Gallery: The Surprising Ways Humans Continue to Evolve
01humanity-2-0-now-more-evolvable
It's easy to think humans have stopped evolving, but nothing could be farther from the truth. Though modern medicine and civilization's graces make the struggle to survive more subtle, evolution's engine keeps churning. In the last few thousand years, in fact, a time when human evolution was once thought to have slowed, it may actually have sped up. [](http://stag-komodo.wired.com/images_blogs/wiredscience/2013/02/darwin_photoshop_tennis2.jpg) Charles Darwin, born on this day in 1809, might have been pleasantly surprised. At least at first, the father of evolution -- pictured at right in the later stages of Wired's [Darwin photoshop tennis contest](http://www.flickr.com/groups/pstennis/discuss/72157603874335559/) -- didn't talk much about the human implications of his theory. "Light will be thrown on the origin of man and his history," wrote Darwin in 1859's *On the Origin of Species*, leaving it to scientists like Thomas Huxley to make the full and then-controversial case for [humanity's origins in a common ancestor with apes](http://en.wikipedia.org/wiki/Man%27s_Place_in_Nature#Comparison_with_Lyell.27s_Antiquity_of_Man). Only with [*The Descent of Man*](http://en.wikipedia.org/wiki/The_Descent_of_Man,_and_Selection_in_Relation_to_Sex), published in 1871 for audiences that had finally wrapped their heads around evolution itself, did Darwin tackle its existence in humans. Though much of the book focused on the importance of mate preferences to shaping traits, he speculated in one section that humankind's altruistic tendencies may have changed our evolutionary trajectory, giving people who would once have died a chance to reproduce. This type of reasoning would lead to a widely held view that human evolution had slowed or even stopped, but research over the last several decades, and in particular the last few years, has led to a very different view. Human evolution is still going strong. [](http://stag-komodo.wired.com/images_blogs/wiredscience/2013/02/rare_variant_age660.jpg) __Above:__ Humanity 2.0: Now More Evolvable -------------------------------- Humanity hasn't yet spawned X-Men-style superheroes, at least not outside the cosplay community, but there's a kernel of truth to the comic-book trope of unknown powers latent in humanity's masses. Over the last 10,000 years or so, human populations have grown from a few million to [more than 7 billion](http://stag-komodo.wired.com/wiredscience/2011/10/7-billion-people/). Every successful fusion of sperm and egg carries a few brand-new mutations; this population explosion means that [humanity is awash with new mutations](http://stag-komodo.wired.com/wiredscience/2012/11/recent-human-evolution-2/), the raw material of evolution. The image above is a graphical representation of these genetic patterns. It depicts a population-wide tabulation genetic variations collectively present in each part of the human genome, dated to before (left) and after (right) the population boom. Some mutations will have no effect. Others will be harmful. Others may, in the right genetic or environmental circumstances, contain the seeds of extraordinary traits. *Images: 1) X-Men cosplayers. ([James Hennigan](https://secure.flickr.com/photos/greyloch/3219663202/)/Flickr) 2) Charles Darwin Photoshop tennis iteration. ([emmanuelrio76](http://www.flickr.com/groups/pstennis/discuss/72157603874335559/#comment72157603905149965)/Flickr) 3) Fu et al./Nature*
02evolution-accelerated
Evolution Accelerated? ---------------------- Some genetic analyses suggest that humanity doesn't just possess more new mutations, but that evolution itself has picked up pace in the last 40,000 years. Unexpectedly large portions of our genetic heritage [contains genomic signatures of recent evolutionary pressure](http://stag-komodo.wired.com/wiredscience/2007/12/humans-evolving). Studies of these patterns don't make many specific claims about what the changes mean -- the analytical methods were relatively low-resolution, and the genetics of complex traits are poorly understood to begin with -- but whatever is happening seems to be happening fast. In the image above, the number of mutations at selected points in our genome are categorized by age. It drops off precipitously in the present, but this is because the techniques used to estimate age lose power with extremely young variations, and not because new mutations have stopped arising. *Image: Hawks et al./PNAS*
Picasa 2.703frontier-fertility
Frontier Fertility ------------------ Human populations grew exponentially in the last several thousand years, an explosion that sent people into previously uncolonized (or, in many cases, in areas where the previous inhabitants were freshly exterminated.) Evolutionary theory suggests that colonization's dynamics favor traits that enable newcomers to gain a fast, firm foothold -- and what better way to do so than by having lots of children, fast? In what may be the [most recent evidence of human evolution](http://stag-komodo.wired.com/wiredscience/2011/10/recent-human-evolution/) ever detected, the average age of first birth among mothers in a Quebec island town dropped from 26 to 22 between 1800 and 1940. The town's moms didn't simply have a chance to give birth earlier; they seem to have changed biologically over time. *Image: A pioneer family in South Dakota, circa 1889. ([National Endowment for the Humanities](http://www.neh.gov/humanities/2012/mayjune/statement/the-life-norwegian-pioneer))*
04modern-reproduction
Modern Reproduction ------------------- The tendency to reproduce at an early age, and the large families that resulted, would have been useful on the frontier, but what happens when frontier is replaced by industrial-age urbanity? Analyses of the Framingham Heart Study, a long-term research project on the residents of one Massachusetts town that started in 1948 and has involved more than 10,000 people, suggests that reproductive traits continue to evolve. Framingham women are, on the average, [able to give birth slightly earlier and later](http://www.ncbi.nlm.nih.gov/pubmed/19858476) than their recent ancestors did. Because some physical traits tend to be associated with fertility, Framingham should also be slightly shorter and stouter, with lower cholesterol levels. *Image: [Pieterjan Vandaele](https://secure.flickr.com/photos/pjanvandaele/3992752224/)/Flickr*
05milk-it-does-a-population-good
Milk: It Does a Population Good ------------------------------- For nearly all of human history -- heck, for nearly all the history of a lineage that started 85 million years ago [with this shrew-like furball](http://stag-komodo.wired.com/wiredscience/2013/02/mammals-and-dinosaurs/) and ended with us -- milk was consumed in infancy. The genetic processes involved in breaking down lactose, milk's main sugar, shut down when babies finished weaning. Then, about 9,000 years ago, cattle were domesticated for the first time, offering great advantage to anyone who could take sustenance from their milk. Lactose-processing mutations spread fast and wide, first in north-central Europe and [later in Africa](http://www.nytimes.com/2006/12/10/science/10cnd-evolve.html). The majority of humankind is now lactose-tolerant, making these mutations among the fastest-spreading in known human history. *Image: [bluewaikiki](https://secure.flickr.com/photos/lfl/2132323232/)/Flickr*
06humans-are-becoming-dumber-or-not
Humans Are Becoming Dumber. Or Not. ----------------------------------- It's easy to think that evolution has a purpose, that it optimizes design in some predictable, self-evidently appealing way. On the grand scale, this is probably true: evolution filled a dead, ammonia-choked Earth with biological processes that run on water and sunlight, and should keep going for the next few billion years. On a narrower scale, though, evolution's outcomes aren't necessarily for the better. They might even be for the worse. Take human intelligence. According to geneticist Gerald Crabtree of Stanford University, humanity is, for reasons involving the genetic architecture of intelligence and the nature of modern life, [becoming emotionally and intellectually dumber](http://www.sciencedirect.com/science/article/pii/S0168952512001588). Crabtree thinks we reached a peak several thousand years and have declined ever since. This is, to be sure, just a hypothesis unsupported by data, and [one that's received much criticism](http://www.jasoncollins.org/2012/11/the-decline-in-intelligence/). But even if Crabtree is wrong, his argument makes for an enjoyable read. "A hunter–gatherer who did not correctly conceive a solution to providing food or shelter probably died, along with his/her progeny," [wrote Crabtree in *Current Biology*](http://bmi205.stanford.edu/_media/crabtree-2.pdf), "whereas a modern Wall Street executive that made a similar conceptual mistake would receive a substantial bonus and be a more attractive mate." *Image: [Eliot Phillips](https://secure.flickr.com/photos/hackaday/8200638589/)/Flickr*
07humans-smell-worse
Humans Smell Worse ------------------ Well, we don't exactly smell worse, not in the hold-your-nose sense. But there's reason to think our sense of smell has ossified: Unlike most animals, we no longer rely on that sense to make crucial everyday decisions (although it does seem that [the ability to smell potential mates with compatible immune system profiles](http://en.wikipedia.org/wiki/Body_odor_and_subconscious_human_sexual_attraction) is still active.) Just as cave-dwelling fish gradually lose their no-longer-necessary sense of sight, evidence suggests that [mutations impairing our sense of smell](http://www.ncbi.nlm.nih.gov/pubmed/22906809) have accumulated in human genomes. *Image: [Mark Rosenwald](https://secure.flickr.com/photos/rosenwald/5098032592/)/Flickr*
08cultural-evolution
Cultural Evolution ------------------ People, including this science journalist, tend to emphasize biology when thinking about human evolution, but that focus contains an element of [looking-for--my-keys-under-the-streetlight reasoning](http://en.wikipedia.org/wiki/Streetlight_effect). Genetic evolution can be rigorously measured and quantified. *Cultural* evolution is messy and difficult to study in journal-appropriate ways, yet in many ways culture -- our social practices and institutions, including the all-important vehicle of language -- is more powerful than biology. After all, if we could travel back in time a few hundred thousand years, *Homo sapiens* would be quite recognizable. It's culture that truly distinguishes us. In the last decade, researchers have developed tools for studying cultural evolution, from [patterns of linguistic change](https://encrypted.google.com/search?q=evolution%20of%20language%20site:wired.com&ie=UTF-8&oe=UTF-8) to folktale relatedness (above) to interpretations of [Polynesian canoe design](http://stag-komodo.wired.com/wiredscience/2009/09/cultural-evolution/). As with biological evolution, cultural evolution is clearly continuing: The advent of digital communications technologies, for example, makes new types of cultures possible. For now, though, an *Origin of Species* for cultural evolution hasn't yet been written. *Image: Ross et al./Proceedings of the Royal Society B*
