0:00:03 > 0:00:08There was a time when myths and science were entwined,
0:00:08 > 0:00:14when mermaids and unicorns could mysteriously appear.
0:00:14 > 0:00:17Nature was weird.
0:00:19 > 0:00:23When science revealed the truth behind these imaginary creatures,
0:00:23 > 0:00:27it found real animals lay behind the legends.
0:00:29 > 0:00:33Today science still makes astonishing discoveries,
0:00:33 > 0:00:36but nature seems just as weird.
0:00:37 > 0:00:42It's just that fact has broken free from fiction.
0:00:57 > 0:01:01Even familiar animals indulge in strange activities.
0:01:01 > 0:01:04MIAOWING
0:01:07 > 0:01:15Cats from far and wide are irresistibly drawn to a seemingly insignificant plant.
0:01:17 > 0:01:22In the presence of catnip, they do the unexpected.
0:01:22 > 0:01:27They not only eat its flowers, they rub, sniff and chew its leaves.
0:01:28 > 0:01:31LOUD PURRING
0:01:31 > 0:01:36Cats are strangely addicted to this fragrant herb.
0:01:38 > 0:01:43They return for a fix of its heady scent again and again.
0:01:49 > 0:01:53Its aromatic oils make them frisky and playful.
0:02:02 > 0:02:09As they fall deeper under its influence, their mood changes in other odd ways.
0:02:15 > 0:02:22As well as rolling around, apparently in ecstasy, they chase imaginary mice.
0:02:26 > 0:02:34This odd behaviour is triggered by chemicals resembling those in tomcat urine.
0:02:34 > 0:02:39Courting females writhe in this provocative way,
0:02:39 > 0:02:42but strangely, catnip affects both sexes.
0:02:44 > 0:02:50Cats even inherit this sensitivity. Three-quarters are affected in some way.
0:02:54 > 0:03:02This weird journey shows how natural chemicals influence animal behaviour and reveals much about ourselves.
0:03:14 > 0:03:19Aromatherapy is now more popular than ever.
0:03:22 > 0:03:25But we are in surprising company.
0:03:29 > 0:03:35Starlings use aromatic herbs to decorate their nests.
0:03:42 > 0:03:47As science studies the human benefits of aromatherapy,
0:03:47 > 0:03:53starling research shows that herbs help their chicks' immune system.
0:03:57 > 0:04:03Their herbs contain the same essential oils as those we use.
0:04:10 > 0:04:14In starlings the oils are absorbed through the shell.
0:04:14 > 0:04:19They boost the embryo's white blood cells that fight infection.
0:04:22 > 0:04:30Chicks reared with herbs grow faster and cope better with stress when they leave the nest.
0:04:39 > 0:04:44Twice as many birds from herbal nests survive the first year.
0:04:45 > 0:04:53In a dangerous world, the smallest variation in fitness makes the difference between life and death.
0:05:08 > 0:05:10CHIRPING
0:05:14 > 0:05:19Many birds of prey bring vegetation back to the nest.
0:05:19 > 0:05:27The black eagle returns with garlands of aromatic leaves throughout its three-month nesting season.
0:05:28 > 0:05:35Like the oil in herbs, leaf oils are the plant's natural defence against insects.
0:05:35 > 0:05:40In the nest they seem to act as bug-busters,
0:05:40 > 0:05:44tackling infestations of flies, ticks and mites.
0:05:44 > 0:05:50Local people use the same leaves as insect repellents in their homes.
0:05:56 > 0:06:01Perhaps like starlings, eagles also gain other health benefits.
0:06:01 > 0:06:06Whatever the truth, birds clearly know what's good for them.
0:06:06 > 0:06:09So do chimpanzees.
0:06:12 > 0:06:17Chimps use over 30 different plants to treat stomach complaints.
0:06:17 > 0:06:20This is aspilia.
0:06:20 > 0:06:26Their young learn about self-medication by watching their elders.
0:06:26 > 0:06:32Aspilia leaves need special handling. They must be rolled, not chewed.
0:06:33 > 0:06:37This preserves hairs which trap intestinal worms.
0:06:40 > 0:06:45The leaves are also dosed with anti-parasitic chemicals,
0:06:45 > 0:06:49giving a double whammy.
0:06:50 > 0:06:56Many chimp remedies are also used by local people as herbal medicines.
0:06:56 > 0:07:04A growing knowledge of animal pharmacy is giving science insights into human treatments.
0:07:04 > 0:07:09There is much that nature can teach us.
0:07:13 > 0:07:17The axolotl has miraculous powers of regeneration.
0:07:21 > 0:07:25It dwells in a few lakes near Mexico City.
0:07:25 > 0:07:30This salamander tadpole never grows up.
0:07:30 > 0:07:35Adults keep their gills and spend their whole lives submerged.
0:07:39 > 0:07:43Lake Xochimilco is a tough place to live.
0:07:44 > 0:07:49It is the most popular boating spot in Mexico.
0:07:52 > 0:08:00The way the axolotl copes with the hazards has made it the focus of scientific study.
0:08:02 > 0:08:07Limbs lost in accidents mysteriously re-grow.
0:08:07 > 0:08:14Their process of regeneration is providing insights into the repair systems of our own bodies.
0:08:19 > 0:08:24They take just three months to replace a severed leg.
0:08:24 > 0:08:30If we can unlock the axolotl's secrets, we too might re-grow lost limbs.
0:08:34 > 0:08:40Such studies into the weird side of nature may unlock the key to our future health.
0:08:48 > 0:08:53Nature can even tackle its own environmental health problems.
0:08:58 > 0:09:03Many birds like the rook employ pest controllers.
0:09:06 > 0:09:10They enlist the unwitting help of ants.
0:09:10 > 0:09:16It surrenders to the frenzy of bites with outstretched wings.
0:09:17 > 0:09:22The ants also squirt formic acid, a natural insecticide.
0:09:28 > 0:09:35This vinegary acid keeps down feather mites and seems to double as a plumage conditioner.
0:09:45 > 0:09:52Smoke triggers the same odd contortions. So it probably acts as a pesticide too.
0:09:53 > 0:09:56It must fumigate their plumage.
0:10:01 > 0:10:08The rook's posture resembles the mythical phoenix - a bird reborn from fire.
0:10:11 > 0:10:16Did a bird indulging in pest control spawn the phoenix legend?
0:10:26 > 0:10:30Other familiar animals perform equally strange rituals.
0:10:34 > 0:10:37Hedgehogs are immune to many poisons
0:10:37 > 0:10:43and even have a taste for noxious substances. Like creosote.
0:10:43 > 0:10:49Their substance abuse is harmless but it provokes a peculiar reaction.
0:10:53 > 0:10:58They contort their body and lick saliva onto their spines.
0:11:07 > 0:11:15Discarded cigarettes are another popular stimulant. They induce the same effect.
0:11:15 > 0:11:20Why hedgehogs perform this bizarre ritual is a mystery.
0:11:20 > 0:11:25But self-anointing is triggered by any pungent taste.
0:11:29 > 0:11:34Perhaps the spittle cleans spines that are impossible to groom
0:11:34 > 0:11:40and when mixed with the noxious stimulant it might deter parasites.
0:11:48 > 0:11:54Nicotine is the tobacco plant's natural insecticide.
0:11:54 > 0:11:59Human addiction is an accidental effect of this powerful chemical.
0:11:59 > 0:12:02What have you done with my fags?
0:12:02 > 0:12:09But the link between addiction and insecticides may not be purely accidental.
0:12:09 > 0:12:12Millipedes are extremely poisonous.
0:12:12 > 0:12:16But in Madagascar they are gathered with enthusiasm.
0:12:30 > 0:12:34These black lemurs don't eat their finds.
0:12:34 > 0:12:38They just annoy them by biting them gently.
0:12:48 > 0:12:54The millipede sprays out defensive chemicals including cyanide.
0:12:54 > 0:12:58The lemur spreads these toxins over its fur.
0:13:02 > 0:13:08Lemurs crave these dangerous substances and grab every millipede within reach.
0:13:12 > 0:13:18There is reason behind their addiction. The poisons repel insects
0:13:18 > 0:13:23and keep malaria-carrying mosquitos at bay.
0:13:30 > 0:13:36As the self-anointing ritual continues, something strange happens.
0:13:36 > 0:13:39The lemurs enter a blissful state.
0:13:41 > 0:13:47The secretions seem to act as a narcotic, giving the lemur pleasure as a reward.
0:14:20 > 0:14:27Their drug habit must be harmful but its benefits as an insecticide must outweigh the risks.
0:14:37 > 0:14:42Millipedes usually survive the experience relatively unscathed.
0:14:45 > 0:14:49The lemur takes a little longer to recover.
0:14:56 > 0:15:01Our own liking for intoxication has its roots in the natural world.
0:15:03 > 0:15:06We even have similarities with bees.
0:15:07 > 0:15:12Hives are complex societies with each bee assigned a role.
0:15:12 > 0:15:16Visitors are identity checked by guard bees.
0:15:22 > 0:15:25Workers gather nectar and pollen.
0:15:25 > 0:15:30They are especially partial to the sugary sap of lime trees.
0:15:32 > 0:15:38But the sap soon ferments into an alcoholic drink.
0:15:44 > 0:15:52Alcohol affects bees much as it affects us. Their beeline back to the hive takes a few turns for the worse.
0:16:03 > 0:16:08As well as losing coordination, they lose their sense of direction.
0:16:10 > 0:16:14Those that stagger back not only have to land successfully...
0:16:16 > 0:16:20..they have to pass the security check.
0:16:23 > 0:16:29Like bouncers, the guards evict drunk and disorderly bees from the premises.
0:16:32 > 0:16:39Their role is to stop behaviour that disrupts the smooth running of the hive.
0:16:39 > 0:16:48Bee bouncers give all drunks the same rough treatment. Persistent offenders may even have their legs bitten off.
0:16:48 > 0:16:51They literally end up legless.
0:17:00 > 0:17:04Similarities with our own behaviour may be purely coincidental,
0:17:04 > 0:17:12but true insights into our love affair with alcohol can be found in nature.
0:17:18 > 0:17:22This is the sleepy island of St Kitts in the Caribbean.
0:17:25 > 0:17:33300 years ago, vervet monkeys were brought here from West Africa along with slaves serving the rum industry.
0:17:33 > 0:17:40Escaped monkeys acquired a taste for alcohol by eating fermented sugar cane in the fields.
0:17:40 > 0:17:45Today they satisfy their thirst by raiding local bars.
0:17:46 > 0:17:49They have learned to be sneaky.
0:17:52 > 0:17:56Picking the right moment is everything.
0:18:06 > 0:18:14For years the monkeys have been studied for insights into our own drinking habits.
0:18:16 > 0:18:22Just as we vary in our taste for alcohol, so do the monkeys.
0:18:25 > 0:18:30Some do anything for an alcoholic cocktail.
0:18:37 > 0:18:41But just as some people are teetotal, so are some monkeys.
0:18:41 > 0:18:47These reject alcohol in favour of soft drinks.
0:18:53 > 0:19:00Significantly, the percentage of teetotal monkeys matches the non-drinkers in the human population.
0:19:07 > 0:19:11In line with humans, most drink in moderation.
0:19:11 > 0:19:1612% are steady drinkers and 5% drink to the last drop.
0:19:20 > 0:19:27This similarity between us shows that a liking for alcohol is determined mainly by our genes.
0:19:36 > 0:19:38After each daily raid,
0:19:38 > 0:19:41other human parallels soon appear.
0:19:48 > 0:19:55But unlike us, monkeys that are heavy drinkers make better leaders, respected by other monkeys.
0:20:00 > 0:20:04They seem to tolerate leaders that monkey around.
0:20:09 > 0:20:15Like monkeys, our taste for alcohol began when we scoured the forest for ripe, fermenting fruit.
0:20:20 > 0:20:25Food and alcohol became linked with intoxicating effect.
0:20:32 > 0:20:37In Peru, spider monkeys have the equivalent of a detox programme.
0:20:37 > 0:20:42They come to this muddy spa to eat dirt.
0:20:43 > 0:20:50The mud contains kaoline, a neutralising clay used to treat our own stomach upsets.
0:20:54 > 0:21:00Peccaries, a kind of pig, visit this jungle pharmacy for the same medicinal treatment.
0:21:00 > 0:21:03So do parrots.
0:21:03 > 0:21:08The leaves and fruits of rainforest trees are poisonous.
0:21:08 > 0:21:13A daily dose of clay detoxifies these meals.
0:21:14 > 0:21:17A full health spa attracts hunters.
0:21:31 > 0:21:34SCREECHING
0:21:40 > 0:21:44Cats have their own tastes in medicines.
0:21:47 > 0:21:53Just as pet cats eat grass, large cats like jaguars eat leaves.
0:21:53 > 0:21:58When regurgitated they cleanse their digestive system.
0:22:06 > 0:22:12But like catnip, some plants induce other effects.
0:22:20 > 0:22:28Yage is one of the commonest rainforest vines. It seems to cause playful, kittenish behaviour.
0:22:29 > 0:22:33But could something deeper be happening?
0:22:38 > 0:22:44The vines are used by forest people in their hallucinogenic rituals.
0:22:44 > 0:22:50They take them to enhance their senses and gain the jaguar's hunting power.
0:22:59 > 0:23:06They believe the jaguar also takes yage to heighten its senses when it hunts.
0:23:09 > 0:23:14Like so much of weird nature, there is still so much to know.
0:23:17 > 0:23:20GROWLING
0:23:41 > 0:23:47In the Arctic Circle, this fungus also has magical associations with animals.
0:23:51 > 0:23:58Fly agaric contains hallucinogenic chemicals and is a favourite food of reindeer.
0:24:01 > 0:24:07For thousands of years the lives of reindeer and Sami people have been entwined.
0:24:07 > 0:24:12Fly agaric was important to both of them.
0:24:16 > 0:24:23In autumn, reindeer seek out the mushrooms, even under an early fall of snow.
0:24:30 > 0:24:36No-one knows whether the reindeer are affected, but in the past,
0:24:36 > 0:24:41Sami shamans took fly agaric in their visionary rituals.
0:24:43 > 0:24:48They even drank urine from reindeer believed to be under the influence.
0:24:55 > 0:25:00In trance they contacted the great reindeer spirit.
0:25:05 > 0:25:11On humans the drug heightens senses and creates visions of flying.
0:25:15 > 0:25:22Some believe the greatest of all modern myths arose in the Samis' visionary flights of fancy.
0:25:22 > 0:25:24Ho, ho, ho!
0:25:24 > 0:25:31Perhaps early 19th century ideas drew on these stories to create a Christmas legend.
0:25:43 > 0:25:51Weird Nature explored strange animal behaviour against settings of modern myths and human lives.
0:25:51 > 0:25:56It began by revealing the odd ways that some animals move.
0:25:59 > 0:26:06But compared with nature's movements, our two-legged walking is one of the oddest on the planet.
0:26:08 > 0:26:11Animals have many devious defences.
0:26:17 > 0:26:21But we have no natural defences at all.
0:26:26 > 0:26:31Some animals have fantastic ways to catch prey.
0:26:31 > 0:26:36But we need artificial help to catch ours.
0:26:37 > 0:26:41Creatures have struck up strange partnerships.
0:26:41 > 0:26:46But we depend on more animal partners than any other.
0:26:47 > 0:26:50There are fish that change sex.
0:26:53 > 0:26:57And males that give birth.
0:26:59 > 0:27:05But biologically, most of our breeding habits are strange.
0:27:08 > 0:27:14All in all, we are one of nature's strangest animals.
0:27:14 > 0:27:17We are weird nature.
0:27:20 > 0:27:28There is another way that we are unique. Our imagination can conjure up the most fanciful creatures.
0:27:31 > 0:27:37But science has shown us that even these have roots in reality.
0:27:39 > 0:27:44Giant octopus have been found with tentacles that span over 30 feet.
0:27:59 > 0:28:07When science separated myth from reality, it found that real creatures had fed our fertile imagination.
0:28:12 > 0:28:15But whatever our minds dream up,
0:28:15 > 0:28:18science is stranger than myth.
0:28:48 > 0:28:53Subtitles by Alison Foy, Subtext for BBC Broadcast - 2002
0:28:53 > 0:28:57email us at subtitling@bbc.co.uk