(electronic music) - Hi, I'm author and
biologist Sean Carroll. Thanks for tuning. I wish we could be together in person, but COVID has prevented that. Today I'll share with you a
few stories from my new book that ask the questions, why is the planet the way it is? How did we get here? Does everything happen for a reason, or are some things left to chance? Philosophers and theologians have been pondering those
questions for millennia, and modern philosophers still do. But nothing put those beliefs to the test like trauma or a close call. In 2001, Seth MacFarlane
was the 27-year-old creator and executive producer of the not-yet-hit "Family Guy." Had he made a splash at such a young age, he was asked to speak at his
alma mater in Rhode Island, and he tells the rest of
the story to Piers Morgan. - A combination of two things. I was giving a lecture at
my college the night before, and went out with some
of the faculty afterwards and had a few pints. - [Interviewer] You got drunk. - Yes. Coupled with the fact that my travel agent had listed the flight on my itineraries leaving 10 minutes later than it did. I was generally late for flights. I've missed a lot of
flights prior to that, so it wasn't like it was anything
crazy out of the ordinary, but I got to the counter and I said, "Yeah, I'm booked on Flight 11," and the one beside the counter said, "Sorry, you're too late,
they just closed the gate." And said, "All right,
I'll take the 11 o'clock." Went into the lounge, fell asleep, woke up about 45 minutes
later to a commotion and the first plane had hit, and sat there and watch
the second plane hit, and they announce what flight it was, and I turned at the guy next to me, and said that was the flight
I was supposed to be on. I was late. I missed it. - MacFarlane was not the only celebrity to miss Flight 11. Mark Wahlberg was also
schedule to be on the flight, but changed his plans. And 11 years later, MacFarlane
and Wahlberg teamed up to make that movie, "Ted." Now what are the odds these
two guys would both miss America Flight 11 and
later make a hit movie? Were their escapes from
mass murder just dumb luck, or were their lives spared so that our lives would be enriched by a trash talking teddy bear? - Michelob Ultra Tuscan Orange Grapefruit. My god, America is imploding. - Dumb luck, accident,
chance, call it what you will. MacFarlane's late arrival to the airport was purely an accident, albeit an accident with
profound personal consequences. What a difference just
30 minutes can make. It's sobering to think
what a thin line there is between life and death. And what governs that thin line is a major focus of my new book. Because over the past 50 years, as scientists have learned so much more about the history and
workings of the planet, we've been startled to discover how the course of life as been buffeted by a variety of cosmological accidents, without which we would not be here. And as we probed human biology and the factors that impact
our individual lives, we've caught chance red-handed, reigning over that line
between life and death. So today I'm gonna highlight
a few of those events that revealed just how much we live in a chance-driven world, and then briefly explore what that means for how we think about ourselves. So speaking of thin lines, that exactly what puzzled the geologist working outside the beautiful
town of Gubbio, Italy in the 1970s. Geologist Walter Alvarez
saw an interesting pattern in a column of rock just outside of town. He noticed that in this large
stack of limestone layers there was a switch in color
from white at the bottom to red above. And when Alvarez looked closer, he saw that there was a
peculiar layer of grayish clay, showing here where the
coin is on the right, that separated the two
colors of limestone. Alvarez's decryption of that
one centimeter thin line began to reveal the story of the most important day on Earth in the last 100 million years, a day that was very, very unlucky
for most everything alive, but what eventually turned out to be extremely fortunate for us. And on that day, a long long time ago, 30 minutes would make all the difference. The Gubbio rock formation was once part of an ancient seabed, so it contains the fossilized shells of tiny creatures called
foraminifera or forams for short, shown here in the electron microscope. These abundant single-celled creatures are part of the ocean's
plankton community and food web. And when forams die, their
shell settle in ocean sediments and form parts of limestones which can be later pushed
up by tectonic forces as they are in Italy. When Alvarez looked at the forams from the rock outside Gubbio, he said the white layer
of rocks on the bottom contained a diverse array
of large fossil forams. But the reddish layer of rock above lack those species and
contained only a few smaller species of forams. And that thin layer of clay in between appear to lack fossils altogether. Alvarez realized something dramatic had happened in the ocean that had driven many foram species extinct in a short period of time. Now that boundary
represented by the clay line, that's also known from
terrestrial deposits, like this one from the
Western United States. The pocket knife is
pointing to that boundary, which marks a dividing
line between two worlds 66 million years ago. Below the boundary lay the
rocks of the Cretaceous period, which make up the last
third of the age of reptiles when dinosaurs ruled the land. Above the boundary lay the Paleogene, which contains no dinosaurs, but marks the beginning
of the age of mammals in which furry animals emerged to become the largest animals
on the land and in the seas. Alvarez and his colleagues wondered what on Earth could've
caused the disappearance of widespread tiny organisms like forams, as well as much larger
creatures like dinosaurs. As you most likely heard, there was traces of the element iridium in that thin layer of
clay that ticked them off, that wasn't something on Earth, but something from space. An asteroid six miles wide and traveling approximately
50,000 miles per hour slammed into the Yucatan Peninsula. The enormous mass of rock
blasted out of the crater was hurled in all directions, a thick curtain of ejecta traveled at several thousand miles per hour and rained down across North America, while the impact plume
consisting of super heated air, carbon dioxide, water and sulfur vapor, vaporized rock, chunks of target rock, that shot ejecta at velocities greater than the Earth's escape velocity, more than 25,000 miles per hour, into and beyond the atmosphere, which then fell back down across the globe as trillions of red hor meteors. The result was hell on Earth. The following ejecta heated the air to four to 600 degree
Fahrenheit, like a baking oven, and triggered global wildfires. the impact plume and
soot from the wildfires blocked out the sun. Global temperatures then dropped by at least 20 degree
Fahrenheit, probably more. Food chains collapsed. And this blackout lasted for at least 10, perhaps as many as 30 years. During that time and afterwards, 3/4 of all plant and
animal species on Earth, including the great
dinosaurs, went extinct. But this asteroid impact is the mother of all accidents, and that's because
we've come to appreciate that there were pretty
special circumstances for this mass extinction to happen. The destructive power of the plume depends upon the mineral
content of the impact site. Geologists have figured that only one to 13% of the Earth's surface contains the right kinds of rocks to trigger a mass extinction if vaporized. So what that means with the Earth rotating in a thousand miles per
hour, had this asteroid, which has been circling the solar system for perhaps four billion years, had it entered the Earth's atmosphere just 30 minutes earlier, it would've landed in the Atlantic. 30 minutes later, it would've
landed in the Pacific. And in either case, there
would be no mass extinction. The dinosaurs would still
be here, and we would not, and of course there would be no "Ted" and, god forbid, no "Ted 2." Now let me show you another collision. This one's a little more personal. In this clip, the collision
at the upper right also triggers a shower of chemicals, but this time lift does
not end, it begins, because this is the
moment of fertilization. The trembling and shower
are part of the sequence of dramatic physical and chemical changes that occur in the egg that preventer
fertilization by other sperm and begin the process of
embryonic development. Out of a swarm of a hundred
million or more contenders, only a single lucky sperm will swim all the way
up the fallopian tube and successful fertilize the egg. The fertilized egg is
the union of two genomes, half of its chromosome from the sperm and half from the unfertilized egg. Now here's an astounding fact. No two fertilized human
eggs will ever be the same. That's right, ever be the same. To see why, let's try a pop quiz. You're ready? So, by each contributing 23 chromosomes, how many genetically unique children do you think your parents could have? 23? 46? 92? Now try again. How about 70 trillion? That's right, 70 trillion. Now what that means is that
each of us, each one of us, is a one in a 70 trillion event, which means at fertilization, it's the accident of all mothers. To see why, let's break down the math. The number of possible
chromosome combinations from dad can easily be calculated because you can get two different
version of each chromosome, and there are 23 chromosomes. And so there are two to the 23rd power or 8,388,608 possible chromosome
combinations from dad. Same math for mom. 23 chromosomes, two alternatives
for each chromosome, 8 million-plus possibilities. But the number of possible
combinations of sperm and egg, remember that possible combinations would each create a different child, is the product of those two numbers, which gives you 70,380,744,177,664
unique children. After my arrival at 10 pounds five ounces, my mom stopped at four. But this enormous number is
actually an underestimate because of another important contributor. Mistakes. I'm talking about the copying of DNA, three billion letters in each sperm, three billion letters in each egg. Heck, it's so easy to make mistakes with much shorter lines of text. Let me show you a couple
of my favorite examples. So I'm a passionate baseball fan, started when I was a kid. And in the early days, I read
the sports pages every day. And when I saw this story
in 1974, I clipped it out, and kept it forever. There are three mistakes in
this very short sports article. See if you can spot them all. All right, you're ready? There's the first one. There's the second one. And yep, there's the third one. That must've been quite a wallop. I don't think these were intentional. These are random mistakes, typos. Here's another howler from
a slightly higher authority than the Toledo Times. This is the 1631 version
of the King James Bible, and I'm drawing your attention
to the Seventh Commandment. I'm pretty sure this is
the copy of the Bible that's in the White House bedroom. The blasphemy was not detected for a year, and King Charles I was, well, he was royally pissed. He ordered that all copies be burned. He revoked the printer's license, one of whom died in debtors' prison. What a difference a single
letter or word can make. The same is absolutely
true in life's alphabet. Let me show you what a
difference one type can make. I'm gonna show you a very
short piece of genetic text. The original line reads
this, the single letter code. And just one type, changing
that middle M to R, has killed more than 33 million people. Now how could such a
small change be so deadly? I'll tell you that in a few minutes. The crux of the matter is
the cause of that change, and that leads us to the DNA molecule. Now this is the structure on the left that was worked out, first,
by Watson and Crick in 1953. And the key breakthrough was the discovery of the rules for the pairing of the bases that hold the double helix together. G with C, A with T. They are located on the opposite strands of the double helix. Now a footnote to that discovery is actually of central importance
to my discussion today. So fair warning, I'm gonna
talk a little chemistry because the details are so regulatory. Don't worry, you're
gonna get the gist of it. It turns out that the bases occur in two alternative chemicals forms. They differ by the
position of one hydrogen. Okay. So on the top form, you can see that the
oxygen up there in red does not have a hydrogen bound to it, but in the bottom form it does. Similarly, you'll see a
hydrogen above on that nitrogen. It's lacking down here. And this is called the keto form and the enol form of this basis. At first, Watson only knew
about this less common form, the enol form, and that stumped him. But he learned form the colleague that the keto form is
actually the more common form, and history was made. The important detail, however, is that these two different forms, they bond with different bases. Now only very recently has been possible to capture and measure the transition between
the two forms in DNA, and that revealed
something very important. The enol form is fleeting. It's flickering back and forth. Enol, keto, enol, keto. But the enol form last
only 1/1,000 of a second before flipping to the keto form. You might say, "Well, so what?" Well, the so what is if that happens where
the DNA is being copied and the copying machinery is passing by, moving at about 1,000 bases per second, if it just happens by chance to pass when the enol form is present, well, the wrong base gets inserted, and that creates a mutation. So that flickering is random, and it's just a matter of chance of whether that DNA is
being copied at that moment. So this is the process of random mutation. It's fundamentally what's happening. And what does it tell us? It tells us the event
at the root of mutation is an inescapable fundamental
matter of physics, this quantum transition
between chemical states, a little chance shape
shift at the atomic level. And that tells us that mutation is a feature, not a bug in DNA. In every organism, in every cell, whenever DNA is copied, changes will occur because of
the intrinsic characteristics of the very basis that endowed
DNA with its properties. Change, evolution, it's
unavoidable, inevitable. Now of course because every
specie's DNA is different because of this process, every individual DNA is different, it's changed in this way. This tells us that chance is
the source of all innovation, all beauty, all diversity
in a living world. That's pretty hard to imagine, isn't it? How can change generate everything we see in a living world? Well, that's a long story, but let me just show you one example, one example of how chance invents. And speaking of beauty,
get a load of this guy. Okay, the most important thing about the Antarctic eelpout
is not how it looks, but where it lives. It lives in waters that are very cold, about minutes 1.8 degrees Celsius, below the freezing point of fresh water, lives in the Antarctic Ocean. And the main enemies
of fish in these waters is not so much the cold, but ice. The water contains small ice crystals that if they get into the
fish through its gills or get swallowed, that'll nucleate the formation
of larger ice crystals and bam, they're fish sticks. It would freeze the animals were it not for a key invention, and that invention is antifreeze. Eelpout blood does not
freeze until it reaches about minus 2.1 degrees Celsius,
colder than the ocean. The reason being that it's
chock-full of proteins that works as antifreeze. The antifreeze binds to small ice crystals and prevents them from growing larger, and it lowers the temperature at which those ice crystals can then grow. Now the really neat part of this story is that we can track the origin of the genetic code for antifreeze, how it evolved from an
entirely different gene, which gives us a forensic trail of how this invention arose, and it shows how chance
mutation is an inventor. Now a key clue came when it was noticed that the antifreeze protein
bore an uncanny resemblance to a section of another proud
protein found in other fish, in fact, in all sorts of other animals. The protein is an enzyme called SAS that's involved in the
making of a specific sugar. We're not gonna get into those details. The antifreeze sequence is very similar to a short sequence at the end of SAS over there at the tail end. Now the reason for the strong resemblance was deciphered by some expert sleuthing through the DNA of
eelpouts and other fish. And that detective work revealed that the antifreeze gene evolves from a chunk of the SAS gene. A mutation deleted really sort
of the core, the SAS gene, leaving behind the part that
had some ice binding activity. That remaining chunk encoded
a protein that on its own could bind to ice crystals, and that was the genesis of
the first antifreeze gene. The eelpouts ancestors then ran or rather swam with this invention, and made many copies
of the antifreeze gene, expanding it to more than 30 copies, which enables the fish to
make a lot of antifreeze. So if you look alone in genome, a lot of the chromosome of the eelpout, you'll see these other genes
just like other fish have, and there's, boom, this
battery of antifreeze genes. It's a telltale sign that
it's a peculiar adaptation to where it lives. The eelpout has over
30 copies of this gene, all tandemly arrayed. And that tandem arrangement tells us there was another
mutation mechanism at work that we know quite well, that duplicates individual
or blocks of genes. Now I could show many more examples of the creativity of mutations. I'll spare you and let
this one make the point that mutation, this
chance, is the inventor. And what this means is, as
you look around the world, that we live in a world of
mistakes governed by chance. Genetic accidents occur at random. They change genes without regard to the potential consequences. Now the eventual fate of those mutations, well that depends on
external circumstances, in a sieving process we
call natural selection. Fair to ask then, what determines those
external circumstances. So let's look at the eelpout example. The most relevant thing about the eelpout is the coldness of the Antarctic Ocean. So we ask, how and why did the Antarctic
Ocean become so cold? The answer involves tectonics. You may know that the
Earth's oceans and continents are on tectonic plates that move around the globe very slowly and have moved over time. Now with respect to the Antarctic, a couple plates are most
relevant to becoming cold, and that involves the former joining of the South American
and Antarctic continents that existed or were joined
at least 65 million years ago. And the position of the
Indian subcontinent, which 65 million years
ago was below the equator, whereas today it's now up in Asia. It was that collision of
the Indian subcontinent that triggered global cooling and glaciation of the Antarctic. And the separation of
Antarctic from South America isolated the southern ocean and led to cooler currents
circulating the continent. Okay, so I'm talking about tectonics, but then you might ask, and why did these plates
move in the way they did? Well, the movements of these plates has to do with their size, their shape, and their speed is determined
very much by their thickness. So way do these plates
move the way they did? Well, they were parts
of a super continent, Gondwanaland, 140 million
years ago that broke up. And from what we can tell, it broke up much like
a kitchen plate breaks when it hits the floor. It broke into random pieces. Some of these pieces were
larger, some were smaller. The smaller pieces like
the Indian subcontinent moved more quickly, and the
slammed into other continents. So what does that tell us? The size, shape, and speed of these plates is a matter of chance? So what that tells us
is that chance invents. This internal mechanism
based on DNA is the inventor, and the fate of that
invention depends upon external circumstances shaped by chance. We're long, long way way from providence, and I don't mean the
capital of Rhode Island. It is astonishing that blind chance is the source of all novelty,
diversity, and beauty in the living world. I hope that you are awestruck that what an asteroid,
sliding tectonic plates, and a flicker polymer of
just four bases have wrought. But our chance-driven existence also poses the unsettling quandary that we don't live in the
best of all possible worlds, just our world. And this view of course
shatters traditional beliefs about cause and effect in our world. Those beliefs are
represented, for example, by this book and quote
from theologian R.C. Sproul who categorically rejects the existence of chance
in his book "Not a Chance: The Myth of Chance in Modern
Science and Cosmology." Sproul says it's not
necessary for chance to rule in order to supplant God. Indeed, chance requires
little authority at all if it is to depose God. All it needs to do the job is to exist. The mere existence of chance is enough to rip God
from his cosmic throne. Chance does not need to rule. It does not need to be sovereign. If it exists as a mere
impotent, humble servant, it leaves God not only out
of date, but out of a job. All right, so according to Sproul, chance puts God out of a job, or at least many of the jobs we've traditionally
assigned to him or her. God is not in the conception business choosing the winning sperm and egg, nor the genetic engineering business designing creatures' DNA and traits, nor the weather-making business, nor the cancer business, nor, as it turns out,
the pandemic business. Remember that piece of
code I showed you before about how much difference
one typo can make? Well, now I'll reveal to
you that the original text was nine letters I'm showing you is a small part of a virus called a Simian Immunodeficiency Virus that infects, for example, chimpanzees. And that the altered
text, without one typo, is the corresponding part of the human immunodeficiency
virus, the HIV virus. What we know about that change is that that mutation leading from M to R enables chimpanzee virus to infect humans, and that has occurred by accident at least three separate times
and trigger the AIDS pandemic. What a difference one typo can make. So if not theologians, who do we turn to to think about chance
and its implications? So I choose Novelist Kurt Vonnegut. Now Vonnegut wrote a lot about
our accident-driven world, and our struggle for meaning
in many of his works. And I wanna share with
you one particular story that comes from his
semiautobiographical novel, "Slapstick." He explains that his sister Alice was dying of cancer at the age of 41, and he and his brother went to visit her on what turned out to be
the last day of her life. He wrote, "Hers would have been an
unremarkable death statistically, if it were not for one
detail, which is this. Her healthy husband, James, Carmalt Adams, the editor editor of a trade
journal for purchasing agents, which he put together in
a cubicle on Wall Street, had died two mornings before, on The Brokers' Special, the only train in American
railroading history to hurl itself off a open drawbridge." Think of that. This really happened. Now a great humorist concocted many fantastic scenarios in his books, but this really did
happen just as he said. The train plunged off an open draw bridge, killing 48 people, including
Vonnegut's brother-in-law. Now he and his brother decided they would keep this information
from their sister Alice because she of course concerned about the future for her children. They had four children together. But another patient told
Alice about the accident. She read the newspaper and saw her husband among the list of victims. And her response to that? Vonnegut writes, "Since
Alice had never received any religious instruction, and since she had led a blameless life, she never thought of her awful luck as being anything but
accidents in a very busy place. Good for her." Accidents in a very busy place indeed. We now know that we are all here, both collectively and individually through a series of accidents, cosmological, geological,
and biological accidents. Vonnegut's books help me to realize that, next to scientists, the one group of people
that seemed least inclined to think everything happens for a reason, rather than blind chance
governs the world, are humorists and comedians. So many present day
comedians, Seth MacFarlane, Eric Idle, Bill Maher, Ricky Gervais, Sarah Silverman, and many more. And late greats from Mark Twain, to Vonnegut, to George Carlin have rejected traditional
beliefs about cause in the world. So many very funny people in
fact that it made me wonder, why is this so? What do scientists and
comedians have in common? Why are comedians drawn
towards such subjects? I reached out to several, some of whom kindly
took the time to reply, and I'll leave that conversation for those who wanna read the book. But I'm gonna close today
with a couple of gems from two comedians. The first comes from Ricky Gervais who told "60 Minutes" the following. "It always comes back to us. Why are we here? Well, we just happen to be here. We couldn't choose it. We're not special. We're just lucky, and this is a holiday. We didn't exist for 14 1/2 billion years. Then we got 80 or 90 years if we're luck, and then we'll never exist again. So we should make the most of it."
