Archive for February 23rd, 2007
Spider monkeys already know: Sometimes you need a hug.
Animals that live in groups often break into smaller groups (fission), and later recongregate (fusion). Fission-fusion behavior is often tied to resource availability, 
but can also be related to social dynamics (competition among group members can lead to conflict, and breaking into smaller groups can alleviate the conflict). While fissioning into subgroups can relieve tension and conflict, bringing the subgroups back together can often be a trigger for aggression.
Spider monkeys live in groups, and break into smaller groups to hunt and eat. It has been noted for some time that when hunting parties return to the larger group, those returning often embrace the waiting spider monkeys.
Scientists from the UK studying two populatations of spider monkeys in the Yucatan have observed that the individuals who engage in this hugging are much less likely to behave in an aggressive fashion, either to each other or to others in the larger group.
Filippo Aureli and Collene Schaffner believe theirs is the first evidence for deliberate conflict management at fusion, and believe it may indicate the reason for similar greetings exhibited by other fission-fusion species such as spotted hyenas, bonobos, and humans.
- Morell V (2007) Hug it out, Monkey. ScienceNOW 21Feb
- Aureli F and Schaffner CM (2007) Aggression and conflict management at fusion in spider monkeys. Biology Letters, Vol 3, no. 2. (published early online)
Little Rock Zoo’s gorilla family, Sekani, Fossey & Mosi playing
Alright, I’m assuming that if I need a break from our recent discussions on chimps using spears, stress & primate physiology, ethics, and new species then so do you. So, to break the monotony here’s a set of entertaining and heart-warming videos of one of Little Rock Zoo‘s 
gorilla families.
In the first video you will see Sekani, the mother, and Fossey, the big bad softy of a silverback dad, enjoying a play bout while 3 month old Mosi goes along for the ride. The second video, you will be seeing Fossey bonding with his little one. The videos show how gentile and docile gorillas can be to one another.
Please thank Daphne Brock Pfeiffer, one of the gorilla keepers for uploading this to YouTube and sharing this all with us. There is also a photo album of the trio up over here, I especially like this tender moment between father and child here.
Don’t expect this break to last very long, I’ll be posting about a new publication with reanlayzes the human divergence from other great apes, as well as a paper on primate brain evolution.
One more word on, and a video of, chimps hunting with spears
Two more things about the chimps using spears to hunt other primates.
Firstly, it looks like Christopher Mims is just as unsurprised as I have been about the news of the chimps using spears to hunt. He outlines why, in the form of what we already know about chimpanzees. I skimmed over these reasons, so here’s his list, albeit a bit truncated (you should check out his list for examples):
- They use objects in their environment as tools.
- Chimpanzees modify objects in order to make them more effective tools.
- Tool use varies from one population of chimps to another–in other words, chimps exhibit variations in culture.
- Chimps learn by observation and practice how to make and use tools–in part, they learn by imitation.
Amidst all this press and blogosphere hype it is good to have a voice of reason to outline that this is not particularly breakthrough research. All the other work both Christopher and I mentioned supports the fact that chimps are capable of this behavior, if not more.
The only truly extraordinary aspect of this finding is if chimps are really making spears, with a sidenote that females are hunting with spears more than males.
Which is the second thing I wanted to address in this post. The paper mentions the Savanna chimps exhibited spear making over 20 times, however they include only 1 image of a spear. You’d think they’d have several examples of spears, no? Also, the video I linked up didn’t quite capture the hunt. This is a bit curious.
I’ve uploaded the various clips the authors provided in the supplemental materials to the paper over on YouTube. You can judge for yourself what you see or don’t see. Here it is:
