Message 106 of 153 (594425) 12-03-2010 12:15 PM

Reply to: Message 100 by Catholic Scientist 12-02-2010 5:11 PM

I did say that earlier in the thread. The difference between the modern skateboard bearings and the older bearings is that there is a gap between the bearings in the older models which allows them to rattle around.

But to get back to pattern recognition, I think it is a holistic thing. I remember quite vividly the moment I put the rattling and the rustling together. What popped in my head was the picture of a snake, immediately followed by intense panic. And yes, it made me feel like an absolute fool. I think it is a matter of having just enough information to trigger the response.

Message 107 of 153 (594427) 12-03-2010 12:20 PM

Reply to: Message 92 by Akhlut 12-01-2010 3:02 PM

First, although the ant does have a fairly simple brain, it still has over 250,000 brain cells - no small feat to hyjack and manipulate in such a way to get the desired behavior. It would take a tremendous amount of trial and error.

The ant don't just "climb to the highest point" but climb to just the height the fungus likes to be at to release its spores and on the proper side of the plant. The fungus then disolves the ant innards but leaves the muscles holding the mandibles intact and thus preventing the ant carcass from dropping to the forest floor and failing to release its spores.

quote:

---

Having successfully taken over an ant, the fungus compels it to leave its normal haunts high in the forest canopy and directs the unfortunate insect down into the dark, moist basement layers of the jungle. There the luckless creature is compelled to clamber onto the underside of a leaf in the O unilateralis' favoured location for reproduction - some 25cm above the ground, on the northwestern side of the tree or plant in question.

Once in such a location, the dying ant is made to clamp its mandibles - jaws - firmly shut onto the leaf, and then hangs lifelessly from them to become a food supply and home for the burgeoning, ghastly fungus-children within. Most of the insect's innards are gradually converted into food and consumed, but the muscles holding the mandibles shut are cunningly left alone.

---

http://www.theregister.co.uk/2009/08/12/ant_zombie_fungus_horror/

I don't believe fungi have neurotranmitters of their own, but release chemicals that bind to host neurotranmitters effectively short circuiting them. Not as simple to get a very specific behavior - and this behavior is very specific not just general wandering around and clamping onto a plant leaf. Its not like they have eaten a "magic mushroom" and are going crazy with halucinations.

I realize you are probably just simplifing for the sake of space and explaination time, but come on, a one sentence explaination for memory and instinct? How do these alleles code for a specific memory? How does the genetic code specify a particular image implant or an instinctive behavior?

Do you really believe that snakes and spiders presented that great of a selective pressure on our ancestors? Perhaps in certain parts of the world there is greater pressure, but overall, I can't imagine there is enough selective pressure to drive adaptive phobias.

Idk, maybe you could develop one of these topics a bit rather than saying nothing about everything.

Message 108 of 153 (594430) 12-03-2010 12:25 PM

Reply to: Message 107 by herebedragons 12-03-2010 12:20 PM

If these phobias are ingrained deep in our evolutionary history, then yes it is very possible. Many of the mammals that made it through the K/T extinction event were small, burrowing, nocturnal mammals which are the very description of a snake's favorite prey.

Edited by Taq, : No reason given.

Message 109 of 153 (594468) 12-03-2010 2:09 PM

Reply to: Message 107 by herebedragons 12-03-2010 12:20 PM

Fungi tend to have really small generation times, so they'd have plenty of time to engage in such "trial and error."

The ant don't just "climb to the highest point" but climb to just the height the fungus likes to be at to release its spores and on the proper side of the plant. The fungus then disolves the ant innards but leaves the muscles holding the mandibles intact and thus preventing the ant carcass from dropping to the forest floor and failing to release its spores.

Okay, I oversimplified a bit and was basing things off of memory. Mea culpa.

I don't believe fungi have neurotranmitters of their own, but release chemicals that bind to host neurotranmitters effectively short circuiting them. Not as simple to get a very specific behavior - and this behavior is very specific not just general wandering around and clamping onto a plant leaf. Its not like they have eaten a "magic mushroom" and are going crazy with halucinations.

It's still rather simple behavior, though: climb to a certain height, clamp on, and then sit there. Most of this can be achieved through changing photopreference on behalf of the ant and then forcing a bite reaction once a preferred height is reached.

I realize you are probably just simplifing for the sake of space and explaination time, but come on, a one sentence explaination for memory and instinct? How do these alleles code for a specific memory? How does the genetic code specify a particular image implant or an instinctive behavior?

They don't code for memory, but for instinct: two distinctly different things.

Anyway, because instincts are hundreds/thousands of discrete behaviors, it is difficult to generalize beyond "alleles control brain structure, hormones, and neurotransmittors," however, I can use some examples. For instance, in most mammals, being monogamous or polygamous is a very instinctual behavior, insofar as if a species follows one strategy, it is unlikely to follow the other all that much. Apparently, at least in rodents, vasopressin mediates monogamy to a large extent; thus, if you introduce a gene that strongly expresses vasopressin in a vole species that are normally polygamous, they'll be much more likely to be monogamous after the introduction of that gene. ( http://www.sciencedaily.com/...ases/2001/09/010917075347.htm )

To speak about phobias: I, personally, am unsure how phobias to certain stimuli would be more genetically prevalent (i.e. how fear of snakes in specific would function from a genetic perspective), however, fear in mice has at least a partial genetic component: http://www.ncbi.nlm.nih.gov/pubmed/18830130 From this, we can conclude that there are genetic components to fear in general, and it can probably create susceptability to more specific fears (snakes, spiders, heights, whatever).

Do you really believe that snakes and spiders presented that great of a selective pressure on our ancestors? Perhaps in certain parts of the world there is greater pressure, but overall, I can't imagine there is enough selective pressure to drive adaptive phobias.

Snakes: definitely. Our primate ancestors lived in Asia and Africa for tens of millions of years alongside very dangerous snakes (large constrictors and highly venomous snakes), thus making a fear of snakes a very rational trait to evolve. Hence, phobias of snakes existing in numerous other primate species. Arachnophobia has probably been much less selective since our ancestors became larger, but it may also not have been selected against, and thus remained semi-fixed in the population.

Message 110 of 153 (594529) 12-03-2010 8:06 PM

Reply to: Message 108 by Taq 12-03-2010 12:25 PM

I don't have a lot of confidence in the explanatory power of statements such as this. For example, why would the fear of snakes be deeply ingrained but other survival instincts you mentioned - burrowing, nocturnal - be lost? I think I can anticipate the answer ... because they were no longer needed. Couldn't the same be said for instinctive fear of snakes and spiders? What about the fear of hawks flying over head? and so on ...

My daughter is terrified by spiders, but not by snakes. Is it because of a deeply ingrained instinct? She didn't inherit it from me - maybe her mother. Maybe its because she saw a program on Animal Planet about spiders that frightened her. But she has seen those same kind of programs about snakes too. So is it learned or instinctive? My 3 year old is leery (but not quite afraid) of spiders, but he calls almost every thing that creeps and crawls a spider. I think its more of just being uncomfortable with creatures that are different and a bit creepy (although the idea of what is "creepy" may be kind of instinctive). Some children are afraid of hamsters, horses and even bunnies; none of which should be perceived as a threat by our ancient instincts.

Don't get me wrong, there definitely is a connection between biology and behavior. Programming of instincts by genetic factors is undeniable. However explaining them is much more difficult. Humans being such social creatures makes it that much more complicated. I did a paper on Nature verses Nurture last year and there is just about an equal case to be built for either side. So do we learn fear or is it built in. Probably both.

Wait, what was the topic of this thread...? Oh yeah, genuine puzzles in biology. I would say that both issues, instincts and phobias are still genuine puzzles. Yeah we have learned stuff about both topics, but we really know almost nothing compared to what there is to know. My mammalian ancestors being snake bait millions of years ago doesn't begin to explain it for me.

Message 111 of 153 (594628) 12-04-2010 5:18 AM

Reply to: Message 105 by Dr Adequate 12-03-2010 12:11 PM

I've been a member here for a long time but usually only read the topics because as I said, Biology has largely passed me by. I am a huge fan of Dawkins and was once a huge fan of Randi until my experiences over at the JREF made me reconsider my position on him.

What happened to the Severus Snape avatar?

Message 112 of 153 (594629) 12-04-2010 5:40 AM

Reply to: Message 111 by William Rea 12-04-2010 5:18 AM

It sounds like you have a story to tell.

Well, you know, Randi himself has never had anything to do with the JREF forums. In fact, he doesn't even run the JREF itself any more. Just because it's named after him doesn't mean that he personally approves of everything that happens on the forums that he has never administered of the institution that he is no longer in charge of.

I just like the "A" avatar better. Apart from anything else, some people thought that the Snape avatar was a picture of me, rather than realizing that it's a picture of the actor Alan Rickman. It's a bit of a let-down when they discover that in real life I'm small, shy, boyish, and have a tendency to giggle.

Edited by Dr Adequate, : No reason given.

Message 113 of 153 (594656) 12-04-2010 12:15 PM

Reply to: Message 109 by Akhlut 12-03-2010 2:09 PM

I just find it kind of frustrating when very complex issues are waved away as simple as if we know everything there is to know about it, when we really know very little.

I just don't see this as simple behavior. Simple maybe compared to migration instincts, or mating rituals or driving a car. We have a fungus, without any intelligence, able to grow within an ant's brain, overpower the ant's natural instincts, reprogram them to its own purposes (even accepting that its purposes evolved along with the ant's behavior) and is able to avoid digesting the muscles that clamp the mandibles. The whole scenario is absolutely amazing.

I am not suggesting that there is anything magical or supernatural. I am sure there is a biological explanation, but we don't understand how it works. It is still a mystery - a genuine puzzle in biology.

Right. that was my mistake. I was referring to memory as images or recognition mechanisms that would need to be stored in order for an organism to recognize food, shelter, danger, etc... That could all be grouped under instinct I guess. But the point is more that I don't believe we understand how that process happens. Developmental biology is a fairly new field and has soooo much to discover. There is very little known about how the DNA and epigenetic marks function to control development and formation of complex, highly organized tissues, organs and systems. We have learn some things, but the whole area of development, instinct and memory remain clouded in mystery.

I have no doubt that most (if not all behaviors) have a genetic component. If nothing else, a disposition to behave in a certain way; ie. some people are prone to be angry and violent, some are prone to be happy and carefree. Our personalities have a definite genetic component, but we don't understand too much about it yet.

Message 114 of 153 (594659) 12-04-2010 1:21 PM

Reply to: Message 110 by herebedragons 12-03-2010 8:06 PM

(Yes, I did have a bad encounter with a wasps' nest as a child but there have been no negative effects. No, I didn't even know that spiders could bite until long after my fear of them was well-established.)

The only six-legged creature that I will willingly kill is a mosquito but that's mostly a matter of self-defense, I think.

I also don't like centipedes and snakes, which is why I joke that it's too many legs or not enough legs that bothers me. (On the other hand, I have nothing against fish.)

Message 115 of 153 (594700) 12-04-2010 4:49 PM

Reply to: Message 97 by Taq 12-02-2010 3:50 PM

Well, it's really not reasonable to suggest that spiders have been a big enough danger to our ancestors to have influenced human evolution.

Spider bites rarely noticeably influence an individual's biological fitness, so it's difficult to see how the specific fear of spiders would improve fitness predictably enough to make a difference. There may be more of a case to make for snakes, given the bigger and more predictable danger they pose, but I am completely out of my expertise there.

I suspect that the ability for pattern recognition, as a general cognitive trait, is hard-wired due to natural selection for danger avoidance; but the individual patterns that are recognized are not hard-wired.

Darwin loves you.

Message 116 of 153 (594709) 12-04-2010 6:22 PM

Reply to: Message 115 by Blue Jay 12-04-2010 4:49 PM

Agreed, the way other cultures deal with creepy crawlies makes me think we westerners may have just watched Arachnophobia too many times.

Lurker

Message 117 of 153 (594710) 12-04-2010 6:44 PM

Reply to: Message 116 by Itinerant Lurker 12-04-2010 6:22 PM

For example, I am a seafood freak. Such things as clams, oysters, crab, lobster etc. The two that freak some people out are squid & octopus. To others escargot (snails). While I was statioed in Korea, I used to eat in a number of small semi-outdoor restaurants. I was enjoying a meal of squid in a chililike sauce when 2 GIs walked by. One looked at what I was eating and nearly puked.

Who gave anyone the authority to call me an authority on anything. WT Young, 1969

Since Evolution is only ~90% correct it should be thrown out and replaced by Creation which has even a lower % of correctness. W T Young, 2008

Message 118 of 153 (595023) 12-06-2010 9:50 AM

Reply to: Message 114 by ringo 12-04-2010 1:21 PM

I believe I saw where you had said this up-thread. It goes along with my idea that we are afraid of things we perceive as creepy-crawly. Do you have cicadas where you are from? scared the @#$% out of me first time I saw one (the nymph in particular). I am not afraid of them now that I know what they are and that they are harmless (they sure don't look harmless).

Personally, any fear I have of animals is based on a threat or perceived threat. I am not afraid of snakes, but when I was kicking around in an abandoned barn one day and heard a rattlesnake rattle, I was scared. I am not particularly afraid of bears, but if I ran into a 300# black bear in the woods, I would definitely be worried. A 1000# grizzly - very afraid!

You seem to be suggesting that your fear of spiders is instinctive. What about your parents and siblings? Do they share your fear of spiders? Even if they are it could be said that they "taught" you to fear spiders. It is curious, though, that you had a bad encounter with wasps as a child and haven't developed a fear of them, but don't seem to have a reason for your fear of spiders.

My personal opinion is that these types of fears have to do mostly with temperament and personality rather than an instinctive fear of a particular creature with a specific number of legs However, I do believe personality and temperament in particular, are based largely on genetics. So, deep seated fears would be indirectly genetic. Of course, I don't have a whole lot of data or research to support this. I am just basing it on personal observations and the limited research I have done.

Message 119 of 153 (595027) 12-06-2010 10:26 AM

Reply to: Message 118 by herebedragons 12-06-2010 9:50 AM

This happened back east and now I live in Arizona and I was stung again a couple of years ago. One thing I did notice is their venom is much stronger than the bees back east. I became ill from that sting.

Message 120 of 153 (595040) 12-06-2010 11:23 AM

Reply to: Message 94 by Blue Jay 12-02-2010 12:30 PM

Thank you for sharing your knowledge of spiders. I assume you are referring to extant species. While your evidence is suggestive, it doesn’t rule out the possibility that our ancestors encountered more dangerous species that are now extinct. In fact, it is possible that a genetic predisposition to learn to fear spiders and snakes started with mammalian ancestors that predated the first primates.

While the facts you mention cast doubt on the evolutionary threat hypothesis, there is a fair amount of empirical evidence on the other side of the issue. In a recent study, Vanessa LoBue of Rutgers University writes:

LoBue’s paper provides “the first evidence of enhanced visual detection of spiders in young children.” She writes:

A previous study in preschoolers showed similar results for snakes. Although it is possible that there were cultural influences on the preschoolers, these studies suggest a genetic predisposition because the researchers were measuring visual attention, not fear, and because even people who did not fear spiders or snakes showed greater visual attention to those putative evolutionary threats.