[Music] [Applause] [Music] the first visitors called them the encantadas the enchanted aisles at times they seem to disappear if they were ever there at all the creatures who inhabited them were just as strange and curious like no other animals on Earth familiar yet different isolated from from the rest of the world in this exotic archipelago they were slowly and surely evolving different bodies different heads different beaks into this world the adventurers came Robinson cruso among them and the naturalist Charles Darwin whose name would be forever linked here soon the secrets of these Enchanted Galapagos Islands were uncovered by 1977 hundreds of scientists had probed and poked them tourists had claimed them a vacation spot like a fle the Galapagos Islands became a cous ious imprint of the magic that happened here no one expected more but the enchanted Islands had a surprise for [Music] them hello I'm Bill Curtis in the Galapagos Islands 160 years ago Charles Darwin walked here on James Island for one week he thought the marine iguanas were hideous and stupid looking of the finches he wrote in his diary the most curious fact is the perfect gradation in the size of the beaks there are no less than six species with graduated beaks it didn't make that much of an impression on him here but when he got back to England and began writing up his notes he realized the finches held the secret to the origin of life it was one of the most important discoveries in the age of science but it was only a theory today two scientists Peter and rosemary Grant have picked up where Darwin left off they've come back to the Galapagos to study Darwin's finches they have observed over 20 years and measured to confirm Darwin's theory in the process they have seen things Darwin never dreamt of seeing [Music] [Applause] [Music] the Galapagos Islands sit uncomfortably on the equator 621 Mi west of Ecuador in the Pacific there are 18 Islands only five are inhabited it's a strange and uneasy place there's little beauty even less calm the world for the few of God's creatures who live here is raw and frantic life and death coexist easily but through scientists eyes especially evolutionary biologists this is the most wonderful place on Earth is not too bad I wish it was a little bit lower yeah there's a p come to greet us Peter and rosemary Grant made their first trip here 22 years ago to this island called dfan major to begin a field study on a group of birds called Darwin's finches there a finch y to land on dhne you truly have to want to get on this island there's one rock to jump onto surrounded by 300 ft of shark infested water [Music] come okay yet before they climb up straight up they'll rinse everything tents Nets food in the ocean okay I will if you'll give me some in a bucket I'll do it here bringing in any new plants or Predators could be disastrous to the finches oh bringing in anything that might alter the environment parasites insects could be disastrous to their study is are those washed y they're [Applause] [Music] washed well I'm washed to [Music] [Applause] you the finches on DNE like the rest of the animals in the Galapagos have no fear of humans they simply don't know they should they have few enemies except for an occasional owl and even fewer competitors for food their main enemy is the weather and whatever toll it takes on the vegetation they eat these humans are simply curious okay I'll take these over to camp now before they get to work the grants will spend the better part of the day setting up their Camp under the watchful eyes of some old [Music] [Applause] [Music] friends there are 13 species of Darwin's finches in the Galapagos named for Charles Darwin the first person to collect them they vary in size from 3 to 6 in In Color by a matter of Shades their average lifespan is about 5 years though the grants know one 16-year-old who lives above the [Music] criter they separate during the dry season between June and December when food is scarce and come back together at the first sign of rain in January when the males begin to [Music] [Music] sing they sing to attract mates some mate for life others will have as many as 11 mates in their lifetimes and when they're young are born the father will take his turn feeding and imprint his young with his song the islands here are rich in food for finches but because they are enchanted Islands no two have the same vegetation the finches have adapted from Island to Island species to species none have the same beak on Daphne where Cactus is plentiful the cactus Finch has a long beak to reach into the flower for its nectar on Espanola the ground finch with its short deep beak concentrates on seeds under the soil on Santa Cruz the tree Finch with its parrot shaped beak strips the tree bark looking for [Music] insects and so it goes through 13 distinctive species with 13 distinctive beaks their food choices sometimes overlap but for the most part they only compete for food during extreme weather conditions the variation in their beaks is often so slight only careful measurements can show the difference but they they are different Darwin's fines have evolved should we put out the the Nets first yes and they're up there okay Darwin theorized it other evolutionary biologists explained it and finally these two people have seen it happen twice in the last 20 years Ki just about 15 M below you and slightly to the right once Camp is set up the grants begin their inventory of the island to see who made it through the summer what is the Cordia here a mixture or is it it's it's a mixture it's exactly half there we are oh it's 307 I believe 307 was one of the Ws born in 19 91 yep 307 it may be nesting there so let's see if there's a Magner rois down here yep there may be yeah one of the Grant's researchers was once asked to describe DNE major it's not nice it's simple he said that's why they go there a tour guide had an easier description it's a hell hole it's 100 acres of volcanic rock with some plants thrown in for humor there's no shade except for the leanos the grants put up no water or food except what they bring that courtship feeding involved an unbanded female yes I got that yes the closest island is a 2-hour boat ride away there's a shortwave radio in case of an emergency but they've learned to be self-sufficient you want to go down first the strange white birds with yellow brown feet they're Daphne's version of a roadblock masked boobies they seem to choose their territories by carefully calculating where a human will walk and then pecking or flapping to try and make the person fall into the ocean or it just seems that way the grants know their tricks and frankly there are other birds taking their full attention right now one one is that one one or I think it's one oh there's a bird there one I'll leave that one to you is that 306 that's 306 30 metal 6 yes there's a brown bird down here I'll try and find it they first came to Daphne major in 1973 with three questions they wanted to answer the question of whether species compete the reason why populations are so variable at least some are and then the third one the question of how species are formed all of those questions could be addressed with a study a field study of Darwin's fines in the galapagus: population we could get a handle on most of the birds on this island so it was like working in a little laboratory in a sense there were only two main inhabitants on the island scandan the cactus Finch and forus the medium ground finch the cactus Finch which fed exclusively on the cactus nectar might have seemed the more interesting bird but it would be the medium ground finch with its stubby beak eating seeds Cactus just about anything that would teach them what made Darwin's finches tick we found that they were extraordinarily variable so if we were to think in human terms they would be the equivalent of a population where there were 2T to 10t adults humans so they were enormously variable in size and build size and shape what about CIA they got to work first observing what the finches ate add three more Tribulus there are 40 species of plants we know them all so uh we can easily document the abundance of each of the species that are significant in the lives of finches not only that since the finches are so tame um we can observe exactly what they're eating they are so tame that in some cases we have to put our binoculars away we can't focus down closely enough enough in order to see what they're doing or we back away until they come into Focus Bird by bird year by year they log deaths and births pairings and courtships and idiosyncrasies he's just taken out the stigma and flicked it out in order to get down to the nectar the length of the stigma is exactly the same distance from the tip of the bill to the eye and we think that they just remove it just to get it out of the way and to be able to get into the nectar then they began to bend them in order to understand who survives best under what conditions we put bands on it and we code the color bands in such a way that we never need to capture the bird again disappeared that was something three at one point in their study they banded every Finch on the island about 1,000 of them they still know everyone 837 is um a cactus Finch um that was born in 1987 we know it entire history we know uh its parents I've forgotten the parents at the moment but they're in the computer back at home we know that it bred for the first time in 1981 it stayed on this territory throughout its whole life other than making little foraging trips out to steal food from other territory owners um it's had two mates one in 91 and '92 uh and again in '93 and a new one this year I think the female the original female died we know the number of Offspring It produced and a few more years time we'll know the number of those offspring that themselves are breeding are recruited to the population as breeding adults um there are other birds we know very much more about because they have lived very much longer I think that's 10826 is made darling she survived him that all 3 75 or 74 75 isn't it little 375 they try to find them all alive or dead to follow each one's history through to the end no I can't read it it's so faint I'll have to use my binoculars a microscope and the numbers get worn almost to the point of disappearance this one ended up as an owl's dinner looks like 15666 as their database began to grow they set up a vigil either they or colleagues would be here every season if anything changed in the finch population on DNE they'd know it the finch Investigation Unit as they would be called had set about the business of furthering Darwin's theory of evolution though they didn't know it at the time n she is 14492 she's a favored bird she comes wherever we are we can be on the other side of the island banding finches and she'll somehow find us really yeah and she doesn't it's not for food she just comes really she just likes you the temperature on Daphne today is 114° that's normal for January I saw one up there there's one feeding there oh that one it just carried some portulaca flow it snipped it off while they continue their inventory on the island the grants are taking me through the paces of Finch Evolution so that bill was 835 83 on one leg metal five light green on the right leg and what would that tell you that tells me it's an adult male uh I know that bird in particular it was banded a couple of years ago it's 2 years old and it nests in one of those Cactus bushes up there I think I'm prepared having read Jonathan Weiner's Pulitzer prizewinning book on their study the beak of the finch and I remember some of what I learned about evolution in school the theory is simple enough the two main ingredients are natural selection and genetics in natural selection there is a climatic change on Earth which causes competition in the case of the finches it's competition for food those best adapted to eat the food survive those who aren't die that's natural selection in genetics the genes of the survivors are passed down to the Next Generation and the next if the climatic conditions stay the same the survivors line will continue to thrive and here's the interesting part their beaks may even begin to change becoming better adapted to their food source almost like [Music] tools but Darwin said it took millions of years to achieve any measure of evolution represented the moment the grants are about to show me it doesn't you go to the net you don't know what is there we head for the Nets is this where you catch all the birds we catch them all over the island here's one good place because the birds Roost here and you put it up when it was cool yes and we're going to get these birds out before the sun rises up and Strikes the net because we want to measure the birds and release them before before it gets too hot can you tell immediately what species they are yes this is a scandent I'll have to check the book to see if it's a backat cross but it looks like a scandens uh 5069 he owns the territory over there and then here we have foris a small foris small beak foris that's right you have a magnar ostras down there big beak yes doubtedly big beak and then this one is a Fortis M the birds don't get hurt by this but they get a little bit Tangled so I take the legs out first and then I take the wings out and then I've got to move this netting over the head and there it comes mhm one four metal four now you can see this one is a smaller beak this one is thicker heavier and yet they're the same species now why the difference part of the reason for the difference is that the medium BR pinch hybridizes with the smaller species and with the larger species by hybridizing or mating with another species and producing Offspring the medium ground finch has become a species of both small and large beaked birds the difference is only a millimeter or more small by our standards but significant by finches well under other conditions that's unusual the next step is to measure the birds Peter's job like that pinch it there so that it can't come back I mean fly backwards and upwards and out I then weighed 18.6 G and again the reason for that uh measuring size different aspects of the size of the birds in order to understand who survives best under what conditions we need to measure so many birds and now I'll measure the length of one element of the the leg and then the next one I take is the length of the beak now this seems to be the most critical measurement you're going to make the beak dimensions are the critical feature at least one critical feature determining success or failure of these birds so I measure the depth or the height of the beak in the plane of the nostril and that is 8.6 and then I measure the width of the beak at the base of the lower mandible there and that one is also 8.6 while Peter does the measurements Rosemary takes blood samples and now release it after 33 years of marriage they've learned to watch out for each other don't sit down and the finches I'm going to do this if we could lift his head I'll be all right I think we enjoy working with each other very well we can easily differ in opinions I mean we quite often do no lift the head right up if you could the moments that I have most enjoyed um intellectually are often when Peter and I are really we have a difficult problem that we are um we discuss with each other and this can go on for days or even weeks when we're just trying to Fathom out something um rather difficult after 3 weeks of observing catching and measuring the finches on Daphne the grants have finished their inventory a check beneath a few cactus plants has turned up some disturbing news I have about 10 of them underneath the cactus Bush there this is what you've been finding we found by looking at the underneath the cactus bushes and where they sleep at night we found a large number of dead birds and we think that they probably did not have enough food um for them to last the night and so they they just died du due to starvation at night it always raises an alarm when they find something like this are you ever personally affected when you see the dead birds oh yes especially if there a bird that um maybe has been around Camp a lot and and then there are other birds that you just a either they're long lived or you just get to know or you just get to know their little their sort of odd quirky ways then it's always sad when they die their early estimate is that as many as 50% of the birds have died and why um probably because there were a large number of birds on the island and um there hadn't been any rain for about 10 months and so the food Supply was extremely low there was probably a lot of interaction over the food and um a large number of birds died or disappeared during that time it's bad but they've seen [Music] worse the drought of 1977 was the most severe drought to to hit the Galapagos in a decade the islands were Without Rain for 550 days plants and animals alike shriveled and died we were on the island in November 1977 with the children and it had been this Dreadful drought when really just seemed to be nothing alive on the island except for Cactus and a lot of the birds had died the medium ground BR finches that had coexisted peacefully began to fight for the little food that was left there's a Tribulus Tribulus and noria another Tribulus the grants were four years into their study 600 of the finches had been banded and measured now on hands and knees they began to study the Finch's only remaining food supply seeds we had been sampling systematically the food supply twice in 1976 three times in 1977 and then several times in subsequent years and been able to establish how many seeds were available for the finches at different times of the year so you can see here that there's a variety of seed types Hy small seed Tribulus being the large seed we knew then from estimating the seeds available in our grids that these ones were were diminishing in numbers relatively slowly over that drought period and these small ones were diminishing rapidly and so we have been able to piece together the fact that the finches were eating these at a high frequency then increasingly as these ones and those ones and yet other small ones became increasingly rare the birds turned their attention to these ones and we found out that the small beak birds could not crack those at all and it's only the very Lar lest beat members of the forest population that are capable of picking one whole Tribulus mericarp up and crunching it cracking it open and splitting open the seeds so in a drought when this is the only food available the food of Last Resort the bird that is going to be able to crack and get at that food source is going to be the one that survives that's right it's the crucial seed that made the difference between success and failure for many of the finches during the drought of 1977 the drought lasted 18 months when it was over they recorded the death toll how many of the small finches died during the drought about 4 to 500 of the smaller members of the 40s population died this was clearly a natural selection event oh absolutely right yes it was an event which selectively favored the large beat birds and selectively penalized the small beat Birds because they were not able to deal with with this remaining large and hard fruit that's a rather new observation about natural selection isn't it yes and that um I don't think uh most scientists would have thought that um the size of individuals mattered very much that a small bird would survive just as well as a medium bird just as well as a large bird but in fact the detailed measurements that we were able to make and the ability that we have on this island to follow the fates of of known individuals with known measurements enable us to show that in fact natural selection operates under stressful conditions and that size does make a difference whether an individual survives or [Music] not what they did next would be crucial when they returned to DNE the following year they would band and measure the next generation of finches only then would they know whether they had discovered what not even Charles Darwin had seen it was a cloudy day when the Beagle arrived in the Galapagos Darwin had been at sea for nearly 4 years collecting animal and geological specimens along the South American coast and getting very seasick he wrote a friend the misery I endured from seasickness is far beyond what I ever guessed at the real misery only begins when you are so exhausted that a little exertion makes a feeling of faintness come on I found nothing but lying in my hammock did any good but he was anxious to see the Galapagos and its volcanoes the Beagle landed on San Christal on September 17th then sailed on to Isabella floriana and Santiago in the month he was there saw only those four Islands he wrote of the black lava fields and the broken remains of a crater he sent specimens of plants to his professor at Cambridge and then turned his attention to the [Music] wildlife [Music] [Applause] he wrote in my walk I met two large tortoises one was eating a cactus and then quietly walked away the other gave a deep and Loud hiss and then Drew back his [Music] head the tortoise is very fond of water drinking large quantities and wallowing in the [Music] mud the rocks on the coast abound with great black lizards between 3 and 4 ft [Music] long and on the Hills an ugly yellowish Brown species was equally common [Music] when not frightened they slowly crawl along with their tails and bellies dragging on the ground a gun here is almost Superfluous for with the muzzle of one I pushed a hawk off the branch of a tree he was impressed but confused by the finches writing little about them the few dull colored birds cared no more for me than they did for the great tortoises I must suspect they are only varieties if they were not such facts would undermine the stability of [Music] species Darwin's finches became our symbols of evolution based on the theory that that all 13 species evolved from just one that had landed in the Galapago somewhere between 1 and 3 million years ago it was a violent time the young Islands were still settling volcanoes life was hard food rare to survive the finches scattered to various islands where isolated from each other they evolved into 13 species with 13 distinct [Music] beaks because the islands are still young and weather conditions on the equator Mercurial the Galapagos continue to be a hot bed for evolution it's not the only place scientists are seeing Evolution today there are over 100 studies going on around the world but it's still the classic as for our own Evolution some scientists say we humans have reached the end of our line others believe disease and viruses will continue to select out the weakest of us we're the lucky ones all but 1% of the species that ever lived on the Earth are extinct all but 1% and Darwin's finches with those kinds of odds how is it that all 13 species have survived that's the question evolutionary biologists since Darwin have been asking and why the grants chose to study [Music] them Peter and rosemary Grant made their Fifth and most important trip to the Galapagos in 1978 to do the measurements that would tell them if the medium ground finch had evolved to find out whether it had occurred we went around the island found as many nests as we could of the parents whose measurements we knew we banded The Offspring as nestlings allow them to grow up and after 60 days when growth has just about ceased we caught them when we made the comparison between the size of The Offspring generation and the population before selection we found a measured evolutionary response had taken place and it was almost identical to what we had predicted MH Darwin's finches had evolved the offsprings beaks were three to 4% deeper than their grandparents the medium ground finch was becoming a larger [Music] species it is a study that has demonstrated evolution in action and I think it is important for everybody not just evolutionary biologist to know that Evolution can be studied Within in a relatively short space of time by which I mean over a period of months maybe one or two years rather than centuries or the Millennia that Darwin thought would be necessary to follow the evolutionary change taking place in a lineage of mammals or birds or any types of plants for that matter that's where I would place a significance it's getting really hot I think but the grants weren't finished yet every year from 19 77 to 1982 they returned to DNE to collect more data on the medium ground finch to see if the large birds continued their dominance on the island it went on that way for 6 years nothing and then in 1983 the weather on the equator erupted [Music] again this time it was an El Nino the most severe El Nino in 400 years and it took the Galapagos by surprise on Santa Cruz they recorded three times the rainfall of their worst storm I remember one time when it rained for 11 days on end and everything even when it was in metal boxes got damp and you had no more dry clothes left and you were putting you were literally pouring out water from your boots I remember we even used wax crayons to doubly seam seal our tents because water seemed to get through that and the vines would grow up the guy ropes of the tents and over the tent you could even measure the growth of the vines every day it was truly extraordinary when the grants left for the season it continued to rain it rained for 8 months at the Charles Darwin research station the animals were thriving with tortoises on the um carpes of the tortoises when they're very young you can see growth rings we could definitely see on on The Young and the wild the El Nino of 83 was a huge growth ring I mean there was so much food available and and they did very well on Daphne the finches began to breed and didn't stop for 10 months finches started to breed right at the beginning uh bread in the first months of November bread again in December bread again in January and so on and so on all the way through to August producing eight clutches and eight Broods of nestlings in total just an extraordinary amount of production the population Grew From 150 to more than 1,000 but the elino had changed something else too the vegetation now the tables were turned and the king of the island the large Finch was suffering the Tribulus seeds which they are very good at cracking with their large um bills the plant is very low and that was completely covered by grasses and Vines the winner of the drought was the loser in the rainstorm this time the Victor in the Battle of natural selection was the small Finch so the larger build fors suffered and died and the smaller build fors um that were good at eating the small seeds survived and so this is why we got this natural selection event favoring those birds with smaller bills now you may ask why didn't they just turn to small seeds well the small seed supply was on the decline also in this dry period following El Nino and I think it was difficult for them to uh try to find hard seeds as well as make up their daily diet with small seeds and they died as a result starvation that's right that's right the El Nino of 1982 was pulling the finches in the opposite direction now toward becoming a smaller species when the next generation of birds was born and the grants did their measurements they saw what they thought they'd only been lucky enough to see once in their lifetime Darwin's finches had evolved again so you had now two examples of natural selection right there in front of both with an evolution evolutionary response which would answer the question why doesn't one the large species simply get larger and larger and continue that's right there's a tendency for the species to shift in size average size in One Direction and then it's reversed when the climatic conditions reverse and environmental circumstances change so we see over the long term the population fluctuating back and forth between larger and smaller sizes but with a long-term average set by the long-term average food conditions on the island after the 1983 El Nino the grants continued to monitor the finches on Daphne there were droughts and rainstorms but nothing significant enough to cause the finches to evolve again still they returned there's always something to study about Darwin's finches now they're looking at hybrids to see what will come of them it's hard not to wonder what Charles Darwin would have thought of all this he never got the chance to return to the Galapagos to see the finches Who Bore his name the trip on the Beagle seems to have made him ill off and on for the rest of his life but on his return to England in 1836 he continued to think about what he'd seen here and he wrote a theory that would get the entire world think thinking about Evolution do you feel close to Darwin oh yes we are undoubtedly following in his footsteps there's an element of exploration which we still experience in what we're doing uh building upon Darwin's observations his insights and the questions that he was asking not only when he was here but later uh how does species form why are there as many species as there are of different types how can they coexist we're still grappling with those questions and uh let us hope building upon the foundation that he [Music] established so not a bad day today you found a hybrid MH and a magnar stous nest oh that's right that's [Music] right oh here you're having them to eat yeah look 044 you should know better first bird to kick my beer over goes into the sea today the medium ground fines of Daphne major continue their push and pull game with Evolution leaving them somewhere in between but tomorrow who knows what will happen on these Enchanted [Music] Islands Thursday night don't quit on me now we've got places to go people to see we even have all of Canada to explore for Pete's sake if we hurry we can catch the last train across Canada tomorrow night at 8 now Great Performances kicks off its 23rd season with a Gaya celebration at Carnegie Halls opening night next on Channel [Music] 2 [Music] w [Music]