Chimpanzees Make Spear Weapons For Hunting
February 26, 2007
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Chimps are well-known to hunt monkeys, and some have argued they do so cooperatively, with particular roles in mind, so to speak. Chimps are also well-known to make and use tools, most commonly stones and anvils for breaking open nuts, as well as trimmed sticks to dip into mounds of ants and termites.

However, this last week news broke of chimpanzees using spears to hunt bushbabies (little nocturnal prosimian primates). The linked article explains the behavior and links to the chimp videos of them in action.

I'm not surprised the chimps can do this. The prerequisites (tool use and hunting) are present in the species, and apparently there is ecological pressure here in terms of lacking a usual prey item. But what I found most interesting about the report is that mainly females and juveniles are doing it, and it only occurs in this one group. This would make it worth investigating how the behavior arises in these individuals and if social learning (or socially-facilitated learning) might be involved.

Chimps live in fission-fusion societies, meaning at some times they are together as a large group, but often they break up into smaller groups (say, for foraging for food). Since the normal monkey-hunting groups are all-male, females may be spending a lot of time separately and with juveniles around. This could lead to those members picking up this unusual tool-use behavior from each other while the males are away, probably not by teaching but by either imitating or simply having their interest and attention brought to the relevant items by watching another spear bushbabies. Of course, alternately they might simply all pick up the skill by themselves because of the particular ecology there, so it would doing a longitudinal study of who hangs around whom when spear-hunting happens and see in what conditions the behavior shows up in a new spear-user.

If social learning of some sort is involved, it would add yet more evidence of chimpanzee culture. And the more we learn about the great apes, the more we see similar abilities that suggest many of our skills and flexible behaviors are not unique to humans.

Hammock Logic shares a nice little list on how to live a full life. A few may not apply, or may be less important than others, but some damn good little nuggets in here. Worth a quick (or slow, rather) perusal.

At least, that seems to be the claim of a study at the University of Rochester (press release here). Basically, they compared 30 hours of Tetris playing to 30 hours of playing the first-person shooter Unreal Tournament (UT). Those who played UT improved a significant amount in some aspects of visual processing (spatial resolution). Tetris players showed no improvement in that area. Interestingly, the improvement in visual processing applied outside just the center of vision where the monitor would be - periphery vision improved.

Of course, they failed to mention one important detail. Playing fast-paced action games like UT trains you not to blink - blink and you die - and can lead to staring at a nearby screen for long periods of time. So your vision processing may improve in the short term, but I wonder if further play leads to much more troublesome long-term consequences. (I say this as someone who plays and fully supports the playing of video games for blurred-vision-inducing hours on end - vision be damned).

Most of all, I'm just really jealous these guys get NIH funding to do video game studies, and now to construct a 360-degree virtual-reality computer lab. Maybe I'm in the wrong field. Then again, I'm currently working with equipment funded by NIH and NSF to teach monkeys to play video games, so maybe I can't complain.

I just stumbled on a cool press release out of Max Planck: chimps cracked nuts 4,300 years ago. In other words, this tool use is a long-standing behavior, not something recently learned (it was only discovered in the 19th century). Previous research has suggested the skill is socially transmitted, that it is in some sense cultural.

The very intriguing suggestion made by the authors is that stone tool use may have developed before humans qua humans were around, i.e. before apes and us split off from a common ape-like ancestor. Maybe our common ancestor used stone tools and the ability was socially transmitted through time, passing down to both humans and apes. Of course, this is just a hypothesis and it remains to be seen whether good evidence might support it, but for now it is a very interesting suggestion.

Also, the link above leads to video clips of chimpanzee nut cracking behavior, located at the bottom of the page. It certainly appears more similar to how a human would crack a nut than the nut cracking behavior found in capuchin monkeys (the only monkeys known to routinely use tools). Not surprising given the size difference: a capuchin has to lift a stone of near its own body weight bimanually, then slam it down on a nut on an anvil, whereas a chimp can wield a large enough stone in one hand.

The real interesting research, in my opinion, is the work on how an individual acquires skilled tool use behavior. What factors are involved? Not every creature can just watch another and then imitate the skill, but some non-human primates definitely show signs of something like imitation. There appears to be socially-facilitated learning, but is it a matter of actually figuring out a task by watching someone else do it, or is it merely a matter of someone else's behavior drawing your attention to an object, which you subsequently play with and learn to use on your own?

What is the relationship of general curiosity, especially haptic/object curiosity, to acquiring tool use? Is play related? Or neophilia (love of new things)? Maybe those who like to play with and explore new objects or use them in new ways are most likely to become tool users. Future work will help us understand this better. But we can now be sure that tool use is a behavior that has been around for a long time in our non-human primate cousins, so we will have a lot of time to study it as long as we don't kill them all off in the bushmeat trade or lead to their extinction through deforestation and encroachment.

All of the four great apes are listed as endangered. The bonobo - commonly called the pygmy chimp - is found in only one location on Earth, in the war torn Democratic Republic of Congo. They could be completely gone soon, and the other apes might follow. Even if a few remained in zoos, research facilities and sanctuaries (where it is harder to get them to reproduce in the artificial environment), human-reared primates behave differently than wild-born ones. We would lose all the information about their natural behavior in the wild, all the information that helps us better understand ourselves and our place in the world, and where our own cognitive abilities came from.

In the book Lila, Robert Pirsig talks about a time he was sailing into port at Cleveland. He thought he was at a particular harbor when in fact he had unknowingly come in elsewhere many miles away. For quite a while, he did not realize his mistake; the landscape seemed to match up with the chart. But of course, he realized later he had been ignoring differences between the chart and where he was because he figured the shoreline must have changed some since the map was made. Writing in the third person:

"Wherever the chart disagreed with his observations he rejected the observations and followed the chart. Because of what his mind thought it knew, it had built up a static filter, an immune system, that was shutting out all information that did not fit. Seeing is not believing. Believing is seeing.

"If this were just an individual phenomenon it would not be so serious. But it is a huge cultural phenomenon too and it is very serious. We build up whole cultural intellectual patterns based on past 'facts' which are extremely selective. When a new fact comes in that does not fit the pattern we don't throw out the pattern. We throw out the fact. A contradictory fact has to keep hammering and hammering, sometimes for centuries, before maybe one or two people will see it."

The thing is, we all do this, and not just in science. I think it's a psychological mechanism built into our brains. Through our lives we unconsciously develop assumptions about how the world works, a framework in which to integrate new facts and against which to test others' claims. That framework includes various filters to notice useful information and ignore noise. But we tend to become practiced at unconsciously biasing ourselves in regards to the information we let through to consciousness.

It is useful to have a basic view of the world, so that you can respond with appropriate incredulity when someone claims that, for example, elephants can fly. But this same mechanism can unconsciously cause us to be overconfident in our views, and to perhaps ignore (by filtering out before we even think about it) crucial data points that might help us refine our mental framework. Just means we have to remain vigilant against our own biases and sometimes just step back and question even some of our basic assumptions.

Adel Hamad is a prisoner at the Guantanamo base in Cuba. He is a teacher and an aid worker. He was taken as an enemy combatant because it is alleged that the hospital he worked in - WAMY (World Assembly of Muslim Youth) - may support "terrorist ideals". Of course, he was not the head of the hospital, nor a financial supporter. His job was to buy food for the Afghani hospital, to write vouchers, to take employee attendance. He later worked at the WAMY office in Pakistan where his job was to get food, blankets and clothing to refugees coming across the border.

Of course, Adel Hamad didn't get a trial to defend himself - he is off U.S. soil, and not an American citizen. All he got was an Administrative Review, where he could not even prepare his own defense. Yet at this administrative review, an Army Major dissented from the decision to keep Hamad locked up, arguing that his imprisonment is unconscionable, that even if WAMY supported terrorist ideals, we should not declare every employee of the hospital an enemy combatant. The Administrative Review panel argued that Hamad may have come into contact with Al-Qaeda or Taliban members in the course of providing aid to refugees, but the dissenting Army Major mentions that by this logic we should classify every local merchant as an enemy combatant.

The fact is, Hamad was not captured on the battlefield. He was arrested from home in the middle of the night, with a valid passport and work visa. Pakistani intelligence found nothing incriminating in his home. Other doctors and aid workers he worked with said he was a kind man who had no extreme views. He has not been accused of any terrorist acts or acts supporting terrorism, nor of any belligerent act. He got picked up on a routine sweep for Arabs in Pakistan because he worked for the wrong hospital.

What is disturbing here is not that such mistakes could happen. What is disturbing is that because we allow a place like Guantanamo to exist outside the normal legal framework, and allow the higher ups in the executive branch to classify anyone as an enemy combatant willy-nilly, people who are wrongly accused do not get a fair and impartial trial to prove their innocence. Mistakes happen, but our legal system was built to allow the opportunity for the accused to defend themselves so that those mistakenly accused can be set free. Just because these are not American citizens does not mean it is okay for us to take people from their homes - many of them admittedly innocent - and ship them across the world to be trapped in a high security facility (established offshore to avoid recourse to appeals under U.S. federal law), and never give them a real chance to prove their innocence.

I originally wrote about Guantanamo (back when it was called Camp X-Ray) early on, and unfortunately things there have not changed much. The recently established Administrative Review Board has not served its alleged purpose. The status reviews did not allow the suspects to have legal counsel, they were not allowed to know what allegations they had to defend themselves against, and there was no presumption of innocence (like you would find in a court on U.S. soil). And of course, those people who were set free by the status reviews (i.e. mistaken prisoners) had already been in prison for years before the first set of reviews happened in 2005. For more information on the Guantanamo camp's current status, you can start off at the Guantanamo Wikipedia page, which provides sources for most claims.

Below is a documentary produced to raise awareness of Adel Hamad's situation, though I hope people will keep in mind that regardless of this one man's guilt or innocence - even if he is freed - there are countless others being kept in this situation with no real legal recourse against the accusations, no real chance to prove their innocence. This is why all Americans should fight to abolish legal-limbo situations like that in Guantanamo and ask the military to only hold those who actually deserve to be held.

Story via Boing Boing.

The video below is a cool little news story about a blind boy who uses echolocation to navigate the world. Granted, the story lacks the scientific rigor of a journal article that might address questions of how fully blind he is, etc. But it is still very impressive to watch a blind person beat someone at foosball.

Regardless of whether it is full-on echolocation or a combination of it and some other visual-like sensitivity, it is a cool story. And it should not be very surprising, given that previous studies have shown even sighted people can make use of echolocation to gain information about the world (e.g., approach a wall and stop in front of it). Schwitzgebel and Gordon have a philosophical article about human echolocation [PDF] available for free online.

I'm not sure this is quite the same as a bat's use of echolocation, but regardless of whether we want to consider it a distinct "sense", different from normal hearing or vision, I would mention a reminder that we humans have many more than five senses.