Introduction

> Studying biology on Earth is unique and fundamental; it's the only place to truly understand the rules of selection that led to the diversity of life we see. Evolution and biology are key to unraveling how life has utilized the vast sequence space available in chemistry.

> As an astrobiologist, delving into the essential biological attributes of life, I am constantly reminded of the profound connection between the history of our planet and the emergence of life.

History of life on Earth

> The phylogenetic tree of life is a profound representation of the interconnectedness of all living beings, illustrating that "the tree starts at a common ancestor." It’s exhilarating to think about how we can study the present-day organisms at the branches and gradually reverse engineer back to understand our ancient roots.

> Delving into the origins of life is incredibly captivating; the "fun stuff" lies in exploring the early single-celled organisms and the biological innovations that shaped our planet. We’re working with limited fossil records, yet through a combination of geology and biology, we can piece together an intricate history that stretches back billions of years.

Origin of life

> My work focuses on utilizing bacteria to explore early life and evolutionary innovations, particularly using organisms like cyanobacteria and E. coli. The ability to engineer these bacteria allows us to poke at the DNA and study its mechanisms, especially in areas like nitrogen fixation, which is crucial for life on Earth.

> Nitrogen fixation is fundamental because it converts atmospheric nitrogen into a usable form for cells. This process is exclusively performed by nitrogenase, a specific enzyme. Without this biochemical innovation from ancient microbes, life as we know it wouldn't exist.

> The translation machinery within cells is a highly complex and unique system that reads RNA sequences and translates them into functional proteins. It's like a sophisticated chemical and computational system simultaneously acting as an enzyme, processor, and biological machine. It plays a pivotal role in the baseline functioning of life.

> Philosophically, the translation machinery's ability to convert information into function showcases a beautiful interplay of chemistry, computation, and biology, offering a glimpse into the robustness and resilience of life's molecular foundations. This system is not just a functional necessity but an evolutionary marvel.

Genetic language of life

> When looking at the alphabet of life, it's fascinating how all life starts with the same code, with the start being consistent across different organisms. This uniformity in the genetic code is a core element in understanding the origin and evolution of life.

> Exploring the language of life through the four letters that compose the genetic code, we can track the evolution of life on Earth from a molecular perspective. Despite the complexity, this genetic language evolved naturally, reflecting a highly optimized chemical and informational code shaped by evolution.

> The intricate mechanism of translation, essential for cellular function, highlights the importance of understanding how errors can affect the entire system. The evolutionary processes shaping this genetic code and the resilience to errors remain a significant challenge in biology, representing a crucial yet enigmatic aspect of life's origins.

Life and energy

> Life fundamentally revolves around two key processes: "translation and metabolism," where translation is highly dynamic, repetitive, and essential for processing information. It's this intricate relationship that defines how life maintains its energy efficiency and complexity.

> The definition of life is inherently fluid, not a strict binary. As I reflect, “we know it when we see it," and it's more about recognizing dynamic patterns rather than confining life to a rigid structure; this flexibility in defining life is crucial, especially when contemplating extraterrestrial forms.

> Memory plays an integral role in life, as it allows systems to build upon previous solutions over billions of years. Life isn't merely about "chemistry sampling" in the moment; it’s about maintaining a history that fosters exploration and adaptation within an ever-evolving landscape of possibilities.

Ancient DNA

> Evolution shows a remarkable inability to multitask efficiently, particularly when confronted with significant changes. Even when we introduced variations in the elongation process of translation, bacteria responded by focusing on fixing that specific issue rather than optimizing multiple systems simultaneously. This highlights a fundamental limitation in the adaptive process.

> When we swapped a modern elongation factor with an ancestral one, the bacteria exhibited slower growth and were less healthy. Observing how they adapt provided invaluable insights. For example, the more evolutionarily distant the introduced variation, the harsher the impact on the cell, which then led to more pronounced adaptive responses – though never fully recovering to optimal function.

> Despite isolating various proteins involved in translation and examining their evolutionary adaptations, we discovered that only one module – the most affected one – was prioritized for repair, stalling overall optimization. This experiment underscores a seemingly lazy approach in evolutionary mechanisms: tackle the most immediate, apparent problem first and let other issues persist, much like only cleaning the messiest part of a cluttered closet.

Evolution

> Evolution has seen critical singular events that shaped life on Earth, including the emergence of translation, cyanobacteria, aerobic photosynthesis, eukaryotes, and plants. These rare innovations occurred over billions of years, setting the course for life's development.

> Skepticism towards evolution often stems from a broader distrust of science, but focusing on the remarkable leaps in evolution, such as the inventions of eukaryotes, photosynthesis, and human intelligence, sheds light on the mysteries that science is still uncovering. It prompts us to consider the possibility of deeper, undiscovered truths in the future.

> Reflecting on the origins of life leads to a humbling realization of our place in the grand scheme of nature. Understanding the complexity and history of life on Earth underscores the importance of appreciating and protecting our planet, as we strive to uncover the deep questions surrounding our existence through the lens of chemistry, physics, and biology.

Alien life

> The universe is full of possibilities when it comes to life; it's fascinating to consider whether we are the only conscious beings or if life thrives elsewhere. "I think there is life everywhere out there," which invites a profound exploration of how life forms respond to their unique environments and challenges.

> Understanding the origin of life is crucial, not just for our planet but potentially for others as well. We must focus on "what is possible" rather than merely attempting to replicate Earth's processes, as the complexities of life could reveal themselves in myriad forms across different planets.

> Our approach to potentially seeding life elsewhere needs to be respectful and rooted in genuine understanding. It’s not about making planets Earth-like, but rather "empowering" those places by studying their chemistry and environments before making any suggestions for life initiation.

> Ultimately, it's essential to maintain optimism, especially in the face of suffering that life inevitably brings. "We cannot just have fear of suffering stopping us from doing marvelous things," and as we confront ethical dilemmas about life’s propagation, we should carry hope for future possibilities and the beauty that can arise from our understanding of life.

Panspermia

> Exploring the origins of life often brings us to the intriguing concept of panspermia, but I prefer to think in terms of "protospermia," which considers the spread of chemical ingredients rather than intact life forms. The idea is that these chemical building blocks could act as a sort of 'fertilizer', compatible with the planetary body, thus setting the stage for life organically originating there, as opposed to importing fully-formed life or cells.

> The debate around panspermia can be inspiring, but it complicates scientific inquiry by shifting the problem of life's origin out of our immediate experimental reach. Thus, focusing on the chemistry and physics here on Earth feels more practical. By understanding the local conditions deeply, we stand a better chance to piece together the puzzle of life's origins, without attributing unexplained failures to extraterrestrial influences. This methodical approach keeps us grounded in measurable, experimental science.

Restarting life on Earth

> When considering the rerun of Earth's history, I wonder about the role of environmental conditions in evolutionary processes. Are geological events and environmental conditions repeating in the same way each time, or is there more randomness at play? The timing, frequency, and intensity of these events could significantly impact the course of evolution.

> Life's adaptations and innovations do not always align with the most abundant resources in an environment. For example, nitrogen-fixing metabolisms show a preference for certain elements despite their scarcity in ancient oceans. It's not a straightforward relationship of "you are what you eat," highlighting the complexity of biological evolution.

> The molecular tricks and innovations that shaped life on Earth may have been pivotal in defining the forms and functionalities of different organisms. These molecular events at the very core of life's processes could have been instrumental in generating the diversity and complexity we see today, sparking intriguing questions about the inevitability of certain biological traits and structures.

Where ideas come from

> Ideas are an ever-flowing river; there are good and bad, exciting and mundane. For me, the essence lies in being open to risk, accepting that some ventures will fail. “If you are disappointed that your idea didn’t work, then it wasn’t a risk,” and embracing that uncertainty is how true creativity flourishes.

> Additionally, the art of letting go is critical in both science and life. "If something isn’t working, you should wrap it up and move on." It’s vital not to fall in love with failures, as clinging to them can hinder progress. Cultivating patience and trusting your instincts, rather than chasing fleeting approval, fosters genuine impact over time.

Science and language

> Reflecting on the intricacies of language and science, I emphasized that translating scientific work across boundaries is more than a simple exchange of words — it’s about capturing the human pursuit of knowledge. Understanding different languages and cultures adds depth and diversity to our perspective, much like incorporating various scientific disciplines creates a rich, innovative blend rather than just a mix.

> My roots in Istanbul, a city that straddles two continents, instilled in me deep values of human connection and generosity. Growing up, the cultural emphasis on community and ensuring no one goes hungry left a lasting impact on me, reinforcing the importance of empathy and support in all my endeavors, both scientific and personal.

Love

> Love is a skill that can be learned and cultivated, even if one has not experienced it firsthand. "It's something that you can learn... give yourself the thing that wasn't given to you and then ultimately give it to others."

> Learning to love is a fundamental part of the human experience. "There is no excuse to not learning to love... It is a very sad thing if any one of us passes this planet without knowing what love is."

Advice to young people

> Life’s opportunities are abundant, but they aren’t always evenly distributed. “There’s whole areas of this Earth that have so much brilliance but unfortunately so little opportunity." I’ve seen this firsthand, especially in places like Bosnia where young people are eager to rise from the challenges of their past, and it moves me to see them embrace the chance to be the first in their families to explore new horizons.

> It's crucial for young people to recognize that “their voice matters” and that they have the power to change the narrative in their lives. It starts with trusting themselves and respecting who they are. “You don’t need to be defined by what others see in you.” True growth comes from within, and by nurturing self-love and respect, they can cultivate the connections and support they need to thrive.

Meaning of life

> "Beauty in the universe exists because we choose to see it that way." This encapsulates my belief that beauty and meaning are subjective, and our capacity to find beauty in the world is a testament to human perception rather than an inherent quality of nature.

> "Leave it as you want to find it." This piece of wisdom from Turkish bathrooms resonates deeply with me, suggesting that the meaning of life can be found in the simple act of maintaining the world in a way that reflects how we wish to encounter it, embodying responsibility and respect for what we leave behind.