00:00 There are whole communities of unusual organisms
00:04 that live in the lagoons of Patagonia.
00:06 And they are among the first forms of life ever existing.
00:09 Nobody knew them until two scientists, Brian and Maria,
00:14 went to explore some areas in Patagonia.
00:17 Patagonia occupies almost half of Argentina,
00:20 and few people live there.
00:21 Only a few farmers and sheep farmers
00:24 who mainly stay near the rivers
00:26 and grow things like apples, pears and alfalfa.
00:30 A long time ago, it was a wild and remote place
00:33 where Indian tribes lived,
00:35 for example the Tehuelch.
00:37 But this time, we will follow the traces of life
00:40 that appeared long before humans
00:42 and take a closer look at these interesting microorganisms
00:45 that Brian and Maria found.
00:47 These two had to drive for nine hours
00:50 on difficult roads to reach their destination.
00:53 They stayed in a small village,
00:55 only 35 people live there.
00:57 Six genes depend on a single source
01:00 because it almost never rains there.
01:02 On the last night in the village,
01:04 Brian realized that the satellite images he had taken
01:07 showed a set of lagoons,
01:09 which were only 16 km away.
01:11 The next day, the small team jumped in a car
01:14 and went up the road as far as they could,
01:17 until it became too difficult to drive.
01:20 They continued to hike the rest of the way.
01:23 It was difficult because they had to carry water
01:26 to face the intense sun.
01:28 In some places, they ended up sinking
01:31 to the knees in a salt bath.
01:33 Up there, there were 12 lagoons with perfectly clear waters.
01:36 The place itself did not offer much
01:38 apart from very acidic and salty water
01:40 and a direct and intense sun.
01:42 But it was a bit like a time travel,
01:45 because these conditions looked like what the Earth looked like
01:48 many, many years ago.
01:51 When Brian examined the lagoons,
01:53 he was surprised to see many unusual microorganisms there.
01:57 We call them.
01:59 And they are so small that we can't even see them without a microscope.
02:02 But they come together and form large communities.
02:06 In the past, many unusual species lived this way,
02:10 for example cyanobacteria.
02:13 They were important at the time because they produced oxygen.
02:17 The Earth, at its beginning, did not have much of this gas in its atmosphere.
02:23 The first stromatolites could have been formed by different types of bacteria
02:27 which did not necessarily produce oxygen,
02:30 but simply lived their peaceful lives there.
02:33 They formed layers, stacking on top of each other,
02:36 so that at least some of them could receive a little sunlight.
02:40 They used sand and glue liquids to stay close to each other.
02:45 Brian was also incredibly surprised
02:48 because it was in his head that the largest living stromatolites he had ever seen.
02:53 Living stromatolites usually grow up to more than one meter high,
02:57 but those that had just been discovered were 5 meters wide and a few feet high,
03:02 which is gigantic compared to those living in other places.
03:06 And the fossils were even bigger.
03:09 A long time ago, they could have grown bigger than today
03:12 because there were not many other species that could eat or harm them.
03:16 In addition, there are many other organisms today that can develop faster
03:21 and more massively than them and take their place.
03:24 This is why stromatolites can only survive in rare places
03:29 where almost nothing else can live,
03:31 such as in these salt lagoons located at high altitudes,
03:35 more than 3,650 meters, in the Apuna of Atacama.
03:39 The stromatolites found there are the most famous
03:42 because they could be among the best examples of the first forms of life on our planet.
03:47 However, they are not really the first form of life on Earth.
03:51 The oldest of their fossils are 3.5 billion years old,
03:55 while other evidence we have tells us that life on our planet
03:59 appeared about 4.1 billion years ago.
04:03 Maybe some stromatolites also lived at that time.
04:06 But the Earth has changed a lot since then,
04:09 and the places where they could have lived have not survived.
04:12 All this may not seem like much at first glance,
04:15 because no one has yet found an exotic and strange beast
04:18 that our world has never seen before.
04:21 But these are notable examples of what life search elsewhere in the universe could look like.
04:26 Scientists interested in the study of Mars
04:29 often come to this place because it could look like what the red planet looked like a long time ago.
04:35 If fossils were hidden in ancient rocks on Mars,
04:38 they could look like these stromatolites.
04:41 Another distant country has revealed some of its secrets.
04:44 It is Antarctica with an ancient "lost world" found under its ice.
04:48 Antarctica has not always been this isolated and icy land of snow and ice.
04:53 In the past, it was part of the supercontinent Gondwana,
04:57 with those which is now South America, Africa, Australia, the Arabian Peninsula and the Indian subcontinent.
05:03 But at one point, it separated and began to build a life apart.
05:08 It formed when other terrestrial masses began to move,
05:12 which formed its coast.
05:14 But Antarctica was also different in many ways at that time.
05:18 It was a land covered with magnificent forests and rivers full of life.
05:22 Scientists used radars and satellites to explore a mysterious world hidden under the ice there.
05:28 This ancient land, which is close to the Indian Ocean, is as large as the American state of Maryland or Belgium.
05:34 It is more than 14 million years old.
05:36 Some studies say that this area was formed more than 34 million years ago,
05:40 long before Antarctica fell into its great ice.
05:43 At first, the temperatures were higher there,
05:46 perhaps like the weather in Patagonia or the cold-tempered rain forests of Tasmania, New Zealand,
05:52 or perhaps even more tropical than that.
05:55 But as the climate became cooler, small glaciers began to form on the hills near the rivers.
06:01 The valleys sank further because of all this ice covering them.
06:06 And then, the temperatures dropped again.
06:09 And a huge layer of ice covered the entire continent, hiding these ancient glaciers.
06:14 Rivers shaped this lost world a long time ago,
06:17 long before they ended up being covered with ice almost 3.2 km thick in some places.
06:23 Scientific studies in this region have shown that these landscapes were filled with highlands and mountains.
06:29 The ice that had formed on Antarctica made the entire region very cold,
06:33 so that the landscape could no longer erode.
06:36 This means that everything remained essentially the same and intact under the ice for millions and millions of years.
06:43 What is interesting is that we know less about this hidden land under the ice than on the surface of Mars.
06:49 One way to explore it further would be to forest ice caps to check for sediment samples below.
06:56 They could tell us more about the flora and fauna frozen below.
07:01 This is not a new method.
07:03 A similar method has been used to collect samples from 2 million years ago in Greenland.
07:08 Australia also has its own secret world.
07:11 Ancient organisms have been found hidden in rocks from the north of the continent,
07:15 dating back to about 1.6 billion years ago.
07:19 These microscopic things are part of a family called the Eukaryotes.
07:23 The members of this family that exist today include plants,
07:27 mushrooms, animals, and even these tiny organisms have a single cell, such as amoebas.
07:34 All living beings with nuclei in their cells, including us,
07:38 can trace their genealogical tree to one of the oldest members of this family.
07:43 This is called the last common ancestor, Eukaryote,
07:47 and it lived more than 1.2 billion years ago.
07:51 These ancient organisms were more complex and larger than bacteria.
07:56 Perhaps they were the first predators on Earth, hunting bacteria.
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