learn issue number 700 published on 14 June 1975.

Giant tortoise, picture, image, illustration

Giant tortoise

A cone fell from a tree in Nevada, U.S.A. nearly five thousand years ago, took root and began to grow. Today, it has developed into a magnificent bristlecone pine tree and is the oldest thing alive.

Scientists dated it in the early sixties, probably by cutting a core through to the heart of the trunk and counting the rings revealed in this.

When a tree is cut down, the concentric rings across the trunk reveal the age of the tree, each ring representing one year’s growth. One bristlecone pine that had been felled was found to have five thousand rings, showing that it had begun growing at about the time the ancient Egyptians started to build their pyramids.

The surviving bristlecone pine, however, sprouted into life when the pyramids were already desert land marks 4,900 years ago. It is even older than the giant sequoia, known as the California big tree, which has a life span of between 3,500 and 4,000 years.

Compared to these, longevity in the animal kingdom is an insignificant thing. No creature’s average age is longer than that of Man’s. Few people live beyond the age of 110, although the average age is nearer seventy. Man’s closest rival is the tortoise, which holds the record for long life among the vertebrates. A common box tortoise has lived to become 138 and a European pond tortoise more than 120.

Read the rest of this article »

Small is beautiful; microscopic can be deadly

Posted in Animals, Biology, Fish, Nature, Plants on Wednesday, 2 May 2012

This edited article about nature’s smallest animals and plants originally appeared in Look and Learn issue number 699 published on 7 June 1975.

Pygmy shrews, picture, image, illustration

Pygmy shrews

Our smallest native bird is the Goldcrest, but this is a giant compared with the world’s smallest bird the tiny Bee Humming Bird, found in Cuba and Ecuador. It gets its name because it is no bigger than a large bumble bee.

Its wings beat so fast that they are just a blur when it hovers in front of a tropical flower, its long beak dipping into the nectar in quest of nourishment. The adult females are slightly larger than the males.

Our smallest animal is the Pygmy Shrew, at two and one quarter inches, (57 mm), slightly smaller than the long-tailed Harvest Mouse. Even smaller is the Etruscan Shrew with a body length of only 1 and a half inches (38 mm) and reputed to be the smallest animal in the whole world.

Apart from animals, there are also a great number of microscopic insects. Some of these are so minute that they are scarcely visible to the naked eye.

The Dwarf Beetle, for instance, is small enough to pass through the eye of a small needle. The Small Blue Butterfly, less than 1 and a quarter inches (about 25 mm), across the wings, is the smallest British butterfly.

Unlike most of its kindred, it is only on the wing during the months of May and June.

Read the rest of this article »

Nature and nurture in the field of animal intelligence

Posted in Animals, Biology, Nature, Science on Tuesday, 1 May 2012

This edited article about animal intelligence originally appeared in Look and Learn issue number 699 published on 7 June 1975.

Chimpanzees' tea party, picture, image, illustration

Tea for four chimps at the zoo by James E McConnell

When, at a very early age, we stood upright and hesitatingly took our first few steps, our parents were probably very proud of us.

After all, we had been trying to walk for quite a number of months. We learned how to crawl and use our complicated system of muscles. Finally came the most difficult lesson of all – standing on two feet and walking.

But let us think about what happens a few minutes after a foal is born. The frail little creature makes a few jerky movements, staggers up on its four spindly little legs – and then walks almost perfectly!

The ability of animals to do many complicated things without apparently having to learn them is called instinct.

Biologists are not at all certain exactly how these animal instincts or “built-in skills” have come about.

In fact some scientists are beginning to think that some instincts are not really built-in at all. Instead of the skill being inherited from the animals’ parents, it might still have been learnt.

Read the rest of this article »

The sense of smell is a useful tool in crime detection

Posted in Biology on Monday, 30 April 2012

This edited article about the sense of smell originally appeared in Look and Learn issue number 697 published on 24 May 1975.

Scent bottles, picture, image, illustration

Bottles of perfume

When anyone talks about a “keen sense of smell” we often think of dogs in general – and bloodhounds in particular.

Yet in spite of the fact that smell is the weakest of our five senses, human noses can detect very small traces of certain chemical odours, even if they are in the air with a concentration of less than one part in a million.

Our ability to smell begins with the nostrils. These lead into what is called the “nasal cavity” which is lined, at its top part, with thousands of olfactory (smell-detecting) cells. From these cells nerve fibres lead to the brain.

When air is breathed into the nasal cavity, any gases, dust particles or traces of vapour in the air irritate the sensitive olfactory cells, which then send “odour messages” to the brain.

Many substances, of course, do not affect the olfactory cells so that we cannot smell them. Water vapour and air itself are good examples.

Because these don’t cause odour messages to be sent to the brain, we simply say they are “odourless” or don’t smell.

In general, we tend to divide odours into two kinds – pleasant and unpleasant. Most of us agree that the smell of a rose is pleasant, but that the odour of decaying food is not.

But sometimes it can be a matter of opinion – some people get quite ill when they smell lavender-scented soap while others like the smell of ripe gorgonzola cheese!

Most things have a characteristic odour because of some chemical substance they contain. It is this chemical which acts upon the olfactory cells in the nasal cavity and produces the “smell” sensation.

The familiar odour of bananas, for example, is caused by a pale yellow liquid chemical called amyl acetate which is present in the fruit.

The bad smells from decaying food are caused by certain gases, like phosgene, from decaying fish, and hydrogen sulphide from rotten eggs.

Our olfactory cells are really sensitive chemical laboratories which analyse separate smells.

The most pleasant odours are often a mixture of many chemical substances. Modern perfumes can contain more than two hundred chemicals, all expertly blended together.