Genuine Puzzles In Biology?

Several issues in evolutionary biology have remained controversial for decades:1) Why do most organisms grow old and die, while some (e.g., hydra) are immortal?2) Why do so many organisms engage in sexual reproduction when asexual reproduction has the advantage of passing on ALL of one's genes to the next generation?3) Is the individual the only important unit of selection, or does group selection play an important role in evolution?

Has the Amazon molly, a unisexual fish, found a way around this problem? SeeQuantifying the threat of extinction from Muller's ratchet in the diploid Amazon molly (Poecilia formosa) | BMC Ecology and Evolution | Full TextPerhaps we can learn something from this little fish. Because according to the article below, high mutation rates in asexually reproducing human mitochrondria could lead to our species' extinction.http://archive.evolution.ws/...e-l/Loewe2006-MitoRatchet.pdfOr perhaps our mitochrondria have already evolved a solution to the disadvantage of asexual reproduction.Edited by Stephen Push, : Correct typo.Edited by Stephen Push, : Replaced reference to abstract with reference to full article.

You do not believe that the accumulation of deleterious mutations is a disadvantage of asexual reproduction? What do you see as the advantages of sexual reproduction (other than the fact that it's fun :-) )?Edited by Stephen Push, : Rephrased second question.Edited by Stephen Push, : Added smiley.

Intuitively I agree with this account of the value of imagination. But as a scientific explanation it seems problematic because it presupposes the existence of free will, a property that appears to defy scientific analysis. Is there any way to establish that free will actually exists, not to mention how it could have evolved?Edited by Stephen Push, : Corrected typo.

By way of suggesting a practical value of imagination, you seem to be describing a conversation with yourself in which you choose from two or more options. That seems to suggest the exercise of free will. Unless this internal conversation is just an illusion without effect on the outcome. But if so, where is the practical value?

Well put. I see your point and agree. Thank you.

Well put. I see your point and agree. Thank you.

A study has shown that crows actually do not use autombiles as nutcrackers.Nevertheless, this anecdote points to another set of Genuine Puzzles in Biology: animal cognition and consciousness.Are animals conscious? What emotions do they feel? Do they have a theory of mind? Many interesting questions.Edited by Stephen Push, : No reason given.Edited by Stephen Push, : No reason given.

Thanks for the tip on links, nwr.

While we can't rule out the possibility that the particular crow in the video learned to use cars as nutcrackers, anecdotal evidence can be misleading. In the study, reasearchers did 231 paired observations of crows with and without cars approaching. The crows were no more likely to drop walnuts on the road if cars were approaching than if cars were not approaching. Yes, tool use in crows is well documented. Definitions are part of the problem. Researchers in this field often have different definitions of what they mean by consciousness. We don't even understand consciousness in humans, so it's probably not possible at this stage to understand it in animals.Even sentience is a problem. I can make a good case that mammals are sentient. But what about fish? Or crustaceans? There are serious researchers who claim all of these animals can feel pain. These claims seem plausible, but I don't see the objective tests. Maybe your friend's dog was embarassed; or maybe it was reacting to your behavior. For example, many dog owners believe their dogs display a guilty look after misbehaving. But a study shows that the so-called "guilty look" is a reaction to the behavior of the owner when the owner believes the dog has misbehaved. "Theory of mind" refers to the ability to recognize that individuals other than oneself have beliefs and desires. Humans have this ability. Some researchers claim that some other species have this ability, too. But the interpretation of this research is ambiguous, since the observed behaviors may have other explanations, such as prior trial-and-error learning.

What about Gallup's mirror test? Don't you think that demonstrates self-awareness in chimpanzees, dolphins, and the other species that have passed the test?Edited by Stephen Push, : No reason given.

Thanks. I'd hate to think I failed the Turing test.Because of your answer, I conclude that you have a theory of mind. But I might be wrong, too.

It demonstrates that the animal knows it is seeing a refection of itself. In chimpanzees, for instance, the chimp will touch its own forehead when it sees a dab of paint on the forehead in the reflection.

From a blog called Neurophilosophy:

Visual images of snakes and spiders stimulate a brain network centered on the amygdala, which in turn triggers the fear response. Conscious processing (e.g., you realize its a rubber snake, not a real snake) can halt this porcess.Some fears are learned. But our brains appear to be hardwired to recognize images of snakes and spiders.