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Author Topic:   Genuine Puzzles In Biology?
Blue Jay
Member (Idle past 805 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


Message 121 of 153 (595065)
12-06-2010 12:32 PM
Reply to: Message 120 by Stephen Push
12-06-2010 11:23 AM


Re: Amygdala & Fear
Hi, Stephen.

Stephen Push writes:

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.

Agreed. But, I'm still skeptical that any species of spider has ever been a major selective agent on any species of mammal larger than a small rodent. The possibility is there, and I won't deny it outright, but I doubt it.

-----

Stephen Push writes:

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.

Well, I've argued for the evolution of a genetic predisposition to learn fear: I'm only arguing that a genetically-determined fear specifically of spiders is difficult to explain evolutionarily.

I would also suggest that pushing the origin further back in mammal evolution would make it less tenable from an evolutionary standpoint, because it would imply that natural selection has maintained the specific fear for a much longer period of time. Alternatively, it might imply that arachnophobia is atavistic or on its way out.

-----

Stephen Push writes:

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

I haven't really researched the topic at all from a psychological or behavioral point of view, and I don't have institutional access to the journal of the spider paper, so I haven't prepared a proper rebuttal.

I would argue that this study doesn't really distinguish between learned and genetically-determined fear.


-Bluejay (a.k.a. Mantis, Thylacosmilus)

Darwin loves you.


This message is a reply to:
 Message 120 by Stephen Push, posted 12-06-2010 11:23 AM Stephen Push has responded

Replies to this message:
 Message 122 by Stephen Push, posted 12-07-2010 12:54 PM Blue Jay has not yet responded

Stephen Push
Member (Idle past 2967 days)
Posts: 140
From: Virginia, USA
Joined: 10-08-2010


Message 122 of 153 (595210)
12-07-2010 12:54 PM
Reply to: Message 121 by Blue Jay
12-06-2010 12:32 PM


Re: Amygdala & Fear
Bluejay writes:

I would argue that this study doesn't really distinguish between learned and genetically-determined fear.

As I understand it, the environmental threat hypothesis doesn't assume that fear is genetically determined. Rather it proposes that we are genetically predisposed to notice and learn to fear some stimuli more than others.

I appreciate your skepticism about spiders as an evolutionary threat. But the psychological research seems sound, based as it is on a numerous studies conducted by several different researchers working with several different species. Other than the evolutionary threat hypothesis, I can't think of why humans and monkeys should be more visually attentive to things that look like spiders and more likely to learn to fear spiders than other stimuli.

Perhaps the evolutionary threat was scorpions and the visual processing system didn't distinguish between scorpions and spiders. The only problem I have with that idea is I would think scorpions would be easily distinguished from spiders.


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 Message 121 by Blue Jay, posted 12-06-2010 12:32 PM Blue Jay has not yet responded

Stephen Push
Member (Idle past 2967 days)
Posts: 140
From: Virginia, USA
Joined: 10-08-2010


Message 123 of 153 (595211)
12-07-2010 1:16 PM
Reply to: Message 93 by herebedragons
12-02-2010 11:27 AM


Re: Animal Cognition & Consciousness
herebedragons writes:

Is this the type of consciousness that you are refering to ... being aware of our impact upon other organisms and a feeling of moral and ethical responsibilities to those impacts?

I agree that kind of consciousness is probably unique to humans. But there are other kinds of consciousness that may be present in non-human animals:


  • At the very least, many animals show a difference between wakefulness and sleep, coma, etc. So on some level they can be said to be "conscious" because there are times when they are not "unconscious."
  • Veterinarians, along with the rest of us, routinely assume that animals can experience pain. Many researchers also agree that animals experience certain emotions, such as hunger or rage.
  • While many scientists will agree that some animals are "aware," it is much more controversial to say that they are "aware that they are aware," i.e., that they are self-conscious. Some people think that mirror experiments have shown self-awareness in chimps, dolphins, and a few other species.
  • I don't know of anyone who proposes that any non-human animal has sufficient self-awareness to be considered a moral agent. In fact, there are some scientists and philosophers who deny that human free will exists, in which case none of us would be moral agents.

This message is a reply to:
 Message 93 by herebedragons, posted 12-02-2010 11:27 AM herebedragons has responded

Replies to this message:
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herebedragons
Member
Posts: 1498
From: Michigan
Joined: 11-22-2009


Message 124 of 153 (596011)
12-12-2010 10:17 AM
Reply to: Message 123 by Stephen Push
12-07-2010 1:16 PM


Re: Animal Cognition & Consciousness
I was asking in context of your original question which you proposed as a biological puzzle:

message 69 writes:

Are animals conscious?

I wasn't so much making a point that humans are the only moral agents but trying to understand what your question was. You also stated

message 74 writes:

Definitions are part of the problem. Researchers in this field often have different definitions of what they mean by consciousness.

So I was trying to clear up how you were defining consciousness.

If consciousness means "show a difference between wakefulness and sleep, coma, etc." ... not much of a puzzle.

Self-awareness is more of a challenge. Does simply recognizing one's self in a mirror constitute awareness? I would personally think that to be considered "aware" and conscious it would require not only recognizing your own image, but using that recognition to make an assessment of one's self such as "Man, I'm having a bad hair day!" or "All this hair sure makes me look fat!" I guess that would be "aware they are aware"?

I find it difficult to imagine how anyone could make a reasonable argument against free will. But I suppose people imagine all sorts of other ridiculous and nonsensical ideas. Wouldn't just the idea of speculating and reasoning about the presence of free will support the presence of freewill? But regardless, even if we have no free will, we at the least have the illusion of being moral agents, which pretty much makes us moral agents. We can make decisions about what we believe to be "good" behavior and "bad" behavior. And even though that decision is very subjective, I would say that to be able to distinguish between the two makes us moral agents.

I like my "definition" of consciousness. It is not just being aware of self, but being aware of self in context of the world around you and how you fit into that world. So, when you ask "Are animals conscious?" what are you meaning by conscious? And do you think it is a puzzle because we have difficulty defining it or because we have difficulty understanding why we have consciousness at all?


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Tupinambis
Junior Member (Idle past 2763 days)
Posts: 18
Joined: 12-12-2010


Message 125 of 153 (596017)
12-12-2010 11:24 AM


fear of snakes
I don't believe that a fear of anything beyond tormenting pain and death can really be genetically encoded. A fear of snakes is, more likely than not, attributed to learned behavior and individual personality than genetics. I think people react more to certain attributes of snakes than the actual snakes themselves; I.E. hissing.

Present a small child with a baby corn or hognose snake and they'll probably be enamored by it. Present them with an adult King Cobra as it flairs its hood, hisses, and lunges at them and they'll probably be filled with an overwhelming sense of terror.

From my casual observations most animals capable of hearing react very strongly to anything that sounds like hissing. It seems to be one of the best ways for different species to communicate their antagonism with one another. Imagine a Pomeranian aggressively approaching an adult monitor/iguana/tegu/whatever, barking and doing all that other annoying crap that I hate Pomeranians for. Lizard responds by facing the little dog, flaunting its teeth (which are barely visible), and hissing. Little dog runs away in terror.
Why should this be? The dog's wolf ancestors [probably] never encountered big lizards in its natural habitat. Unless the lizard in question was a perentie or a crocodile monitor none of them would have posed a threat to the wolf either (both species are Australian, and thus would probably not have been encountered).

Now, the little dog clearly did not have a pre-disposed fear of the giant lizard itself even though it was clearly large and strong enough to kill and eat it. If it did it wouldn't have approached in the first place. It did have an immediate reaction to it hissing though. I imagine this originates from it's (and our) ancestors' encounters with venomous and constricting snakes. Many people don't initially fear snakes until they've learned to do so; either by being taught so by their parents or experiencing one hissing and lunging at them.

As for spiders... I have no idea. Perhaps our ancestors would commonly seek food hiding in crevasses and would get a less-than-pleasant surprise when it stuck its hand in. Of course, that would probably have also lead to a pre-disposed fear of land crabs which we don't have. Land crabs also make me skeptical of the scorpion idea. A crab can look very much like a spider, especially the small ones, yet when a person encounters a crab in their yard or even their house they're probably not going to have as strong a reaction as if it were a giant spider.


Replies to this message:
 Message 132 by Taz, posted 12-15-2010 3:44 PM Tupinambis has responded

  
Tupinambis
Junior Member (Idle past 2763 days)
Posts: 18
Joined: 12-12-2010


Message 126 of 153 (596019)
12-12-2010 11:34 AM
Reply to: Message 6 by bluegenes
05-27-2010 4:26 PM


Re: Green mammals?
bluegenes-
I know it's an old one, but why are there no truly green mammals?

I'm going to give my best shot at this one. The reason there are no truly green mammals is because, with one exception, there are no mammals which really require being green to aid in their survival. You get green lizards and snakes because it helps them camouflage and, more importantly, tree-dwelling snakes and lizards (well, the bigger ones anyway) cannot effectively run away from an approaching threat while in the trees. Reptiles much prefer to hide and not move opposed to running; much more so than mammals. Ground dwelling mammals hide in burrows and tree dwelling ones are fast enough to escape. The sloth gets green algae on it, so it may not be green itself but it gets the job done.
No mammal can also change its color like a chameleon or an anole can.


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Livingstone Morford
Junior Member (Idle past 2881 days)
Posts: 28
From: New Mexico
Joined: 12-13-2010


Message 127 of 153 (596419)
12-14-2010 6:49 PM
Reply to: Message 1 by Dr Adequate
05-27-2010 12:05 PM


So would anyone like to add to the list? What is genuinely puzzling in biology --- what are the questions that need answers and don't yet have them?

Whether or not genetic equidistance is the result of epigenetic complexity of organisms or whether it is the result of genetic drift et al. I argue for the former.


This message is a reply to:
 Message 1 by Dr Adequate, posted 05-27-2010 12:05 PM Dr Adequate has responded

Replies to this message:
 Message 128 by Dr Adequate, posted 12-15-2010 12:37 AM Livingstone Morford has responded
 Message 129 by nwr, posted 12-15-2010 8:53 AM Livingstone Morford has responded
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Dr Adequate
Member
Posts: 16093
Joined: 07-20-2006
Member Rating: 9.0


Message 128 of 153 (596468)
12-15-2010 12:37 AM
Reply to: Message 127 by Livingstone Morford
12-14-2010 6:49 PM


Whether or not genetic equidistance is the result of epigenetic complexity of organisms or whether it is the result of genetic drift et al.

The meaning of this sentence is obscure. However I suspect that if and when you ever elucidate your meaning, this will turn out not to be a genuine puzzle in biology but rather a question to which every biologist knows the answer.

Edited by Dr Adequate, : No reason given.


This message is a reply to:
 Message 127 by Livingstone Morford, posted 12-14-2010 6:49 PM Livingstone Morford has responded

Replies to this message:
 Message 131 by Wounded King, posted 12-15-2010 1:50 PM Dr Adequate has not yet responded
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nwr
Member
Posts: 5585
From: Geneva, Illinois
Joined: 08-08-2005


Message 129 of 153 (596501)
12-15-2010 8:53 AM
Reply to: Message 127 by Livingstone Morford
12-14-2010 6:49 PM


Livingstone Morford writes:
Whether or not genetic equidistance is the result of epigenetic complexity of organisms or whether it is the result of genetic drift et al.

I'm not a biologist, but it sure seems pretty obvious that it is the result of genetic change, rather than epigenetics. The measurement of genetic distance is done by comparing protein structure of different species, and the protein structure is encoded in the DNA.

Livingstone Morford writes:
I argue for the former.

You didn't actually argue anything. You just asserted.

If you believe that you have a good argument, start a thread on the question. I expect that the biologist members will be be able to refute your argument in pretty short order.


Jesus was a liberal hippie
This message is a reply to:
 Message 127 by Livingstone Morford, posted 12-14-2010 6:49 PM Livingstone Morford has responded

Replies to this message:
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Taq
Member
Posts: 7694
Joined: 03-06-2009
Member Rating: 4.5


Message 130 of 153 (596519)
12-15-2010 12:18 PM
Reply to: Message 127 by Livingstone Morford
12-14-2010 6:49 PM


Whether or not genetic equidistance is the result of epigenetic complexity of organisms or whether it is the result of genetic drift et al. I argue for the former.

You seem to have confused your terms. Epigenetics refers to DNA methylation and histone packaging. Genetic comparisons use the actual DNA sequence, as does genetic drift.

Perhaps you meant to refer to DNA regulation as a function of DNA sequence instead of epigenetics?


This message is a reply to:
 Message 127 by Livingstone Morford, posted 12-14-2010 6:49 PM Livingstone Morford has not yet responded

Wounded King
Member (Idle past 2202 days)
Posts: 4149
From: Edinburgh, Scotland
Joined: 04-09-2003


Message 131 of 153 (596542)
12-15-2010 1:50 PM
Reply to: Message 128 by Dr Adequate
12-15-2010 12:37 AM


Archaism?
I think he may be using epigenetic in a more archaic sense, if you can call terms from the 1940s archaic, which essentially means developmental. So the phrase would probably be more easily understood as developmental or morphological complexity. Alternatively it may be used to refer to all non-genetic factors influencing development, but I'm not sure how this would fit.

Or it could be something else entirely.

TTFN,

WK


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Taz
Member (Idle past 1399 days)
Posts: 5069
From: Zerus
Joined: 07-18-2006


Message 132 of 153 (596558)
12-15-2010 3:44 PM
Reply to: Message 125 by Tupinambis
12-12-2010 11:24 AM


Re: fear of snakes
Tupinambis writes:

I don't believe that a fear of anything beyond tormenting pain and death can really be genetically encoded. A fear of snakes is, more likely than not, attributed to learned behavior and individual personality than genetics. I think people react more to certain attributes of snakes than the actual snakes themselves; I.E. hissing.


Actually, it's just not the fear of snakes that's deeply ingrained in us. It's pretty much fear of anything that doesn't look like us. The farther away in appearance the thing is to us, the more "scary" it looks to us.

This is why people instinctively fear harmless things like certain kinds of arthropods. Take the spider for example. It looks totally alien compared to us, and there are more arachnophobes out there than we can count. Would you want to hold something like this in your hand?

Snakes look alien to us because there's no limbs. And before nitpickers come snooping around, yes I am aware of the vestigial limbs. But generally speaking, the snake is a total alien to us, which is probably why we instinctively fear it.


This message is a reply to:
 Message 125 by Tupinambis, posted 12-12-2010 11:24 AM Tupinambis has responded

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Livingstone Morford
Junior Member (Idle past 2881 days)
Posts: 28
From: New Mexico
Joined: 12-13-2010


(1)
Message 133 of 153 (596595)
12-15-2010 7:20 PM
Reply to: Message 128 by Dr Adequate
12-15-2010 12:37 AM


"The meaning of this sentence is obscure. However I suspect that if and when you ever elucidate your meaning, this will turn out not to be a genuine puzzle in biology but rather a question to which every biologist knows the answer."

The genetic equidistance phenomenon suggests that the number of different residues between two organisms is largely determined by the amount of time since the two species diverged [Margoliash, 1963]. This view not only presupposes that a neutral mutation in a given organism is also neutral in all other organisms, but it also assumes that the epigenetic complexity of an organism does not impose a restraint on the amount of genetic diversity that organism can tolerate. Taft et al. (2007) propose that organismal complexity may be defined as the number and different cell types in that organism, as well as the amount of cellular organization.

If the epigenetic complexity of an organism does impose a restraint on the number of mutations that organism can tolerate, then the phenomenon of genetic equidistance would still be manifested, even if all species diverged at the same time. This is because different species can tolerate different levels of mutations, since different organisms have different numbers of cell types.

It is difficult to determine whether the phenomenon of genetic equidistance is the result of the amount of time that has passed since two or more species diverged, or whether this phenomenon is the result of the epigenetic complexity of the organisms imposing restraints on the number of mutations tolerated. This is because the number of cell types in organisms has, in general, increased as evolutionary history progressed [Valentine et al., 1994] .

I am proposing that this is a genuine problem in biology. I would be more than willing to elaborate on this if I am somehow still being obscure.

References:

Margoliash E. Primary Structure And Evolution Of Cytochrome C. Proc. Natl. Acad. Sci. U.S.A. 50: 672–9 (1963).

Taft, R.J., Pheasant, M. and Mattick, J.S. (2007) The relationship between non-protein-coding DNA and eukarotic complexity. BioEssays 29:288-200.

Valentine James W., Collins Allen G., Meyer C. Porter. Morphological Complexity Increase in Metazoans. Paleobiology, 20(1994):2:131-142.


This message is a reply to:
 Message 128 by Dr Adequate, posted 12-15-2010 12:37 AM Dr Adequate has responded

Replies to this message:
 Message 135 by Dr Adequate, posted 12-15-2010 7:34 PM Livingstone Morford has responded
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Livingstone Morford
Junior Member (Idle past 2881 days)
Posts: 28
From: New Mexico
Joined: 12-13-2010


Message 134 of 153 (596601)
12-15-2010 7:30 PM
Reply to: Message 129 by nwr
12-15-2010 8:53 AM


"I'm not a biologist, but it sure seems pretty obvious that it is the result of genetic change, rather than epigenetics. The measurement of genetic distance is done by comparing protein structure of different species, and the protein structure is encoded in the DNA."

It's obviously the result of genetic change, but the question is not if it is the result of mere change at the molecular level (since that is very, very obvious). With the observation of the genetic equidistance phenomenon there emerges a paradox: how do we know that this phenomenon is the result of the amount of time that has lapsed since the divergence of two organisms, or whether it is the result of the epigenetic complexity of the organisms imposing a restraint on the number of mutations tolerated in a given protein, since as time progresses, the number of cell types increases.

"You didn't actually argue anything. You just asserted."

I never suggested, implied, or proposed that I argue for the former in this forum. However, I have argued for the former in other places. Also, you might want to consider not nitpicking on semantic details. Just a thought.

"I expect that the biologist members will be be able to refute your argument in pretty short order."

You shall see what you shall see.


Biology rocks!
This message is a reply to:
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Replies to this message:
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Dr Adequate
Member
Posts: 16093
Joined: 07-20-2006
Member Rating: 9.0


Message 135 of 153 (596603)
12-15-2010 7:34 PM
Reply to: Message 133 by Livingstone Morford
12-15-2010 7:20 PM


But what is being suggested here is not that "epigenetic complexity" causes "equidistance" but rather that it limits it. The cause of the (neutral) divergence would still be drift.
This message is a reply to:
 Message 133 by Livingstone Morford, posted 12-15-2010 7:20 PM Livingstone Morford has responded

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