Hello, my name is Chris Kempes.
I'm a physical biologist and professor at the Santa Fe Institute.
And welcome to this course on the Origins of Life.
How life originated is one of the most interesting, complicated,
difficult, and still open questions in modern science.
And throughout this course, we're gonna introduce you to why
it's such a tricky question.
And all the different ways that people are trying to solve this unanswered question.
Since the time of Darwin, we've come to understand how life
progresses, changes, diversifies, finds new niches, evolves greater complexity
and yet we still don't understand how to take that back to
the original formation and initiation and origin of life.
So, in saying that it's important to recognize that life lives on a spectrum.
And that spectrum goes from a completely abiotic world
all the way up to multicellular creatures like us, and entire societies.
And at some point along this trajectory, we have this transition to something
that we would call life.
And so how is it that we go from this abiotic world to a biotic world
understanding that this is all part of one evolutionary continuum.
So why is that question so challenging?
Well, one of the things that makes it challenging is that it requires
a lot of diverse types of knowledge to begin to understand
this process and to answer this question.
And so those types of knowledge draw from a variety of different disciplines.
Traditional disciplines.
So for example, we need to understand something about Earth science,
biology, chemistry, and physics and how all of these different concept areas
intersect with one another and help us to understand exactly what happened
when life first formed.
And throughout this course, we will introduce you to the main questions in
each of these concept areas and how they relate to the origins of life.
And we will also start to begin to paint a picture of where the intersection and
synthesis of these different concepts live hopefully moving towards a better theory
of how life started and evolved into greater complexity.
So within these concept areas, what are the main questions?
So if we take Earth science as a concept area, the main questions,
as they relate to the origin of life, tend to be things like
"what was the environment like during the time when life originated?"
So we understand that the early Earth was very different than the modern Earth.
And we need to understand something about what chemistry was possible then
and how that might come together to help life form in the first place.
Another question, is "in this early Earth, what was the diversity and complexity of
various micro-environments?"
So if we think about the early Earth, not only as a different average chemical
space than what we currently have, but also lots of different unique types of
micro-environments existing in this very different planetary environment, which of
those micro-environments were most likely to give us life in the first place or to
have the right type of chemical complexity to at least start down that trajectory
towards a living organism.
And then another very interesting question is "once you get life in the first place,
once you get early life, how does it and this geosphere, this environment,
start to coevolve?"
So we understand in the modern Earth, how life interacts with the overall planetary
system, we understand through lots of the history of life how life interacts,
has a large feedback with, and modifies the geological environment and the
geosphere. And the question is when life first started, "how did that--what did
that feedback look like and what did this coevolution--how did this coevolution
happen and how important was that for the specific trajectory that life took once
it was formed?"
From a biological perspective, the questions we're interested in are mostly
how do we take everything we know about modern life and try to look as far back in
time as we can? So how do we wind back the clock on modern life to understand what
early life might've looked like?
So this involves taking a lot of phylogenetic or genetic perspectives to
look back in time. It also asks--involves asking questions like "what does the
composition structure and function of modern life tell us about life's origin?"
Another way to say all of this is "which aspects of modern life are general and
which are arbitrary?"
So, what are the features that we see in modern life that are really essential to
life through any origin and trajectory and which are contingent on the particular
evolutionary history that we happened to have seen in--for more recent life.
Also in that vein, how do we take everything we know about modern
evolutionary theory and start to apply that to things like protolife which
might have a much less formal version of inheritence or genetics,
how can we use evolutionary theory to think about the simplest early life which
might be radically different but also is almost certainly undergoing some sort of
evolutionary process.
From a chemical perspective, our main interest is "how does life arise from the
huge space of chemical reactions and compounds?"
So we understand that chemistry gives us this really vast set of possibilities,
this really rich high-dimensional space, which is great for allowing something
like life to form but it makes it very complicated to understand exactly what
combinations and processes and trajectories are actually necessary or
were the ones that led to the life that we have.
Another question which relates back to Earth science is "what was early living
chemistry like? What was that-- how was that possible in early Earth? And how do
we start to define sort of living chemistry that isn't quite yet life?"
And then, a really interesting question is "how do we go from complicated chemistry
or complicated chemical environment to something that's even more complicated
and complex?" And that's the simplest cells.
So even the simplest cells have a set of chemistry and feedback and dynamics and
interconnections that is much more complicated than things that we see in the
environment and so how do we make that transition?
Finally, from a physical perspective, the questions we're interested in "are how do
physical constraints--for example, the laws of thermodynamics--start to constrain
or bound the possibilities for life?"
So how do we take everything we know about physics and use that to say what is
and isn't possible for life, especially as it first forms.
Another question is really to ask "what can we take from what we know about which
processes are easy and hard in physics, without any biology, to help us understand
what might've happened for life in the first place.
So for example, we understand that in purely physical systems, it's possible to
get very rich pattern formation and dynamics and so how much-- how important
are those sorts of naturally emergent-- occurring phenomena to thinking about the
first formation of life and how we start to apply some of those concepts of
emergence and simple pattern formation to interact with
how life began in the first place.
Another final question that physics-- or final set of ideas that physics can lend
to us is "how do we take everything we know about physical concepts, physical
laws and start to generalize those to use them in a biological way?"
So how do we port physical concepts over to biology in general and in particular,
how do we port those ideas over to the origins of life?
So, as you can see this is a very rich set of questions coming out of a variety
of concept spaces across a huge range of science and in this course we've gathered
people from this wide diversity of scientific perspectives to really layout
the details of each of these questions in specific ways and then bring those details
together in a way that we have a broader and more complete understanding of how
life might have formed in the first place.
And we certainly hope that you enjoy that trajectory and this course overall.
So, thank you.