The human population will become more alike as races merge, he said, but "Darwin's machine has lost its power. That's because natural selection—Darwin's "survival of the fittest" concept—is being sidelined in humans, according to Jones. The fittest will no longer spearhead evolutionary change, because, thanks to medical advances, the weakest also live on and pass down their genes. When On the Origin of Species was published in , only about half of British children survived to Today that number has swelled to 99 percent.
In developed countries, "the fact that everybody stays alive, at least until they're sexually mature, means ['survival of the fittest' has] got nothing to work with," Jones said. For instance, a study published last month in the journal Proceedings of the National Academy of Sciences suggested that women of the future could become shorter and stouter.
A team led by Yale University evolutionary biologist Stephen Stearns found that, due to ovulatory characteristics, shorter, slightly plumper women tend to have more children than their peers.
These physical traits are passed on to their offspring, suggesting natural selection in humans is alive and well. Geoffrey Miller, an evolutionary psychologist at the University of New Mexico, believes Darwinian evolution in humans is actually speeding up. He highlighted sexual selection through mate choice as one key driver. Miller added that artificial selection using genetic technologies will likely accentuate these changes in the future.
So I think there will actually be a leveling effect, where both the poor and the rich are going to be able to have the best kids they can genetically. But "regular" natural selection will also continue to play a major role, Miller believes. A philosophy known as transhumanism sees humans taking charge of their evolution and transcending their biological limitations via technology.
In essence, the old-fashioned evolution of On the Origin of Species may be beside the point: The future may belong to unnatural selection. Nick Bostrom, director of the Future of Humanity Institute at the University of Oxford, said Darwinian evolution "is happening on a very slow time scale now relative to other things that are leading to changes in the human condition"—cloning, genetic enhancement, robotics, artificial intelligence, and nanotechnology, for starters. Transhumanism raises a spectacular array of possibilities, from supersoldiers and new breeds of athletes to immortal beings who, having had their brains scanned atom by atom, transfer their minds to computers.
In addition to living forever, "uploaded" beings would be able to "travel at the speed of light as an information pattern," download themselves into robots for the occasional stroll through the real world, think faster when running on advanced operating systems, and cut their food budget down to zero, Bostrom imagines in his paper "The Transhumanist FAQ.
Whereas the current human generational cycle takes some 20 years, a digitalized individual could replicate themselves in seconds or minutes, Bostrom said.
We know that when early humans were threatened with extinction they fanned out across Africa in search of new homes, eventually leaving the continent entirely. This urge to break away from home and wander has saved us before and could save us in the future. If we colonize other planets, then we will be imitating the survival strategy of our ancestors. Scattering to the stars echoes our journey out of Africa—and it could be our best hope for lasting through the eons. Every year since , an international group of scientists and entrepreneurs holds a meeting in Washington State to plan for a space elevator that they hope to build in the next few decades.
Other groups are figuring out ways to reengineer our entire planet to slow the release of greenhouse gases and grow enough food for our booming population.
These projects, designed to improve cities on Earth while paving the way for life on other worlds, are just a few examples of how humans are getting ready for the inevitable mega disasters that await us. They are also powerful evidence that we want to help each other survive. We can pass on stories of how to cope with disaster and make it easier for the next group who confronts it. Our tales of survival pass over borders and travel through time from one generation to the next.
Humans are creatures of culture as well as nature. Call them tales of pragmatic optimism.
Before these methods were available, index fossils of a particular geologic period were used to give an approximate date to other fossils. Schaffner, et al. Biology Letters. In a landmark study conducted in , scientists examined the mitochondrial DNA of a Neanderthal fossil and a modern human. One form of Homo sapiens, known as Neanderthals, eventually died out. According to this strand of thought what led to the evolution of advanced intelligence in Homo sapiens was a drastic reduction of the aggressive drive. How this came about is perhaps the most fascinating question of all time.
This book is full of such tales—stories about people whose pragmatic optimism could one day save the world. Scientists, philosophers, writers, engineers, doctors, astronauts, and ordinary people are working tirelessly on world-changing projects, assuming that one day our lives can be saved on a massive scale. As their work comes to fruition, our world becomes a very different, more livable place.
If humans are going to make it in the long term, and preserve our planet along with us, we need to accept that change is the status quo. Our distant ancestors were a group of apelike creatures who started walking upright millions of years ago in Africa, eventually developing bigger brains and scattering throughout the world to become the humans of today. Written into our genomes is the signature left behind by an event when the early human population dwindled to such a small size that our ancient ancestors living in Africa may have come close to extinction.
Population geneticists call events like these bottlenecks. Sometimes the shrinking of a population is the result of mass deaths, and indeed, there is evidence that humans may have been fleeing a natural disaster when we walked out of Africa roughly 70 thousand years ago. But our species probably experienced multiple genetic bottlenecks beginning as far back as 2 million years. And those earlier bottlenecks were caused by a force far more powerful than mass death: the process of evolution itself.
In fact, the African bottlenecks are an example of the paradoxical nature of human survival. They provide evidence that humans nearly died out many times, but also tell a story about how we evolved to survive in places very far away from our evolutionary home in Africa. Given our enormous, globe-spanning population size, humans have remarkably low genetic diversity—much lower than other mammal species. All 6 billion of us are descended from a group of people who numbered in the mere tens of thousands.
Put another way, humanity is like a giant dance party full of billions of diverse people. But population geneticists, elite party animals that they are, have managed to find the one ideal VIP area that contains a small group of people who very roughly capture the diversity of the party as a whole. If they all started randomly having sex with each other, their children might loosely reproduce the diversity and genetic drift of our actual, billions-strong population. The weird part is that compared with our actual population size, the human effective population in that VIP area is very low.
As a point of comparison, the common house mouse is estimated to have an effective population size of , How could there be so many of us, and so little genetic diversity? This is one of the fundamental mysteries of human evolution, and is the subject of great debate among scientists. We are descended from a group of proto-humans who were fairly diverse 2 million years ago, but whose diversity crashed and passed through a bottleneck while Homo sapiens. That crash limited our gene pool, creating the small effective population size we have today.
Remember H.G. Wells and “The Time Machine”, how humanity had . What will be the next major step in the evolution of the human species?. Top 10 Possible Next Steps in Human Evolution It is far easier to remember where you put the book containing juicy facts, than to recall the.
Does some kind of terrible disaster lurk in the human past? An event that could have winnowed our population down to a small group of survivors, who became our ancestors?
Evolutionary biologist Richard Dawkins has popularized the idea that the population crash came in the wake of the Toba catastrophe, a supervolcano that rocked Indonesia 80, years ago. Instead of some Holly wood special-effects extravaganza, human history was more like a perilous immigration story. To understand how immigration can turn a vast population into a tiny one, we need to travel back a few million years to the place and time where we evolved. Over the next few million years, Australopithecus walked from the tip of what is now South Africa all the way up to where Chad and Sudan are today.
Our ancestors also grew larger skulls, anticipating a trend that has continued throughout human evolution. By about 2 million years ago, Australopithecus was evolving into a very human-looking hominin called Homo ergaster sometimes called Homo erectus. Similar in height to humans today, a couple of H.
Another thing that would make our H. There are many ways to tell the story of what happened to H. But each group had its own unique collection of genes, some of which still survive today in Homo sapiens. This path is both a physical and a genetic one.
Glass-enclosed panoramas offer glimpses of what we know about how H. Reconstructed early human skeletons stand near sparse fossils and tools, a reminder that our ideas about these people come, literally, from mere fragments of their bodies and cultures. One thing we know for sure is that early humans were wanderers. Not only did they spread across Africa, but they actually crossed out of it many times, starting about 2 million years ago.
Anthropologists can track the journeys taken by H. Tattersall believes there were at least three major radiations, or population dispersals, out of Africa. Instead, they were all spurred by evolutionary developments that allowed humans to master their environments. Members of H. Tattersall explained that there were environmental changes in Africa during this time, but not enough to suggest that humans fled environmental destruction to greener pastures. As early humans walked into new regions, they separated into different, smaller bands.
Each of these bands continued to evolve in ways that suited the environments where they eventually settled. About 1. These hominins soon found themselves in a very different environment from their siblings back in Africa; the winds were cold and snow y, and the steppes were full of completely unfamiliar wild- life. Over the millennia, H. Scientists have reconstructed the spread of H. From what we can piece together, it seems that H.
Over the next million years, other groups of humans followed in H. Walking in small groups, these humans were slowly expanding the boundaries of the hominin neighborhood. Fossil remains in Europe suggest that about , to , years ago, some of H. These Europeans evolved into H. Neanderthals evolved a thicker brow and more barrel-chested body to cope with the colder climate. Back in Africa, H. By , years ago, H. A species we would recognize as H. But suddenly something happened that started a different pattern.
What changed? Tattersall said there are no easy answers, but evolution often works in jumps and starts like that. For example, birds evolved feathers millions of years before they started flying, and animals had limbs long before they started walking. In what anthropologists call a cultural explosion over the past , years, humans developed complex symbolic communication, from language and art to fashion and complex tools.