29 posts · 32,128 views
In primates, it has been noticed that if you live in a competitive mating system and you’re a male, you’ll have a very fancy penis. Maybe some spines, or a few ridges here and there. These embellishments are keratinous structures and act to promote rapid ejaculation, which is useful if you’ve got nine other males [...]... Read more »
Seney, M., Kelly, D., Goldman, B., Šumbera, R., & Forger, N. (2009) Social Structure Predicts Genital Morphology in African Mole-Rats. PLoS ONE, 4(10). DOI: 10.1371/journal.pone.0007477
I’ve been working on a post about Grehan and Schwartz’s new orangutan paper, but I’ve been getting sidetracked by teaching and doing my own research along the way. To make matters worse, a friend was telling me about an anteater that he saw at the zoo and mentioned that it was a knuckle-walker! I wondered [...]... Read more »
Orr, C. (2005) Knuckle-walking anteater: A convergence test of adaptation for purported knuckle-walking features of african Hominidae. American Journal of Physical Anthropology, 128(3), 639-658. DOI: 10.1002/ajpa.20192
Salvador Moyà-Solà and his colleagues describe a new Miocene Hominoid in this week’s PNAS. They’ve dubbed it Anoiapithecus brevirostris, and it hails from what is now Spain. Like many other Miocene apes, it’s a mix of the primitive and the derived, the unique and the shared. It’s commonly said that apes were as diverse in [...]... Read more »
Moya-Sola, S., Alba, D., Almecija, S., Casanovas-Vilar, I., Kohler, M., De Esteban-Trivigno, S., Robles, J., Galindo, J., & Fortuny, J. (2009) A unique Middle Miocene European hominoid and the origins of the great ape and human clade. Proceedings of the National Academy of Sciences. DOI: 10.1073/pnas.0811730106
We’ve already covered Ardi’s hands here, so let’s move on to what is possibly the most interesting aspect of her skeleton: The feet.
As humans, we have pretty special feet. They’re good at dissipating all of the force that comes with walking on only two feet. They’re also good at propelling us forward, since [...]... Read more »
Lovejoy, C., Latimer, B., Suwa, G., Asfaw, B., & White, T. (2009) Combining Prehension and Propulsion: The Foot of Ardipithecus ramidus. Science, 326(5949), 72-72. DOI: 10.1126/science.1175832
Alternative mating strategies!
When we learn about sexual selection theory, we usually learn about it as a binary system: Females choose males, and males try to be chosen. Female peahens choose male peacocks with the most and prettiest eyespots because it’s an indicator of their health, and she wants healthy offspring. Female deer choose bucks [...]... Read more »
Mark D. Norman, Julian Finn, & Tom Tregenza. (1999) Female impersonation as an alternative reproductive strategy in giant cuttlefish. Proceedings of the Royal Society B, 1347-1349.
HARRISON, M., & CHIVERS, D. (2007) The orang-utan mating system and the unflanged male: A product of increased food stress during the late Miocene and Pliocene?. Journal of Human Evolution, 52(3), 275-293. DOI: 10.1016/j.jhevol.2006.09.005
Hunt, J., & Simmons, L. (2001) Status-dependent selection in the dimorphic beetle Onthophagus taurus. Proceedings: Biological Sciences, 268(1484), 2409-2414. DOI: 10.1098/rspb.2001.1758
The femur can be an extremely informative bone when reconstructing the locomotor behaviors of fossil primates. The head and neck are particularly informative. The morphology of the head can tell you how flexible the hip joint is. If you can get a good CT scan, the distribution of cortical bone at the [...]... Read more »
Lovejoy, C., Suwa, G., Spurlock, L., Asfaw, B., & White, T. (2009) The Pelvis and Femur of Ardipithecus ramidus: The Emergence of Upright Walking. Science, 326(5949), 71-71. DOI: 10.1126/science.1175831
Meet the White-faced Saki, Pithecia pithecia. P. pithecia lives in South America, where it scampers about the low canopy eating the seeds of fruit with tough outer shells. To get through those tough outer shells, it has robust, stout canines that are able to pierce the skins and dig out the soft fruit and seeds [...]... Read more »
Beard, K., Marivaux, L., Chaimanee, Y., Jaeger, J., Marandat, B., Tafforeau, P., Soe, A., Tun, S., & Kyaw, A. (2009) A new primate from the Eocene Pondaung Formation of Myanmar and the monophyly of Burmese amphipithecids. Proceedings of the Royal Society B: Biological Sciences. DOI: 10.1098/rspb.2009.0836
Last night, I was sleeping soundly. I don’t have AC, so the windows were open and my ceiling fan was on. I woke up rather suddenly, and it took me a minute to realize that there was something else in my room… something really flappy and kind of loud. A bat!
I’m doing some work with [...]... Read more »
Ryan, M. (1998) Sexual Selection, Receiver Biases, and the Evolution of Sex Differences. Science, 281(5385), 1999-2003. DOI: 10.1126/science.281.5385.1999
Rodd, F., Hughes, K., Grether, G., & Baril, C. (2002) A possible non-sexual origin of mate preference: are male guppies mimicking fruit?. Proceedings of the Royal Society B: Biological Sciences, 269(1490), 475-481. DOI: 10.1098/rspb.2001.1891
As everyone has already heard by now, the long-awaited Ardipithecus ramidus has finally been published, and boy is she a beauty! So many “anatomical surprises”! There are so many strange and new things about this skeleton that it took an entire issue of Science to describe them. Clearly then, it will take a few blog [...]... Read more »
Lovejoy, CO., Simpson, S., White, T., Asfaw, B., & Suwa, G. (2009) Careful Climbing in the Miocene: The Forelimbs of Ardipithecus ramidus and Humans Are Primitive. Science, 326(5949), 70-70. DOI: 10.1126/science.1175827
Microcephaly is a disease in which the brain is smaller than normal. A small brain can result from several different developmental conditions. Babies can be born with normal-sized crania and brains which then fail to develop with the rest of the head, in which case it’s indicative of a neurodegenerative disorder that may be caused [...]... Read more »
WOODS, C., BOND, J., & ENARD, W. (2005) Autosomal Recessive Primary Microcephaly (MCPH): A Review of Clinical, Molecular, and Evolutionary Findings. The American Journal of Human Genetics, 76(5), 717-728. DOI: 10.1086/429930
Sherwood, C., Subiaul, F., & Zawidzki, T. (2008) A natural history of the human mind: tracing evolutionary changes in brain and cognition. Journal of Anatomy, 212(4), 426-454. DOI: 10.1111/j.1469-7580.2008.00868.x
HOLLOWAY, R. (2004) Posterior lunate sulcus in Australopithecus africanus: was Dart right?*1. Comptes Rendus Palevol, 3(4), 287-293. DOI: 10.1016/j.crpv.2003.09.030
What could possibly be a better Christmas present than a new fossil primate? Nothing, that’s what!
The most recent addition to our family bush is a Pliopithecine from Spain named Pliopithecus canmatensis. Pliopithecoids are gibbon-like in many ways, including their long limbs, large hands, and maybe the ability to brachiate. However, the pliopithecoids are much too [...]... Read more »
Alba, D., Moyà-Solà, S., Malgosa, A., Casanovas-Vilar, I., Robles, J., Almécija, S., Galindo, J., Rotgers, C., & Mengual, J. (2009) A new species of Gervais, 1849 (Primates: Pliopithecidae) from the Middle Miocene (MN8) of Abocador de Can Mata (els Hostalets de Pierola, Catalonia, Spain) . American Journal of Physical Anthropology. DOI: 10.1002/ajpa.21114
We had lots of clues that this was the case before Ardi, but now that we’ve got Ardi- the palmigrade extraordinaire, we know that humans did not go through a knuckle-walking phase, and that chimpanzee knuckle-walking has evolved since the split with our last common ancestor with them. Which would also means that it [...]... Read more »
Lovejoy, C., Simpson, S., White, T., Asfaw, B., & Suwa, G. (2009) Careful Climbing in the Miocene: The Forelimbs of Ardipithecus ramidus and Humans Are Primitive. Science, 326(5949), 70-70. DOI: 10.1126/science.1175827
Well-informed skepticism is the best!
Earlier this week, Eric Michael Johnson drew my attention to a post by psychologist Christopher Ryan at his blog Sex At Dawn. Ryan attacks Lovejoy’s monogamous humans model by citing many different lines of evidence.
I became so distracted by the reported testes:body mass ratio of 1/160 in humans that I couldn’t [...]... Read more »
Lovejoy, C. (2009) Reexamining Human Origins in Light of Ardipithecus ramidus. Science, 326(5949), 74-74. DOI: 10.1126/science.1175834
Frisch, J. (1963) Sex-differences in the canines of the gibbon (Hylobates lar). Primates, 4(2), 1-10. DOI: 10.1007/BF01659148
Leutenegger, W., & Kelly, J. (1977) Relationship of sexual dimorphism in canine size and body size to social, behavioral, and ecological correlates in anthropoid primates. Primates, 18(1), 117-136. DOI: 10.1007/BF02382954
February 21-27 is National Eating Disorders Awareness Week. I have a history of some pretty disordered eating which landed me in the hospital a few years back, but it’s not something that I’m extremely comfortable talking about. In the spirit of “awareness,” I’ve decided that it’s something I should talk about more. In my personal [...]... Read more »
Frank, G. (2000) CSF oxytocin and vasopressin levels after recovery from bulimia nervosa and anorexia nervosa, bulimic subtype. Biological Psychiatry, 48(4), 315-318. DOI: 10.1016/S0006-3223(00)00243-2
Knuckle-walking is a pretty special mode of locomotion. Amongst primates, only the African apes do it habitually, and anteaters are the only other mammal who does it. It would seem, then, that the most parsimonious explanation for such a specialized form of locomotion would be that the African apes all share a common [...]... Read more »
Kivell, T., & Schmitt, D. (2009) Independent evolution of knuckle-walking in African apes shows that humans did not evolve from a knuckle-walking ancestor. Proceedings of the National Academy of Sciences. DOI: 10.1073/pnas.0901280106
RENDALL, D., & DIFIORE, A. (2007) Homoplasy, homology, and the perceived special status of behavior in evolution. Journal of Human Evolution, 52(5), 504-521. DOI: 10.1016/j.jhevol.2006.11.014
Blythe Williams, Richard Kay, and Christopher Kirk have published a new article in the PNAS which does a very nice job in synthesizing some new fossils and new genetic data with current hypotheses for the origins of anthropoids, the group which includes old world monkeys (catarrhines), new world monkeys (platyrrhines) and apes (hominoids).
One of the [...]... Read more »
Williams, Richard Kay, Christopher Kirk and Callum Ross have published a new paper in the Journal of Human Evolution reassessing the phylogenetic placement of Darwinius masillae, the much-hyped Adapid fossil published last summer. Brian Switek at Laelaps and Eric Michael Johnson at The Primate Diaries have written some excellent posts summarizing the most recent [...]... Read more »
Williams, B., Kay, R., Christopher Kirk, E., & Ross, C. (2010) Darwinius masillae is a strepsirrhine—a reply to Franzen et al. (2009). Journal of Human Evolution. DOI: 10.1016/j.jhevol.2010.01.003
Franzen, J., Gingerich, P., Habersetzer, J., Hurum, J., von Koenigswald, W., & Smith, B. (2009) Complete Primate Skeleton from the Middle Eocene of Messel in Germany: Morphology and Paleobiology. PLoS ONE, 4(5). DOI: 10.1371/journal.pone.0005723
The following guest post by Eric Michael Johnson is part of the Primate Diaries in Exile blog tour. You can follow other stops on this tour through his RSS feed or by following him on Twitter. If this is your first time visiting A Primate of Modern Aspect make sure to browse some of the [...]... Read more »
McLean, C., Reno, P., Pollen, A., Bassan, A., Capellini, T., Guenther, C., Indjeian, V., Lim, X., Menke, D., Schaar, B.... (2011) Human-specific loss of regulatory DNA and the evolution of human-specific traits. Nature, 471(7337), 216-219. DOI: 10.1038/nature09774
BMC Biology has recently published a paper (It’s Open Access!) which explores trends in brain size in the Primates. A trend toward a larger brain is usually considered one of the “hallmarks” of the Primates, but Stephen Montgomery and his colleagues have shown that in many lineages, there is a trend towards secondarily “shrunken” brains.
The [...]... Read more »
Montgomery, S., Capellini, I., Barton, R., & Mundy, N. (2010) Reconstructing the ups and downs of primate brain evolution: implications for adaptive hypotheses and Homo floresiensis. BMC Biology, 8(1), 9. DOI: 10.1186/1741-7007-8-9
A new paper published in PLoS ONE by David Carrier tests the hypothesis that bipedalism in humans evolved because it helps them to fight better. The first fatal flaw lies in the first sentence: Many quadrupedal animals stand on their hindlimbs to fight. How then, does this explain human uniqueness? Clifford Jolly wrote in The [...]... Read more »
Carrier, D. (2011) The Advantage of Standing Up to Fight and the Evolution of Habitual Bipedalism in Hominins. PLoS ONE, 6(5). DOI: 10.1371/journal.pone.0019630
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