Everything you thought you knew about human evolution is wrong. I’m kidding of course, but this is often the impression given by news headlines. While this is far from the truth (scientists have made huge leaps in understanding human origins in recent decades), there are small nuggets of reality reflected in this massive exaggeration. And as is so often the case, the reality is far more fascinating than anything that can be encapsulated in a headline.

It’s not that everything we think we know has been wrong, it’s just that paleoanthropologists keep finding new pieces of evidence that refine theories and understandings of the human past. This is normal, scientific knowledge is provisional—it is constantly being tested, corrected, and sometimes overturned. The science of human evolution has been uniquely susceptible to corrections in knowledge, given that the field was once faced with an extremely limited fossil record, and data is now accumulating at an unprecedented pace—leading to seemingly many disturbances.

Year in and year out, scientists are being forced to reconsider evidence, reexamine long-held ideas, and rethink conclusions. This, dear readers, is why I am so fascinated with this field. It keeps you on your toes, rewarding those who look in places you never thought to look and those who think about things from new angles. 2018 was no exception. With that in mind, let’s revisit my top ten favorite discoveries of the year—many of them are finds that overturned (or at least significantly altered) what we thought we knew about the past:

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Cave art, Kalimantan. Credit: Pindi Setiawan

10. Figurative painting, Borneo (Kalimantan). As Carl Zimmer excellently introduced this in his NY Times piece: “On the wall of a cave deep in the jungles of Borneo, there is an image of a thick-bodied, spindly-legged animal, drawn in reddish ocher. It may be a crude image. But it also is more than 40,000 years old…making this the oldest figurative art in the world.” While older pieces of “art” have been discovered elsewhere in the world, they were mostly abstract lines and patterns. Some scientists think the switch to figurative art (like animals) marks an important shift in how humans think about the world around them.

To find this type of ancient art in Borneo is surprising, in part because we know something similar was happening around the same time in Europe. What does that mean? That an important shift was “essentially happening at the same time at the opposite ends of the world,” as Maxime Aubert, an archaeologist at Griffith University, put it. I could go on about how cool this is to think about, but instead I’ll just provide the link and leave you with an image of how hard it was to get to this cave site in Kalimantan: the team had to travel upriver by boat into the rainforest, backpack up mountains for days, and hack a path with machetes. Impressive stuff.

9. Neanderthal teeth, France. In a study that some scientists have called “mind blowing,” the intimate details of the lives of two Neanderthal toddlers and their mother were revealed. A close look at the teeth of these Neanderthals shows that lived through some harsh winters and were even exposed to lead. The study provides “powerful insight into some of the most intimate moments of life—the relationship between the Neanderthal as a baby and its mama,”  as paleoanthropologist Leslea Hlusko put it.

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Neanderthal tooth. Credit: Tanya Smith/Griffith University

8. Neanderthal cave art, Spain. Scientists recently dated cave art deep in three caves located in Spain. The art, which includes a series of ladder-like shapes, dots, and handprints, appear to have been created about 64,000 years ago. Why is this a big deal? Well, as far as we know, the only hominins who appear to have been living in Spain 60,000 years ago were Neanderthals. That means this is possible Neanderthal art! The researchers who published this shocking study waited three years to publish their results after finding the first clearly pre-human date, anticipating objections about the dating method. They worked to collect multiple examples and published their entire methodology. There still are some skeptical opinions, but it’s certainly exciting to think about.

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Neanderthal art? Credit: P. Saura

7. Butchering animals, Algeria. The strongest evidence of early humans having butchered animals in North Africa was announced this year. The evidence came in the form of stone tools that date to 2.4 million years ago. This discovery suggests that East Africa was not the only location for early stone tool technology, and that there could have been multiple origins points or even exchange between the two areas. Among other things, this find is a nice reminder that preservation has the potential to craft the story in powerful, sometimes misleading ways. As Chris Stringer commented, “We should beware of building elaborate origins scenarios based on where we have the best preservation.”

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Algeria tools. Credit M Sahnouni

6. Dating Sterkfontein, South Africa. Trying to date hominin fossils in South Africa has long been a nightmare. In comparison to East Africa, where volcanic explosions provide a nice timeline, South African rocks have eluded many dating methods for the deep past. Until now. By looking closely at flowstone layers, a team of scientists has begun to paint a more precise picture of the timing of depositional events in multiple cave chambers within the Cradle of Humankind, creating a better timeline of human evolution there. “This is the most important advance to be made since the fossils themselves were discovered,” paleoanthropology Bernard Wood commented on the study. “Dates of fossils matter a lot. The value of the southern African evidence has been increased many-fold by this exemplary study of its temporal and depositional context.” As a historian who has been working on a history of these sites over the course of the last century, it strikes me that the dating of the fossils has been a problem from day 1. Therefore, this advance is crazy cool.

5. Rhino butchering, Luzon. If each of us created our own list, I can guarantee no two would look the same. With that in mind, I might be putting this find higher than most, would but that shouldn’t surprise many of you, given my current fascination with SE Asia. This year, scientists announced a fossilized Ice Age rhinoceros that had been butchered on the island of Luzon, Philippines. The date of this butchery? About 700,000 years ago! That’s a crazy long time ago. Who butchered the rhino? This is the best part: we don’t know! We don’t really even know who was in the Philippines at this time. It seems unlikely that it would have been Homo sapiens, given that there’s no evidence they were around this part of the world yet. Maybe it was Homo erectus? Or, just maybe, it was a creature related to their island neighbors, Homo floresiensis? Pure speculation, of course. Either way, the rhino suggests that early hominins were more widespread than previously thought in island Southeast Asia.

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Butchered Rhino. Credit: Thomas Ingicco

One lesson from this find is, as paleoanthropology Adam Brumm put it, “it’s now becoming increasingly clear that ancient forms of hominins were able to make significant deep-sea crossings.” That’s pretty wild. On that note, I have to add that on Flores, years passed in which archaeologists examined tools from mystery hominins before the tool makers themselves—the hobbits—were uncovered. Could a similarly shocking discovery follow this early glimmer of evidence in the Philippines? We still need some hominin fossils to know who dined on this rhino many years ago, but I will remain hopeful that it could be something as crazy as a hobbit. Oh, the possibilities.

4. Little Foot, South Africa. After almost two decades of waiting, and seeing a sneak peek this time last year, the Little Foot skeleton from South Africa is finally published. After a long and difficult excavation, the specimen from the Sterkfontein caves recently emerged in a series of papers that examined the head, the foot, the endocast, and other parts of the skeleton. There’s even a paper on Little Foot’s inner ear! The publications haven’t come without controversy, but now that the data is out there, the comparative work, influx of alternative opinions, and overall magic of science can now begin. (By magic, I mean the testing and retesting of hypotheses that will unfold and help scientists reach a better understanding of the particulars of this incredible skeleton. Interestingly (and controversially), the researchers named Little Foot to the species Australopithecus prometheus, a name given to a skull fragment in 1948 by Raymond Dart, which has since fallen by the wayside.

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Little Foot, Australopithecus prometheus.Credit: Ron Clark

3. Misliya jaw, Israel. It feels like a decade ago now, but in January we learned of a new fossil from the Misliya Cave that upends our understanding of when humans left Africa. The jaw and associated teeth date to around 177,000–194,000 years ago. At that age, these fossils hold the record for earliest modern-human outside Africa. As a historian, I love this find even more because it’s from a cave on Mt Carmel, which has been a fascinating site of research since the 1920s when legendary archaeologist Dorothy Garrod first ran excavations there (think Skhul and Qafzeh). Also, it is truly one beautiful maxilla (upper jawbone).

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Misliya upper jaw. Credit: Israel Hershkovitz, Tel Aviv Univ.

2. 2 million-year-old artifacts, China. Every now and then, there’s a discovery that is difficult to even wrap your head around. This discovery, for me, is that. Researchers recently announced that they found stone tools in modern-day China that date back to 2.1 million years ago. This date means that hominins were living their lives, making tools, outside Africa earlier than scientists previously knew. Which hominins? Again, we don’t know–we only have their tools. The site, a place named Shangchen, has revealed 96 stone tools that look fairly similar to tools made in Africa about the same time. What were the stone tools used for? Scientists don’t know yet. But wow, the implications. Asia is one of the places to keep an eye on for paleoanthropological discoveries if you ask me!

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Stone tools, China. Credit: Zhaoyu Zhu, Nature

1.Denny, Siberia. Despite my unabashed affinity for fossils, it has been ancient DNA find that have topped my list the last couple of years—and this year is no exception. That is because, every year, a study has appeared that makes me feel like we are living in a science fiction novel. This year, it was Denny. Denny is an incredible sliver of bone that was sequenced for its ancient DNA. It turns out, this bone fragment came from an individual whose father was a Denisovan and whose mother was a Neanderthal. To find such a rare “hybrid,” the direct offspring of two types of hominins, was so shocking that the scientists first thought it was an error.

As population geneticist Pontus Skoglund put it: “To find a first-generation person of mixed ancestry from these groups is absolutely extraordinary. It’s really great science coupled with a little bit of luck.” Denny has even been called “the most fascinating person who’s ever had their genome sequenced.” For more about the amazing methodology that led to the discovery, be sure to check out this wonderful piece by one of the authors about how they discovered Denny: “It all started with a piece of bone, so small that it was impossible to tell that it was human…”

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Denny. Credit: Thomas Higham/University of Oxford

Conclusion: “the world was a much more interesting place not that long ago.”

That’s my list for 2018! It seems to me it’s been an incredible year for the science. Do you agree, disagree, think I missed something huge? One of the unexpectedly fun things about writing these end-of-the-year roundups is getting to see the continuity in the discoveries over the years. Look closely and you see knowledge building, techniques being refined, and ideas advancing. Undoubtedly, you also see these advances lead to overturning certain aspects of what scientists thought they knew about the past.

So it’s not that everything you thought you knew about human evolution is wrong. It’s just that, in 2018, we learned (once again) that the past was immensely complicated. There was a lot was going on, from multiple species’ existence, to intermixing and diverse migrations, to independent technology invention. Any simplified image of a lone Homo sapiens species or its ancestor has clearly never been further from the truth. And, quite honestly, doesn’t that make the whole thing more fun? Speaking about the complexity of genetics in recent human evolution, Josh Akey of the University of Washington recently said: “If we look around the world today, we are really the only hominin game in town. People assume that’s the way it must have always been. In fact, the world was a much more interesting place not that long ago.

It seems to me this is true everywhere we look, from genetics to the fossil record. It’s this idea that keeps me excited about the science of human evolution. Cheers to another amazing year, a sincere thank you for all of the scientists who labored for years (sometimes decades) to bring us these discoveries, and fingers crossed as we look ahead to a wonderful 2019.

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