Bursting the Limits of What’s Possible: Best Paleoanthropology of 2016

Last year’s hero, naledi

It almost goes without saying, but 2016 has been a tough year. However, we did learn a lot in the realm of paleoanthropology this year (as we do every year)! And because focusing on the positive is a good coping strategy, I think a look back the incredible science announced this year is in order. Last year I wrote that 2015 would be a hard year to beat–indeed, the announcement of 1,500 fossils of a brand new species (naledi) is hard to beat.But despite not surpassing 2015’s find of a lifetime, 2016 did have its fair share of surprises and interesting discoveries. So I’m counting down my favorites. Here we go!

10. Homo erectus footprints. Scientists working in Kenya uncovered 97 footprints from approximately 20 Homo erectus individuals, dating back to 1.5 million years ago. Some argue that these beautifully preserved tracks could be interpreted as human-like social behavior because these tracks suggest a cooperative group all in motion together.

9. Lucy’s death. This year, some scientists suggested that our favorite ancestor, Lucy, might have died from falling out of a tree. Full disclosure: I don’t really buy this argument, but I include this in my countdown because I think it raises interesting issues. Most importantly: why do we care some much about how this individual died 3 million years ago? I wrote about this in another post, examining the fascinating phenomenon that captures our imaginations when this box of old bones becomes imagined as a living, breathing creature who may or may not have fallen out of trees.

8. Neandertal genes. By now, we know that modern humans interbred with Neanderthals on multiple occasions. Of course, then, their genes became mixed in with ours, and some have been carried to the present. Using modern medical records in new and interesting ways, scientists are beginning to identify the lasting legacy of Neandertal genes that live in our bodies. Are they affecting our health or are they simply useless? We are starting to get glimpses of answers to these questions, Ed Yong covers this story.

7.  Tooth size in our ancestors. A super cool study looks at the role of development in determining hominin tooth size. This study proposes a rule that governs how tooth size evolves in hominins, which is especially interesting in the case of Homo, who tend to have unique tooth proportions. This rule is exciting because it is predictive, making it a testable way to examine the evolution of teeth.

Australopithecus footprints (Raffaello Pellizzon)

6. Chewie’s footprints. 3.66 million years ago, a couple of Australopithecines were walking across what is now Tanzania, and scientists have recently discovered their footprints. One of the tracks was made by an Australopith who–based on body size calculations–seems to have been bigger than other A. afarensis we’ve ever found, standing at 1.65 meters tall. Scientists have nicknamed him Chewie, after Chewbacca!

5. Ancient cancer. This year scientists announced the discovery of a malignant tumor on an ancient toe bone from Swartkrans cave, South Africa. The bone is approximately 1.7 million years old, making this is the first evidence that cancer is embedded deep in the human evolutionary past.

Sculpture Garden (Michel Soulier/CNRS via AP)

4. New Homo naledi studies. The discovery that electrified 2015 was 1,500 bone fragments, found deep in a South African cave. A discovery of this magnitude meant that analyses would take some time. Indeed, in 2016 we learned a little bit more about naledi, pretty much confirming the major message from the first round of analyses: these fossils are crazy. Through examinations of naledi‘s arm, leg, and skull, scientists showed that these hominins exhibit an incredible mixture of primitive, modern, and unique traits. For example, naledi‘s shoulder and upper arm are very primitive, while it’s lower arm looks more modern. What to make of this? Stay tuned as the analyses keep rolling in!

3. Neandertal sculpture garden. 176,000 years ago, a bunch of Neandertals deliberately broke hundreds of pieces of stalagmites and arranged them in rings and piles. This find, buried deep in a cave in France, raises a ton of interesting questions. Why construct these things? We don’t know. Some have argued this was some sort of a “meeting place” for a type of “ritual social behavior.” This is a very human thing to do–and it’s making some people reexamine what they thought they knew about Neandertals. Ed Yong wrote a great piece about the find and check out Nature‘s video as well. I like to think of this as interior decorating.

Mata Menge Mandible (Kinez Riza)

2. Hobbit ancestors from Mata Menge. It’s no secret I’m a big fan of Homo floresiensis (the hobbit), a fossil species found back in 2003 on the Indonesian island of Flores. In 2016, we learned where these hobbits may have come from. The 700,000 year old Mata Menge fossils appear to be the hobbit’s ancestors. The Mata Menge remains, which consisted of a partial jaw and a few scattered teeth, were found only 74 kilometers away from the hobbit site! Like the hobbit, this jaw was incredibly small. The coolest thing about this discovery is that it proves the hobbits were not diseased modern humans, but were indeed a true hominin species with their own evolutionary history. These little creatures are an interesting evolutionary experiment, “It’s kind of like Flores is its own little laboratory of early human evolution,” one researcher said.

1. Nuclear DNA from Sima de los Huesos. 430,000 year old fossils from the wonderful Sima de los Huesos (Pit of Bones) site in Spain have yielded part of their nuclear genome. Let’s put this into context quickly: in the not-too-distant-past, we didn’t even know if DNA could survive in bones after death. Then, we didn’t know if DNA could survive and be sequenced in 40,000 year old Neanderthals. Now, scientists are sequencing genomes of creatures almost half a million years old–truly a difficult task. What did we learn from this DNA? It suggests that the Sima hominins are very likely the ancestors of Neandertals, which pushes back in time when we should be looking for the common ancestor of Neandertals and humans.
   

   Powder from a Sima femur (Javier Trueba)

Paleoanthropologist Maria Martinón-Torres beautifully summed up the degree of incredibleness about this find: “it’s like science fiction.” I couldn’t agree more. “We are really reaching the limits of what is possible,” an ancient-DNA specialist also commented. I would take this one step further and say this has not only reached, but broken, some previous ceilings. Breakthroughs like this challenge the limits we set for ourselves, pushing the boundary of what we think is knowable. And that, to me, demands a number one slot.

Conclusion

So overall, while we can’t quite top a year as epic as 2015 (what do you mean, scientists don’t discover a crazy cache of new fossils every year?!), I’d say 2016 was pretty darn cool for paleoanthropology. I want to hear from you, which discoveries especially brightened your year, challenged you to think in new ways, or just completely surprised you? When I get down about the state of humanity, I remember incredible scientific findings like these and it helps give me hope. This is especially true in the field of human origins because I believe the more we know about ourselves and our past, the better we will be able to shape our future. Cheers to 2016, here’s hoping 2017 is a better year for humanity.