Revolutionary Science During My Lifetime

Lockwood-Mathews Mansion, Norwalk CT.

During my 81 years, many scientific discoveries have struck me as remarkable. This is my personal list, and doesn’t purport to identify all that are truly revolutionary, only those that dramatically changed how I think about the world. Typically, I would hear about these discoveries through Scientific American, which I have read faithfully for the last 65 years, and through books aimed at the informed layperson. Sometimes I hear about them directly from scientists; most often, they cross my attention two or more years after they appear in the scientific literature.

Sadly, magazines that try to popularize science are caught in the crossfire between the growing complexity of significant discoveries, the right-wing attack on science in general and evolution in particular, competition from visual media, lack of training among scientists on presenting material to the public, and the reduced attention span of their potential readership. The response of Scientific American is that articles are often written by science writers instead of the scientists themselves, excess coverage is given of “sexy” subjects such as extraterrestrial planets and cosmology, and complex subjects are dumbed down to the point of incomprehensibility. I have almost given up on Scientific American.

New Tools

Throughout my life, the technology for making scientific observations has developed at an accelerating pace. In the typical case, theoretical advances follow breakthroughs in the sensitivity of scientific tools: more powerful telescopes and microscopes, computers and electronics, spacecraft, rapid gene sequencing, finer instruments, more powerful particle accelerators, etc. There is a dialectic between theory and the particular tools that are developed: theory informs their design, while new data uncovered by the tools suggests new theories.

Plate Tectonics

I recall giving a report in an ROTC class on Alfred Wegener’s proposal that continents drifted. Despite the extensive evidence he presented supporting his ideas, the geology establishment dismissed his ideas because they couldn’t think of any physical mechanism that could move continents. However, various theorists were gradually assembling data that would coalesce by 1965 into a coherent theory of plate tectonics. It was a beautiful, comprehensive theory that, like Darwin’s theory of evolution by natural selection, made sense out of an entire scientific discipline. It had special meaning for me because the Alvin submersible that explored the Mid-Atlantic Ridge to help verify the theory was invented by and named for a friend and neighbor, Allyn Vine.

DNA and the Genetic Code

In 1953, during my first semester at UC Berkeley, I lived in a dormitory. One evening we were treated to an informal talk by the famous scientist George Gamow (sitting on one of the dining tables), who was closely following the race between the team of Watson, Crick, Franklin and Wilkins at Cambridge and Linus Pauling at Caltech. At that moment, Pauling had settled on a triple-helix structure for DNA, which Gamow explained to us. It was only a few weeks later that Watson and Crick, thanks to the exquisite X-Ray crystallographic images produced by Rosalind Franklin, came up with their theory, which they quickly published in their famous paper on the double-helix.

Later, in 1964, Crick correctly determined that triplets of nucleotide bases in DNA coded for specific amino acids, which were then transcribed by RNA. Like the double-helix, this discovery was accessible to the general reader, and the results were widely published.

Human Evolution

Year after year new fossils are discovered, and gene sequencing has resolved many issues, while raising new ones. Recently it was determined that the ancestors of modern humans left Africa about 70,000 years ago, and had made it to Australia by 50,000 years ago. They had a sophisticated culture, including art and very likely fully developed language.

Another surprise was the fossil hominin Ardipithecus ramidus (nicknamed “Ardi”). Hominins are those species of ape that branched off from chimpanzees about six or seven million years ago and include humans. Ardi lived about 4.4 million years ago and was a tree-dweller that also walked upright. Upright stance frees the arms to attack prey with projectiles, a key advantage that led to the dominance of hominins – in my view the key advantage.

The discovery of Homo floresiensis, nicknamed the Hobbit, was another surprise. Only  three and a half feet high and descended from some other line of hominin, lived until the arrival of modern humans about 50,000 years ago (megafauna also disappeared from the island after humans arrived, as usual).

The timing and interdependence of various key human traits (bipedalism, large brains, opposable thumbs, control of fire, hairlessness, language, etc.) is still far from settled. For example, was the control of fire (increasing the amount of protein in the diet) a necessary condition for a larger brain? When and how did language evolve?

Cognitive Science

The discovery that our prized rationality has little control over our behavior, and that the “self” is an artifact of our brains has had the effect of knocking humans almost completely off our pedestal. Granted that after the Copernican and Darwinian revolutions there wasn’t much of a pedestal left, we still could pretend we were the masters of reason. In parallel we have discovered that animal cognition is far more subtle and complex than we thought.

The Death of Progress

Science has extended lifespan and for the top tier of humans, making life fabulously safe and comfortable. But as we move into the Anthropocene (yet to become an officially sanctioned era) we are awakening to the fact that the dominance of humanity and our population explosion is a death-knell for vast numbers of organisms on the planet, and potentially for ourselves. Global warming, the Sixth Extinction, pollution, resource depletion and the threat of nuclear annihilation have forced us to re-evaluate what we mean by “progress,” since its normal implication of “improvement” increasingly is a source of irony. We had better make some major changes in how we live very soon. The alternative is unimaginable.

I am sure I have omitted a few discoveries that changed how I view reality, but this will do for the nonce.

“The Vital Question” by Nick Lane

Artist’s model, 2016

Occasionally a book comes along that completely transforms how you look at a subject, and this is one of them. Nick Lane is an English biochemist with a gift for writing about complex science for a lay readership. Readers vary in their background knowledge of a subject, and the science writer faces a tradeoff between reaching a broad audience on a superficial level and a smaller audience with some technical background. I think Lane has achieved the right balance, but to present his subject in enough detail to depict the tight logic supporting his findings and speculations, the balance was necessarily skewed toward the technical.

And what an amazing, intricately woven theory he presents! His argument is based on solid findings from a variety of scientific disciplines, extended by careful logic into testable hypotheses to form what is almost a biological theory of everything.

In an environment where genetics dominates both research and its popularization, Lane injects basic issues of physics and chemistry that in my experience as an avid science reader are seldom raised in writings about biology. Physics and chemistry seriously constrain the options available to support life, and from these constraints Lane derives a convincing story about the origin of life in general and complex life in particular.

In discussing how cells use nutrients to create the energy needed to sustain life processes, he brings to life the staggering complexity of the microscopic machines that do the job. In this essay, I will explain some terms and quote Lane’s vivid description.

Organic (carbon-containing) molecules in organisms can be classified as proteins, fatty acids, carbohydrates and nucleotides (such as DNA and RNA). One nucleotide, ATP (short for adenosine triphosphate) is a small molecule often referred to as the “molecular unit of currency” that provides the energy to drive cellular processes such as the synthesis of proteins and membranes, movement, cellular division, and transport of materials within a cell.

ATP stores its energy as mechanical stress in a chemical bond, and releases this energy when one of its three phosphate groups breaks free, relaxing the bond. Each cell “spends” on average a staggering ten million ATP molecules a second, and our 40 trillion cells spend our body weight of ATP every day. We only have about 6 grams of ATP molecules, so they must be recharged with energy every minute of so.

The cellular machinery that recharges ATP molecules is as universal as the genetic code, implying that it arose at the origin of life. The system is surprisingly complicated and counter-intuitive, which highly constrains the environmental conditions necessary for such a system to evolve. Discarding one proposal after another, Lane makes a convincing case that life began within the minute pores of alkaline hydrothermal vents, larger and cooler cousins of the more famous “black smokers” found by the submersible Alvin on the seafloor at spreading centers. Detail by detail, he traces the likely sequence of events that resulted in this universal power plant of life.

The centerpiece of the book is Lane’s proposal for resolving what he calls the “black hole” at the center of life’s evolution. The single-celled bacteria and their archaea cousins – prokaryotes – are the original life forms that evolved early in the history of the planet. While by any standard bacteria and archaea are soberingly complex, eukaryotes – protists, animals, plants, algae, fungi and yeasts – exceed them in size and complexity by many orders of magnitude.

The great puzzle is that in the fossil record, eukaryotes appear fully formed, around 1.5 billion years ago. Instead of the expected radiation of different kinds of eukaryotes, and of intermediate forms between prokaryotes and eukaryotes, there is one branch, one LECA (last eukaryotic common ancestor), seemingly fully formed like Athena from the head of Zeus, with all the complex machinery found in its descendants. Why did this happen?

Lynn Margulis established that mitochondria, the organelles in eukaryotes that contain the machinery for producing ATP, are descended from a bacteria that was somehow incorporated into an archaea as an “endosymbiont,” “endo” meaning inside (much later, a photosynthesizing cyanobacteria was incorporated into plants and algae as an endosymbiont, the chloroplast). Mitochondria have their own tiny genome that is passed down through mothers; perhaps you have heard of “mitochondrial Eve”, the mother of us all.

Lane proposes that the newly incorporated mitochondria rapidly transferred their DNA to their new host, causing havoc that was only averted successfully on one occasion. Endosymbiosis is extremely rare, and because of the conflict between the genomes of the host and the endosymbiont, most such natural experiments quickly lead to extinction. But plainly it worked for LECA or we wouldn’t be here. At the end of the book he describes a recently discovered bacterium with an endosymbiont, that appears to be developing complexity. Its extreme rarity demonstrates the difficulty for such collaborations to survive and evolve.

Mitochondria are the heroines of the book, and I will close with Lane’s description of an imaginary trip through a mitochondrion by an ATP-sized person:

Take a dizzying ride down into one of your cells, let’s say a heart muscle cell. Its rhythmic contractions are powered by ATP, which is flooding out from the many large mitochondria, the powerhouses of the cell. Shrink yourself down to the size of an ATP molecule, and zoom in through a large protein pore in the external membrane of a mitochondrion. We find ourselves in a confined space, like the engine room of a boat, packed with overheating protein machinery, stretching as far as the eye can see. The ground is bubbling with what look like little balls, which shoot out from the machines, appearing and disappearing in milliseconds. Protons! The whole space is dancing with the fleeting apparitions of protons, the positively charged nuclei of hydrogen atoms. No wonder you can barely see them! Sneak through one of those monstrous protein machines into the inner bastion, the matrix, and an extraordinary sight greets you. You are in a cavernous space, a dizzying vortex where fluid walls sweep past you in all directions, all jammed with gigantic clanking and spinning machines. Watch your head! These vast protein complexes are sunk deeply into the walls, and move around sluggishly as if submerged in the sea. But their parts move at amazing speed. Some sweep back and forth, too fast for the eye to see, like the pistons of a stream engine. Others spin on their axis, threatening to detach and fly off at any moment, driven by pirouetting crankshafts. Tens of thousands of these crazy perpetual motion machines stretch off in all directions, whirring away, all sound and fury, signifying…what?

You are at the epicentre of the cell, the site of cellular respiration, deep within the mitochondria….

I hope you are inspired to explore this remarkable book.