In one of the most iconic scenes in Spanish cinema, from the film Amanece que no es poco (Dawn Breaks, Which Is No Small Thing), someone shouts: “Mayor, we are all contingent, but you are necessary!” More than 30 years ago, in a small office at the Polytechnic University of Catalonia, two doctoral students — one passionate about biology, the other about physics — began exchanging problems to draw the other into their respective fields. One of these problems stated that if life on Earth had followed its initial course, today there would be no humans, no animals, no plants, no complex life forms; only microbes. In that scenario, not everything could be left to chance; there had to be a necessary step, a decisive transition that no one had yet been able to define.
The two former students — Jordi Bascompte and Bartolo Luque — along with two physicists who later joined their collaboration, Fernando Ballesteros and Enrique Muro, have just been awarded the Cozzarelli Prize from the prestigious U.S. National Academy of Sciences. Their study was selected as the best biology paper of the year for identifying that crucial, non‑contingent step in the evolution of complex life.
The Cozzarelli Prize, created 20 years ago, recognizes the top research published annually across six scientific categories in the Academy’s journal. This is only the second time the award has gone to researchers from Spain.
“It’s one of the most beautiful articles of my career,” Bacompte, a 59-year-old Catalan biologist who works at the University of Zurich in Switzerland, tells EL PAÍS. “The problem lies at the heart of the evolution of life, but the solution was only possible through physics and computing,” he adds.
“Frontier science, where different fields intersect, is very fruitful, but unfortunately, not many people are doing it,” notes Fernando Ballesteros, an astrophysicist at the University of Valencia specializing in the study of extrasolar planets.
Both Ballesteros and Bacompte say that their work is also a rare example of “slow science”: roughly 33 years passed between the initial question posed in that small office back in 1993 and the publication of the final solution.
“The theoretical tools we use have been accumulating over time, and it seems that they have all converged in the same place, because the data have turned out perfectly,” adds Bartolo Luque, a 59-year-old from Barcelona and professor of applied mathematics at the Polytechnic University of Madrid.
“For half of Earth’s history, evolution was at a dead end,” Bacompte continues. The first living beings were microbes that appeared some 3.5 billion years ago. These creatures invented respiration and the ability to convert light into food — photosynthesis — but their increasing complexity depended on their ability to manufacture ever-longer proteins, using the recipe written in their DNA. The possibilities of that code were finite, and there came a moment when it was no longer possible to lengthen those molecules any further. “They hit a wall that prevented the complexity of biological systems,” Bacompte explains.
The solution came in two steps. First, as biologist Lynn Margulis proposed — and was ridiculed for by many of her colleagues — one microbe assimilated another and, instead of digesting it, accepted it as a new organ that provided it with energy. This was the origin of the hundreds of mitochondria that today exist in each of our cells and allow us to obtain the energy needed to live.
But the problem of genetic complexity continued, and this is where the arsenal of mathematics, physics, and computing comes in. The award-winning work of these four scientists describes that there was an “algorithmic phase transition” that allowed, for example, a single gene to produce several proteins, and for complexity to continue increasing.
This capacity arose in non-coding DNA sequences, which did not contain the recipe for making proteins. Without these long genetic sequences — the so-called junk DNA — which are capable of multiplying throughout the genome, the leap, the revolution, could not have occurred 1 billion years after the appearance of life. This revolution made possible the later emergence of complex cells and of multicellular organisms: fungi, plants, and animals, including humans.
Evolutionary biologist Nick Lane calls this the black hole of biology: why do we see a radical leap between simple and complex life forms with nothing in between? “What our work shows,” Bascompte points out, “is that there can’t be intermediate forms, because that change, that transition, has to happen, as physics predicts, with a phase transition. And that implies rapid and abrupt change.”
These four scientists have also received a wave of criticism from experts in population genetics, Luque acknowledges. “All order emerges from chance and evolution, the basis of Darwin’s theory,” he explains.
The evolutionary biologist Stephen Jay Gould illustrated this with a thought experiment: if we could rewind the tape of life to 541 million years ago and press play again, humans — and many other mammals — would probably not be here.
Evolution is a process of trial and error that is completely random. By contrast, the new work may come as a shock because it is deterministic, Luque warns.
“Once evolution achieved the first, simplest cell, already with a self-regulating genetic system, the physics of the problem determined that, exactly 1 billion years later, something truly new would appear. We didn’t know exactly what it would be, but we did know it would be an algorithmic transition. It’s surprising, but that’s what the data say,” he concludes.
Sign up for our weekly newsletter to get more English-language news coverage from EL PAÍS USA Edition
