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  • Writer's pictureEdgar Chicurel H

Peak Evolution


Life has been evolving on our planet for 3.5 billion years. At long last, humans have arrived. Are we the peak of evolution?


It is common to think of evolution as a slow but deliberate process that has taken life, step by generational step, from the first relatively simple unicellular organisms to the pinnacle of complexity: self-aware beings capable of unrivaled dominance, abstract thought, artistic sensibility, limitless technological achievements and even a sense of humor. From our human perspective, it would seem that the “goal” of evolution was never creating a beetle with a horn, a gigantic dinosaur or a really cool owl. These were simply wonderful offshoots along the path. Dinosaurs and mammoths were big, but they didn't survive. Some animals fly, some have sonar, some see more colors, but evolution wasn't going to stop there. The "goal", we might surmise, was intelligence.


But was the process of evolution always leading, inevitably to intelligence? How do you even define a "goal" in evolution? Let's examine our very human-centric interpretation of evolution and try to make sense of these ideas.


We think of evolution as a progression, in which organisms become better adapted to their environments through genetic mutation and selection. This concept was put into mathematical and graphic terms by the extraordinary American geneticist Sewall Wright. Wright, brilliant from an early age, made major contributions in genetics, evolution, and statistical analysis writing on these and other subjects beginning amazingly at the age of 7, in 1887 all the way to the age of 98 in 1988 spanning a total of 92 years! In 1932 Wright proposed a way to study evolution by means of an adaptive or fitness landscape. Imagine a landscape with mountains and valleys in which genotypes vary as you move in any horizontal direction and the elevation is correlated with fitness. As a species evolves it will logically move toward higher elevations until it finds a peak where it will stay. Moving in any direction away from the peak will result in decreased fitness, so, if environmental conditions do not vary it will stay there. Giraffes evolved from creatures with shorter necks, acquiring an anatomy in which the longer neck size is ideally suited for its environment. A longer neck however, comes at a price, requiring greater energy for pumping blood , for example. At some point a longer neck gave no additional net fitness advantage and an evolutionary peak was achieved. But some fitness peaks cannot be reached through gradual change such as a slowly increasing neck length. Doctor and biologist Stuart Kauffman asks the question of how an organism finds peaks when a landscape is rugged, that is, has many mountains. For this, he introduces the NK Model, which allows "tuning" of a landscape's ruggedness, and explores how and in what cases a species can jump from a local peak where it has arrived through the process of gradual evolution to a higher peak, which will require making large genetic changes so as not to fall into a fitness valley, where it will be less likely to thrive and , subsequently reproduce. One way to do this is through variations in mutations in master genes known as Homeobox genes which can create substantial change in an organism from one generation to another, thus allowing evolution to explore areas of the fitness landscape that may be far from the local peak an organism finds itself in.


Flying is an interesting example of a fitness peak that is not so readily achieved for vertebrates. In a world without vertebrates capable of flight, the ability to fly is clearly advantageous. Flight offers great benefits in escaping predators as well as finding food. In other words, attaining the ability of flight would quickly put a vertebrate in a position where it could thrive, metaphorically and literally rising above its competitors. But the intermediate steps to developing wings and the necessary muscles for powered flight are adaptations that may actually take a species down the fitness slope.


It is believed that the first vertebrates to achieve flight were the Pterosaurs, 220 million years ago in Pangea before the continents drifted apart. Vertebrates had already invaded the land a very long time before, but had not flown. Most of them then died off during the Permean Triassic extinction which wiped out about 70% of all terrestrial vertebrates. So, millions of years into the evolution of land vertebrates, imagine one of the first pterosaur ancestors that was well on the way to achieving flight but was still a few generations away. Since evolutionary changes from generation to generation are very slight, we can assume this creature probably had some sort of wing membrane covering slender arms and strong shoulder muscles, almost enough to fly. Almost, but not quite. These adaptations were probably not very useful at this point. In fact, one would imagine that in a competitive environment they would actually be a hindrance: wing membranes and powerful pre-flight muscles create additional energy demands but what are they useful for? Perhaps gliding among tree branches. Perhaps. But many proto-flyers probably never made the last generational step and just lost these adaptations as mutations further developing the wings were never successful. It took millions of years, plus an extinction event that more or less re-set land vertebrate evolution but finally, flying vertebrates did evolve. In fact, amazingly, they evolved in different evolutionary branches which means that the adaptation from a non-flying to a flying generation was achieved more than once. How can a vertebrate go from non-flying to flying over generations of evolution with the constraint of not falling too far down the fitness landscape so as to become unviable? Evolution, through the mechanics that Kauffman explains, is able to find fitness peaks which require substantial adaptations on various biological fronts, traversing the precarious path of dips in fitness on its way. What about intelligence?


Let’s consider now the ability of a species to build a broad variety of artifacts such as weapons, clothing, vehicles and houses, in other words,advanced technological ability. Clearly this ability provides great fitness benefits. Of course, we only have one example of a species, or to be more precise a particular branch of primates that has acquired these capabilities. Not to put too fine a point on it, we can pretty much agree that humans at this point are the dominant species on the planet, and this thanks to our technological capabilities.

But if flight was a difficult fitness peak for vertebrates to climb, that is to say, it took millions of years and probably many failed attempts, advanced technological capability took even longer. This may seem counter-intuitive, as the fitness road to technological capability seems more direct than the road to flying. But is it?

To be technologically capable a species needs to have some means to manipulate and modify objects and, of course, a brain that can understand the concept and use of tools. It would seem, from our human-centric perspective that as vertebrates evolved one of the first things that would provide fitness advantages would be to improve intelligence and the ability to manipulate objects. Not only that, but it would seem that every step in that direction would hold a fitness benefit and evolution would simply take this apparently “easy” road all the way to its limits. Somehow though, this argument is not quite right. Our human-centric perspective may be to blame.


The first vertebrates inhabited the seas, and technological capability was never achieved. Of course, making things underwater poses additional challenges to making them on land. But the first wave of land vertebrates that appeared 400 million years ago and then were replaced by the dinosaurs did not achieve any sort of advanced technological capability either. Neither did the dinosaurs. From our human point of view this is truly stunning! For millions of years creatures roamed the planet, evolved into the most astoundingly diverse shapes and sizes, developed countless abilities, including the ability to fly, but no technology. Along the way there obviously were many species that discovered some naturally occurring objects could be used as tools of some sort, for example twigs for nests, or rocks for cracking open things to eat. But these abilities stopped there. The benefits of slowly improving on these abilities were not worth the evolutionary trouble so to speak. It took a second mass extinction re-set, an asteroid hitting the earth 66 million years ago that stopped photosynthesis and ended all non-avian dinosaurs to finally pave the way for technological ability. But even after this event that gave mammals the opportunity to thrive, it took a mind boggling amount of evolutionary roads and developments spanning over 65 million more years for technological capability to finally appear and then lead to dominance.


Flying is a fitness peak that is very difficult to achieve, however it is unquestionably a useful ability, and has evolved separately in bats, birds, dinosaurs and insects and persisted through multiple extinction events. Technological capability is apparently even more difficult to achieve and has only arisen once, for, so far, a tiny period of time. But technological capability is superior in its value even to flight, in fact, in a sense, vertebrate flight evolved again very recently for a fifth time in technology endowed humans.


Advanced technological capability is undoubtedly a fitness peak, but it is a very difficult peak to attain. On Earth, not only did it take a vast amount of time, it also depended on a very rare mass extinction event. Was it a fluke? Or does life always find the road to this fitness peak within the generally long span of a planet’s existence? As with so many of the Big Questions, we have only one case to study, one single data point on which to base our theories. If the earth were to be born again would evolution again, slowly but inevitably produce a technologically capable species?


There is, obviously no definitive answer to that question, but it can be posed in a different form. Somewhere in the galaxy on another earth-like planet will evolution produce intelligence? The famous Drake equation proposes a method for calculating the number of intelligent life forms we could communicate with on other planets in our galaxy and takes into account a number of factors. One of them f(i) is defined as the fraction of planets with life that actually go on to develop intelligent life. If intelligence is the inevitable outcome of evolution, the factor is 1. In fact, when the equation was first presented by Drake in 1961 f(i) was estimated to be 1. But, as we have seen, intelligence on our planet did not come quickly and may have been contingent on a mass extinction event. Is intelligence really an inevitable outcome of biological evolution? And, if it is, is it the culmination of evolution?


We can safely say that technological capability is extremely powerful, but also extremely hard to achieve. Going back to the Drake equation, fixing the value for f(i) at 1 seems to be overly optimistic. Couldn’t it just as well be, say, 0.1 or 0.0000001?


But the question that now seems even more interesting is, where does evolution go next? There are two ways to look at this: First is to continue thinking of evolution as the process by which genes mutate, nature selects for the fittest genotypes and new fitness peaks arise. This is interesting to consider on large timescales. What will the ecosystems and dominant life forms be like in a million or ten million years? Will technological capability persist? Or will it be snuffed out to give way to a more solid peak, massive dinosaur type creatures who already proved they could survive essentially forever barring a catastrophic event altering their habitat. Or maybe, if humans disappear, a new technologically capable species will evolve. Don’t hold your breath, though, it did take about half a billion years the first time.


There is, however, a second way to look at evolution. In a broader sense, natural evolution is only the first part of the process. Now the baton has been passed on to technological evolution. Or perhaps, more accurately, technology has kidnapped the process. Technology finds fitness peaks much faster than nature. It took natural selection millions of years to develop flight. If we consider technological capability to have arisen, say, during the Bronze Age, it took technological capability only 6,000 years. The scene from 2001 a Space Odyssey comes to mind. A prehistoric man-ape bangs on the skeleton of a fallen animal his clan has killed thanks to the discovery of a first weapon. A piece of bone flies out from the carcass rising high with the force of the man-ape’s brutal celebration of achievement and dominance, then, as it reaches its peak, in a blink, the bone is replaced by a spaceship on the way to the moon.

There is a frenetic evolutionary process taking place now in technology, and, although it is created by humans, it is no longer controlled by humans. No person, no country, no organization can really put a brake on it. In a way it has taken on a life of its own.


Looking at it from the first perspective, evolution may have achieved a great fitness peak with our species, it may even be the highest one ever, and a culmination of complexity and dominance for any species. But it may end up being only one more interesting, improbable side-step, like the beetle with a horn.

Looking at it from the second perspective, evolution, having attained technological capability, may have just reached the first base camp. Perhaps the great climb begins now.


LINKS

Sewell Wright's Fitness Landscape Metaphor Explained (YouTube)

General explanation of fitness landscape (YouTube)

What is the Drake Equation (YouTube)

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