Anthro News

#MeetAlesi

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So, the big fossil news that the Leakey Foundation was teasing when last I posted? It was this:

Alesi_anterior view
Anterior view of the cranium of Nyanzapithecus alesi (Nengo et al. 2017)

BS&M Blog readers, meet Nyanzapithecus alesi, a new 13 million-year-old Miocene ape from Kenya. HOW COOL IS THAT?!

I will tell you how cool. VERY COOL. I’m biased (as always – because I pick the things I want to write about for the blog, which are things that I think are very cool), but seriously. There are a bunch of reasons this discovery is awesome, like:

1) You don’t often find complete crania (the skull minus the jaw) of fossil apes. Typically, the bones at the back of the skull (the ones that form the brain case) break sometime before a fossil is found (if it’s found at all, which is a whole different issue). If you want to become a primate fossil, it takes specific circumstances and a lot of luck.

2) You really don’t find fossil ape crania in Africa dated to between 10-14 million years old. Alesi is it. Other fossil ape partial crania are known from this time period in Europe (Pliobates cataloniae at 11.6 mya and Pierolapithecus catalaunicus at 12.5-13 mya from Spain, and Rudapithecus hungaricus at 10 mya from Hungary, to name a few) and Asia (Sivapithecus indicus at 12.3 from Pakistan), which might say something about where fossil apes originated or it might either be the result of less digging having happened in Africa resulting in a deficient fossil record or the difficulty in identifying the earliest apes.

MioceneApe_crania
Pliobates (Alba et al. 2015), Pierolapithecus (Moya-Sola et al. 2004), and Rudapithecus (Begun et al. 2012). (Left to right)

3) You also rarely find infant material in the primate fossil record. (Yes, I know, the Taung Child is an exception to this rule, too.) Infant bones are smaller and more fragile than those of adults, which makes them even less likely to fossilize and be recovered later.

Alesi is also awesome, simply by virtue of being a Miocene ape (my Miocene bias is definitely showing). The Miocene (23-5.3 mya) often gets called a “planet of the apes” because there was a huge diversity of hominoids (the fancy taxonomic group name for apes, including us, is Hominoidea) that lived through Europe, Africa, and Asia at that time. Which is SUPER AWESOME because they were “experimenting” with different types of locomotion at that time (which is totally my jam), but also makes it really hard to tell our potential ancestors from our side-branch cousins. A classic problem for people who work on Miocene apes is that they have ape faces and monkey bodies, and the field disagrees about which is more important (the face or the body) for figuring out who is related to who. Hopefully one of the authors of the Alesi paper (shout out to Kelsey Pugh!) will be able to work some of these relationships out with her dissertation research.

My final thought/question (for now) on Alesi is: the authors suggest that gibbon-like features evolved in parallel several times in different branches of the hominoid lineage – why couldn’t these features be ancestral, rather than derived? If that was the case, it would just require that a different set of facial features evolved in parallel instead. So why the gibbon-like ones and not the other ones?

That’s all for now! Hopefully BS&M will be back on September 8th – catch you then!

References
Alba, D.M., Almécija, S., DeMiguel, D., Fortuny, J., de los Ríos, M.P., Pina, M., Robles, J.M. and Moyà-Solà, S. (2015). Miocene small-bodied ape from Eurasia sheds light on hominoid evolution. Science350(6260), aab2625.

Begun, D. R., Nargolwalla, M. C., & Kordos, L. (2012). European Miocene hominids and the origin of the African ape and human clade. Evolutionary Anthropology: Issues, News, and Reviews21(1), 10-23.

Moyà-Solà, S., Köhler, M., Alba, D. M., Casanovas-Vilar, I., & Galindo, J. (2004). Pierolapithecus catalaunicus, a new Middle Miocene great ape from Spain. Science306(5700), 1339-1344.

Nengo, I., Tafforeau, P., Gilbert, C.C., Fleagle, J.G., Miller, E.R., Feibel, C., Fox, D.L., Feinberg, J., Pugh, K.D., Berruyer, C. and Mana, S. (2017). New infant cranium from the African Miocene sheds light on ape evolution. Nature548(7666), 169.

Anthro News

Big-headed babies and manspreading

August has arrived, the summer is winding down, and those anthropologists lucky enough to be off doing fieldwork have started to come home. A new academic year will begin soon and, with it, the official resumption of the Bones, Stones, and Monkeys journal club! I’m looking forward to getting some new, interesting discussion posts going, but for now, two more pieces of anthro news.

This week’s news comes from the world of #scicomm (aka, public science communication). Science communication/outreach is definitely picking up steam as a major movement lately (though it has always been important) and some excellent #scicomm is being done by anthropologists. We’re lucky enough to study something that people always seem to find interesting – themselves!

First up, Dr. Julienne Rutherford (U. Illinois – Chicago) gave a public radio interview about how modern birth practices might affect human evolution. The overarching question this type of research is trying to answer is, essentially, how does culture interact with and shape biological evolution. Humans babies have relatively large heads compared to those of most other primate babies, which tends to make giving birth difficult. We’ve gotten around the complications of this issue culturally via C-section, but before surgical interventions were possible the size of a baby’s head was a serious selective pressure on birth canal size – too large a head could mean death for both mother and infant. With that pressure removed, Dr. Rutherford suggested that we could potentially see even more variation in female pelvis/birth canal size and somewhat bigger-headed (though not super genius) babies as a result. I’d be curious to see estimates of how long it might take for infant head size/female pelvis size and shape to decouple, given that there has been some cool previous research on how these two things are linked.

Next up, Dr. Caroline VanSickle threw down about “manspreading.” Spoiler alert – it’s a cultural phenomenon, not a biological one. Basically, an emeritus kinesiology professor suggested in an interview that manspreading is the result of sexual dimorphism (sex-related differences in appearance/shape/size) between the male and female pelvis. Specifically, the narrow pelvis of men causes their hip joints to pinch when their knees are together – an issue that is allegedly alleviated by manspreading. Dr. VanSickle shoots this down as not being a biological reality. Behavior isn’t determined by one’s skeleton, which changes during life depending on what you do with it. We call this Wolff’s Law (and I’m probably biased in my enthusiasm for her invocation for it – my entire dissertation was on Wolff’s Law and the pelvis). In addition to being able to shape your skeleton with your behavior, she also mentions research showing that manspreading does not occur in all cultures or with the same frequency between cultures. Personal bias aside, Dr. VanSickle’s case against biological determinism as an excuse for rude behavior was nicely made, so let’s all just keep our knees to ourselves on public transportation, okay?

That’s all I’ve got today from the world of anthro news! The Leakey Foundation tweeted today that they have “exciting fossil news to share tomorrow,” so stay tuned!

Disclaimer: I know Caroline (as I’ve said before, the pelvis world is small). She’s still right. 

Further Reading
Fischer, B., & Mitteroecker, P. (2015). Covariation between human pelvis shape, stature, and head size alleviates the obstetric dilemma. Proceedings of the National Academy of Sciences112(18), 5655-5660.