Why We are Alone in the Galaxy | Marc Defant | TEDxUSF

I wrote a book about history from life and I started noticing when I did my research that there were the statistically improbable events seemingly that had to occur in order for us to get life here intelligent life here on our planet and SETI has been now searching for the search for extraterrestrial intelligence they've been searching for life for 54 years and of course haven't found any intelligent life and so I got to thinking well maybe they weren't finding it because it's extremely difficult to occur evolutionary or whatever so tonight what I'd like to do is I'd like to give you three examples of these statistically improbable events but please keep in mind that there are literally hundreds of these events which need to occur in order to get intelligent life on this pant planet in my opinion well I need to go back to the Big Bang and talk a little bit about the Big Bang Theory and I hope to god that when I said the Big Bang Theory that the first thing that came to your mind wasn't the television show because we're all in trouble if that's the case and it could be a long talk too well in the Big Bang 13.8 billion years ago there was hydrogen and helium that's it so scientists recognize that we need another source for all the other elements that we find in our universe and we now know that that source is a supernova and a supernova is literally the death of a giant star it collapses in on itself it forms all of the elements in the periodic table other than hydrogen and helium and then it explodes and it sends that material out into its local space well now I want you to picture something called a solar nebula this is a gaseous cloud that once existed out there that later collapses to form our solar system and that cloud was originally enriched only in hydrogen and helium so we have to have all of the supernovae erupting out there and enriching that solar nebula in all of the elements requisite for life intelligent life in particular on our planet and if we don't have that then we can't get intelligent life and then at some point there has to be a soap a supernova nearby our solar nebula which forces it to collapse now how do I know that there was a supernova out there that forced our solar nebula to collapse well I think that's one of the most interesting scientific discoveries of all time and it doesn't get much press so I'd like to share it with you tonight the I end a meteorite is believed to be material that formed from our solar nebula as it was collapsing to form our solar system one of the reasons we know that is that it has calcium aluminium inclusions in it the date to 4.5 6 seven-30 billion years ago so that's the oldest state that we find in our solar system and we now use that date as the beginning or the origin of our solar system well in these calcium aluminate inclusions is a strange thing we find an isotope of magnesium called magnesium 26 and we shouldn't have magnesium and calcium aluminium inclusions so scientists were puzzled over this and they recognized though at some point that magnesium 26 is the decay product of aluminum 26 aluminum 26 has a relatively short half-life of 717 thousand years so that means that in seven to ten million years all of the aluminum 26 is going to decay away to magnesium-26 we don't have any aluminum 26 on the planet today that's because it all decayed away billions of years ago when it first formed from a supernova so I think you can see here what's happening we had a a supernova nearby our solar nebula and injected it with all of the requisite elements including aluminum 26 and forced it to collapse and as it collapsed the calcium aluminium inclusions form rich in aluminum 26 and that aluminum 26 then decayed the magnesium pointing 6 hence the reason we have magnesium in these calcium aluminum inclusions so so I don't know I think that's an incredible scientific discovery I'm a little prejudiced but think about that we can take things that we see today we can look at them we can study and then we can extrapolate back to things that were happening four-and-a-half billion years ago it's amazing I think and where does the statistical improbability come into play here well think about what has to happen you have to have our solar nebula out there with just hydrogen and helium in it to begin with and then you have to have all you super novae going off which inject it with all of these elements bigger than hydrogen and helium and just the right amount and none of them can force our solar nebula to collapse and then you have to have this supernova which we know occurred close enough to our solar nebula to force it to collapse and when it collapses at just the right time when our solar nebula has just the right composition then it collapses and it forms and eventually it leads to us well that seems remarkable to me an improbable event if there ever was one and we're here pop possibly as the result of it well that's the first statistically improbable event I'd like to talk about tonight but the second one has to do with this graph this is a graph of a log of brain mass versus the log of body mass and one of the things I'd like to show on this diagram is I'd like to show the relative intelligence of animals on the planet and in order to do that you can't just show brain mass you also have to show log mass or log of the body mass and I think you can see what I'm talking about when you see of this field this is the field for fish and phibian x' and reptiles and as you can see for a given body mass the rep these creatures have a lower brain mass compared to many of the other elements or I should say animals on our planet well you're not going to find any brain surgeons in and among the fish amphibians and reptiles that's sure look where the mammals fall the mammals fall at much higher brain mass for a given body mass and that's because mammals have a neocortex and that's what evolved into our gray matter so it's not surprising to see that the mammals fall higher than than the fish amphibians and reptiles and then the primates you can see where they fall they have some of the largest frames in the animal kingdom and I'm going to talk a little bit more about the primates and explain why they might have gotten those big brains but first of all I first I want to talk about and concentrate on this red dot because the red dot falls towards low body mass and very high brain mass and that's where people that come to TED Talks fall but you might like to know okay what we all learn from Jurassic Park that the dinosaurs were geniuses I mean think about this they learn how to open doors for God saves but I'm here to tell you that they weren't as smart as we think they were in Jurassic Park was lying to us look where the dinosaurs fall towards very high body mass but relatively low brain minutes they weren't the sharpest knives in the door that's for sure well now once we get the dinosaurs and we see how they fall you know they work this brings me to an important point and that is about about evolution and that is that evolution doesn't always select for the brightest creatures in the case of the dinosaurs they were selected for their large body mass and they were immensely successful they ruled the planet for 135 million years and what were mammals doing during that time well the mammals first appear in the Triassic about 200 million years ago they were little tiny creatures scurrying around trying not to get stepped on by the dinosaurs and and they were that way throughout the entire Mesozoic and if it weren't for the demise of the dinosaurs I'm going to suggest to you that we'd still be little tiny creatures running around and I wouldn't be up here talking to you tonight and it's that the is the dinosaurs that leads me to my second improbable event and that has to do with the destruction of the dinosaurs these are the alvarez's they're standing next to what we call the cretaceous-tertiary boundary it's an ash layer and that ash layer was deposited by the alvarez has discovered this 66 million years ago by a meteorite impact strong it hit Mexico well it didn't hit Mexico but it hit 66 million years ago Mexico wasn't there but you get my point it hit in that area and it sent ash into the atmosphere and those that Ash was carried around the planet by the atmospheric currents it caused the planet to be darkened for months and it stressed the largest animals on the planet the dinosaurs it wiped out every one of them and here's something a lot of people don't know it killed off 75% of the species on planet Earth it was horrendous event now where does this statistical improbability come into play here well think about this the Alvarez has discovered that that meteorite was 10 kilometers in diameter if that meteorites a little bit bigger than 10 kilometers you might kill off all life on planet and if it's a little smaller than 10 kilometers you might not kill off the dinosaurs and we'd still be little tiny creatures so I hope you can see the fine-tuning that's required here and the fortuitous event this must been think about it we have to have just the right size of a meteorite striking planet Earth in order for us to get here that seems like a statistically improbable event to me and I hope it does to you too so what happens after the dinosaurs are gone well we see the mammals radiate out into all of the niches previously held by the dinosaur one of the areas that they radiate into are the trees and the trees are where we get primates and when you're jumping around from limb to limb a lot of the things that are required of that process is they are things that need big brain power a lot of computing power so we see big brains let me give you a couple examples the the primates have three-dimensional vision they have color vision and they have these digits and it takes a lot of fine motion to move these digits so it takes immense immense computing power and and not surprisingly these things that were selected for in the primate well they also come with it a big brain and so we see big brains and primates as you saw in that that graph I showed you earlier now I hear from certain sectors that we had we were given digits so that we could type on computers and throw footballs but that's not the case we have digits in three-dimensional vision in color because we evolved from creatures that once lived in trees I hope that's obvious well here's where I'm going with this and that is that we need all of these we need this event to take place and we need it to take place oh that is getting rid of the duh the excuse me we primates we need to get them out of the trees and onto the ground and this is where the the third statistically improbable event takes place that I want to talk about tonight and has to do with the East African Rift zone the East African Rift zone started tearing Africa part about ten million years ago and it's been rifting africa part ever since then the faults are in red here the large triangles their big volcanoes the RIT and the red and those blues blue dots those are hominid localities now I don't have almond there but most the main ones are on there and these hominid localities are where we find fossils of upright walking bipedal creatures I mean if somebody says to you well we're all where are all of the missing links well we'll show on this diagram that's where all the missing links are they're everywhere out there we not only have our direct ancestors we have our first cousins our seconds you name it they're out there you know that seven million years ago we find a fossil that was walking in East Africa upright and it had it had bipedal motion and it had a brain about the size of a chimpanzee and it's just when genetic clocks tell us it should be there so I think that's amazing so where what if what has to happen to cause this bipedal walking motion and the big brains that we have today well it has to do with the East African Rift zone the East African Rift zone caused conditions to dry and become arid in East Africa and it destroys the jungles and it forces the primates out of the trees and onto the ground and then we see this amazing thing happening we start to see these creatures that are walking upright we start to see them develop amazing sized brains and it's like nothing in the history of life on the planet I'm not kidding you well don't see this anywhere in the history of life and within I'm going to give you an example here Australopithecus about three to four million years ago it was an upright walking creature and had a brain just a little bit bigger than a chimpanzee and and this Australopithecus dude it evolves into stone tool makers then Homo habilis Homo erectus and then us Homo sapiens and it moves on Africa a hundred thousand years ago and populates the planet US and that happens because of aridity in East Africa that's an amazing event in my opinion and where is the statistical improbability come from well think about this if this was an East South American Rift zone or an East North American Rift zone we might not be here that rift zone needs to cause aridity where the primates are and not just the primates the largest primates the great apes so it has to occur in East Africa well that's a fortuitous event an improbable of them now I don't want to come from an anthropocentric point of view tonight I'm not suggesting that God made all of these statistically improbable events occur so that would be we would be here that seems mildly arrogant to me know what I'm suggesting is than in a nearly infinite universe that there might be a few localities where you have all of these statistically improbable events occurring at just the right times to get intelligent life like us but in most of the places out there and I'm talking about the rest of our galaxy and most of the universe you might have a few of these statistically improbable events but not all of them and not in right in the right order and that's why I think that SETI is having trouble finding intelligent life now now I'm not on some campaign to shut down SETI I'm not on the warpath to get rid of SETI that's not my point here in fact that's a relatively negative point of view and that's a that's not the way I want to finish I want to finish with a positive point and my point is and I and I hope you recognize that life is is very very rare I mean think about how difficult it was to get our species here and then I want to point out to you that every one of you are rare very rare I mean I think about this I mean every one of your ancestors and I'm talking about your parents your great grandparents your grandparents all the way back to the first cell every one of them had to be successful at at least one thing and that was getting their genes passed on to the next generation and if they weren't you wouldn't be here well that's amazing I think of the gazillions of things that had to happen in order for you to be here well it's an astounding thing and so what I would like to leave you with tonight is is that life is rare life is precious and we need to take advantage of it and I can't see it I don't think any better than John Lennon so I'm going to leave you with John Lennon's words tonight and I want to thank you very much for this opportunity to come and speak to you thank you

Channel: TEDx Talks

Views: 868,801

Rating: 3.6496885 out of 5

Keywords: TEDxTalks, English, United States, Science (hard), Science, Space

Id: _nCOhrYV7eg

Length: 17min 30sec (1050 seconds)

Published: Thu Mar 17 2016

Reddit Comments

[u/sololipsist]

So Feynman has this famous quote, right? "Today as I was walking through the parking lot, and I saw license plate JTG894. What are the odds of that!?" Or, you know, something like that.

I feel like this talk is seventeen and a half minutes of that, but not ironically.

[u/Syx78]

Eh, I got into a debate on this earlier. My thinking is that biological intelligence takes awhile to work up to but it is an evolutionary advantage in some circumstances so it will probably come up eventually.

So let's not look at human intelligence, we have too small of a sample size for it. Instead, let's look at dog intelligence as a step towards human intelligence (say a 50 million year gap as opposed to a 3 billion year gap between dog intelligence and human intelligence).

The number of species with dog level intelligence over time is:

1 billion years ago: None

500 million years ago: 1 lineage. Cephalopods maybe (Cephalopod intelligence is tricky to study the evolution of because they don't fossilize well)

70 million years ago: 2 lineages. Cephalopods and Therapod dinosaurs like Velociraptor with its pack hunting.

1 million years ago - present: At least 6. Cephalopods, Therapod Dinosaurs (Grey Parrots and New Caledonian crows being the brightest), Elephants and relatives, Primates, Canines & relatives, and Cetaceans.

It seems like on Earth there's some sort of pressure towards higher intelligence such that over time there's more of it. If humans went extinct tomorrow I'd fully expect another "higher intelligence" species to arise in ~20 million years (from one of those lineages that is close to it). And further, that it'd have a lot more species close to its level than modern humans do (i.e. more creatures like chimps which are dumber than humans but not by a ton).

The same argument can probably be made towards "Evolution of Complexity" in general. For instance "Eukaryotes may take awhile to get to, but once they're there they have a distinct advantage in certain circumstances and can be used as a bridge towards further complexity"

[u/PlayingChicken]

I was very surprised to see the log brain mass vs log body mass graph, but when I google the same thing humans don't seem to stand out nearly as much, e.g. https://universe-review.ca/I10-83-brainmass.jpg

What am I missing here?

[u/tehbored]

Biological intelligence isn't that hard, civilization is hard. There are plenty of animals with intelligence not that far off from humans. Chimps, parrots, dolphins, elephants, and possibly others are close enough to us in intelligence that it's quite possible they might have evolved human-like intelligence under slightly different circumstances.

We humans, for most of our history, were every bit as vulnerable to natural forces as other animals. One time we even came within a razor's edge of extinction, despite our intelligence. It was only in the last 20k years, a mere 10% of our existence as a species, that we truly differentiated ourselves from other animals.