Was human evolution inevitable, or do we owe our existence to a once-in-a-universe stroke of luck? ... At first glance, everything that’s happened during the 3.8 billion-year history of life on our planet seems to have depended quite critically on all that came before. And Homo sapiens arrived on the scene only 200,000 years ago. The world got along just fine without us for billions of years. Gould didn’t mention chaos theory in his book, but he described it perfectly: ‘Little quirks at the outset, occurring for no particular reason, unleash cascades of consequences that make a particular future seem inevitable in retrospect,’ he wrote. ‘But the slightest early nudge contacts a different groove, and history veers into another plausible channel, diverging continually from its original pathway.’ ... One of the first lucky breaks in our story occurred at the dawn of biological complexity, when unicellular life evolved into multicellular. ... Throughout human prehistory, biological change and technological change ran in parallel. Brains were increasing in size – but this was not unique to our ancestors, and can be seen across multiple hominin species. Something very complicated was going on – a kind of arms race, Tattersall suggests, in which cognitive capacity and technology reinforced each other. At the same time, each branch of the human evolutionary tree was forced to adapt to an ever-changing climate.

In the 1980s, two ecologists, Jim Brown at the University of New Mexico and Brian Maurer at Brigham Young University, coined the term macroecology, which gave a name and intellectual home to researchers searching for emergent patterns in nature. Frustrated by the small scale of many ecological studies, macroecologists were looking for patterns and theories that could allow them to describe nature broadly in time and space. ... Brown and Maurer had been influenced heavily by regularities in many ecological phenomena. One of these, called the species-area curve, was discovered back in the 19th century, and formalized in 1921. That curve emerged when naturalists counted the number of species (of plants, insects, mammals, and so on) found in plots laid out in backyards, savannahs, and forests. They discovered that the number of species increased with the area of the plot, as expected. But as the plot size kept increasing, the rate of increase in the number of species began to plateau. Even more remarkable, the same basic species-area curve was found regardless of the species or habitat. To put it mathematically, the curve followed a power law, in which the change in species number increased proportionally to the square root of the square root of the area. ... Power laws are common in science, and are the defining feature of universality in physics. They describe the strength of magnets as temperature increases, earthquake frequency versus size, and city productivity as a function of population.

Burgers and fries have nearly killed our ancestral microbiome. ... A group of Italian microbiologists had compared the intestinal microbes of young villagers in Burkina Faso with those of children in Florence, Italy. The villagers, who subsisted on a diet of mostly millet and sorghum, harbored far more microbial diversity than the Florentines, who ate a variant of the refined, Western diet. Where the Florentine microbial community was adapted to protein, fats, and simple sugars, the Burkina Faso microbiome was oriented toward degrading the complex plant carbohydrates we call fiber. ... Scientists suspect our intestinal community of microbes, the human microbiota, calibrates our immune and metabolic function, and that its corruption or depletion can increase the risk of chronic diseases, ranging from asthma to obesity. ... Numerous factors are implicated in these disappearances. Antibiotics, available after World War II, can work like napalm, indiscriminately flattening our internal ecosystems. Modern sanitary amenities, which began in the late 19th century, may limit sharing of disease- and health-promoting microbes alike. Today’s houses in today’s cities seal us away from many of the soil, plant, and animal microbes that rained down on us during our evolution, possibly limiting an important source of novelty. ... But what the Sonnenburgs’ experiment suggests is that by failing to adequately nourish key microbes, the Western diet may also be starving them out of existence.

Around 540 million years ago, the ancestors of most modern animal groups suddenly appeared on the scene, in an outburst of speciation known as the Cambrian explosion. Many of these pioneering creatures left fossils behind. Some are so well preserved that scientists have been able to use scanning electron microscope images to piece together their inner anatomy, eyes included, and reconstruct their owners’ view of the world. ... But these eyes were already complex, and there are no traces of their simpler precursors. The fossil record tells us nothing about how sightless animals first came to see the world. This mystery flustered Charles Darwin. “To suppose that the eye, with all its inimitable contrivances ... could have been formed by natural selection, seems, I freely confess, absurd in the highest possible degree,” he wrote in Origin of Species. ... in the very next sentence, Darwin solves his own dilemma: “Yet reason tells me, that if numerous gradations from a perfect and complex eye to one very imperfect and simple, each grade being useful to its possessor, can be shown to exist … then the difficulty of believing that a perfect and complex eye could be formed by natural selection, though insuperable by our imagination, can hardly be considered real.” ... The gradations he spoke of can be shown to exist. Living animals illustrate every possible intermediate between the primitive light-sensitive patches on an earthworm and the supersharp camera eyes of eagles. ... Even under the most pessimistic conditions, with the eye improving by just 0.005 percent each generation, it takes just 364,000 years for the simple sheet to become a fully functioning camera-like organ. As far as evolution goes, that’s a blink of an eye. ... But simple eyes should not be seen as just stepping-stones along a path toward greater complexity. Those that exist today are tailored to the needs of their users. ... Nothing that sees does so without proteins called opsins—the molecular basis of all eyes. Opsins work by embracing a chromophore, a molecule that can absorb the energy of an incoming photon. The energy rapidly snaps the chromophore into a different shape, forcing its opsin partner to likewise contort. This transformation sets off a series of chemical reactions that ends with an electrical signal.

There is a common story about what money is, which is based on a common story about how money came to be. In the beginning, people lived in small communities of blood relatives and fended for themselves. They hunted and gathered for their subsistence, and learned how to weed out undesirable plants so that they would have easy access to plants that produce food. As people became more adept at cultivation, populations grew. And people found that they could not always grow or procure from nature the things they needed in order to survive. Trade was born. ... People in different communities had surpluses of different goods. They traded these goods with one another. They established value and conducted their trade by bartering a certain quantity of one good for a quantity of a different good. ... lugging around his own goods in sufficient quantities to trade became burdensome and impractical. Furthermore, stockpiling his surplus might have worked up to a point, but once the mice and the weather got at it, it quickly became worthless. ... In some accounts, people decided to use a thing of value to them, and intrinsically recognisable as valuable to others, for money. It would initially serve as a means of exchange, and would gradually take on other classic functions of money as people expanded their use of it to include the payment of fines, tribute or fees (as in ancient administrative states, tribute-based empires or the tax collectors of the Old Testament). Certain kinds of shells were good: they were pretty, of uniform size and shape, easily transportable, and durable. Precious metals were even better: they were universally valued; they did not rot, rust or degrade; and they were easy to store and to transport. ... Other accounts consider implausible the idea that certain things are of intrinsic value. ... an important problem in the history of money: is it a commodity in itself, or a token of an existing agreement, an agreement in turn resting on a prior social relationship? ... are new forms of money really more efficient? They often come at a price, after all. What does efficiency mean? Efficient for what purposes, and when?

As we go about our daily lives, we tend to assume that our perceptions — sights, sounds, textures, tastes — are an accurate portrayal of the real world. Sure, when we stop and think about it — or when we find ourselves fooled by a perceptual illusion — we realize with a jolt that what we perceive is never the world directly, but rather our brain’s best guess at what that world is like, a kind of internal simulation of an external reality. Still, we bank on the fact that our simulation is a reasonably decent one. If it wasn’t, wouldn’t evolution have weeded us out by now? The true reality might be forever beyond our reach, but surely our senses give us at least an inkling of what it’s really like. ... Not so, says Donald D. Hoffman, a professor of cognitive science at the University of California, Irvine. Hoffman has spent the past three decades studying perception, artificial intelligence, evolutionary game theory and the brain, and his conclusion is a dramatic one: The world presented to us by our perceptions is nothing like reality. What’s more, he says, we have evolution itself to thank for this magnificent illusion, as it maximizes evolutionary fitness by driving truth to extinction.

Biological systems don’t defy physical laws, of course — but neither do they seem to be predicted by them. In contrast, they are goal-directed: survive and reproduce. We can say that they have a purpose — or what philosophers have traditionally called a teleology — that guides their behavior. ... By the same token, physics now lets us predict, starting from the state of the universe a billionth of a second after the Big Bang, what it looks like today. But no one imagines that the appearance of the first primitive cells on Earth led predictably to the human race. Laws do not, it seems, dictate the course of evolution. ... Animals are drawn to water not by some magnetic attraction, but because of their instinct, their intention, to survive. Legs serve the purpose of, among other things, taking us to the water. ... there appears to be a kind of physics of things doing stuff, and evolving to do stuff. Meaning and intention — thought to be the defining characteristics of living systems — may then emerge naturally through the laws of thermodynamics and statistical mechanics.

Thousands of subsequent experiments have confirmed (and elaborated on) this finding. As everyone who’s followed the research—or even occasionally picked up a copy of Psychology Today—knows, any graduate student with a clipboard can demonstrate that reasonable-seeming people are often totally irrational. Rarely has this insight seemed more relevant than it does right now. Still, an essential puzzle remains: How did we come to be this way? ... new book, “The Enigma of Reason” (Harvard), the cognitive scientists Hugo Mercier and Dan Sperber take a stab at answering this question. ... point out that reason is an evolved trait, like bipedalism or three-color vision. It emerged on the savannas of Africa, and has to be understood in that context. ... Stripped of a lot of what might be called cognitive-science-ese, Mercier and Sperber’s argument runs, more or less, as follows: Humans’ biggest advantage over other species is our ability to cooperate. Cooperation is difficult to establish and almost as difficult to sustain. For any individual, freeloading is always the best course of action. Reason developed not to enable us to solve abstract, logical problems or even to help us draw conclusions from unfamiliar data; rather, it developed to resolve the problems posed by living in collaborative groups. ... Presented with someone else’s argument, we’re quite adept at spotting the weaknesses. Almost invariably, the positions we’re blind about are our own.

The capital of the Kunene region, Opuwo lies in the heartland of the Himba people, a semi-nomadic people who spend their days herding cattle. Long after many of the world’s other indigenous populations had begun to migrate to cities, the Himba had mostly avoided contact with modern culture, quietly continuing their traditional life. But that is slowly changing, with younger generations feeling the draw of Opuwo, where they will encounter cars, brick buildings, and writing for the first time. ... How does the human mind cope with all those novelties and new sensations? By studying people like the Himba, at the start of their journey into modernity, scientists are now hoping to understand the ways that modern life may have altered all of our minds. ... Like an irregular lens, our modern, urban brains distort the images hitting our retina, magnifying some parts of the scene and shrinking others.

In his new book, Adaptive Markets: Financial Evolution at the Speed of Thought, M.I.T. finance professor Andrew Lo attempts to account for the messier, more feeling realities of human behavior. A key premise is that markets evolve, like species, but much faster: “evolution at the speed of thought.” And that this evolution happens in fits and starts, in response to changes in the environment—hence, what he calls the “adaptive” markets hypothesis. It’s during these times of change that human emotions play their biggest role. Lo believes we are in one of those times now and, in his book, he applies biology, psychology, neuroscience, and history toward the goal of improving on the efficient markets hypothesis—which, Lo says, is not only flawed but is becoming increasingly so as the financial environment continues to change. ... The efficient markets hypothesis is a special case of adaptive markets. Markets are efficient if the environment is stable and investors interact with each other and natural selection operates over a long period of time.

Above a certain temperature, a cell will collapse and die. One of the most straightforward explanations for this lack of heat hardiness is that the proteins essential to life — the ones that extract energy from food or sunlight, fend off invaders, destroy waste products and so on — often have beautifully precise shapes. They start as long strands, then fold into helixes, hairpins and other configurations, as dictated by the sequence of their components. These shapes play a huge role in what they do. Yet when things start to heat up, the bonds that keep protein structures together break: first the weaker ones, and then, as the temperature mounts, the stronger ones. It makes sense that a pervasive loss of protein structure would be lethal, but until recently, the details of how, or if, this kills overheated cells were unknown. ... One of the clearest observations was that in each species, the proteins did not unfold en masse with a temperature boost. Instead, “we saw that only a small subset of proteins collapses very early,” Picotti said, “and these are key proteins.” ... This paradox — that some of the most important proteins seem to be the most delicate — may reflect how evolution has shaped them to do their jobs. ... The more copies the cell made, they reported, the more heat it took to break a protein down.

Suppose you wanted to build the perfect dog from scratch. What would be the key ingredients in the recipe? Loyalty and smarts would be musts. Cuteness would be as well, perhaps with gentle eyes, and a curly, bushy tail that wags in joy in anticipation of your appearance. ... You needn’t bother trying. Lyudmila Trut and Dmitri Belyaev have already built it for you. The perfect dog. Except it’s not a dog, it’s a fox. A domesticated one. They built it quickly—mind-bogglingly fast for constructing a brand new biological creature. It took them less than 60 years, a blink of an eye compared to the time it took for wolves to become dogs. They built it in the often unbearable negative 40 degrees Fahrenheit cold of Siberia, where Lyudmila and, before her, Dmitri, have been running one of the longest, most incredible experiments on behavior and evolution ever devised. ... Except for house pets, most domesticated animals do not form close relationships with humans, and by far the most intense affection and loyalty forms between owners and dogs. What made the difference? Had that deep human-animal bond developed over a long time? Or might this affinity for people be a change that could emerge quickly, as with so many other changes Lyudmila and Belyaev had seen in the foxes already? Would living with a human come naturally to a fox that had been bred for tameness?

The most intriguing part of the antenna, though, is that it gives him an ability the rest of us don’t have. He looked at the lamps on the roof deck and sensed that the infrared lights that activate them were off. He glanced at the planters and could “see” the ultraviolet markings that show where nectar is located at the centers of the flowers. He has not just matched ordinary human skills; he has exceeded them. ... He is, then, a first step toward the goal that visionary futurists have always had, an early example of what Ray Kurzweil in his well-known book The Singularity Is Near calls “the vast expansion of human potential.” ... But are we on the way to redefining how we evolve? Does evolution now mean not just the slow grind of natural selection spreading desirable genes, but also everything that we can do to amplify our powers and the powers of the things we make—a union of genes, culture, and technology? And if so, where is it taking us? ... Conventional evolution is alive and well in our species. Not long ago we knew the makeup of only a handful of the roughly 20,000 protein-encoding genes in our cells; today we know the function of about 12,000. But genes are only a tiny percentage of the DNA in our genome. More discoveries are certain to come—and quickly. From this trove of genetic information, researchers have already identified dozens of examples of relatively recent evolution. ... In our world now, the primary mover for reproductive success—and thus evolutionary change—is culture, and its weaponized cousin, technology. ... One human trait with a strong genetic component continues to increase in value, even more so as technology grows more dominant. The universal ambition of humanity remains greater intelligence.