Spear Wielding Chimps Hunt for Dinner!
We tend to think of the stereotypical Chimpanzee as an active, zany creature who eats bananas and kind of hangs out with other chimpanzees; well it seems nothing could be further from the truth. Researchers at the University of Iowa have documented numerous observations of chimpanzees fashioning spears from tree branches and using them to hunt prey called lesser bush babies. Dr. Jill D. Pruetz of Iowa State University in Ames, Iowa was head of the research team that documented 22 separate instances where the chimpanzees in the study used makeshift spears to capture smaller primates for eating.[1](www.current-biology.com) Members of a chimpanzee population at a habitat in Senegal were closely studied by field observers as they repeatedly went through a five step routine to spear prey. Amazed researchers watched as the chimpanzees went through a routine of preparation once a potential nest was located. Hunters were seen choosing branches of sufficient length and weight that could be pushed into a nest to immobilize prey, breaking these branches off of the tree, then stripping the leaves and side branches before trimming the end (in some cases they trimmed both ends) and using their teeth to sharpen the end to a point.
Apparently they were not just using tools to procure their prey, Dr. Pruetz' team also observed them sniffing and licking the points of their spears after pushing them into nests, thus adding a sensory dimension to the process. According to Dr. Pruetz, "almost without fail, every time they would withdraw the tool, they would sniff it or lick it, and then proceed to stab it in there again." All of this sniffing and licking had a purpose; it let the tool wielding apes know if their hunting implement had hit the mark.
Dr. Pruetz commenting on the deliberateness of these actions was astounded by the connection remarking,"… they did it so forcibly that our assumption is the bush babies would have been injured if there were bush babies in the hollow." What does this mean in the greater scheme of things? Well quite a lot actually.
During all of the 22 observed instances the chimpanzee hunters were immature males and adult females. Observing this particular segment of the population doing the hunting for live prey is stunning news to the scientific community. It lays the groundwork for further study of the historical role of females in the use of tools to acquire prey and how this skill may have impacted human evolution. This research took place is an open savannah; an environment similar to what evolutionary biologists think may have supported the earliest humans of our species. Dr. Pruetz, an anthropologist, sees chimpanzees as a not-so-distant cousin to modern humans. "Looking at our closest living relatives in a habitat that is fairly similar to what we see characterizing early hominids six million years ago can help researchers understand early human ancestors' behavior and ecology," she said. [2](www.anthr.iastate.edu/pruetz.shtml)
As with any observed phenomenon in animal behavior that can only be described as ground breaking, there is a mini-controversy over the use of the word 'spear'. Since the chimps are wielding the spear and not actual throwing it at prey, Craig Stanford, a primatologist at USC, prefers the term "bludgeoner".
[3](www.usc.edu/dept/elab/anth/FacultyPages/stanford.html) Whatever one chooses to call the teeth-sharpened tree branch used to procure a previously alive meal, the fact remains that apes do in fact use tools to hunt. Now if they could only learn to shoot back at the poachers who invade their protected habitat…that would be a true achievement!
I have posted a link [4](www.youtube.com/watch?v=NivAusARwd8) to a youtube video where chimps use tools to crack nuts. This opens up legitimate questions of 'learning'...do the younger ones learn by the example of the older chimps?...I will continue to check for other data relevant to questions raised in comments.
[1]Current Biology : http://www.current-biology.com/
[2]Jill Pruetz: www.anthr.iastate.edu/pruetz.shtml
[3]Craig Stanford : http://www.usc.edu/dept/elab/anth/faculty/stanford.html
[4]http://www.youtube.com/watch?v=NivAusARwd8
Posted by : Catherine Stubbington
Course Participant Bio 312
posted by PWH @ 3:35 AM
9 comments
9 Comments:
I would assume that there exists a relation between this primitive tool crafting, and the development of more complex tools in the Hominidae family. Australopithecus, an extinct Hominind, is assumed to have used tools nearly 4 million years ago (only a couple million years after the most recent common ancestor between humans and the chimpanzee) (cite 1). A complete anthropological pogression of tool development would be very interesting to see (and useful for chronological purposes).
It would be fascinating to delve back 7 millions years and observe our most recent common ancestor with the chimpanzee (cite 2). Would this ancestor display chimp/ primitive hominid behavior? or more specifically, would it wield tools and exhibit complex skills? Given insight into this new research, the notion of tool use doesn't seem impossible.
(cite 1)
http://www.ecotao.com/holism/hu_austral.htm
(cite 2)
http://www.sciencebuff.org/quotes_on_the_chimpanzee_relationship.php
posted by AKE
Chimps, as well as many of human ancestors, have been using tools for a while to get their food. One of the simplest forms was the 'termite stick', which is used by plunging it into a termite nest and eating the ones which end up on it.
There are also other populations that have done things like wash their food before they eat it. There was an experiment where food would be thrown on the ground for the animals to eat, in the process, it became quite dirty. One of the younger in the population tried dipping the food in a nearby stream before eating it. Soon after, the rest of the young population began to do this, whereas the older members of the tribe were not. This was a learned trait that went against the norm of their society, so the older ones would not adjust. This is very similar to the computer age in our lives, where some of the older generation refused to get involved, and the younger ones became more prominent in the behavior.
So I agree with everything you said, chimpanzees, as well as other primates, are much more than what we have thought of them for a very long time.
paradis6
Ake...you raise some interesting points, while this is the first announced use of tools for hunting per se, the use of tools by chimpanzees has been previously documented re: the acquisition of food and I have attached the most recent one, published earlier this month.
http://www.seedmagazine.com/news/
2007/02/chimps_used_tools_as_early_as.php
I also would suspect that anthropological evidence of previous spear use might be difficult to 'dig up'...since they are made of wood, and those specimens that did survive decomposition might not be identifiable as having been used as "spears" unless specifically examined for such residue (should any remain).
Your point re: complexity in skill use is on point and the steps followed by the hunters to acquire a suitable branch to strip and sharpen the implements used is quite extraoridinary.
Catherine
I find your blog extremely interesting! I knew that chimps used tools in a variety of ways, but I never heard of them piercing prey. I find it quite ironic, that only recently people seemed to be sure that chimps don't even eat meat (as Jane Goodall pointed out) and now we discover that they hunt using spears!
Another thought that I find very interesting is that you said how both males and females use the spears to hunt. I think that this statement will definitely make scientists reconsider the thought that gender roles sprung up from our ancestors.
21831371
The sexual makeup of the hunting groups makes some degree of sense. Adult male chimps often spend a fair amount of time attempting to prevent males from neighboring areas from entering their area. Mature females would be more likely to engage in food gathering behaviour simply because they are not spending their time patrolling the area.
I can't come up with a solid reason why only immature males and not immature females joined the expeditions.
Looking at chimps and their tool use seems a poor idea in terms of attempting to observe some parallel between their tool use and our early ancestors' tool use. I say this for one very simple reason: Our ancestors' ecology did not contain a few billion modern humans. That sort of pressure can't be ignored.
Current primate tool users experience a pressure toward mobility in their tool development. In order to survive, they need to be able to migrate from an area if humans should threaten it. This pressure would likely result in tools being simple, easy to make, and easilly reproducible.
Another incredible piece of information I was not aware of. Does this discovery suggest that the chimps are evolving into a more intelligent species? Haven't they used tools before these events took place? I fined it almost frightening that these animals are sharpening these sticks into spears and deliberatley trying to stab their prey. Let's hope this doesn't become a "Planet of the Chimps". I'm also curious to know why it is only young males and adult females? Why do the adult males not interact in this activity? I know that research has shown that chimps more or less fend for themselves. Could this be a reason why adult females, perhaps with babies, use these weapons to get easy prey? Thank you for this entry. Now I have a million questions I need answered!
-morsbac6
I thought that this article was very well written. There are clear relationships between humans and chimpanzees, as one would expect. Chimpanzees are the closest ancestors that we have, so similar behavior is not surprising.
The development of tools for defense, food, or other means of survival is something that is present among all species throughout evolution. The making of spears by chimpanzees shows that they are not so far behind humans on the road to development.
I found it very interesting that both male and female chimpanzees were creating the tools. I have to wonder if they worked together or made them each on their own.
Julie
puldaj6 said, "I have to wonder if they worked together or made them each on their own."
This makes me wonder at something.
How much regional variation is there in the tools, and do various chimp groups swap around their variant of the spear making technology?
Chimps are social animals. They pass around little bits of culture to one another. I read an article a few years ago about a chimp which had learned that dipping a type of potato into a certain mineral rich body of water made the potato taste better. Soon, neighboring groups of chimps all displayed that cultural development.
In lecture today, the professor mentioned that there was a great variety to the types of tools the chimps used. One has to wonder at the method of dispursion for the specific permutations of the technologies.
I found this video to be quite amazing regarding the use of tools...the facility with which rock is used as a tool to open the nuts is quite amazing!
http://www.youtube.com/watch?v=NivAusARwd8
Catherine
Post a Comment
<< Home