As The Verge’s resident headphones obsessive, I should probably be expected to recoil in horror at the sight of a product named Sound Huggle that is two parts earmuffs, one part wireless headphones. It’s like presenting a watch with a clown face to an horology enthusiast. But, as strong as my natural instinct to flee may be, I have to say that I just can’t bring myself to hate these earmuff headphones.
Let’s get the obvious out of the way first: the Sound Huggle muffs very likely sound like absolute tinny garbage. They’re an Indiegogo project by a young couple, neither of whom is an audio engineer by trade. These are whimsical, cutesy, fun things; their specs and design…
We all know what Neanderthals looked like: the beetling brow ridges, thick nose, long skull, massive bone structure – and probably red hair and freckled skin. You might do a double-take if you saw one on the subway, wearing a suit, or you might not. But you would surely look twice at the hunter-gatherers that populated Europe between 7,000 and 8,000 years ago, whose DNA scientists are analysing now. They had dark skin and, very likely, bright-blue eyes, like the beautiful child from Afghanistan you see in the photograph above. This combination essentially vanished from ancient Europe, replaced by light-skinned, brown-eyed farmers who moved in from the Middle East over the course of several centuries, and who looked like most of the population of southern Europe today.
These early farmers, who depended on milk, have the gene for lactose tolerance that is missing in the old hunter-gatherer population. They ate much less meat and far more starch than the original meat-eating Europeans, and depended both on milk and on sunlight for vitamin D – hence their lighter skin. As for the dark, blue-eyed people, they disappeared from Europe, swamped genetically by the invaders over time.
This is a tale of fast human evolution. New ways of living – farming crops, and herding animals rather than hunting – led to the rapid expansion of genes that took advantage of these cultural adaptations. The ancestral dark skin, probably inherited from our common forebears in Africa, could have been a disadvantage if most calories came from cultivated grains rather than meat from wild animals, rich in vitamin D. Blue eyes remained, though the form of the gene (called an allele) for blue eye colour is recessive, and easily swamped by alleles for brown eyes. So within some span of time – we can’t say exactly how long – ancient Europeans began to look quite different. There was also an influx of genes from east Asia, from peoples likely resembling the modern Chukchi and other native Siberian groups closely related to Native Americans. Ancient Europe was a melting pot, but certain alleles, for light skin and brown eyes, became dominant as the hunter-gatherer way of life receded against an influx of farmers and farming.
We think of evolution, described by Charles Darwin in 1859, as a slow dance: nature chooses the best-adapted organisms to reproduce, multiply and survive in any given ecosystem. As organisms adapt to changing ecological circumstances over millennia, the varieties best-suited to the environment thrive, allowing species to emerge and evolve. This is the process known as natural selection, or differential reproduction, which simply means that the organisms best-adapted to their particular, immediate circumstances will pass on more genes to the next generation than their less-well-adapted conspecifics (members of the same species).
Permanent change, of the kind we see in the fossil record, takes more time. Just look at the plodding trajectory of the several-hoofed Hyracotherium, a dog-sized forest-dwelling mammal that gradually lost its side toes (four on the front legs and three on the back) as the central one enlarged. It took 55 million years for it to evolve into the large, single-hoofed, grass-feeding horse we know today.
But sometimes evolution happens fast. As the biologists Peter and Rosemary Grant at Princeton University in New Jersey showed in their studies of Galapagos finches, small beaks can change into large beaks in a single generation, depending on climate conditions and the type of food to be found on those harsh islands. The small-beaked birds might die out, while the large-beaked prevail, for a while at least. But those rapid changes aren’t often permanent. Though the Grants might have witnessed the evolution of an entirely new, heavy-bodied finch species, many of the changes they saw in finches’ beaks were reversed, again and again. Changes in vegetation could mean that large beaks become a handicap. This shifting process – small changes over short periods of time – is called ‘microevolution’.
The evolutionary biologists David Lahti of Queens College at the City University of New York and Paul W Ewald of the University of Louisville both argue that there’s nothing exceptional about fast evolution. Rapid change, transient or lasting, simply reflects the intensity of selection, the strong action of Darwin’s ‘hostile forces of nature’, including predation, heat, cold, parasites. Difficult times could mean extinction for some species, or fast evolution for others. But to enable fast evolution, you must have enough genetic variation present in the underlying gene pool for selection to work upon. Hence the swift replacement of the hunter-gatherer with the farmer in ancient Europe. Light-skin genes overtook dark-skin genes because, likely, those genes better fit both the European environment and a new way of life.
Lahti adds that for human populations social selection becomes paramount: the presence of other hostile groups and the human ability for in-group cooperation drove the emergence of human social complexity and the evolution of the human brain. We don’t know whether the contact between European hunters and Middle Eastern farmers (or the East Asian people who also contributed their genes to the European pot) were friendly or hostile. Likely, in ancient Europe, there were skirmishes; likely, also, there were peaceful exchanges. We can’t know: all we see is the result, the apparent swamping of one set of traits for others that gradually became fixed in the area.
Of course, blond hair and light skin came to characterise Europe in the far north, among the ancestral Scandinavian population; pale skin here is likely an adaptation to vitamin D shortage. Dark skin remains a useful adaptation in hot, sunny climates. As climate changes, perhaps local variations in human appearance will be favoured in ways we don’t yet know.
Human evolution and the forces that produce it have never stopped. Some people will always be favoured genetically, and their offspring will be more likely to survive. That’s the essence of natural selection. And so adaptation and human evolution go on all the time. As a species, it’s impossible to say that we’re evolving in a particular direction – towards bigger heads and spindly limbs, say, as science fiction often suggests. But on the local level, adaptation and natural selection are always at work, adapting us to combat whatever threats – new diseases, climate change, new social selection processes – are now, often invisibly, at hand.
This article was originally published at Aeon and has been republished under Creative Commons.
The post It Is Impossible to Predict How Humans Will Evolve appeared first on Futurism.
As an astrophysicist, I am always struck by the fact that even the wildest science-fiction stories tend to be distinctly human in character. No matter how exotic the locale or how unusual the scientific concepts, most science fiction ends up being about quintessentially human (or human-like) interactions, problems, foibles and challenges. This is what we respond to; it is what we can best understand. In practice, this means that most science fiction takes place in relatively relatable settings, on a planet or spacecraft. The real challenge is to tie the story to human emotions, and human sizes and timescales, while still capturing the enormous scales of the Universe itself.
Just how large the Universe actually is never fails to boggle the mind. We say that the observable Universe extends for tens of billions of light years, but the only way to really comprehend this, as humans, is to break matters down into a series of steps, starting with our visceral understanding of the size of the Earth. A non-stop flight from Dubai to San Francisco covers a distance of about 8,000 miles – roughly equal to the diameter of the Earth. The Sun is much bigger; its diameter is just over 100 times Earth’s. And the distance between the Earth and the Sun is about 100 times larger than that, close to 100 million miles. This distance, the radius of the Earth’s orbit around the Sun, is a fundamental measure in astronomy; the Astronomical Unit, or AU. The spacecraft Voyager 1, for example, launched in 1977 and, travelling at 11 miles per second, is now 137 AU from the Sun.
But the stars are far more distant than this. The nearest, Proxima Centauri, is about 270,000 AU, or 4.25 light years away. You would have to line up 30 million Suns to span the gap between the Sun and Proxima Centauri. The Vogons in Douglas Adams’s The Hitchhiker’s Guide to the Galaxy (1979) are shocked that humans have not travelled to the Proxima Centauri system to see the Earth’s demolition notice; the joke is just how impossibly large the distance is.
Four light years turns out to be about the average distance between stars in the Milky Way Galaxy, of which the Sun is a member. That is a lot of empty space! The Milky Way contains about 300 billion stars, in a vast structure roughly 100,000 light years in diameter. One of the truly exciting discoveries of the past two decades is that our Sun is far from unique in hosting a retinue of planets: evidence shows that the majority of Sun-like stars in the Milky Way have planets orbiting them, many with a size and distance from their parent star allowing them to host life as we know it.
Yet getting to these planets is another matter entirely: Voyager 1 would arrive at Proxima Centauri in 75,000 years if it were travelling in the right direction – which it isn’t. Science-fiction writers use a variety of tricks to span these interstellar distances: putting their passengers into states of suspended animation during the long voyages, or travelling close to the speed of light (to take advantage of the time dilation predicted in Albert Einstein’s theory of special relativity). Or they invoke warp drives, wormholes or other as-yet undiscovered phenomena.
When astronomers made the first definitive measurements of the scale of our Galaxy a century ago, they were overwhelmed by the size of the Universe they had mapped. Initially, there was great skepticism that the so-called ‘spiral nebulae’ seen in deep photographs of the sky were in fact ‘island universes’ – structures as large as the Milky Way, but at much larger distances still. While the vast majority of science-fiction stories stay within our Milky Way, much of the story of the past 100 years of astronomy has been the discovery of just how much larger than that the Universe is. Our nearest galactic neighbour is about 2 million light years away, while the light from the most distant galaxies our telescopes can see has been travelling to us for most of the age of the Universe, about 13 billion years.
We discovered in the 1920s that the Universe has been expanding since the Big Bang. But about 20 years ago, astronomers found that this expansion was speeding up, driven by a force whose physical nature we do not understand, but to which we give the stop-gap name of ‘dark energy’. Dark energy operates on length- and time-scales of the Universe as a whole: how could we capture such a concept in a piece of fiction?
The story doesn’t stop there. We can’t see galaxies from those parts of the Universe for which there hasn’t been enough time since the Big Bang for the light to reach us. What lies beyond the observable bounds of the Universe? Our simplest cosmological models suggest that the Universe is uniform in its properties on the largest scales, and extends forever. A variant idea says that the Big Bang that birthed our Universe is only one of a (possibly infinite) number of such explosions, and that the resulting ‘multiverse’ has an extent utterly beyond our comprehension.
The US astronomer Neil deGrasse Tyson once said: ‘The Universe is under no obligation to make sense to you.’ Similarly, the wonders of the Universe are under no obligation to make it easy for science-fiction writers to tell stories about them. The Universe is mostly empty space, and the distances between stars in galaxies, and between galaxies in the Universe, are incomprehensibly vast on human scales. Capturing the true scale of the Universe, while somehow tying it to human endeavours and emotions, is a daunting challenge for any science-fiction writer. Olaf Stapledon took up that challenge in his novel Star Maker (1937), in which the stars and nebulae, and cosmos as a whole, are conscious. While we are humbled by our tiny size relative to the cosmos, our brains can none the less comprehend, to some extent, just how large the Universe we inhabit is. This is hopeful, since, as the astrobiologist Caleb Scharf of Columbia University has said: ‘In a finite world, a cosmic perspective isn’t a luxury, it is a necessity.’ Conveying this to the public is the real challenge faced by astronomers and science-fiction writers alike.
Welcome to the Universe: An Astrophysical Tour by Michael Strauss, Neil deGrasse Tyson and J Richard Gott is out now through Princeton University Press.
This article was originally published at Aeon and has been republished under Creative Commons.
The post It’s Almost Impossible to Understand How Unfathomably Massive Our Universe Truly Is appeared first on Futurism.