Original subtitles

There was a time when myths and science were entwined,

when mermaids and unicorns could mysteriously appear.

Nature was weird.

When science revealed the truth behind these imaginary creatures,

it found real animals lay behind the legends.

Today science still makes astonishing discoveries,

but nature seems just as weird.

It's just that fact has broken free from fiction.

Even familiar animals indulge in strange activities.

MIAOWING

Cats from far and wide are irresistibly drawn to a seemingly insignificant plant.

In the presence of catnip, they do the unexpected.

They not only eat its flowers, they rub, sniff and chew its leaves.

LOUD PURRING

Cats are strangely addicted to this fragrant herb.

They return for a fix of its heady scent again and again.

Its aromatic oils make them frisky and playful.

As they fall deeper under its influence, their mood changes in other odd ways.

As well as rolling around, apparently in ecstasy, they chase imaginary mice.

This odd behaviour is triggered by chemicals resembling those in tomcat urine.

Courting females writhe in this provocative way,

but strangely, catnip affects both sexes.

Cats even inherit this sensitivity. Three-quarters are affected in some way.

This weird journey shows how natural chemicals influence animal behaviour and reveals much about ourselves.

Aromatherapy is now more popular than ever.

But we are in surprising company.

Starlings use aromatic herbs to decorate their nests.

As science studies the human benefits of aromatherapy,

starling research shows that herbs help their chicks' immune system.

Their herbs contain the same essential oils as those we use.

In starlings the oils are absorbed through the shell.

They boost the embryo's white blood cells that fight infection.

Chicks reared with herbs grow faster and cope better with stress when they leave the nest.

Twice as many birds from herbal nests survive the first year.

In a dangerous world, the smallest variation in fitness makes the difference between life and death.

CHIRPING

Many birds of prey bring vegetation back to the nest.

The black eagle returns with garlands of aromatic leaves throughout its three-month nesting season.

Like the oil in herbs, leaf oils are the plant's natural defence against insects.

In the nest they seem to act as bug-busters,

tackling infestations of flies, ticks and mites.

Local people use the same leaves as insect repellents in their homes.

Perhaps like starlings, eagles also gain other health benefits.

Whatever the truth, birds clearly know what's good for them.

So do chimpanzees.

Chimps use over 30 different plants to treat stomach complaints.

This is aspilia.

Their young learn about self-medication by watching their elders.

Aspilia leaves need special handling. They must be rolled, not chewed.

This preserves hairs which trap intestinal worms.

The leaves are also dosed with anti-parasitic chemicals,

giving a double whammy.

Many chimp remedies are also used by local people as herbal medicines.

A growing knowledge of animal pharmacy is giving science insights into human treatments.

There is much that nature can teach us.

The axolotl has miraculous powers of regeneration.

It dwells in a few lakes near Mexico City.

This salamander tadpole never grows up.

Adults keep their gills and spend their whole lives submerged.

Lake Xochimilco is a tough place to live.

It is the most popular boating spot in Mexico.

The way the axolotl copes with the hazards has made it the focus of scientific study.

Limbs lost in accidents mysteriously re-grow.

Their process of regeneration is providing insights into the repair systems of our own bodies.

They take just three months to replace a severed leg.

If we can unlock the axolotl's secrets, we too might re-grow lost limbs.

Such studies into the weird side of nature may unlock the key to our future health.

Nature can even tackle its own environmental health problems.

Many birds like the rook employ pest controllers.

They enlist the unwitting help of ants.

It surrenders to the frenzy of bites with outstretched wings.

The ants also squirt formic acid, a natural insecticide.

This vinegary acid keeps down feather mites and seems to double as a plumage conditioner.

Smoke triggers the same odd contortions. So it probably acts as a pesticide too.

It must fumigate their plumage.

The rook's posture resembles the mythical phoenix - a bird reborn from fire.

Did a bird indulging in pest control spawn the phoenix legend?

Other familiar animals perform equally strange rituals.

Hedgehogs are immune to many poisons

and even have a taste for noxious substances. Like creosote.

Their substance abuse is harmless but it provokes a peculiar reaction.

They contort their body and lick saliva onto their spines.

Discarded cigarettes are another popular stimulant. They induce the same effect.

Why hedgehogs perform this bizarre ritual is a mystery.

But self-anointing is triggered by any pungent taste.

Perhaps the spittle cleans spines that are impossible to groom

and when mixed with the noxious stimulant it might deter parasites.

Nicotine is the tobacco plant's natural insecticide.

Human addiction is an accidental effect of this powerful chemical.

What have you done with my fags?

But the link between addiction and insecticides may not be purely accidental.

Millipedes are extremely poisonous.

But in Madagascar they are gathered with enthusiasm.

These black lemurs don't eat their finds.

They just annoy them by biting them gently.

The millipede sprays out defensive chemicals including cyanide.

The lemur spreads these toxins over its fur.

Lemurs crave these dangerous substances and grab every millipede within reach.

There is reason behind their addiction. The poisons repel insects

and keep malaria-carrying mosquitos at bay.

As the self-anointing ritual continues, something strange happens.

The lemurs enter a blissful state.

The secretions seem to act as a narcotic, giving the lemur pleasure as a reward.

Their drug habit must be harmful but its benefits as an insecticide must outweigh the risks.

Millipedes usually survive the experience relatively unscathed.

The lemur takes a little longer to recover.

Our own liking for intoxication has its roots in the natural world.

We even have similarities with bees.

Hives are complex societies with each bee assigned a role.

Visitors are identity checked by guard bees.

Workers gather nectar and pollen.

They are especially partial to the sugary sap of lime trees.

But the sap soon ferments into an alcoholic drink.

Alcohol affects bees much as it affects us. Their beeline back to the hive takes a few turns for the worse.

As well as losing coordination, they lose their sense of direction.

Those that stagger back not only have to land successfully...

..they have to pass the security check.

Like bouncers, the guards evict drunk and disorderly bees from the premises.

Their role is to stop behaviour that disrupts the smooth running of the hive.

Bee bouncers give all drunks the same rough treatment. Persistent offenders may even have their legs bitten off.

They literally end up legless.

Similarities with our own behaviour may be purely coincidental,

but true insights into our love affair with alcohol can be found in nature.

This is the sleepy island of St Kitts in the Caribbean.

300 years ago, vervet monkeys were brought here from West Africa along with slaves serving the rum industry.

Escaped monkeys acquired a taste for alcohol by eating fermented sugar cane in the fields.

Today they satisfy their thirst by raiding local bars.

They have learned to be sneaky.

Picking the right moment is everything.

For years the monkeys have been studied for insights into our own drinking habits.

Just as we vary in our taste for alcohol, so do the monkeys.

Some do anything for an alcoholic cocktail.

But just as some people are teetotal, so are some monkeys.

These reject alcohol in favour of soft drinks.

Significantly, the percentage of teetotal monkeys matches the non-drinkers in the human population.

In line with humans, most drink in moderation.

12% are steady drinkers and 5% drink to the last drop.

This similarity between us shows that a liking for alcohol is determined mainly by our genes.

After each daily raid,

other human parallels soon appear.

But unlike us, monkeys that are heavy drinkers make better leaders, respected by other monkeys.

They seem to tolerate leaders that monkey around.

Like monkeys, our taste for alcohol began when we scoured the forest for ripe, fermenting fruit.

Food and alcohol became linked with intoxicating effect.

In Peru, spider monkeys have the equivalent of a detox programme.

They come to this muddy spa to eat dirt.

The mud contains kaoline, a neutralising clay used to treat our own stomach upsets.

Peccaries, a kind of pig, visit this jungle pharmacy for the same medicinal treatment.

So do parrots.

The leaves and fruits of rainforest trees are poisonous.

A daily dose of clay detoxifies these meals.

A full health spa attracts hunters.

SCREECHING

Cats have their own tastes in medicines.

Just as pet cats eat grass, large cats like jaguars eat leaves.

When regurgitated they cleanse their digestive system.

But like catnip, some plants induce other effects.

Yage is one of the commonest rainforest vines. It seems to cause playful, kittenish behaviour.

But could something deeper be happening?

The vines are used by forest people in their hallucinogenic rituals.

They take them to enhance their senses and gain the jaguar's hunting power.

They believe the jaguar also takes yage to heighten its senses when it hunts.

Like so much of weird nature, there is still so much to know.

GROWLING

In the Arctic Circle, this fungus also has magical associations with animals.

Fly agaric contains hallucinogenic chemicals and is a favourite food of reindeer.

For thousands of years the lives of reindeer and Sami people have been entwined.

Fly agaric was important to both of them.

In autumn, reindeer seek out the mushrooms, even under an early fall of snow.

No-one knows whether the reindeer are affected, but in the past,

Sami shamans took fly agaric in their visionary rituals.

They even drank urine from reindeer believed to be under the influence.

In trance they contacted the great reindeer spirit.

On humans the drug heightens senses and creates visions of flying.

Some believe the greatest of all modern myths arose in the Samis' visionary flights of fancy.

Ho, ho, ho!

Perhaps early 19th century ideas drew on these stories to create a Christmas legend.

Weird Nature explored strange animal behaviour against settings of modern myths and human lives.

It began by revealing the odd ways that some animals move.

But compared with nature's movements, our two-legged walking is one of the oddest on the planet.

Animals have many devious defences.

But we have no natural defences at all.

Some animals have fantastic ways to catch prey.

But we need artificial help to catch ours.

Creatures have struck up strange partnerships.

But we depend on more animal partners than any other.

There are fish that change sex.

And males that give birth.

But biologically, most of our breeding habits are strange.

All in all, we are one of nature's strangest animals.

We are weird nature.

There is another way that we are unique. Our imagination can conjure up the most fanciful creatures.

But science has shown us that even these have roots in reality.

Giant octopus have been found with tentacles that span over 30 feet.

When science separated myth from reality, it found that real creatures had fed our fertile imagination.

But whatever our minds dream up,

science is stranger than myth.

Subtitles by Alison Foy, Subtext for BBC Broadcast - 2002

email us at subtitling@bbc.co.uk