What will humanity look like in 10,000 years?

Humans are the incredible result of 4 billion years of incredible evolution of life on Earth.

The process of reproduction is not perfect, but the mistakes made when copying genes sometimes make organisms better adapt to the environment, and these genes can often be passed on. From self-replicating molecules in the oceans of the Archean Age, to eyeless fish in the Cambrian deep sea, to mammals that silently overtook the dinosaurs. Eventually, Homo sapiens took to the stage.

Evolution has shaped us, but we are not the end of this story. Not only will evolution not stop at humans, we may even evolve faster now than we did before. If humans hadn't gone extinct in climate catastrophes or asteroid impact events over the next ten thousand years, would it be possible for us to evolve further into a species more advanced than we are today?

Predicting the future is naturally very difficult, after all, the world may change in ways we can't imagine. But we can make some well-founded speculations. Perhaps the best way to do this is to look back and assume that the future will continue to follow the previous trend. At the very least, that's a possible future.

But to understand why, we need to take a closer look at biology.

The end of natural selection?

Some scientists believe that the rise of civilization ended natural selection. Indeed, the selection pressures that dominated the past have largely disappeared. Hunger and famine are largely ended by high-yielding crops, fertilizers and family planning. The lions, wolves and saber-toothed tigers that used to hunt us in the dark are no longer even a threat.

But evolution didn't stop there, it became something else. Evolution is not so much about survival of the fittest as reproduction of the fittest. We still need to find partners and raise offspring, so sexual selection has played a bigger role in evolution today.

Even if nature no longer controls our evolution, the unnatural environments we create, such as culture, technology, and cities, bring new pressures for choice. Our adaptation to this modern world has already begun.

When our diets change to include more grains and dairy products, we also have genes to help us digest starch and milk. When densely populated cities create the conditions for the spread of disease, mutations of disease resistance spread with it. The unnatural environment creates unnatural choices.

Growth in longevity

We are also under pressure to make new choices, such as a reduction in mortality. It is almost certain that humans will evolve to live longer and live longer.

The evolution of the life cycle is a response to mortality, which is how likely it is that predators and other threats will kill you. When mortality is high, animals must breed at a young age, or they may not have a chance to reproduce at all. There's also no benefit in evolving mutations that prevent aging or cancer, as you probably won't live that long to use them.

But when the mortality rate is low, the opposite is true. It's also useful to have longevity-extending adaptability and fertility, and they can buy you more time to reproduce. That's why animals with few natural predators tend to evolve to live longer, such as Greenlandan sharks, Galapagos turtles and bowhead whales, which mature so late that they can survive for centuries.

Even before the advent of civilization, man was unique among apes. Hunter-gatherers armed with spears and bows and arrows could fend off predators, and they knew how to share food and avoid starvation. As a result, we evolved delayed sexual maturity and relatively long lifespans, even surviving for 70 years. The problem is that child mortality remains high.

Even after the rise of civilization, child mortality remained high until the 19th century, and we continued to be affected by plagues and famines.

But over the past two centuries, better nutrition, health care and hygiene have reduced youth mortality to less than 1 per cent in most developed countries. Life expectancy worldwide has soared to 70 years, with developed countries reaching 80 years. These increases are due to improved health, not evolution, but they create the conditions for evolution to extend our lifespan.

Now, as our life expectancy has doubled, extended lifespan and adaptation to fertility are now favorable. Given that more and more people are living to be 100 or even 110 years old, it's reasonable to think that our genes can evolve to the point where the average person often lives to 100 or more.

Evolution of body size, strength, and appearance

Early archaic humans were relatively small, probably only 120 to 150 centimeters tall. But later ancient humans, including Homo erectus, Neanderthals, and Homo sapiens, grew taller. We've historically increased our height, in part because of improved nutrition, but genes also seem to be evolving.

Why we're getting bigger is unclear. It takes time to grow, so longer life means more time to grow. At the same time, human women seem to prefer tall males. As a result, lower mortality rates and sexual preferences may make humans higher.

Over the past 2 million years, our bones have become lighter as we rely less on brute force and use more tools and weapons. As farming forced us to settle down, our lives became more stable and bone density declined as a result.

As we spend more time behind desks, keyboards, and steering wheels, these trends are likely to continue. Physical strength becomes less necessary, our muscles continue to atrophy, and our jaws and teeth become smaller.

After people left Africa 100,000 years ago, distant tribes of humanity became isolated because of their distance. Around the world, different selection pressures cause our appearance to evolve in different ways. Each tribe evolved unique skin color, eyes, hair, and facial features.

But with the rise of civilization and the advent of new technologies, different groups of people are once again linked, and we are increasingly becoming a cosmopolitan group, which will create a mixed-race world where skin tone and facial features tend to be globally average. Sexual selection will further accelerate the evolution of our appearance. As most forms of natural selection no longer work, spousal choice will play a greater role.

Dramatic changes in intelligence and personality

Finally, our brains and minds, our most unique human characteristics, will also evolve, perhaps even dramatically.

Over the past 6 million years, human brain size has roughly tripled, driven by tool use, complex societies, and language. Interestingly, however, this trend is not necessarily going to continue. In Europe, brain size peaked between 10,000 and 20,000 years ago, about before we invented farming. Subsequently, the brain becomes smaller and smaller. The brains of modern people are smaller than those of our ancient pioneers, even those of the Middle Ages.

We don't yet know the reasons behind this trend. Probably because, once we switch to farming, fat and protein are scarce, making it more expensive to grow and maintain the brain. In an agrarian society where famines are frequent, the gigantic brain may become a burden.

Or to say that living in a large society of "specialists" requires less mental energy than living in a tribe of "generalists." Stone Age people acquired many skills, and modern people, as part of a vast social network, used the division of labor to play fewer, more specialized roles. In a civilization, each of us may be primarily engaged in one industry and then rely on others to do other things.

Of course, the size of the brain is not everything. Therefore, how much of an impact the loss of brain mass has on overall intelligence is unclear. Perhaps we have lost some abilities while enhancing others that are more relevant to modern life. It's possible that we can maintain processing power by having fewer, smaller neurons.

Our personality must also be constantly evolving. For example, aggressiveness has now become an unsuitable trait. Changes in social patterns can also change people's personalities. Unlike in the past, we now live in large crowds, often moving for work and forming relationships in the process, many of which are fleeting and increasingly virtual.

Of course, not everyone is psychologically well adapted. Admittedly, more and more people are suffering from psychological problems such as anxiety and depression.

New possibilities?

There used to be multiple human species living on Earth, but now only we are left. Will new human species evolve in the future?

To get to this point, we need isolated populations and pressures of different choices. Theoretically, reproductive isolation can be achieved through selective mating. If people were culturally segregated and married according to religion, class, caste, or even politics, different populations, and even species, might evolve with it.

So far, these discussions have been largely from a historical perspective. But in some ways, the future may be very different from the past. Evolution itself has evolved.

One of the more extreme possibilities is directed evolution, where we actively control the evolution of our own species. In the future, we will do so with more knowledge of our own behavior and more control over the genes of our offspring.

We can already screen ourselves and embryos for genetic disorders. It's even possible that we can choose the ideal genes for embryos, just as we would with crops. Direct editing of the DNA of human embryos has proven possible, and of course, this would be morally reprehensible. However, if in the future this technology proves to be absolutely safe and secure, will it turn out that if you don't give your child the best genes, you won't be the best parent?

Discussions about human evolution are often backtracked, but as technology and culture enter a period of accelerated change, our genes will also accelerate their evolution. Perhaps the most interesting part of evolution is no longer limited to the origin of life, dinosaurs or Neanderthals, but what is happening in the present, our present, and our future.

#创作团队:

Nicholas R. Longrich (Senior Lecturer in Paleontology and Evolutionary Biology, University of Bath)

Compile: Takeko

Typography: Wenwen

#参考来源:

https://theconversation.com/future-evolution-from-looks-to-brains-and-personality-how-will-humans-change-in-the-next-10-000-years-176997

#图片来源:

Cover image: max pixel

首图：T. Michael Keesey/Flickr, CC BY-NC-SA