Life

VHS cover

*Life* is the twelfth episode of the third season of Eyewitness. The topic of the episode is about the different processes that define living things, such as growing, obtaining energy and reproducing. The episode aired on 1st December 1997.

Life is based on a book in the Eyewitness Science series that was first published in 1994. This book was then republished in the main Eyewitness series in 1998, and has been republished on several occasions including in 1999 and 2006.

## Episode

### Introductory sequence

Water and mud are shown bubbling before the camera cuts to a rock which explodes and falls apart. Inside is a glowing ammonite fossil which pulsates before the white light envelops the screen.

### Episode outline

Click here for the full transcript for Life.

Life is defined simply as being alive – the condition that separates animals and plants from inorganic matter. We have no simple definition for life. For many people, life is a philosophical and religious matter, with many considering it to be a divine gift. The beliefs and myths of many cultures about the origins of human life are outlined here, from the ancient Egyptians and Christianity to the Zuni tribe.

For centuries, we’ve fantasised about magical ways of creating life. It’s now believed that life may have required some kind of spark but process was chemistry, not magic. New compounds emerged from the volcanic landscapes of the young Earth, including amino acids, the building blocks of life. Scientists believe this was enough to launch life itself – the conditions made it chemically inevitable. In the 1950s two scientists, Miller and Urey, reconstructed the Earth’s primitive conditions on a smaller scale and managed to create the same amino acids that originally created life.

The first life took time. It was millions of years before the chemicals combined to create something with a talent crucial to any lifeform – the ability to copy itself. The benefits of being able to copy are shown, with smaller and more primitive organisms such as mould able to spread quickly by copying. In the competition for food, bigger tends to be better. Sponges pool their talents with others, and are a colony of cells where each has its own position. If shredded it will reassemble itself, with each cell returning to its original position. Having an array of specialist cells allows for a better quality of life than a sponge. Multi-celled life comes in a dazzling array of forms.

How did such specialisation happen? Different theories for specialisation come from the Bible and Rudyard Kipling's stories. Early scientists argued that animals changed according to their needs, including the naturalist Jean Lamarck. We now know that the process is different, as Charles Darwin theorised. He called the process natural selection. As a lifeform copies itself, it sometimes creates a mutation. Most mutations are inferior and do not survive, but sometimes they can offer an advantage. Copying itself, the mutation is the first of a slightly new breed. Darwin noticed how giant tortoises had evolved to match their environments on the Galapagos Islands. It was survival of the fittest. The process of convergent evolution, where two different animals evolve to a similar endpoint, is also explored.

Evolution can result in great solutions, but is chancy and slow. For each useful mutation, there are thousands of useless ones. But sex is a way of speeding up the evolutionary process. Life has many ways of ensuring sexual reproduction, with hydroid polyps, flowering plants and displaying animals including birds-of-paradise, kingfishers, elephant seals and humans all having their own methods. Although sexual reproduction requires lots of energy, nature has no better way of passing characteristics on and enabling change. Farmers know that sexual reproduction can allow the changes of crops and livestock, making them larger or more efficient.

Attempts at selective breeding were not always reliable. Nobody knew why until an Austrian monk called Gregor Mendel hit upon the basics of hereditary genetics in the 19th century, in an experiment involving sweet peas. This knowledge has led to huge improvements in crops.

An essential to all life is growth. Seeds and fertilised eggs know to grow into their respective adult forms. For life to reproduce it needs to grow, otherwise birth would be impossible. Life needs to arrive in small packages and grow before it can reproduce. For shelled animals, this can be challenging. Some animals, like butterflies and jellyfish, metamorphose during their life cycle. Growth has its limits, with the enormous size of some dinosaurs possibly leading to their downfall. Four hundred years ago, Galileo Galilei worked out that ninety metres was about as big as any living thing could be, with the giant sequoia matching this almost to a metre.

But where do the instructions for growth come from? All living things contain their own blueprint in a chemical called DNA, ravelled up in every cell. One double helix of DNA contains the instructions to make any living thing. During sexual reproduction, the double helix from each parent divides, with the offspring getting half the DNA of one parent and half from the other.

To grow and function, an organism must feed. Some animals are carnivores, others are vegetarian. Only plants can make their own food, with an experiment by Jan Baptiste van Helmont involving a willow shoot showing how plants get the material for growth from sunlight and carbon dioxide. Many lifeforms get their energy by eating plants, others by eating other animals. Sometimes the need to eat can create strange relationships, but not as strange as a French taxi driver who consumed an entire single-engined aeroplane ground up in his regular meals.

Converting food into energy needs oxygen, happily the waste product of photosynthesis. Ocean creatures gather oxygen with gills, while ammals and reptiles get their oxygen by expanding their body cavity. Birds are incredible breathing machines, with remarkable lungs and air sacs that allow them to breathe in and out simultaneously. Oxygen is not always a requirement for life, with strange bacteria in the Pacific Ocean thriving on chemicals from volcanic vents. They are the base of a strange community of animals that live two kilometres down on the seabed.

For many lifeforms feeding, growing and breathing aren’t enough – to survive they must be alert to danger and be ready to react to opportunity. Most plants can't react but can move, although some can move with surprising speed. Animals have developed an array of reactive equipment, including the heat-sensing pits of vipers, the sonar of bats, the high-pitched hearing of moths and the low-frequency hearing of sharks. Among the speediest of animals are the cheetah, hummingbird and falcon.

Temperature is key to a body’s chemical processes. Humans, like most mammals, have various control systems to maintain their normal body temperature. Tortoises, like all reptiles, rely on the heat of the sun and in cold weather they welcome a safe place to hibernate. Some life forms seem indestructible, such as Antarctic mites that can thrive in temperatures forty degrees below zero. Some beetles and cockroaches can survive sub-zero temperatures, but this was a mystery as they are mostly made up of water. They were found to contain diethyl sulfide, a form of antifreeze.

The amazing adaptability of life on Earth makes it possible to consider life beyond it. The origins of life from outer space is explored as a theory. The more we learn of life, the more the boundaries blur. A car may be able to consume energy, respire, control its temperature and respond to stimuli, but is not alive at all. All life wears out; there is no life form that does not eventually die. Yet such is the tenacity of life, if catastrophe struck the Earth, destroying every single thing, if just one molecule of DNA survived, could it be enough to start the whole thing over again?

## Animal species filmed for the programme

### Studio footage

* Mallard, *Anas platyrhynchos*
* Tiger, *Panthera tigris*
* Red-footed tortoise, *Chelonoidis carbonarius*
* Hermann’s tortoise, *Testudo hermanni*
* American black bear, *Ursus americanus*
* Chimpanzee, *Pan troglodytes*
* Walking catfish, *Clarias batrachus*
* Asian elephant, *Elephas maximus*
* American alligator, *Alligator mississippiensis*
* Domestic pig, *Sus domesticus*
* Domestic chicken, *Gallus domesticus*
* Aldabra giant tortoise, *Aldabrachelys gigantea*
* Strawberry poison-dart frog, *Oophaga pumilio*
* Monarch butterfly, *Danaus plexippus*
* Peleides blue morpho butterfly, *Morpho peleides*
* Domestic dog, *Canis familiaris*
* Domestic cat, *Felis catus*
* Cheetah, *Acinonyx jubatus*
* Leopard, *Panthera pardus*
* West European hedgehog, *Erinaceus europaeus*
* Red-necked wallaby, *Notamacropus rufogriseus*
* Sun beetle, *Pachnoda marginata*
* Madagascar hissing cockroach, *Gromphadorhina portentosa*

### Stock footage

* Thomson’s gazelle, *Eudorcas thomsonii*
* Hawksbill sea turtle, *Eretmochelys imbricata*
* Brown bear, *Ursus arctos*
* Emperor penguin, *Aptenodytes forsteri*
* Common limpet, *Patella vulgata*
* Sponge, Porifera
* Comb-jelly, Ctenophora
* Hippopotamus, *Hippopotamus amphibius*
* Cheetah, *Acinonyx jubatus*
* Snow leopard, *Panthera uncia*
* Superb lyrebird, *Menura novaehollandiae*
* Atlantic sailfish, *Istiophorus albicans*
* Masai giraffe, *Giraffa tippelskirchi*
* Galapagos giant tortoise, *Chelonoidis niger*
* Yellowfin tuna, *Thunnus albacares*
* Atlantic spotted dolphin, *Stenella frontalis*
* Eastern quoll, *Dasyurus viverrinus*
* Ocelot, *Leopardus pardalis*
* Chimpanzee, *Pan troglodytes*
* African bush elephant, *Loxodonta africana*
* Domestic pig, *Sus domesticus*
* White-tailed bumblebee, *Bombus lucorum*
* Brown argus butterfly, *Aricia agestis*
* Western honeybee, *Apis mellifera*
* Citrus swallowtail butterfly, *Papilio demodocus*
* Masked crimson tanager, *Ramphocelus nigrogularis*
* Greater bird-of-paradise, *Paradisaea apoda*
* Common kingfisher, *Alcedo atthis*
* Red deer, *Cervus elaphus*
* Northern elephant seal, *Mirounga angustirostris*
* White-lipped snail, *Cepaea hortensis*
* Common spiny lobster, *Palinurus elephas*
* Moon jellyfish, *Aurelia aurita*
* Caribbean reef shark, *Carcharhinus perezi*
* Large white butterfly, *Pieris brassicae*
* Eurasian magpie, *Pica pica*
* Domestic cat, *Felis catus*
* Bluebottle, *Calliphora vomitoria*
* Domestic sheep, *Ovis aries*
* Domestic chicken, *Gallus domesticus*
* Portuguese man-o-war, *Physalia physalis*
* Violet raft snail, *Janthina janthina*
* Nudibranch, *Chromodoris magnifica*
* Nurse shark, *Ginglymostoma cirratum*
* African cichlid, Cichlidae
* Brown trout, *Salmo trutta*
* Red-bellied piranha, *Pygocentrus nattereri*
* Tarpon, *Megalops atlanticus*
* Pacific hagfish, *Eptatretus stoutii*
* Tree frog, Hylidae
* American bullfrog, *Lithobates catesbeianus*
* Red-tailed tropicbird, *Phaethon rubricauda*
* Red-billed quelea, *Quelea quelea*
* Whooper swan, *Cygnus cygnus*
* Eurasian skylark, *Alauda arvensis*
* Red-breasted goose, *Branta ruficollis*
* Shrimp, Decapoda
* Vent mussel, *Bathymodiolus thermophilus*
* Hoverfly, Syrphidae
* Copperhead viper, *Agkistrodon contortrix*
* Brown long-eared bat, *Plecotus auritus*
* Violet sabrewing, *Campylopterus hemileucurus*
* Peregrine falcon, *Falco peregrinus*
* Rock dove, *Columba livia*
* Ground beetle, Carabidae

## Stock footage sources

The Lost World (1925) – Black-and-white dinosaur movie footage

The World About Us: The Rotten World About Us (1980) - Time-lapse of mould growing

The Natural World

* Okavango, Jewel of the Kalahari: The Living Jewel (1987) – Hippopotamus
* The Natural World: The Witness Was a Fly (1994) - Maggots

The Trials of Life

* Finding Food (1990) – Bumblebee flying from poppy, masked crimson tanager
* Finding the Way (1990) – Hawksbill sea turtle

## Credits

* Director - Brian Cummins
* Writer - David Stafford
* Music - Guy Dagul
* Graphics Director - Jean Cramond
* Graphic Design - Piers Helm
* Camera - Douglas Hartington and Douglas Young
* Set Design and Visual Effects - Chris Reynolds and Andy David
* Research - Catherine Gryparis
* Production Co-ordinators - Jessica Powell and Sarah Fink
* Production Team - Nicki Weston and Sara Forfar
* Unit Manager - Teresa Watts
* 3-D Animation - Andy Rawlings
* Off-line Editor - Alan Hoida
* Online Editor - Andy Quested
* Dubbing Mixer - Kian Wong
* With thanks to:
	+ van Aaken Developments Ltd

## Making this programme

The ‘making-of’ programme specific to Life has not been uploaded online, but it is part of the Making of Eyewitness 3: Worlds programme. The Life section of this episode first shows how the chicken and egg sequence were filmed. The two halves of the egg were pulled apart with string, but the main problem was that the chicken refused to leave the egg. It took many takes, and adding additional chickens, before the shot was able to work. The other thing shown here is the morphing sequence, from tree to elephant to daisy. Morphing has been used a lot on Eyewitness, and the process involves overlaying the two images, surrounding them with points and then aligning them to each other. The computer then does the rest of the work.

## Home media releases

As well as being released on VHS, Life was released as a DVD in the USA.

Life America-release DVD cover

**Writing staff**: Anne MacLeod • Ben Southwell • Ben Steiner • Brian Meehl • David Hanson • David Stafford • David Helton • George Bloom • Lynette Singer • Mike Tomlinson • Paul Thomas • Stan Cullimore
**Directors**: Gavin Maxwell • Justine Kershaw • David Hutt • Andrew Jackson • Justin Hardy • Ludo Graham • Jerry Foulkes • Derek Hall • Sanjida O'Connell • Caius Julyan • Bonni Cohen • Leanne Pooley • Edwina Vardey • Alexandra Beazley • Sam Hodgkin • Karen Walsh • Jack Weber • Richard Simkin • Alex Hearle • Brian Cummins • Ben Southwell
**Composers**: Guy Michelmore (season one) • Guy Dagul (seasons two and three)

**Season One**: Cat • Fish • Horse • Dog • Jungle • Bird • Amphibian • Insect • Shark • Elephant • Reptile • Dinosaur • Skeleton
**Season Two**: Desert • Tree • Ape • Mammal • Butterfly and Moth • Volcano • Rock and Mineral • Seashore • Pond and River • Weather • Arctic and Antarctic • Prehistoric Life • Shell
**Season Three**: Flight • Bear • Sight • Island • Survival • Mountain • Monster • Human Machine - Plant • Ocean • Planets • **Life** • Natural Disasters