Category: anthropology

It Is Impossible to Predict How Humans Will Evolve

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.

Image source: Nik.vuk/Wikimedia Commons

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.Aeon counter – do not remove

Wendy Orent

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.

Scientists Can Now Extract Ancient Human DNA From 240,000-Year-Old Dirt

The Dirt on DNA

German scientists just made a major breakthrough in sequencing the DNA of our ancient ancestors. While researchers have long relied on painstaking work and pure good luck to uncover the fossilized remains of our predecessors, a new technique has allowed scientists to pull DNA from something far more abundant: dirt.

Amber Encased Prehistoric Creatures Found in 2016
Click to View Full Infographic

Scientists have understood for years that genetic material from a decomposing entity – whether animal, plant, or human — is released into the surrounding sediment and can remain there for a long time. The problem is there’s a lot of it and it’s all mixed up. Parsing out only human DNA deposits from even a tablespoon of dirt has traditionally been very difficult to do.

Led by Viviane Slon, scientists at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, have developed a process for retrieving and sequencing those DNA deposits, and they are now the first researchers to recover ancient human DNA directly from sediment. To do so, they created molecules that would target and extract DNA from mammals, specifically mitochondrial DNA, which is more abundant. The team presented its findings in the journal Science last week.

A New Kind of Discovery

Slon’s team shines a new light on the Denisovans, a cousin to our Neanderthal ancestors that we know very little about. So far, scientists have only recovered a fossilized finger bone and a couple of teeth, both of which came from a single cave in Siberia. If the technique for analyzing DNA from dirt becomes a regular part of field work, there’s the potential for discovering more evidence of this ancient ancestor in places without fossils. It will teach us more about what early humans were doing outside of the caves in which they lived (and apparently died), including migratory information.

For paleontologists and archeologists, the prospect of no longer having to rely quite so heavily on the exciting — but relatively rare — discovery of fossils will likely come as a relief. Even when they are able to find a fossil, putting it through the paces for sequencing can compromise its integrity as a specimen, making researchers no friend to museum curators or civilizations looking to preserve the remains of their ancient ancestors.

Perhaps most exciting of all, though, is the fact that being able to retrieve DNA in the absence of bones could add new branches to humanity’s family tree, giving researchers insight into early humans that we have yet to find skeletal evidence of.

The post Scientists Can Now Extract Ancient Human DNA From 240,000-Year-Old Dirt appeared first on Futurism.

Eternal Memory: You Can Now Wear 1,000 Languages Around Your Neck

Language as Treasure

One of the most significant anthropological finds of human existence was the 1799 discovery of the Rosetta Stone. The stone made it possible to understand the language of ancient cultures, giving us insight that would have been impossible to achieve otherwise.

Given the fragile means by which we currently store information, future civilizations may not be as fortunate. However, efforts are being undertaken to provide a similar, though much more detailed, artifact. And to further one-up the ancient competition, the people behind those efforts are looking to make as many copies as possible to increase the chances of the artifact surviving for millennia to come.

The Long Now Foundation is dedicated to delivering this tool to future intelligent life. The first phase of their project resulted in what they dubbed a Rosetta Disk. The disk contains more than 13,000 pages of content written in more than 1,500 human languages with each page of information only the width of five human hairs. The information etched onto the disc can be read by using a standard microscope capable of a 650x zoom.

The project’s next phase involves scaling down the disc to a wearable form. The foundation is offering a smaller disc featuring 1,000 languages, which measures in at two centimeters (.79 inches). It’s available as a necklace that can be purchased for the price of a lifetime membership to the foundation: $1,000.

Knowledge Preservation

The durability of stone is a major reason the information contained on the Rosetta Stone was preserved. Modern technology, whether in the form of the pages of a book or the digital realm, does not share that same characteristic.

Other means of information storage are also being explored. Researchers have discovered ways to etch the entirety of human history into quartz, which can last fourteen billion years. Diamonds can be used to forge indestructible information vessels as well.

Preserving the knowledge of today is a great way to ensure the innovation of tomorrow. We have learned so much from our ancestors and need to be able to give future beings the same luxury.

The post Eternal Memory: You Can Now Wear 1,000 Languages Around Your Neck appeared first on Futurism.